Image Trace: levelling moves no end of a line by more than 1.6 px

Snap Curves To Lines made every straight piece within 2.5 degrees of level or
upright exactly so, whatever its length: a 200 px line 2 degrees off had each end
moved 3.5 px. Now a piece is levelled only when neither end moves more than
1.6 px; a longer line that far off is left as the image has it.

Technical Drawing (the preset with the option on) on its inputs: largest
distance from the art 4.21 -> 1.46 px (1.43 before levelling existed), mean
0.178 -> 0.126 px; on the askew inputs 98% -> 70% of the outline comes out level
or upright.

Cargo.lock

@@ -4916,7 +4916,6 @@ dependencies = [
  "serde_json",
  "thiserror 2.0.21",
  "vectorcraft-geom",
- "vectorcraft-pathops",
 ]
 
 [[package]]

ROADMAP.md

@@ -6,7 +6,7 @@
 
 **Stage: alpha** · next: beta, ~13 points (ready for real work ~62% → ~75%, and reliable `.ai` exchange) and ~170–270 h away
 
-> **Last reviewed:** 2026-10-10 · **Last updated:** 2026-10-13 · **Change:** minor (community PRs and fixes of late 2026-10-12: type that does not fit its frame is reported, #1471; Tabs panel drags, #1458; template layers in Outline view, #1486; dialog slider rails, #1483; Direct Selection anchor precedence, #1508; print-size images, #1517; French catalog complete again, #1511; headline numbers unchanged; Image Trace colour and photo presets, measured in `docs/image-trace-quality.md`, headline numbers unchanged; community PRs and fixes of 2026-10-12: Split Into Grid options, #1462; Transform Objects and Reflect across an angle, #1448 and #1460; Pathfinder on a group, #1450; unknown parameter keys refused, #1442; grayscale TIFFs with alpha, #1466 in part; many-object edits, #1429 in part; headline numbers unchanged; Image Trace places edges to a fraction of a pixel, measured in `docs/image-trace-quality.md`, headline numbers unchanged; Transform dialogs preview and the transform tools act on direct-selected anchors, #1412 and #1408; `.ai` compound path paint, #1410, overprint, #1388, and text-only PDF parts, #1387; community PRs: strokes wider than their shape, corner drags without the bounding box, pasted pictures, compound paths in `document.inspect`, MCP guide; headline numbers unchanged; community PRs: `.ai` editing-data follow-ups (gradient stops, type of objects with an appearance, short area-type frames), PDF bleed with editing data, dialog keyboard focus, art flush with an artboard, font rescan, symbol instance redraw, `--control` port check; headline numbers unchanged; Rectangular Grid and Polar Grid tool options, #1377 in part; `.ai` files with placed (linked) pictures open from their editing data, #1264; community PRs: `.ai` and PDF bleed and editing-data import, gradient shapes imported as paths, ruler origin, Align To, Live Corners corner selection; headline numbers unchanged; G2: Film Grain added; Photoshop effects 29/57; 28 filters remain; community PRs: graph designs, Graph Data worksheet and Graph Type options; Align both centres; Pen endpoint fixes; earlier: Effect › Brush Strokes landed: Photoshop-style filters 28 of 57, raster effects 40% → 48%; `.ai` gradients, meshes and artboard names from the editing data; headline numbers unchanged; `.ai` art styles and clipping fills from the editing data; headline numbers unchanged; `editingData: "always"`; headline numbers unchanged) · **Target:** Adobe Illustrator 2026 (30.x)
+> **Last reviewed:** 2026-10-10 · **Last updated:** 2026-10-13 · **Change:** minor (community PRs and fixes of 2026-10-13: Polish interface, #1498; compact native saves, #1492; PDF and EPS paste as vector art, #1499; `.ai`, PDF, EPS and SVG import fixes, #1528, #1530, #1531, #1544, #1551, #1553; guide objects, #1534; Join after Average, #1533; Keyboard Shortcuts lists commands outside the menus, #1539; headline numbers unchanged; community PRs and fixes of late 2026-10-12: type that does not fit its frame is reported, #1471; Tabs panel drags, #1458; template layers in Outline view, #1486; dialog slider rails, #1483; Direct Selection anchor precedence, #1508; print-size images, #1517; French catalog complete again, #1511; headline numbers unchanged; Image Trace colour and photo presets, measured in `docs/image-trace-quality.md`, headline numbers unchanged; community PRs and fixes of 2026-10-12: Split Into Grid options, #1462; Transform Objects and Reflect across an angle, #1448 and #1460; Pathfinder on a group, #1450; unknown parameter keys refused, #1442; grayscale TIFFs with alpha, #1466 in part; many-object edits, #1429 in part; headline numbers unchanged; Image Trace places edges to a fraction of a pixel, measured in `docs/image-trace-quality.md`, headline numbers unchanged; Transform dialogs preview and the transform tools act on direct-selected anchors, #1412 and #1408; `.ai` compound path paint, #1410, overprint, #1388, and text-only PDF parts, #1387; community PRs: strokes wider than their shape, corner drags without the bounding box, pasted pictures, compound paths in `document.inspect`, MCP guide; headline numbers unchanged; community PRs: `.ai` editing-data follow-ups (gradient stops, type of objects with an appearance, short area-type frames), PDF bleed with editing data, dialog keyboard focus, art flush with an artboard, font rescan, symbol instance redraw, `--control` port check; headline numbers unchanged; Rectangular Grid and Polar Grid tool options, #1377 in part; `.ai` files with placed (linked) pictures open from their editing data, #1264; community PRs: `.ai` and PDF bleed and editing-data import, gradient shapes imported as paths, ruler origin, Align To, Live Corners corner selection; headline numbers unchanged; G2: Film Grain added; Photoshop effects 29/57; 28 filters remain; community PRs: graph designs, Graph Data worksheet and Graph Type options; Align both centres; Pen endpoint fixes; earlier: Effect › Brush Strokes landed: Photoshop-style filters 28 of 57, raster effects 40% → 48%; `.ai` gradients, meshes and artboard names from the editing data; headline numbers unchanged; `.ai` art styles and clipping fills from the editing data; headline numbers unchanged; `editingData: "always"`; headline numbers unchanged) · **Target:** Adobe Illustrator 2026 (30.x)
 
 VectorCraft is a clean-room, open-source, pure-Rust reimplementation of the Adobe Illustrator workflow. It runs
 on macOS, Windows, Linux, FreeBSD and the web (WASM), and agents can drive all of it over MCP, the CLI and a JSON
@@ -127,6 +127,7 @@ Ranked; detail in [docs/roadmap.md](docs/roadmap.md) and [docs/gaps.md](docs/gap
 
 | Date | What landed |
 |---|---|
+| 2026-10-13 | The interface is available in Polish (`pl`): menus, panels, dialogs and messages, with one/few/many plurals; AI-drafted, native review pending (#1498). Native documents with a lot of path data (traced or generated art, in layers, symbols or patterns) are saved as compact JSON, about a fifth of the size; small documents stay pretty-printed (#1492). Paste takes a PDF or EPS another app copied as editable vector art: from the macOS pasteboard (with SVG), EPS on Windows beside PDF, and `.eps` files copied in a file manager, with the new command `clipboard.importEps` (#1538, fixes #1499). Opening or placing a file with an image too large to decode says so, and the Links panel shows it on the row (#1540, part of #1479). Import: a multi-artboard `.ai` with notes beside its artboards opens from its editing data, a page's art past its artboard no longer lying over the page before it (#1528); a `.ai` gradient whose stops are listed upwards keeps each midpoint on the stop that starts its part of the ramp (#1530); SVG text on a path follows basic shapes (circle, ellipse, rect, line, polyline, polygon) as their SVG 2 equivalent paths (#1531, fixes #1527); PDFs whose alpha soft masks are drawn as images import with the mask instead of empty art (#1551); EPS and PostScript type set in Type 42 (TrueType) fonts imports at its size instead of 1000 times too large (#1553); PDF and EPS import keep a clipping path whose bounding box covers the page but whose shape doesn't (#1544, fixes #1542). Make Compound Path on a group (such as outlined type) keeps the paint of its backmost path instead of drawing nothing, and compound paths joined into one keep their holes (#1537). Live Corners: a round corner next to a curved side curves smoothly instead of sticking out of the shape, and the Smooth tool smooths only the stretch of path under the drag (#1547, fixes #1512). Join merges the selected anchor points that lie on one another, as after Average, into one anchor (#1582, fixes #1533). Guides: Lock Guides also locks the objects made into guides: they can't be selected, moved or deleted (#1543); they are drawn in the guide colour and style of Preferences, and a dragged selection snaps to ruler guides with Smart Guides on (#1583, fixes #1534). Edit › Keyboard Shortcuts lists Edit › Duplicate and the other commands that are in no menu but run without parameters (panel-menu commands such as Break Link to Symbol), so they can be given shortcuts (#1549, #1580, fixes #1539). Raster effects (blur, shadow, glow, grain) drawn after a pattern, radial or freeform gradient fill export at their place and size (#1541, fixes #1536). Fonts: the font scan on Linux also reads the folders fontconfig's configuration lists, such as TeX fonts under `/usr/share/texmf/fonts` (#1548, fixes #1529; not verified on Linux). |
 | 2026-10-13 | Image Trace's colour presets trace flat art with its own colours however many are asked for (noise no longer shatters it: 16 Colors 70 → 4 paths on the harness's flat art; no slivers of in-between colour along anti-aliased edges), and the photo presets trace a photo into smooth tones without specks or hairlines (High Fidelity Photo 3,653 → 121 paths, colour error 2.30 → 1.75; 16 megapixels traced where 4 were refused) ([`docs/image-trace-quality.md`](docs/image-trace-quality.md)). |
 | 2026-10-13 | Image Trace traces anti-aliased and blurred images to a fraction of a pixel in Black and White, Grayscale and Color, with corners put back, straight edges as lines and round outlines as circles; a harness measures every preset before and after ([`docs/image-trace-quality.md`](docs/image-trace-quality.md)): outlines 0.31 → 0.09 px off on average (Default), 0.27 → 0.06 (Black and White Logo). |
 | 2026-10-13 | Effect › 3D and Materials: Inflate takes Twist, Taper and Cap (Hollow leaves the back open), as the 3D docs list for every type. |

crates/color/src/cms/icc.rs

@@ -249,7 +249,7 @@ pub(super) fn builtin_rgb_bytes(name: &str) -> Result<Vec<u8>, CmsError> {
 
 /// Encode `p` as an ICC file. The creation date is fixed so exports are reproducible.
 pub(super) fn encode(p: &ColorProfile) -> Result<Vec<u8>, CmsError> {
-    let mut bytes = p.encode().map_err(|e| CmsError::BadProfile(format!("{e:?}")))?;
+    let mut bytes = aligned(p.encode().map_err(|e| CmsError::BadProfile(format!("{e:?}")))?);
     // Header bytes 24..36: year, month, day, hours, minutes, seconds (u16 each).
     if let Some(date) = bytes.get_mut(24..36) {
         date.copy_from_slice(&[2026u16, 1, 1, 0, 0, 0].map(u16::to_be_bytes).concat());
@@ -257,6 +257,55 @@ pub(super) fn encode(p: &ColorProfile) -> Result<Vec<u8>, CmsError> {
     Ok(bytes)
 }
 
+/// `icc` with every tagged element starting on a 4-byte boundary, padded with zeros, as ICC.1
+/// §7.1.2 requires (moxcms packs them, so a 62-byte `desc` left the next tag unaligned, #1584).
+/// Tags that share data keep sharing it. A profile whose tag table doesn't read is returned as it is.
+fn aligned(icc: Vec<u8>) -> Vec<u8> {
+    const TABLE: usize = 128;
+    let be = |b: &[u8], at: usize| b.get(at..at + 4).map(|v| u32::from_be_bytes([v[0], v[1], v[2], v[3]]) as usize);
+    let Some(n) = be(&icc, TABLE).filter(|n| *n <= 1000) else { return icc };
+    let data_start = TABLE + 4 + 12 * n;
+    let mut entries = Vec::with_capacity(n);
+    for i in 0..n {
+        let e = TABLE + 4 + 12 * i;
+        let (Some(off), Some(size)) = (be(&icc, e + 4), be(&icc, e + 8)) else { return icc };
+        if off < data_start || off.checked_add(size).is_none_or(|end| end > icc.len()) {
+            return icc;
+        }
+        entries.push((off, size));
+    }
+    if entries.iter().all(|(off, _)| off.is_multiple_of(4)) && icc.len().is_multiple_of(4) {
+        return icc;
+    }
+    let mut out = icc.get(..data_start).map(<[u8]>::to_vec).unwrap_or_default();
+    let mut moved: Vec<((usize, usize), usize)> = Vec::new();
+    let mut order: Vec<usize> = (0..n).collect();
+    order.sort_by_key(|&i| entries[i].0);
+    for i in order {
+        let (off, size) = entries[i];
+        let at = match moved.iter().find(|(k, _)| *k == (off, size)) {
+            Some((_, at)) => *at,
+            None => {
+                out.resize(out.len().next_multiple_of(4), 0);
+                let at = out.len();
+                out.extend_from_slice(&icc[off..off + size]);
+                moved.push(((off, size), at));
+                at
+            }
+        };
+        let e = TABLE + 4 + 12 * i + 4;
+        out[e..e + 4].copy_from_slice(&(at as u32).to_be_bytes());
+    }
+    out.resize(out.len().next_multiple_of(4), 0);
+    let len = out.len() as u32;
+    out[0..4].copy_from_slice(&len.to_be_bytes());
+    // The profile ID (an MD5 of the old bytes) no longer matches: zero is "not computed".
+    if let Some(id) = out.get_mut(84..100) {
+        id.fill(0);
+    }
+    out
+}
+
 fn text_tag(s: &str) -> Option<ProfileText> {
     Some(ProfileText::Localizable(vec![LocalizableString::new("en".into(), "US".into(), s.into())]))
 }

crates/color/src/cms/tests_icc.rs

@@ -111,3 +111,26 @@ fn black_point_compensation_maps_the_darkest_ink_to_rgb_black() {
     let abs = |bpc| icc_cmyk(bpc).cmyk_to_rgb(rich, Intent::AbsoluteColorimetric);
     assert_eq!(abs(true), abs(false));
 }
+
+/// #1584: the profiles written here (built-in RGB spaces) have every tag on a 4-byte boundary and
+/// a size that is a multiple of 4 (ICC.1 §7.1.2), and still read back as the same space.
+#[test]
+fn written_profiles_align_their_tags() {
+    for name in [super::SRGB, super::DISPLAY_P3, super::WIDE_GAMUT_RGB, super::PROPHOTO_RGB] {
+        let icc = super::icc_bytes(name).unwrap();
+        let be = |at: usize| u32::from_be_bytes([icc[at], icc[at + 1], icc[at + 2], icc[at + 3]]) as usize;
+        assert_eq!(be(0), icc.len(), "{name}: header size");
+        assert_eq!(icc.len() % 4, 0, "{name}: {} bytes", icc.len());
+        let n = be(128);
+        for i in 0..n {
+            let (off, size) = (be(132 + 12 * i + 4), be(132 + 12 * i + 8));
+            assert_eq!(off % 4, 0, "{name}: tag {i} at {off}");
+            assert!(off + size <= icc.len());
+        }
+        let back = moxcms::ColorProfile::new_from_slice(&icc).unwrap();
+        let orig = moxcms::ColorProfile::new_srgb();
+        if name == super::SRGB {
+            assert_eq!((back.red_colorant, back.green_colorant, back.blue_colorant), (orig.red_colorant, orig.green_colorant, orig.blue_colorant));
+        }
+    }
+}

crates/doc/src/hit.rs

@@ -1,5 +1,7 @@
 //! Hit testing over the document tree.
 
+use std::collections::HashSet;
+
 use vectorcraft_geom::hit::{fill_contains, stroke_contains};
 use vectorcraft_geom::{Point, Rect};
 
@@ -83,6 +85,77 @@ pub fn hit_test_visible(doc: &Document, p: Point, opt: HitOptions) -> Option<Hit
 /// first: what clicks there select, one below the other (Cmd/Ctrl-click selects behind).
 pub fn objects_at(doc: &Document, p: Point, opt: HitOptions, scope: Option<NodeId>) -> Vec<NodeId> {
     let opt = HitOptions { scope: scope.or(opt.scope), ..opt };
+    // Normally one hit test per *object* suffices: layers and sublayers aren't selectable,
+    // while a group (including a clipping group) is selected as one object. Repeatedly
+    // searching the full tree for each hit made a stack of n overlapping paths O(n^2).
+    // Isolation and Edit Contents change where selection groups begin; keep the original
+    // traversal for those cases rather than change their Select Behind semantics.
+    if opt.scope.is_some() {
+        return objects_at_repeated(doc, p, opt, scope);
+    }
+    let mut tops = Vec::new();
+    let mut seen = HashSet::new();
+    for layer in doc.layers.iter().rev() {
+        // Malformed files may contain non-layer roots; let the general traversal handle them.
+        if !layer.is_layer() {
+            return objects_at_repeated(doc, p, opt, scope);
+        }
+        if !layer.visible || layer.locked || layer.is_template() || doc.pattern_edit.as_ref().is_some_and(|e| e.layer != layer.id) {
+            continue;
+        }
+        if !objects_at_layer(layer, p, opt, &mut tops, &mut seen) {
+            // An envelope in Edit Contents may expose objects *within* a top-level group.
+            // The repeated traversal handles that mixed hierarchy precisely.
+            return objects_at_repeated(doc, p, opt, scope);
+        }
+    }
+    tops
+}
+
+/// One traversal through a layer and its sublayers. Each selectable object's subtree is
+/// inspected once (only until its first hit). `false` asks the caller to use the general
+/// algorithm for an envelope whose contents are currently being edited.
+fn objects_at_layer(layer: &Node, p: Point, opt: HitOptions, tops: &mut Vec<NodeId>, seen: &mut HashSet<NodeId>) -> bool {
+    let Some(children) = layer.children() else { return true };
+    if layer.clips() && children.first().is_some_and(|clip| !clip_contains(clip, p)) {
+        return true;
+    }
+    let opt = if matches!(layer.kind, NodeKind::Layer { preview: false, .. }) { HitOptions { outline: true, ..opt } } else { opt };
+    for (i, c) in children.iter().enumerate().rev() {
+        if !may_hit(layer, i, c, p, opt, true) || seen.contains(&c.id) {
+            continue;
+        }
+        if c.is_layer() {
+            if !objects_at_layer(c, p, opt, tops, seen) {
+                return false;
+            }
+            continue;
+        }
+        // Editing an envelope selects its contents rather than the containing object. Even
+        // when nested in a group, the old traversal may select both a member and the group.
+        if c.is_container() {
+            let mut editing = false;
+            c.walk(&mut |n| editing |= edits_contents(n));
+            if editing {
+                return false;
+            }
+        }
+        let skip = |id| seen.contains(&id);
+        let mut chain = Vec::new();
+        let hit = match &c.kind {
+            NodeKind::Group { .. } => hit_children(c, p, opt, &skip, &mut chain, true).is_some(),
+            NodeKind::Blend { .. } => hit_children(c, p, opt, &skip, &mut chain, true).is_some() || hit_leaf(c, p, opt).is_some(),
+            _ => hit_leaf(c, p, opt).is_some(),
+        };
+        if hit && seen.insert(c.id) {
+            tops.push(c.id);
+        }
+    }
+    true
+}
+
+/// The general selection order also handles isolation and nested Edit Contents.
+fn objects_at_repeated(doc: &Document, p: Point, opt: HitOptions, scope: Option<NodeId>) -> Vec<NodeId> {
     let mut tops: Vec<NodeId> = vec![];
     // Each round leaves out the objects found so far (and everything inside them).
     while let Some(top) = hit_test_skipping(doc, p, opt, &|id| tops.contains(&id), true).map(|h| h.top_object(scope)) {
@@ -150,6 +223,22 @@ fn clip_contains(clip: &Node, p: Point) -> bool {
     clip.clip_shapes(Some(&frame)).iter().any(|(bp, rule)| fill_contains(bp, *rule, p))
 }
 
+/// Can a click at `p` hit `c`, the child `i` of `parent`, or something inside it? Not when it is
+/// hidden, when it can't be edited (`editable_only`), when it is the part of a Shaper group that
+/// isn't shown, or when `p` is outside its reach.
+fn may_hit(parent: &Node, i: usize, c: &Node, p: Point, opt: HitOptions, editable_only: bool) -> bool {
+    let source_isolated = |n: &Node| n.children().and_then(|children| children.first()).is_some_and(|source| Some(source.id) == opt.scope);
+    if parent.extras().shaper.is_some() && (i == 0) != source_isolated(parent) {
+        return false;
+    }
+    // Read-only samples can read locked/template art; hidden art never participates.
+    if !c.visible || editable_only && (c.locked || c.is_template()) {
+        return false;
+    }
+    // (An envelope's content sits where it was, not where the envelope draws it.)
+    edits_contents(c) || c.extras().shaper.is_some() && source_isolated(c) || c.reach_bounds().is_none_or(|b| b.inflate(opt.tol, opt.tol).contains(p))
+}
+
 fn hit_children(
     parent: &Node,
     p: Point,
@@ -167,22 +256,7 @@ fn hit_children(
         return None;
     }
     for (i, c) in children.iter().enumerate().rev() {
-        if parent.extras().shaper.is_some() {
-            let construction = children.first().is_some_and(|source| Some(source.id) == opt.scope);
-            if (i == 0) != construction {
-                continue;
-            }
-        }
-        // Read-only samples can read locked/template art; hidden art never participates.
-        if !c.visible || editable_only && (c.locked || c.is_template()) || skip(c.id) {
-            continue;
-        }
-        // (An envelope's content sits where it was, not where the envelope draws it.)
-        if !(edits_contents(c)
-            || c.extras().shaper.is_some() && c.children().and_then(|children| children.first()).is_some_and(|source| Some(source.id) == opt.scope))
-            && let Some(b) = c.reach_bounds()
-            && !b.inflate(opt.tol, opt.tol).contains(p)
-        {
+        if !may_hit(parent, i, c, p, opt, editable_only) || skip(c.id) {
             continue;
         }
         chain.push(c.id);
@@ -619,6 +693,146 @@ world",
         assert!(at(90.0, None).is_empty());
     }
 
+    /// Many overlapping paths: Select Behind must list each exactly once, front to back.
+    /// This is quadratic with repeated full-document hit tests, but linear in tree size with
+    /// the per-object walk.
+    #[test]
+    fn objects_at_large_overlapping_stack() {
+        let mut d = Document::new(100.0, 100.0);
+        let layer = d.layers[0].id;
+        let mut ids = Vec::new();
+        for _ in 0..256 {
+            let id = d.alloc_id();
+            d.insert(Some(layer), usize::MAX, Node::path(id, shapes::rectangle(Rect::new(0.0, 0.0, 50.0, 50.0)), Appearance::default_art())).unwrap();
+            ids.push(id);
+        }
+        ids.reverse();
+        assert_eq!(objects_at(&d, Point::new(25.0, 25.0), HitOptions::default(), None), ids);
+    }
+
+    /// Match the original skip-and-retest algorithm for normal groups, sublayers, clipping,
+    /// invisibility, and path/outline-only settings.
+    #[test]
+    fn objects_at_one_pass_matches_repeated_hits() {
+        let mut d = Document::new(200.0, 200.0);
+        let layer = d.layers[0].id;
+        let add = |d: &mut Document, parent, bounds| {
+            let id = d.alloc_id();
+            d.insert(Some(parent), usize::MAX, Node::path(id, shapes::rectangle(bounds), Appearance::default_art())).unwrap();
+            id
+        };
+        add(&mut d, layer, Rect::new(0.0, 0.0, 60.0, 60.0));
+        let sub = d.alloc_id();
+        d.insert(Some(layer), usize::MAX, Node::layer(sub, "Sublayer", crate::LayerColor::Preset(2))).unwrap();
+        add(&mut d, sub, Rect::new(0.0, 0.0, 60.0, 60.0));
+        let group = d.alloc_id();
+        d.insert(Some(layer), usize::MAX, Node::group(group, Vec::new())).unwrap();
+        add(&mut d, group, Rect::new(0.0, 0.0, 60.0, 60.0));
+        add(&mut d, group, Rect::new(5.0, 5.0, 60.0, 60.0));
+        let clip = d.alloc_id();
+        let mask = Node::path(d.alloc_id(), shapes::rectangle(Rect::new(5.0, 5.0, 45.0, 45.0)), Appearance::default_art());
+        let content = Node::path(d.alloc_id(), shapes::rectangle(Rect::new(0.0, 0.0, 80.0, 80.0)), Appearance::default_art());
+        let mut clipping = Node::group(clip, vec![Arc::new(mask), Arc::new(content)]);
+        clipping.set_clips(true);
+        d.insert(Some(layer), usize::MAX, clipping).unwrap();
+        for (point, opt) in [
+            (Point::new(25.0, 25.0), HitOptions::default()),
+            (Point::new(3.0, 25.0), HitOptions::default()),
+            (Point::new(25.0, 25.0), HitOptions { outline: true, ..Default::default() }),
+            (Point::new(6.0, 25.0), HitOptions { path_only: true, ..Default::default() }),
+            (Point::new(100.0, 100.0), HitOptions::default()),
+        ] {
+            assert_eq!(objects_at(&d, point, opt, None), objects_at_repeated(&d, point, opt, None), "point={point:?}, opt={opt:?}");
+        }
+        if let NodeKind::Layer { preview, .. } = &mut d.node_mut(sub).unwrap().kind {
+            *preview = false;
+        }
+        let p = Point::new(25.0, 25.0);
+        let opt = HitOptions::default();
+        assert_eq!(objects_at(&d, p, opt, None), objects_at_repeated(&d, p, opt, None));
+        d.node_mut(group).unwrap().locked = true;
+        assert_eq!(objects_at(&d, p, opt, None), objects_at_repeated(&d, p, opt, None));
+    }
+
+    /// Documents built at random (nested groups, sublayers, clipping groups, compound paths, blends
+    /// of nothing, hidden and locked objects, outline layers): Select Behind lists the same objects
+    /// in the same order as the hit test repeated over what is left.
+    #[test]
+    fn objects_at_matches_repeated_hits_on_random_documents() {
+        let mut seed = 0x9e37_79b9_u32;
+        let mut next = move |n: u32| {
+            seed ^= seed << 13;
+            seed ^= seed >> 17;
+            seed ^= seed << 5;
+            seed % n
+        };
+        fn fill(d: &mut Document, parent: NodeId, depth: u32, next: &mut impl FnMut(u32) -> u32) {
+            for _ in 0..2 + next(4) {
+                let id = d.alloc_id();
+                let (x, y) = (f64::from(next(60)), f64::from(next(60)));
+                let rect = Rect::new(x, y, x + 10.0 + f64::from(next(50)), y + 10.0 + f64::from(next(50)));
+                let appearance = if next(4) == 0 { Appearance::default() } else { Appearance::default_art() };
+                let mut n = match next(if depth < 3 { 8 } else { 4 }) {
+                    4 | 5 => Node::group(id, Vec::new()),
+                    6 => Node::layer(id, "Sublayer", crate::LayerColor::Preset(2)),
+                    7 => {
+                        let mut g = Node::group(id, Vec::new());
+                        g.set_clips(true);
+                        g
+                    }
+                    _ => Node::path(id, shapes::rectangle(rect), appearance),
+                };
+                n.visible = next(8) != 0;
+                n.locked = next(8) == 0;
+                if let NodeKind::Layer { preview, .. } = &mut n.kind {
+                    *preview = next(3) != 0;
+                }
+                let container = n.is_container();
+                // A sublayer belongs in a layer; in a group it is a group like another to the hit test.
+                d.insert(Some(parent), usize::MAX, n).unwrap();
+                if container {
+                    fill(d, id, depth + 1, next);
+                }
+            }
+        }
+        for round in 0..200 {
+            let mut d = Document::new(120.0, 120.0);
+            let layer = d.layers[0].id;
+            fill(&mut d, layer, 0, &mut next);
+            for _ in 0..12 {
+                let p = Point::new(f64::from(next(120)), f64::from(next(120)));
+                let opt = HitOptions { outline: next(5) == 0, path_only: next(5) == 0, ..Default::default() };
+                assert_eq!(objects_at(&d, p, opt, None), objects_at_repeated(&d, p, opt, None), "round {round}, {p:?}, {opt:?}");
+            }
+        }
+    }
+
+    /// Edit Contents can expose descendants of a top-level group: preserve the original
+    /// selection order by falling back to the general hit traversal.
+    #[test]
+    fn objects_at_edit_contents_uses_general_order() {
+        let mut d = Document::new(100.0, 100.0);
+        let layer = d.layers[0].id;
+        let inner = |id| Arc::new(Node::path(id, shapes::rectangle(Rect::new(0.0, 0.0, 50.0, 50.0)), Appearance::default_art()));
+        let (a, b) = (d.alloc_id(), d.alloc_id());
+        let e = Node::new(
+            d.alloc_id(),
+            NodeKind::Envelope {
+                content: vec![inner(a), inner(b)],
+                kind: Box::new(crate::live::EnvelopeKind::Warp { style: "arc".to_string(), bend: 0.0, h: 0.0, v: 0.0, horizontal: true }),
+                fidelity: 100.0,
+                editing: true,
+                options: Default::default(),
+                frame: Box::new(vectorcraft_geom::Affine::IDENTITY),
+            },
+        );
+        d.insert(Some(layer), usize::MAX, e).unwrap();
+        let p = Point::new(25.0, 25.0);
+        let opt = HitOptions::default();
+        assert_eq!(objects_at(&d, p, opt, None), objects_at_repeated(&d, p, opt, None));
+        assert_eq!(objects_at(&d, p, opt, None), vec![b, a]);
+    }
+
     #[test]
     fn locked_and_hidden_skip() {
         let mut d = Document::new(200.0, 200.0);

crates/doc/src/lib.rs

@@ -1465,6 +1465,14 @@ impl Document {
     pub fn new_graphic_style_name(&self) -> String {
         (self.graphic_styles.len() + 1..).map(|i| format!("Graphic Style {i}")).find(|n| self.graphic_style(n).is_none()).unwrap_or_default()
     }
+    /// `base`, or the first free "`base` N" (N from 2) when a symbol already has that name.
+    pub fn unique_symbol_name(&self, base: &str) -> String {
+        let taken = |n: &str| self.symbols.iter().any(|s| s.name == n);
+        if !taken(base) {
+            return base.to_string();
+        }
+        (2..).map(|i| format!("{base} {i}")).find(|n| !taken(n)).unwrap_or_else(|| base.to_string())
+    }
 }
 
 fn default_graphic_styles() -> Vec<GraphicStyle> {

crates/doc/src/live.rs

@@ -318,8 +318,10 @@ impl WarpStyle {
     }
 }
 
-/// The warp map on normalised coordinates: `b` = bend (-1..1), `dh`/`dv` = distortion (-1..1).
-pub fn warp_point(style: WarpStyle, b: f64, dh: f64, dv: f64, x: f64, y: f64) -> (f64, f64) {
+/// The warp map on normalised coordinates: `b` = bend (-1..1), `dh`/`dv` = distortion (-1..1);
+/// `aspect` is the box's half-height over its half-width along the warp (Arc bends in real
+/// proportions).
+pub fn warp_point(style: WarpStyle, b: f64, dh: f64, dv: f64, aspect: f64, x: f64, y: f64) -> (f64, f64) {
     use WarpStyle::*;
     let t = (y + 1.0) / 2.0; // 0 at top, 1 at bottom
     let par = 1.0 - x * x; // parabola: 1 at centre, 0 at sides
@@ -328,14 +330,18 @@ pub fn warp_point(style: WarpStyle, b: f64, dh: f64, dv: f64, x: f64, y: f64) ->
             if b.abs() < 1e-6 {
                 (x, y)
             } else {
-                // Bend the centre line into a circular arc of equal length (sweep = |b|·180°).
+                // Bend the centre line into a circular arc of equal length (sweep = |b|·180°), in
+                // the box's real proportions (lengths in half-widths, so y counts `aspect` each):
+                // the edges are concentric arcs, and one that would pass the centre stops there
+                // instead of folding over (#1578).
+                let k = if aspect.is_finite() && aspect > 0.0 { aspect } else { 1.0 };
                 let sweep = b.abs() * PI;
                 let r0 = 2.0 / sweep;
-                let yy = if b > 0.0 { y } else { -y };
+                let yy = if b > 0.0 { y } else { -y } * k;
                 let a = x / r0;
-                let r = r0 - yy;
+                let r = (r0 - yy).max(0.0);
                 let (s, c) = a.sin_cos();
-                let (nx, ny) = (r * s, r0 - r * c);
+                let (nx, ny) = (r * s, (r0 - r * c) / k);
                 (nx, if b > 0.0 { ny } else { -ny })
             }
         }
@@ -1122,9 +1128,9 @@ fn surface_of<'a>(kind: &'a EnvelopeKind, src: Rect, frame: Affine) -> Box<dyn F
             Box::new(move |u: f64, v: f64| {
                 let (x, y) = (2.0 * u - 1.0, 2.0 * v - 1.0);
                 let (x2, y2) = if horizontal {
-                    warp_point(st, b, dh, dv, x, y)
+                    warp_point(st, b, dh, dv, hh / hw.max(1e-9), x, y)
                 } else {
-                    let (a, b2) = warp_point(st, b, dh, dv, y, x);
+                    let (a, b2) = warp_point(st, b, dh, dv, hw / hh.max(1e-9), y, x);
                     (b2, a)
                 };
                 frame * Point::new(c.x + x2 * hw, c.y + y2 * hh)
@@ -1711,6 +1717,31 @@ pub(crate) fn max_outset(nodes: &[Arc<Node>]) -> f64 {
 #[cfg(test)]
 mod tests {
     use super::*;
+
+    /// #1578: Arc bends in the box's real proportions. In half-width units (y scaled by the
+    /// aspect), the top and bottom edges are concentric circles about the bend's centre, at their
+    /// real distance from the centre line; an inner edge that would pass the centre stops there.
+    #[test]
+    fn arc_warp_is_round_in_real_proportions() {
+        for (aspect, b) in [(0.25, 0.1), (0.25, 0.5), (0.25, 1.0), (1.0, 0.5), (2.0, 0.3)] {
+            let r0 = 2.0 / (b * PI);
+            for (y, r) in [(-1.0, r0 + aspect), (1.0, (r0 - aspect).max(0.0))] {
+                for i in 0..=10 {
+                    let x = -1.0 + 0.2 * f64::from(i);
+                    let (nx, ny) = warp_point(WarpStyle::Arc, b, 0.0, 0.0, aspect, x, y);
+                    let d = nx.hypot(ny * aspect - r0);
+                    assert!((d - r).abs() < 1e-9, "aspect {aspect}, bend {b}, y {y}, x {x}: {d} vs {r}");
+                }
+            }
+        }
+        // At 100 % on a square the inner edge meets at the centre instead of folding over.
+        let (nx, _) = warp_point(WarpStyle::Arc, 1.0, 0.0, 0.0, 1.0, 0.8, 1.0);
+        assert!(nx.abs() < 1e-12);
+        // A square bent less than that is what it always was.
+        let (nx, ny) = warp_point(WarpStyle::Arc, 0.5, 0.0, 0.0, 1.0, 0.5, 0.25);
+        let (r0, a) = (4.0 / PI, 0.5 / (4.0 / PI));
+        assert!((nx - (r0 - 0.25) * a.sin()).abs() < 1e-12 && (ny - (r0 - (r0 - 0.25) * a.cos())).abs() < 1e-12);
+    }
     use vectorcraft_geom::shapes;
 
     fn rect_node(x: f64, y: f64, w: f64, h: f64, c: Color) -> Arc<Node> {

crates/effects/src/distort.rs

@@ -1,6 +1,7 @@
 //! Distort & Transform effects.
 
 use serde_json::Value;
+use vectorcraft_geom::kurbo::ParamCurveArclen;
 use vectorcraft_geom::{Affine, Anchor, ParamCurve, PathData, Point, Rect, SubPath, Vec2};
 
 use crate::util::*;
@@ -194,7 +195,10 @@ pub fn twist(path: &PathData, b: Rect, angle: f64) -> PathData {
     map_nonlinear(path, pieces, f)
 }
 
-/// Zig Zag: `ridges` extra points per segment, alternately displaced along the normal.
+const ZIGZAG_ARCLEN_ACCURACY: f64 = 1e-4;
+
+/// Zig Zag: `ridges` extra points per segment, evenly spaced along its length and alternately
+/// displaced along the normal.
 pub fn zig_zag(path: &PathData, b: Rect, p: &Value) -> PathData {
     let size = num(p, "size", 10.0).clamp(-1e4, 1e4);
     let amp = if flag(p, "relative", false) { size / 100.0 * mean_size(b) } else { size };
@@ -207,8 +211,12 @@ pub fn zig_zag(path: &PathData, b: Rect, p: &Value) -> PathData {
         let mut k = 0usize;
         for i in 0..segs {
             let c = sp.segment(i);
+            // Ridges are spaced by length, not by `t`: a line's retracted handles bunch `t` up
+            // near the anchors, and so does any uneven curve.
+            let len = c.arclen(ZIGZAG_ARCLEN_ACCURACY);
             for j in 0..=ridges {
-                let t = j as f64 / (ridges + 1) as f64;
+                let s = j as f64 / (ridges + 1) as f64;
+                let t = if j > 0 && len > 1e-9 { c.inv_arclen(s * len, ZIGZAG_ARCLEN_ACCURACY).clamp(0.0, 1.0) } else { s };
                 let nrm = if j == 0 {
                     // Average the normals of the segments meeting at the anchor.
                     let prev = if i > 0 {

crates/effects/src/lib.rs

@@ -249,7 +249,7 @@ pub fn effect_catalog() -> Vec<EffectInfo> {
             "distort.freeDistort",
             "Free Distort…",
             DT,
-            "{corners: [[x,y]×4] new positions of the bounding-box corners TL, TR, BR, BL in unit box coordinates (identity [[0,0],[1,0],[1,1],[0,1]])}",
+            "{corners: [[x,y]×4] (new positions of the bounding-box corners TL, TR, BR, BL in unit box coordinates; identity [[0,0],[1,0],[1,1],[0,1]])}",
             json!({"corners": [[0.0, 0.0], [1.0, 0.0], [1.0, 1.0], [0.0, 1.0]]}),
         ),
         g("distort.puckerBloat", "Pucker & Bloat…", DT, "{amount: % (-200 pucker … 200 bloat, default 0)}", json!({"amount": 0.0})),

crates/effects/src/tests.rs

@@ -244,6 +244,62 @@ fn zigzag_ridge_count_and_amplitude() {
     assert!(b.width() > 100.0 && b.width() <= 120.0 + 1e-6, "{b:?}");
 }
 
+#[test]
+fn zigzag_spaces_ridges_evenly_along_a_straight_line() {
+    // #1554: on a straight line every ridge is the same distance from the line and as far from
+    // the next one, whether the points are corners or smooth.
+    let line = PathData::single(SubPath::polyline(&[Point::new(0.0, 0.0), Point::new(0.0, 500.0)], false));
+    for points in ["corner", "smooth"] {
+        let out = run("distort.zigZag", json!({"ridges": 4, "points": points, "size": 20}), &line);
+        let ps: Vec<Point> = out.subpaths[0].anchors.iter().map(|a| a.p).collect();
+        assert_eq!(ps.len(), 6, "{points}");
+        for (k, q) in ps.iter().enumerate() {
+            assert!(close(q.x.abs(), 20.0, 1e-6), "{points} {k}: {q:?}");
+            assert!(close(q.y, 100.0 * k as f64, 1e-3), "{points} {k}: {q:?}");
+        }
+    }
+}
+
+/// #1554 on curves: a circle's ridges sit at equal angles, at the radius plus and minus the size in
+/// turn all the way round.
+#[test]
+fn zigzag_on_a_circle_is_regular() {
+    let circle = shapes::ellipse(Rect::new(-50.0, -50.0, 50.0, 50.0));
+    let out = run("distort.zigZag", json!({"ridges": 3, "points": "corner", "size": 10}), &circle);
+    let pts: Vec<Point> = out.subpaths[0].anchors.iter().map(|a| a.p).collect();
+    assert_eq!(pts.len(), 16);
+    let start = pts[0].y.atan2(pts[0].x);
+    let mut radii = vec![];
+    for (i, q) in pts.iter().enumerate() {
+        let turn = (q.y.atan2(q.x) - start).to_degrees().abs() / 22.5;
+        assert!(close(turn, turn.round(), 0.02), "point {i} at {turn} sixteenths");
+        radii.push(q.to_vec2().hypot().round());
+    }
+    assert!(radii.iter().all(|r| *r == 60.0 || *r == 40.0) && (0..16).all(|i| radii[i] != radii[(i + 1) % 16]), "{radii:?}");
+}
+
+/// #1554 on an uneven curve: the ridges divide its length, not its parameter, into equal parts.
+#[test]
+fn zigzag_spaces_ridges_by_length_on_an_uneven_curve() {
+    use vectorcraft_geom::kurbo::{ParamCurve, ParamCurveArclen, ParamCurveNearest};
+    let (a, b) = (Point::new(0.0, 0.0), Point::new(300.0, 0.0));
+    let curve = PathData::single(SubPath::new(
+        vec![
+            vectorcraft_geom::Anchor::with_handles(a, a, Point::new(10.0, 40.0)),
+            vectorcraft_geom::Anchor::with_handles(b, Point::new(100.0, 200.0), b),
+        ],
+        false,
+    ));
+    let c = curve.subpaths[0].segment(0);
+    let len = c.arclen(1e-6);
+    let out = run("distort.zigZag", json!({"ridges": 3, "points": "corner", "size": 0}), &curve);
+    let along: Vec<f64> = out.subpaths[0].anchors.iter().map(|q| c.subsegment(0.0..c.nearest(q.p, 1e-9).t).arclen(1e-6) / len).collect();
+    assert_eq!(along.len(), 5);
+    for (k, share) in along.iter().enumerate() {
+        assert!(close(*share, k as f64 / 4.0, 1e-3), "{along:?}");
+    }
+}
+
 #[test]
 fn offset_path_grows_and_shrinks() {
     let grow = run("path.offsetPath", json!({"offset": 10, "joins": "miter"}), &square()).bounds().unwrap();

crates/effects/src/warp.rs

@@ -22,10 +22,10 @@ pub fn warp(path: &PathData, b: Rect, style: WarpStyle, p: &Value) -> PathData {
     let f = |q: Point| {
         let (x, y) = ((q.x - c.x) / hw, (q.y - c.y) / hh);
         let (x2, y2) = if vertical {
-            let (a, b2) = warp_point(style, bend, dh, dv, y, x);
+            let (a, b2) = warp_point(style, bend, dh, dv, hw / hh, y, x);
             (b2, a)
         } else {
-            warp_point(style, bend, dh, dv, x, y)
+            warp_point(style, bend, dh, dv, hh / hw, x, y)
         };
         Point::new(c.x + x2 * hw, c.y + y2 * hh)
     };

crates/engine/src/cmd/brushsym.rs

@@ -526,14 +526,6 @@ fn normalize(mut art: Node) -> Result<(Node, (f64, f64), Point)> {
     Ok((art, (w, h), c))
 }
 
-fn unique_symbol_name(d: &Document, base: &str) -> String {
-    let taken = |n: &str| d.symbols.iter().any(|s| s.name == n);
-    if !taken(base) {
-        return base.to_string();
-    }
-    (2..).map(|i| format!("{base} {i}")).find(|n| !taken(n)).unwrap_or_else(|| base.to_string())
-}
-
 fn instances_of(d: &Document, name: Option<&str>) -> Vec<NodeId> {
     let mut v = vec![];
     d.walk(|n| {
@@ -587,7 +579,7 @@ fn symbol_new(s: &mut Session, p: &Value) -> Result<Value> {
     let ids = roots(s, p)?;
     let art = selection_art(s, p)?.ok_or_else(|| EngineError::Other("nothing selected".into()))?;
     let (art, size, c) = normalize(art)?;
-    let name = unique_symbol_name(&s.doc()?.doc, str_param(p, "name").filter(|n| !n.trim().is_empty()).unwrap_or("New Symbol"));
+    let name = s.doc()?.doc.unique_symbol_name(str_param(p, "name").filter(|n| !n.trim().is_empty()).unwrap_or("New Symbol"));
     let id = s.edit("New Symbol", |d, sel| {
         let art = d.reid(&art);
         d.symbols.push(Symbol { name: name.clone(), art: Arc::new(art) });
@@ -764,7 +756,7 @@ fn symbol_duplicate(s: &mut Session, p: &Value) -> Result<Value> {
     let name = name_param(p, C)?.to_string();
     let d = &s.doc()?.doc;
     let sym = d.symbols.iter().find(|x| x.name == name).cloned().ok_or_else(|| bad(C, format!("no symbol named `{name}`")))?;
-    let new = unique_symbol_name(d, str_param(p, "newName").unwrap_or(&format!("{name} copy")));
+    let new = d.unique_symbol_name(str_param(p, "newName").unwrap_or(&format!("{name} copy")));
     let size = natural_size(d, &name);
     s.edit("Duplicate Symbol", |d, _| {
         let art = d.reid(&sym.art);

crates/engine/src/cmd/buildcmds.rs

@@ -15,7 +15,7 @@ use std::sync::Arc;
 use serde_json::{Value, json};
 use vectorcraft_color::{Color, Paint};
 use vectorcraft_doc::appearance::{AppearanceItem, FillLayer, LineCap, LineJoin, StrokeLayer};
-use vectorcraft_doc::{Appearance, Document, Node, NodeId, NodeKind, Selection, TraceView};
+use vectorcraft_doc::{Appearance, Document, LiveShape, Node, NodeId, NodeKind, Selection, TraceView};
 use vectorcraft_geom::{FillRule, PathData, Point, Rect, SubPath};
 use vectorcraft_pathops as po;
 use vectorcraft_tools::builder::{
@@ -120,7 +120,7 @@ pub fn specs() -> Vec<CommandSpec> {
             "Make",
             ["Object", "Image Trace"],
             None,
-            "{id?: image or Image Trace group (default: selection), preset?: name (imageTrace.presets), params?: {mode: \"blackAndWhite\"|\"grayscale\"|\"color\"|\"logo\", threshold: 0-255, palette: \"limited\"|\"fullTone\"|\"automatic\"|\"documentLibrary\" (color mode; limited: the `colors` best colours, fullTone: as many as the tones need, more with colorDetail, automatic: flat art with its own colours, else fullTone, documentLibrary: at most `colors` of the library's colours, as they are), colors: 2-256, colorDetail: 0-100 (fullTone, automatic), library: \"document\" (the document's swatches) or a swatch library id or name (swatch.library.list; documentLibrary), paths: 0-100, corners: 0-100, noise: px, method: \"abutting\"|\"overlapping\", ignoreWhite, snapCurvesToLines, fills: true, strokes: false (Create: lines up to strokeWidth wide become stroked centre lines; without fills, wider areas become stroked outlines), strokeWidth: px (10), logoColors?: [\"#rrggbb\"…] (mode logo: flat-colour logos only; colours found automatically or named here, white is always its own colour, at most ten; noise = areas under noise/10 px ignored; edges to a fraction of a pixel, sharp corners restored, lines and circles snapped; enclosed transparent areas are painted white unless ignoreWhite makes them holes; fills/strokes are ignored; gradients and photos are refused)}, view?: as imageTrace.setView (default: the traced object's own, else tracingResult), ids?: [id…] (instead of id)} → {id, paths, anchors, colors}",
+            "{id?: image or Image Trace group (default: selection), preset?: name (imageTrace.presets), params?: {mode: \"blackAndWhite\"|\"grayscale\"|\"color\"|\"logo\", threshold: 0-255, palette: \"limited\"|\"fullTone\"|\"automatic\"|\"documentLibrary\" (color mode; limited: the `colors` best colours, fullTone: as many as the tones need, more with colorDetail, automatic: flat art with its own colours, else fullTone, documentLibrary: at most `colors` of the library's colours, as they are), colors: 2-256, colorDetail: 0-100 (fullTone, automatic), library: \"document\" (the document's swatches) or a swatch library id or name (swatch.library.list; documentLibrary), paths: 0-100, corners: 0-100, noise: px, method: \"abutting\"|\"overlapping\", ignoreWhite (leave out white areas), ignoreColor?: \"#rrggbb\" (with ignoreWhite: the colour left out instead of white), snapCurvesToLines, shapes: false (filled outlines that are a circle, an ellipse, a rectangle or a regular polygon come out as that live shape), autoGrouping: false (each path that has others inside it is grouped with them), gradients: false (grayscale and color: an area whose colour changes evenly along one direction is one path with a linear gradient fill), fills: true, strokes: false (Create: lines up to strokeWidth wide become stroked centre lines; without fills, wider areas become stroked outlines), strokeWidth: px (10), logoColors?: [\"#rrggbb\"…] (mode logo: flat-colour logos only; colours found automatically or named here, white is always its own colour, at most ten; noise = areas under noise/10 px ignored; edges to a fraction of a pixel, sharp corners restored, lines and circles snapped; enclosed transparent areas are painted white unless ignoreWhite makes them holes; fills/strokes are ignored; gradients and photos are refused)}, view?: as imageTrace.setView (default: the traced object's own, else tracingResult), ids?: [id…] (instead of id)} → {id, paths, anchors, colors}",
             has_selection_or_ids,
             |s, p| trace_make(s, p, false)
         ),
@@ -703,6 +703,76 @@ fn trace_library(s: &Session, params: &mut tr::TraceParams) -> Result<Vec<([u8;
 /// refused with advice instead (#525).
 pub const MAX_TRACE_ANCHORS: usize = 2_000_000;
 
+/// The live shape for a shape the tracer found (in the image's pixels), placed in the document by `xf`.
+fn traced_shape(shape: tr::TracedShape, xf: vectorcraft_geom::Affine) -> LiveShape {
+    use vectorcraft_geom::Affine;
+    let about = |c: Point, deg: f64| Affine::translate(c.to_vec2()) * Affine::rotate(deg.to_radians());
+    let mut live = match shape {
+        tr::TracedShape::Rectangle { center, width, height, radius, rotation } => LiveShape::Rectangle {
+            w: width,
+            h: height,
+            radii: [radius; 4],
+            kinds: Default::default(),
+            xf: about(center, rotation) * Affine::translate((-width / 2.0, -height / 2.0)),
+        },
+        tr::TracedShape::Ellipse { center, rx, ry, rotation } => {
+            LiveShape::Ellipse { w: 2.0 * rx, h: 2.0 * ry, pie: (0.0, 360.0), xf: about(center, rotation) * Affine::translate((-rx, -ry)) }
+        }
+        tr::TracedShape::Polygon { center, radius, sides, rotation } => {
+            LiveShape::Polygon { radius, sides, xf: about(center, rotation), radii: vec![], kinds: vec![] }
+        }
+    };
+    // (Whether the move changed the shape's own numbers does not matter: its path is made from them next.)
+    let _ = live.transform(xf);
+    live
+}
+
+/// The gradient fill for a linear gradient the tracer found (in the image's pixels), placed in the
+/// document by `xf`.
+fn traced_gradient(g: &tr::TracedGradient, xf: vectorcraft_geom::Affine) -> Paint {
+    use vectorcraft_color::{Gradient, GradientGeom, GradientKind, GradientPaint, GradientStop};
+    let stops = g.stops.iter().map(|&(at, c)| GradientStop::new(at as f32, Color::rgb8(c[0], c[1], c[2]))).collect();
+    let mut paint = GradientPaint::new(Gradient { kind: GradientKind::Linear, stops });
+    paint.geom = Some(GradientGeom { start: xf * g.start, end: xf * g.end, aspect: 1.0, focal: None });
+    Paint::Gradient(Box::new(paint))
+}
+
+/// Auto Grouping: `nodes` (one per traced path, bottom-most first) with each path that has others
+/// inside it (`parents`, as the tracer gives them) in a group with them: the path, then what is
+/// inside it. Without parents, the nodes as they are.
+fn grouped(d: &mut Document, nodes: Vec<Node>, parents: &[Option<usize>]) -> Vec<Arc<Node>> {
+    let n = nodes.len();
+    let mut inside: Vec<Vec<usize>> = vec![vec![]; n];
+    let mut roots = vec![];
+    for i in 0..n {
+        match parents.get(i).copied().flatten().and_then(|p| inside.get_mut(p).filter(|_| p != i)) {
+            Some(of) => of.push(i),
+            None => roots.push(i),
+        }
+    }
+    // Outermost first, so that backwards each path comes after those inside it.
+    let mut order = roots.clone();
+    let mut at = 0;
+    while let Some(&i) = order.get(at) {
+        order.extend(inside.get(i).into_iter().flatten());
+        at += 1;
+    }
+    let mut nodes: Vec<Option<Node>> = nodes.into_iter().map(Some).collect();
+    let mut built: Vec<Option<Arc<Node>>> = vec![None; n];
+    for &i in order.iter().rev() {
+        let Some(node) = nodes.get_mut(i).and_then(Option::take) else { continue };
+        let within: Vec<Arc<Node>> = inside.get(i).into_iter().flatten().filter_map(|&c| built.get_mut(c)?.take()).collect();
+        let made = if within.is_empty() { node } else { Node::group(d.alloc_id(), std::iter::once(Arc::new(node)).chain(within).collect()) };
+        if let Some(slot) = built.get_mut(i) {
+            *slot = Some(Arc::new(made));
+        }
+    }
+    // (Paths that are inside each other in a ring are reached from no root: the tracer makes none,
+    // and they are kept all the same.)
+    let ring = nodes.into_iter().flatten().map(Arc::new).collect::<Vec<_>>();
+    roots.iter().filter_map(|&r| built.get_mut(r)?.take()).chain(ring).collect()
+}
+
 fn trace_make(s: &mut Session, p: &Value, expand: bool) -> Result<Value> {
     const C: &str = "imageTrace.make";
     let mut params = trace_params(p)?;
@@ -763,12 +833,20 @@ fn trace_make(s: &mut Session, p: &Value, expand: bool) -> Result<Value> {
             hidden.visible = false;
             children.push(Arc::new(hidden));
         }
+        let mut traced = Vec::with_capacity(res.paths.len());
         for tp in res.paths {
             let path = tp.path.transformed(xf);
             let mut n = shape_node(d, path, None);
+            // Shapes: a path the tracer found to be a shape is that live shape.
+            if let (Some(shape), NodeKind::Path { path, live, .. }) = (tp.shape, &mut n.kind) {
+                let shape = traced_shape(shape, xf);
+                *path = shape.to_path();
+                *live = Some(Box::new(shape));
+            }
             // A library colour fills with the swatch's own colour (its model kept).
             let color = library.iter().find(|(rgb, _)| *rgb == tp.color).map_or_else(|| Color::rgb8(tp.color[0], tp.color[1], tp.color[2]), |l| l.1);
-            let paint = Paint::solid(color);
+            // Gradients: a path the tracer found to be a linear gradient is filled with it.
+            let paint = tp.gradient.as_ref().map_or_else(|| Paint::solid(color), |g| traced_gradient(g, xf));
             n.appearance = match tp.stroke {
                 // Traced lines: round ends and corners, as drawn lines have.
                 Some(width) => Appearance {
@@ -782,8 +860,9 @@ fn trace_make(s: &mut Session, p: &Value, expand: bool) -> Result<Value> {
                 .into(),
                 None => fill_only(paint).into(),
             };
-            children.push(Arc::new(n));
+            traced.push(n);
         }
+        children.extend(grouped(d, traced, &res.parents));
         let gid = d.alloc_id();
         let mut g = Node::group(gid, children);
         g.name = if expand { None } else { Some(TRACE_NAME.into()) };

crates/engine/src/cmd/docmenu.rs

@@ -489,8 +489,10 @@ fn release_guides(s: &mut Session, _: &Value) -> Result<Value> {
 fn lock_guides(s: &mut Session, p: &Value) -> Result<Value> {
     let v = p.get("locked").and_then(Value::as_bool).unwrap_or(!s.menu.guides_locked);
     s.menu.guides_locked = v;
-    // Locked guides can't stay selected.
-    if v && !s.doc()?.selection.guides.is_empty() {
+    // Locked guides can't stay selected, ruler guides or guide paths ([`Session::select`] lets
+    // those go).
+    let st = s.doc()?;
+    if v && (!st.selection.guides.is_empty() || st.selection.objects.iter().any(|id| crate::is_guide_path(&st.doc, *id))) {
         s.select(|_, sel| sel.guides.clear())?;
     }
     Ok(json!({ "locked": v }))

crates/engine/src/cmd/draw2.rs

@@ -3,7 +3,7 @@
 
 use std::sync::Arc;
 
-use kurbo::{ParamCurve, ParamCurveNearest};
+use kurbo::{CubicBez, ParamCurve, ParamCurveNearest};
 use serde_json::{Value, json};
 use vectorcraft_color::{Color, Paint};
 use vectorcraft_doc::{Appearance, Document, Node, NodeId, NodeKind, PressureProfile, Selection};
@@ -1048,17 +1048,46 @@ fn smooth_subpath(sp: &SubPath, near: &dyn Fn(Point) -> bool, tol: f64) -> Optio
         open.anchors.push(open.anchors[0]);
         m.push(false);
         open.closed = false;
-        let mut res = smooth_open(&open.anchors, &m, tol);
+        let mut res = smooth_open(&open.anchors, &m, near, tol);
         let l = res.pop()?;
         if let Some(r0) = res.first_mut() {
             r0.h_in = l.h_in;
         }
         return Some(SubPath::new(res, true));
     }
-    Some(SubPath::new(smooth_open(&sp.anchors, &marked, tol), false))
+    Some(SubPath::new(smooth_open(&sp.anchors, &marked, near, tol), false))
 }
 
-fn smooth_open(anchors: &[Anchor], marked: &[bool], tol: f64) -> Vec<Anchor> {
+/// The segment `c`, which ends in the drag's reach (`near`) and starts outside it, split where it
+/// enters the reach: the part outside, then the part in reach. `None` when no more than a sliver
+/// is outside.
+fn split_at_reach(c: CubicBez, near: &dyn Fn(Point) -> bool) -> Option<(CubicBez, CubicBez)> {
+    const STEPS: u32 = 32;
+    let step = 1.0 / f64::from(STEPS);
+    // Back from the end in reach to the first sample outside, then halving to the crossing.
+    let outside = (1..=STEPS).map(|i| 1.0 - f64::from(i) * step).find(|t| !near(c.eval(*t)))?;
+    let (mut lo, mut hi) = (outside, outside + step);
+    for _ in 0..20 {
+        let mid = (lo + hi) / 2.0;
+        if near(c.eval(mid)) {
+            hi = mid;
+        } else {
+            lo = mid;
+        }
+    }
+    // A straight segment's parts stay straight, their handles on their ends.
+    let straight = c.p1 == c.p0 && c.p2 == c.p3;
+    let part = |range| {
+        let s = c.subsegment(range);
+        if straight { CubicBez::new(s.p0, s.p0, s.p3, s.p3) } else { s }
+    };
+    (hi > 0.02).then(|| (part(0.0..hi), part(hi..1.0)))
+}
+
+/// `anchors` with each run of `marked` ones refitted, together with the stretch of the segments
+/// leading into the run that is in the drag's reach (`near`): a short drag smooths what is under
+/// it, and the rest of a long segment next to it stays as it was (#1512).
+fn smooth_open(anchors: &[Anchor], marked: &[bool], near: &dyn Fn(Point) -> bool, tol: f64) -> Vec<Anchor> {
     let n = anchors.len();
     let mut runs = vec![];
     let mut i = 0;
@@ -1079,8 +1108,27 @@ fn smooth_open(anchors: &[Anchor], marked: &[bool], tol: f64) -> Vec<Anchor> {
         if hi - lo < 2 {
             continue;
         }
-        let new = refit_run(&out[lo..=hi], tol);
-        out.splice(lo..=hi, new);
+        let mut piece = out[lo..=hi].to_vec();
+        // The anchors outside the reach, kept with the part of their segment that is outside.
+        let (mut head, mut tail) = (None, None);
+        if hi > b
+            && let [.., inner, outer] = piece.as_mut_slice()
+            && let Some((far, reach)) = split_at_reach(CubicBez::new(outer.p, outer.h_in, inner.h_out, inner.p), near)
+        {
+            inner.h_out = reach.p2;
+            tail = Some(Anchor { h_in: far.p1, ..*outer });
+            *outer = Anchor::with_handles(far.p3, reach.p1, far.p2);
+        }
+        if lo < a
+            && let [outer, inner, ..] = piece.as_mut_slice()
+            && let Some((far, reach)) = split_at_reach(CubicBez::new(outer.p, outer.h_out, inner.h_in, inner.p), near)
+        {
+            inner.h_in = reach.p2;
+            head = Some(Anchor { h_out: far.p1, ..*outer });
+            *outer = Anchor::with_handles(far.p3, far.p2, reach.p1);
+        }
+        let new = refit_run(&piece, tol);
+        out.splice(lo..=hi, head.into_iter().chain(new).chain(tail));
     }
     out
 }

crates/engine/src/cmd/edit.rs

@@ -132,7 +132,15 @@ pub fn specs() -> Vec<CommandSpec> {
             has_selection_or_guides,
             clear
         ),
-        cmd!("edit.duplicate", "Duplicate", [], None, "{dx?, dy?} duplicate the selection in place (offset optional)", has_selection, duplicate),
+        cmd!(
+            "edit.duplicate",
+            "Duplicate",
+            ["Edit"],
+            None,
+            "{dx?, dy?} duplicate the selection in place (offset optional)",
+            has_selection,
+            duplicate
+        ),
     ]
 }
 

crates/engine/src/cmd/effectcmd.rs

@@ -280,6 +280,20 @@ fn move_effect(s: &mut Session, p: &Value) -> Result<Value> {
     Ok(json!({ "ids": ids_json(&ids), "index": index, "item": item.flatten() }))
 }
 
+/// The ids of the effects `effect.setParams` with `p` edits, for the check of their parameters
+/// (none when `p` doesn't say which: running it reports why).
+pub(crate) fn set_params_effects(s: &Session, p: &Value) -> Vec<String> {
+    const C: &str = "effect.setParams";
+    let (Ok(index), Ok(item), Ok(ids), Ok(st)) = (index_param(p, "index", C), item_target(s, p, C), appearance_targets(s, p), s.doc()) else {
+        return vec![];
+    };
+    let effect = |id: &NodeId| {
+        let ap = &st.doc.node(*id)?.appearance;
+        Some(ap.effects_at(item.effects_item(ap, C).ok()?)?.get(index)?.id.clone())
+    };
+    ids.iter().filter_map(effect).collect()
+}
+
 fn set_params(s: &mut Session, p: &Value) -> Result<Value> {
     const C: &str = "effect.setParams";
     let index = index_param(p, "index", C)?;
@@ -566,7 +580,7 @@ mod tests {
             for other in ["threeD.revolve", "threeD.extrude", "threeD.rotate"] {
                 assert!(s.execute("effect.apply", &json!({"effect": other, "ids": [id.0], "item": null})).is_err(), "{effect} + {other}");
             }
-            s.execute("effect.setParams", &json!({"index": 0, "params": {"rotationY": 50, "depth": 120}, "ids": [id.0], "item": null})).unwrap();
+            s.execute("effect.setParams", &json!({"index": 0, "params": {"rotationY": 50, "rotationX": 10}, "ids": [id.0], "item": null})).unwrap();
             assert_ne!(effects::solid_art(&node(&s, id)).unwrap(), art, "{effect}: options change the art");
             assert!(s.execute("effect.setParams", &json!({"index": 0, "params": {"bevel": "nope"}, "ids": [id.0], "item": null})).is_err());
             let svg = s.execute("document.serialize", &json!({"format": "svg"})).unwrap();

crates/engine/src/cmd/params.rs

@@ -10,8 +10,10 @@
 //!
 //! Callers outside the app (the control channel, MCP, the CLI) are answered with a parameter error
 //! for a key the description doesn't name ([`check_params`]): a misspelt `widht` no longer runs the
-//! command with its default. [`Session::execute`] itself takes what it is given, so the journal of
-//! an older version still replays.
+//! command with its default. So are the `params` of an effect (#1592): `effect.apply` and
+//! `effect.setParams` answer a key the effect doesn't take, or a value of another type than its
+//! default, with a parameter error ([`check_effect_params`]). [`Session::execute`] itself takes
+//! what it is given, so the journal of an older version still replays.
 
 use serde_json::Value;
 
@@ -150,6 +152,12 @@ fn accepted(doc: &'static str, depth: usize) -> Option<Vec<&'static str>> {
     Some(keys)
 }
 
+/// Does the description `doc` name `key` as a parameter (its own keys, and those of the commands
+/// its `…` entries name)?
+pub(crate) fn takes_key(doc: &'static str, key: &str) -> bool {
+    doc_keys(doc).is_ok_and(|parsed| parsed.keys.contains(&key)) || accepted(doc, 0).is_some_and(|keys| keys.contains(&key))
+}
+
 /// The edits (insert, delete, replace, swap of neighbours) that turn `a` into `b`, ignoring case.
 fn distance(a: &str, b: &str) -> usize {
     let (a, b): (Vec<char>, Vec<char>) = (a.chars().map(|c| c.to_ascii_lowercase()).collect(), b.chars().map(|c| c.to_ascii_lowercase()).collect());
@@ -183,15 +191,56 @@ pub fn check_keys(id: &str, doc: &'static str, params: &Value) -> Result<()> {
         return Ok(());
     }
     let Some(keys) = accepted(doc, 0) else { return Ok(()) };
-    let Some(key) = given.keys().find(|k| !keys.contains(&k.as_str())) else { return Ok(()) };
-    Err(bad(
+    match given.keys().find(|k| !keys.contains(&k.as_str())) {
+        Some(key) => Err(unknown(id, key, &keys)),
+        None => Ok(()),
+    }
+}
+
+/// The parameter error of command `id` for `key`, which isn't one of `keys`: with the nearest of
+/// them, or all of them.
+fn unknown(id: &str, key: &str, keys: &[&str]) -> crate::EngineError {
+    bad(
         id,
-        match nearest(key, &keys) {
+        match nearest(key, keys) {
             Some(near) => format!("unknown parameter `{key}`; did you mean `{near}`?"),
             None if keys.is_empty() => format!("unknown parameter `{key}`; the command takes no parameters"),
             None => format!("unknown parameter `{key}`; the command takes: {}", keys.join(", ")),
         },
-    ))
+    )
+}
+
+/// `params` of built-in effect `effect`, as command `id` was given them (#1592): only keys the
+/// effect takes (those of its dialog defaults and of its params description), each of its
+/// default's type. Numbers out of range pass: the effect clamps them when it draws. An effect
+/// plug-in resolves its own against its manifest, and an unknown effect is the command's to report.
+pub fn check_effect_params(id: &str, effect: &str, params: &Value) -> Result<()> {
+    let Value::Object(given) = params else { return Ok(()) };
+    if effect.starts_with(vectorcraft_plugins::effect::PREFIX) {
+        return Ok(());
+    }
+    let Some(info) = vectorcraft_render::effects::effect_info(effect) else { return Ok(()) };
+    let defaults = info.defaults.as_object();
+    let mut keys: Vec<&str> = defaults.into_iter().flat_map(|d| d.keys().map(String::as_str)).collect();
+    // A description that doesn't parse names no more keys (the tests rule that out).
+    for key in doc_keys(info.params).map(|d| d.keys).unwrap_or_default() {
+        if !keys.contains(&key) {
+            keys.push(key);
+        }
+    }
+    for (key, v) in given {
+        if !keys.contains(&key.as_str()) {
+            return Err(unknown(id, key, &keys));
+        }
+        match defaults.and_then(|d| d.get(key)) {
+            Some(Value::Number(_)) if !v.is_number() => return Err(bad(id, format!("`{key}` must be a number"))),
+            Some(Value::Bool(_)) if !v.is_boolean() => return Err(bad(id, format!("`{key}` must be true or false"))),
+            // (A colour is also taken as `[r, g, b]` or as a colour object.)
+            Some(Value::String(_)) if v.is_number() || v.is_boolean() => return Err(bad(id, format!("`{key}` must be a string"))),
+            _ => {}
+        }
+    }
+    Ok(())
 }
 
 /// Commands whose params aren't checked yet (#1442): they read keys in ways the audit of the
@@ -327,10 +376,16 @@ pub const UNCHECKED: &[&str] = &[
     "webExport.settings",
 ];
 
-/// [`check_keys`] for an engine command, the steps of a `command.batch` included. A command the
-/// engine doesn't have passes: running it reports that.
+/// [`check_keys`] for an engine command, the steps of a `command.batch` included, and
+/// [`check_effect_params`] for the effect `effect.apply` adds. A command the engine doesn't have
+/// passes: running it reports that.
 pub fn check_params(id: &str, params: &Value) -> Result<()> {
     let Some(spec) = find_command(id) else { return Ok(()) };
+    if let ("effect.apply" | "appearance.addEffect", Some(effect), Some(given)) =
+        (id, params.get("effect").or_else(|| params.get("id")).and_then(Value::as_str), params.get("params"))
+    {
+        check_effect_params(id, effect, given)?;
+    }
     if UNCHECKED.contains(&id) {
         return Ok(());
     }
@@ -344,3 +399,18 @@ pub fn check_params(id: &str, params: &Value) -> Result<()> {
     }
     Ok(())
 }
+
+impl crate::Session {
+    /// [`check_params`], and [`check_effect_params`] for the effects `effect.setParams` edits in
+    /// this session's document (not as a step of a `command.batch`: what it edits is only there
+    /// once the steps before it ran).
+    pub fn check_params(&self, id: &str, params: &Value) -> Result<()> {
+        check_params(id, params)?;
+        if let ("effect.setParams", Some(given)) = (id, params.get("params")) {
+            for effect in super::effectcmd::set_params_effects(self, params) {
+                check_effect_params(id, &effect, given)?;
+            }
+        }
+        Ok(())
+    }
+}

crates/engine/src/cmd/path.rs

@@ -4,7 +4,7 @@ use std::collections::BTreeSet;
 
 use serde_json::{Value, json};
 use vectorcraft_doc::{NodeId, NodeKind, Scaling};
-use vectorcraft_geom::{AnchorKind, PathData, Point, SubPath, Vec2};
+use vectorcraft_geom::{Anchor, AnchorKind, PathData, Point, SubPath, Vec2};
 
 use super::create::anchor_from_json;
 use super::pathops::Beside;
@@ -64,7 +64,7 @@ pub fn specs() -> Vec<CommandSpec> {
             "Join",
             ["Object", "Path"],
             Some("Cmd+J"),
-            "{ids?: [path, path] (default: the selected paths), ends?: [\"first\"|\"last\", \"first\"|\"last\"] (which end of each path to join, as the Pen joins them; default: the nearest pair)} join two open paths into one (the first keeps its id, selected), or close a single open path",
+            "{ids?: [path, path] (default: the selected paths), ends?: [\"first\"|\"last\", \"first\"|\"last\"] (which end of each path to join, as the Pen joins them; default: the nearest pair)} join two open paths into one (the first keeps its id, selected), or close a single open path; without ids, direct-selected anchors lying on one another along a path merge into one anchor instead",
             has_selection,
             join
         ),
@@ -300,6 +300,37 @@ fn end_points(sp: &SubPath) -> Option<(Point, Point)> {
     Some((sp.anchors.first()?.p, sp.anchors.last()?.p))
 }
 
+/// Merge each run of `picked` neighbours of `sp` that lie on one another into one anchor, which
+/// keeps the first one's incoming handle and the last one's outgoing handle. Returns how many
+/// anchors went.
+fn merge_coincident(sp: &mut SubPath, picked: impl Fn(usize) -> bool) -> usize {
+    let same = |a: &Anchor, b: &Anchor| a.p.distance(b.p) < 1e-6;
+    let before = sp.anchors.len();
+    // The closing pair of a closed path first: taking the last anchor moves no other index.
+    if sp.closed
+        && before > 2
+        && picked(0)
+        && picked(before - 1)
+        && let [first, .., last] = sp.anchors.as_mut_slice()
+        && same(first, last)
+    {
+        first.h_in = last.h_in;
+        sp.anchors.pop();
+    }
+    // Back to front, so the indices `picked` knows stay true for the anchors still to visit.
+    for i in (1..sp.anchors.len()).rev() {
+        if picked(i - 1)
+            && picked(i)
+            && let Some([a, b]) = sp.anchors.get_mut(i - 1..=i)
+            && same(a, b)
+        {
+            a.h_out = b.h_out;
+            sp.anchors.remove(i);
+        }
+    }
+    before - sp.anchors.len()
+}
+
 fn join(s: &mut Session, p: &Value) -> Result<Value> {
     const C: &str = "path.join";
     let ids = match ids_param(p, "ids") {
@@ -312,6 +343,31 @@ fn join(s: &mut Session, p: &Value) -> Result<Value> {
         }
         None => selected_paths(s)?,
     };
+    // Direct-selected anchors lying on one another along a path (two corners brought together by
+    // Average) become one anchor; the paths themselves are joined only when there are none.
+    if p.get("ids").is_none() {
+        let st = s.doc()?;
+        let mut merged = vec![];
+        for (id, picked) in &st.selection.anchors {
+            let Some(mut path) = st.doc.node(*id).and_then(|n| n.path_data()).cloned() else { continue };
+            let n: usize = path.subpaths.iter_mut().enumerate().map(|(si, sp)| merge_coincident(sp, |ai| picked.contains(&(si, ai)))).sum();
+            if n > 0 {
+                merged.push((*id, path));
+            }
+        }
+        if !merged.is_empty() {
+            let objects = st.selection.objects.clone();
+            s.edit("Join", |d, sel| {
+                for (id, path) in merged {
+                    *path_mut(d, id)? = path;
+                }
+                // The anchor indices changed: the paths stay selected, whole.
+                sel.set(objects);
+                Ok(())
+            })?;
+            return ok();
+        }
+    }
     // The ends to join, as (reverse the first path, reverse the second): the first path's end
     // must come last, the second's first.
     let ends = match p.get("ends") {

crates/engine/src/cmd/pathops.rs

@@ -383,10 +383,15 @@ fn run_pf(s: &mut Session, op: PathfinderOp) -> Result<Value> {
         let mut styles: Vec<Style> = vec![];
         let mut shapes: Vec<po::Shape> = vec![];
         let mut names: Vec<Option<String>> = vec![];
-        let mut push = |mut path: PathData, rule: FillRule, st: Style, name: Option<String>| {
+        let mut push = |mut path: PathData, rule: FillRule, mut st: Style, name: Option<String>| {
             if path.is_empty() {
                 return;
             }
+            // Trim, Merge and Crop remove any strokes (and Merge then merges by fill alone), as the
+            // public Pathfinder documentation describes.
+            if matches!(op, PathfinderOp::Trim | PathfinderOp::Merge | PathfinderOp::Crop) {
+                st.appearance.items.retain(|i| !matches!(i, AppearanceItem::Stroke(_)));
+            }
             if op == PathfinderOp::Divide && st.appearance.items.iter().any(|i| matches!(i, AppearanceItem::Fill(f) if !f.paint.is_none())) {
                 // Filled open contours keep their implicit closing edge. A zero-area line
                 // stays a cutter; normalised area also catches zero-signed-area self crossings.
@@ -498,6 +503,7 @@ fn offset_path(s: &mut Session, p: &Value) -> Result<Value> {
     let roots = selected_roots(s)?;
     let ids = s.edit("Offset Path", |d, sel| {
         let (mut out, mut above) = (vec![], vec![]);
+        let mut paths = false;
         for id in &roots {
             let Some(n) = d.node(*id).cloned() else { continue };
             let mut lv = vec![];
@@ -505,6 +511,7 @@ fn offset_path(s: &mut Session, p: &Value) -> Result<Value> {
             let mut made = vec![];
             for l in lv.iter().filter(|l| !matches!(l.kind, NodeKind::Text(_))) {
                 let Some((path, rule)) = node_path(l) else { continue };
+                paths = true;
                 let base = if matches!(l.kind, NodeKind::Compound { .. }) && path.is_closed() { po::normalize(&path, rule) } else { path };
                 let off = po::offset_path(&base, delta, join, miter);
                 if off.is_empty() {
@@ -527,6 +534,9 @@ fn offset_path(s: &mut Session, p: &Value) -> Result<Value> {
             out.push(new.id);
             above.push((*id, vec![new]));
         }
+        if out.is_empty() && paths {
+            return Err(EngineError::Other("Offset Path: the offset leaves nothing of the selected paths (an inset larger than the shapes)".into()));
+        }
         if out.is_empty() {
             return Err(EngineError::Other("Offset Path: select paths".into()));
         }

crates/engine/src/lib.rs

@@ -578,6 +578,11 @@ fn strip_replay_only(id: &str, p: &mut Value) {
     }
 }
 
+/// Is `id` a path made into a guide (View → Guides → Make Guides)?
+pub(crate) fn is_guide_path(d: &Document, id: NodeId) -> bool {
+    d.node(id).is_some_and(|n| matches!(n.kind, NodeKind::Path { guide: true, .. }))
+}
+
 /// Cheap sanity check after an edit: artboards and the objects just touched (the selection) must
 /// have finite, in-range geometry, so saved files always reload and renderers never see NaN/∞.
 fn doc_sane(d: &Document, sel: &Selection) -> bool {
@@ -1295,16 +1300,35 @@ impl Session {
         true
     }
 
+    /// `spec`'s `enabled` with `ids` selected instead of the selection, which is then put back.
+    fn enabled_with_selection(&mut self, spec: &CommandSpec, ids: Vec<NodeId>) -> std::result::Result<(), String> {
+        let Some(d) = self.active_mut() else { return (spec.enabled)(self) };
+        let old = std::mem::replace(&mut d.selection, Selection { objects: ids, ..Selection::default() });
+        let r = (spec.enabled)(self);
+        if let Some(d) = self.active_mut() {
+            d.selection = old;
+        }
+        r
+    }
+
     /// Execute a command by id. This is THE entry point for every frontend.
     pub fn execute(&mut self, id: &str, params: &Value) -> Result<Value> {
         let spec = find_command(id).ok_or_else(|| EngineError::UnknownCommand(id.to_string()))?;
         // The crate's own tests are the audit of the params descriptions (#1442): a key a test
         // passes that its command's description doesn't name fails the test.
         #[cfg(test)]
-        cmd::params::check_params(id, params)?;
+        self.check_params(id, params)?;
         // Clear's menu needs a selection; an agent supplying explicit targets only needs a
         // document. The command validates those targets before making any edit.
-        let enabled = if id == "edit.clear" && params.get("ids").is_some() { cmd::has_doc(self) } else { (spec.enabled)(self) };
+        let enabled = if id == "edit.clear" && params.get("ids").is_some() {
+            cmd::has_doc(self)
+        } else if let Some(ids) = given_ids(spec.params, params) {
+            // Objects given as `ids` stand in for the selection: the command is enabled as it is
+            // with them selected (#1575).
+            self.enabled_with_selection(spec, ids)
+        } else {
+            (spec.enabled)(self)
+        };
         if let Err(why) = enabled {
             return Err(EngineError::Disabled(id.to_string(), why));
         }
@@ -1482,10 +1506,18 @@ impl Session {
     /// Change only the selection (not an undo step).
     pub fn select(&mut self, f: impl FnOnce(&Document, &mut Selection)) -> Result<()> {
         self.active_appearance_item = None;
+        let guides_locked = self.menu.guides_locked;
         let st = self.doc_mut()?;
         let before = st.selection.objects.clone();
         f(&st.doc, &mut st.selection);
         st.selection.prune(&st.doc);
+        // Lock Guides locks the paths made into guides too (#1534), whatever selects them.
+        if guides_locked {
+            let locked: Vec<NodeId> = st.selection.objects.iter().copied().filter(|id| is_guide_path(&st.doc, *id)).collect();
+            for id in locked {
+                st.selection.remove(id);
+            }
+        }
         // Selecting art makes its layer (or sublayer) the current one, as in the Layers panel of
         // the reference app: new art then goes beside it.
         if st.selection.objects != before
@@ -1757,6 +1789,8 @@ mod tests_halftone;
 #[cfg(test)]
 mod tests_history_mem;
 #[cfg(test)]
+mod tests_ids_without_selection;
+#[cfg(test)]
 mod tests_inline;
 #[cfg(test)]
 mod tests_journal;
@@ -1942,3 +1976,10 @@ mod tests_widthprofiles;
 mod tests_widthtool;
 #[cfg(test)]
 mod tests_xform;
+
+/// The non-empty `ids` given to a command whose params description names `ids` as a key (the
+/// key callers outside the app may pass it, [`cmd::params::takes_key`]).
+fn given_ids(description: &'static str, params: &Value) -> Option<Vec<NodeId>> {
+    let ids = cmd::ids_param(params, "ids").filter(|ids| !ids.is_empty())?;
+    cmd::params::takes_key(description, "ids").then_some(ids)
+}

crates/engine/src/tests_build.rs

@@ -671,6 +671,108 @@ fn image_trace_make_places_paths_over_the_image() {
     assert_eq!(paths[0].appearance.fill_paint(), Paint::solid(Color::rgb8(0, 0, 0)));
 }
 
+/// Shapes: the disc of the test image comes out as a live ellipse where the image lies, the same
+/// circle as its traced path; without the option it is a plain path.
+#[test]
+fn image_trace_shapes_makes_live_shapes() {
+    let mut s = session();
+    image_doc(&mut s);
+    let r = s.execute("imageTrace.make", &json!({"params": {"ignoreWhite": true, "shapes": true}})).unwrap();
+    let n = node(&s, NodeId(r["id"].as_u64().unwrap()));
+    let paths = traced_paths(&n);
+    assert_eq!(paths.len(), 1);
+    let NodeKind::Path { path, live: Some(live), .. } = &paths[0].kind else { panic!("not a live shape: {:?}", paths[0].kind) };
+    let vectorcraft_doc::LiveShape::Ellipse { w, h, .. } = **live else { panic!("{live:?}") };
+    // A circle of r = 30 px, drawn twice the size.
+    assert!(w == h && (w - 60.0).abs() < 0.75, "{w} × {h}");
+    let bb = path.bounds().unwrap();
+    assert!((bb.center().x - 150.0).abs() < 1.5 && (bb.center().y - 150.0).abs() < 1.5 && (bb.width() - 120.0).abs() < 1.5, "{bb:?}");
+    assert_eq!(*path, live.to_path());
+    assert_eq!(paths[0].appearance.fill_paint(), Paint::solid(Color::rgb8(0, 0, 0)));
+    // Off, as documents saved before have it: a path.
+    let mut s = session();
+    image_doc(&mut s);
+    let r = s.execute("imageTrace.make", &json!({"params": {"ignoreWhite": true}})).unwrap();
+    let n = node(&s, NodeId(r["id"].as_u64().unwrap()));
+    assert!(matches!(traced_paths(&n)[0].kind, NodeKind::Path { live: None, .. }));
+}
+
+/// Auto Grouping: a ring and the dot in its hole are a group (the ring first), the square beside
+/// them is not in it; the picture is the same as without, and the group traces again, expands
+/// and releases as any other.
+#[test]
+fn image_trace_auto_grouping_groups_what_is_inside() {
+    let art = vectorcraft_trace::Raster::from_fn(120, 80, |x, y| {
+        let d = (x as f64 + 0.5 - 40.0).hypot(y as f64 + 0.5 - 40.0);
+        if d <= 6.0 || (90..110).contains(&x) && (30..50).contains(&y) {
+            [200, 0, 0, 255]
+        } else if (16.0..=30.0).contains(&d) {
+            [0, 0, 160, 255]
+        } else {
+            [255, 255, 255, 255]
+        }
+    });
+    let make = |grouping: bool| {
+        let mut s = session();
+        add_image(&mut s, &art, Affine::IDENTITY);
+        let r = s.execute("imageTrace.make", &json!({"preset": "6 Colors", "params": {"ignoreWhite": true, "autoGrouping": grouping}})).unwrap();
+        assert_eq!(r["paths"], 3);
+        let g = NodeId(r["id"].as_u64().unwrap());
+        (s, g)
+    };
+    let (mut s, g) = make(true);
+    let items = traced_paths(&node(&s, g));
+    assert_eq!(items.len(), 2);
+    let group = items.iter().find(|n| matches!(n.kind, NodeKind::Group { .. })).expect("a group");
+    let inside = group.children().unwrap();
+    assert_eq!(inside.len(), 2);
+    assert_eq!(inside[0].appearance.fill_paint(), Paint::solid(Color::rgb8(0, 0, 160)));
+    assert_eq!(inside[1].appearance.fill_paint(), Paint::solid(Color::rgb8(200, 0, 0)));
+    assert!(matches!(items.iter().find(|n| n.id != group.id).unwrap().kind, NodeKind::Path { .. }));
+    // The same picture as without.
+    let (flat, fg) = make(false);
+    assert_eq!(traced_paths(&node(&flat, fg)).len(), 3);
+    let shot = |s: &Session| {
+        let img = render_doc(s, true);
+        (0..120).flat_map(|x| (0..80).map(move |y| (x, y))).map(|(x, y)| img.pixel(x, y)).collect::<Vec<_>>()
+    };
+    assert_eq!(shot(&s), shot(&flat));
+    // Traced again without the option, it is flat again; expanded, the groups stay.
+    let r = s.execute("imageTrace.make", &json!({"preset": "6 Colors", "params": {"ignoreWhite": true}})).unwrap();
+    assert_eq!(traced_paths(&node(&s, NodeId(r["id"].as_u64().unwrap()))).len(), 3);
+    s.execute("imageTrace.make", &json!({"preset": "6 Colors", "params": {"ignoreWhite": true, "autoGrouping": true}})).unwrap();
+    let r = s.execute("imageTrace.expand", &json!({})).unwrap();
+    let expanded = node(&s, NodeId(r["ids"][0].as_u64().unwrap()));
+    assert_eq!(expanded.children().unwrap().len(), 2);
+}
+
+/// Gradients: an image that is one linear gradient is one path filled with it, the gradient's line
+/// where the image lies; without the option it is bands of flat colour, as saved documents have it.
+#[test]
+fn image_trace_gradients_fills_with_a_gradient() {
+    let art = vectorcraft_trace::Raster::from_fn(100, 60, |x, _| {
+        let t = (f64::from(x) + 0.5) / 100.0;
+        [(20.0 + 200.0 * t) as u8, 40, (220.0 - 180.0 * t) as u8, 255]
+    });
+    let make = |gradients: bool| {
+        let mut s = session();
+        add_image(&mut s, &art, Affine::translate((50.0, 50.0)) * Affine::scale(2.0));
+        let r = s.execute("imageTrace.make", &json!({"preset": "6 Colors", "params": {"gradients": gradients}})).unwrap();
+        traced_paths(&node(&s, NodeId(r["id"].as_u64().unwrap())))
+    };
+    let paths = make(true);
+    assert_eq!(paths.len(), 1);
+    let Paint::Gradient(g) = paths[0].appearance.fill_paint() else { panic!("{:?}", paths[0].appearance.fill_paint()) };
+    assert_eq!(g.gradient.kind, vectorcraft_color::GradientKind::Linear);
+    assert_eq!(g.gradient.stops.len(), 2);
+    // Level, from the image's left edge (x = 50) to its right one (x = 250), at any height.
+    let geom = g.geom.as_ref().unwrap();
+    let (a, b) = if geom.start.x < geom.end.x { (geom.start, geom.end) } else { (geom.end, geom.start) };
+    assert!((a.x - 50.0).abs() < 3.0 && (b.x - 250.0).abs() < 3.0 && (a.y - b.y).abs() < 2.0, "{geom:?}");
+    let flat = make(false);
+    assert!(flat.len() > 1 && flat.iter().all(|n| matches!(n.appearance.fill_paint(), Paint::Solid { .. })));
+}
+
 #[test]
 fn image_trace_release_and_expand() {
     let mut s = session();
@@ -795,7 +897,8 @@ fn image_trace_presets_query_and_errors() {
     let mut s = session();
     let r = s.execute("imageTrace.presets", &json!({})).unwrap();
     let names: Vec<&str> = r["presets"].as_array().unwrap().iter().map(|p| p["name"].as_str().unwrap()).collect();
-    assert_eq!(names.len(), 13);
+    assert_eq!(names.len(), 15);
+    assert!(names.contains(&"Auto Color") && names.contains(&"Outline"));
     assert!(names.contains(&"Technical Drawing") && names.contains(&"Shades of Gray") && names.contains(&"Flat Logo"));
     let a = rect(&mut s, 0.0, 0.0, 10.0, 10.0);
     assert!(s.execute("imageTrace.make", &json!({"id": a.0})).is_err(), "not an image");

crates/engine/src/tests_draw2.rs

@@ -412,6 +412,29 @@ fn smooth_tool_reduces_jagged_path() {
     assert_eq!(p.subpaths[0].anchors[0].p, Point::new(100.0, 200.0));
 }
 
+/// #1512: a short drag over a small bump smooths the stretch of path under it. The long straight
+/// sides next to the bump stay straight lines from their far ends, which keep their place.
+#[test]
+fn a_short_smooth_drag_leaves_the_rest_of_long_segments_alone() {
+    let mut s = session();
+    let anchors: Vec<_> =
+        [(50.0, 200.0), (190.0, 200.0), (200.0, 192.0), (210.0, 200.0), (350.0, 200.0)].map(|(x, y)| json!({"x": x, "y": y})).to_vec();
+    let r = s.execute("path.create", &json!({"anchors": anchors})).unwrap();
+    let id = NodeId(r["id"].as_u64().unwrap());
+    let before = path(&s, id);
+    drag(&mut s, "smooth", &[(195.0, 194.0), (205.0, 194.0)], Mods::default());
+    let p = path(&s, id);
+    assert_ne!(p, before, "the bump is smoothed");
+    let a = &p.subpaths[0].anchors;
+    let (first, second, last) = (a[0], a[1], a[a.len() - 1]);
+    assert!(first.p == Point::new(50.0, 200.0) && !first.has_out() && !second.has_in(), "the left side is a line still: {first:?} {second:?}");
+    assert!(last.p == Point::new(350.0, 200.0) && !last.has_in() && !a[a.len() - 2].has_out(), "and the right one: {last:?}");
+    // Every other anchor is within the tool's reach of the drag (12 px either way).
+    for x in &a[1..a.len() - 1] {
+        assert!((182.0..=218.0).contains(&x.p.x) && (190.0..=201.0).contains(&x.p.y), "{x:?}");
+    }
+}
+
 #[test]
 fn join_tool_joins_two_lines() {
     let mut s = session();
@@ -1141,6 +1164,31 @@ fn the_pen_continues_any_open_path_and_joins_another() {
     assert_eq!(pts(&s, a), [(400.0, 200.0), (300.0, 200.0), (200.0, 100.0), (100.0, 100.0), (50.0, 50.0)]);
 }
 
+/// #1533: two corners of a rectangle brought together by Average become one anchor on Join, in
+/// one undo step; anchors that aren't on one another leave Join as it was.
+#[test]
+fn join_merges_the_selected_anchors_average_brought_together() {
+    let mut s = session();
+    let r = rect(&mut s, 100.0, 100.0, 100.0, 80.0);
+    let pts = |s: &Session| path(s, r).subpaths[0].anchors.iter().map(|x| (x.p.x, x.p.y)).collect::<Vec<_>>();
+    s.execute("select.anchors", &json!({"id": r.0, "anchors": [[0, 0], [0, 1]], "mode": "set"})).unwrap();
+    assert!(s.execute("path.join", &json!({})).is_err(), "apart: nothing to merge, and the path is closed");
+    s.execute("path.average", &json!({"axis": "both"})).unwrap();
+    s.execute("path.join", &json!({})).unwrap();
+    assert_eq!(pts(&s), [(150.0, 100.0), (200.0, 180.0), (100.0, 180.0)]);
+    assert!(path(&s, r).subpaths[0].closed);
+    let sel = &s.doc().unwrap().selection;
+    assert!(sel.objects == [r] && sel.anchors.is_empty());
+    s.execute("edit.undo", &json!({})).unwrap();
+    assert_eq!(pts(&s).len(), 4);
+    // The closing pair: the first and last anchors of a closed path.
+    s.execute("select.anchors", &json!({"id": r.0, "anchors": [[0, 0], [0, 3]], "mode": "set"})).unwrap();
+    s.execute("path.average", &json!({"axis": "both"})).unwrap();
+    let before = pts(&s);
+    s.execute("path.join", &json!({})).unwrap();
+    assert_eq!(pts(&s), before[..3]);
+}
+
 /// `path.join {ids, ends}` joins the ends asked for, not the nearest pair; bad requests are errors.
 #[test]
 fn join_takes_the_paths_and_the_ends_to_join() {

crates/engine/src/tests_ids_without_selection.rs

@@ -0,0 +1,83 @@
+//! #1575: commands that take `ids` work on the objects given, with nothing selected; the
+//! selection is left as it was.
+
+use serde_json::json;
+
+use super::*;
+
+fn doc_with_rect() -> (Session, u64) {
+    let mut s = Session::new();
+    s.execute("file.new", &json!({"width": 200, "height": 200})).unwrap();
+    let id = s.execute("shape.rectangle", &json!({"x": 10, "y": 10, "width": 50, "height": 40})).unwrap()["id"].as_u64().unwrap();
+    s.execute("select.none", &json!({})).unwrap();
+    (s, id)
+}
+
+#[test]
+fn ids_stand_in_for_the_selection() {
+    for (cmd, params) in [
+        ("object.repeat.radial", json!({})),
+        ("edit.colors.invert", json!({})),
+        ("object.pattern.make", json!({"name": "P"})),
+        ("symbol.new", json!({"name": "S"})),
+        ("object.mesh.create", json!({})),
+        ("object.makePixelPerfect", json!({})),
+    ] {
+        let (mut s, id) = doc_with_rect();
+        let mut p = params;
+        p["ids"] = json!([id]);
+        let r = s.execute(cmd, &p);
+        assert!(r.is_ok(), "{cmd}: {r:?}");
+    }
+}
+
+#[test]
+fn the_selection_is_put_back_and_the_check_still_applies() {
+    let (mut s, id) = doc_with_rect();
+    // Disabled even with the object given: Make with Top Object needs two.
+    let r = s.execute("object.envelope.makeWithTopObject", &json!({"ids": [id]}));
+    assert!(matches!(r, Err(EngineError::Disabled(..))), "{r:?}");
+    assert!(s.doc().unwrap().selection.objects.is_empty(), "the stand-in selection is put back");
+    // Without ids, nothing selected is still nothing selected.
+    let r = s.execute("object.repeat.radial", &json!({}));
+    assert!(matches!(r, Err(EngineError::Disabled(..))), "{r:?}");
+}
+
+#[test]
+fn only_an_ids_key_counts() {
+    let p = json!({"ids": [3]});
+    assert_eq!(given_ids("{ids?: [id]}", &p), Some(vec![NodeId(3)]));
+    assert_eq!(given_ids("{id?|ids?, name}", &p), Some(vec![NodeId(3)]));
+    assert_eq!(given_ids("{grids: n, guides: bool}", &p), None);
+    // A word in what the description says about another key isn't the key.
+    assert_eq!(given_ids("{name: of the swatch the ids of the selection take}", &p), None);
+    assert_eq!(given_ids("{ids?: [id]}", &json!({"ids": []})), None);
+}
+
+/// Every command that names `ids` and is refused with nothing selected: given the object as `ids`
+/// it does what it does with the object selected (the same result or the same error, and the same
+/// document), so no command is let through to run on an empty selection.
+#[test]
+fn ids_do_what_the_selection_does_in_every_command_that_takes_them() {
+    let mut checked = vec![];
+    for spec in command_specs() {
+        let (mut given, id) = doc_with_rect();
+        if !cmd::params::takes_key(spec.params, "ids") || (spec.enabled)(&given).is_ok() {
+            continue;
+        }
+        let (mut selected, _) = doc_with_rect();
+        selected.execute("select.set", &json!({"ids": [id]})).unwrap();
+        let (a, b) = (given.execute(spec.id, &json!({"ids": [id]})), selected.execute(spec.id, &json!({})));
+        match (&a, &b) {
+            (Ok(_), Ok(_)) => {}
+            (Err(x), Err(y)) => assert_eq!(x.to_string(), y.to_string(), "{}", spec.id),
+            _ => panic!("{}: with ids {a:?}, with the selection {b:?}", spec.id),
+        }
+        match (given.doc(), selected.doc()) {
+            (Ok(g), Ok(s)) => assert!(g.doc == s.doc, "{}: the documents differ", spec.id),
+            (g, s) => assert_eq!(g.is_ok(), s.is_ok(), "{}", spec.id),
+        }
+        checked.push((spec.id, a.is_ok()));
+    }
+    assert!(checked.iter().filter(|c| c.1).count() >= 20, "{checked:?}");
+}

crates/engine/src/tests_menucmds.rs

@@ -1249,6 +1249,26 @@ fn ruler_guides_and_lock() {
     assert!(s.execute("guide.remove", &json!({"index": 0})).is_err());
 }
 
+/// #1534: Lock Guides locks the paths made into guides too: they can't be selected (so neither
+/// moved, reshaped nor deleted), by a click, a marquee or Select All, and locking lets them go.
+#[test]
+fn locked_guides_lock_guide_paths() {
+    let mut s = session();
+    let (a, b) = (rect(&mut s, 0.0, 0.0, 10.0, 10.0), rect(&mut s, 20.0, 20.0, 10.0, 10.0));
+    sel(&mut s, &[a]);
+    s.execute("view.guides.make", &json!({})).unwrap();
+    s.execute("view.guides.lock", &json!({"locked": true})).unwrap();
+    sel(&mut s, &[a, b]);
+    assert_eq!(selected(&s), vec![b]);
+    s.execute("select.all", &json!({})).unwrap();
+    assert_eq!(selected(&s), vec![b]);
+    s.execute("view.guides.lock", &json!({"locked": false})).unwrap();
+    sel(&mut s, &[a, b]);
+    assert_eq!(selected(&s), vec![a, b]);
+    s.execute("view.guides.lock", &json!({"locked": true})).unwrap();
+    assert_eq!(selected(&s), vec![b]);
+}
+
 fn guides(s: &Session) -> Vec<(bool, f64)> {
     s.doc().unwrap().doc.guides.iter().map(|g| (g.vertical, g.pos)).collect()
 }

crates/engine/src/tests_params.rs

@@ -2,7 +2,7 @@
 
 use serde_json::json;
 
-use crate::cmd::params::{UNCHECKED, check_keys, check_params, doc_keys};
+use crate::cmd::params::{UNCHECKED, check_effect_params, check_keys, check_params, doc_keys};
 use crate::{EngineError, Session, command_specs, find_command};
 
 fn keys(doc: &str) -> Vec<&str> {
@@ -95,6 +95,50 @@ fn a_batch_checks_its_steps() {
     assert_eq!(refusal("command.batch", json!({"steps": []})), "unknown parameter `steps`; the command takes: label, commands, artboard");
 }
 
+/// #1592: the `params` of an effect are held to the effect's own keys and types, where the effect
+/// is named (`effect.apply`) and where the document says which it is (`effect.setParams`).
+#[test]
+fn effect_params_are_the_effects_own() {
+    use vectorcraft_render::effects::effect_catalog;
+    for e in effect_catalog() {
+        doc_keys(e.params).unwrap_or_else(|why| panic!("{}: {why}", e.id));
+        check_effect_params("effect.apply", e.id, &e.defaults).unwrap_or_else(|why| panic!("{}'s defaults: {why}", e.id));
+    }
+    let apply = |effect: &str, params| json!({"effect": effect, "params": params});
+    assert_eq!(refusal("effect.apply", apply("blur.gaussian", json!({"blurr": 3}))), "unknown parameter `blurr`; the command takes: radius");
+    assert_eq!(
+        refusal("appearance.addEffect", apply("stylize.dropShadow", json!({"opacty": 50}))),
+        "unknown parameter `opacty`; did you mean `opacity`?"
+    );
+    assert_eq!(refusal("effect.apply", apply("blur.gaussian", json!({"radius": "big"}))), "`radius` must be a number");
+    assert_eq!(refusal("effect.apply", apply("threeD.revolve", json!({"shade": 1}))), "`shade` must be true or false");
+    assert_eq!(refusal("effect.apply", apply("threeD.revolve", json!({"edge": 1}))), "`edge` must be a string");
+    // Out of range is the effect's to clamp; a key only its description names is one it takes;
+    // a plug-in's are its manifest's; an unknown effect is the command's to report.
+    for (effect, params) in [
+        ("stylize.dropShadow", json!({"opacity": 500, "x": -3, "color": "#ff0000"})),
+        ("stylize.dropShadow", json!({"color": [1, 0, 0]})),
+        ("threeD.revolve", json!({"segments": 100000})),
+        ("path.outlineStroke", json!({"width": 2})),
+        ("plugin.anything", json!({"whatever": 1})),
+        ("no.such", json!({"whatever": 1})),
+    ] {
+        assert!(check_params("effect.apply", &apply(effect, params.clone())).is_ok(), "{effect} {params}");
+    }
+    // `effect.setParams` names an index: the session knows the effect there.
+    let mut s = Session::new();
+    s.execute("file.new", &json!({})).unwrap();
+    s.execute("shape.rectangle", &json!({"x": 10, "y": 10, "width": 50, "height": 40})).unwrap();
+    s.execute("effect.apply", &apply("blur.gaussian", json!({"radius": 2}))).unwrap();
+    for (params, why) in [(json!({"blurr": 3}), "unknown parameter `blurr`"), (json!({"radius": true}), "`radius` must be a number")] {
+        let e = s.execute("effect.setParams", &json!({"index": 0, "params": params})).unwrap_err().to_string();
+        assert!(e.contains(why), "{e}");
+    }
+    s.execute("effect.setParams", &json!({"index": 0, "params": {"radius": 1e9}, "visible": false})).unwrap();
+    // No effect at the index: the command says so, not the check.
+    assert!(s.check_params("effect.setParams", &json!({"index": 7, "params": {"blurr": 3}})).is_ok());
+}
+
 /// What a command notes for its journal entry is a key its description names, so the entry
 /// passes the check a caller's params get.
 #[test]

crates/engine/src/tests_pathops.rs

@@ -893,3 +893,40 @@ fn divide_keeps_implicitly_closed_filled_paths_including_zero_signed_area() {
         assert!(pieces.iter().all(|n| n.appearance == source.appearance));
     }
 }
+
+/// #1570: Trim, Merge and Crop remove the objects' strokes; Merge then merges same-coloured
+/// fills whatever their strokes were.
+#[test]
+fn trim_merge_and_crop_remove_strokes() {
+    for op in ["trim", "merge", "crop"] {
+        let mut s = session();
+        let (a, b) = two_rects(&mut s);
+        for (id, c) in [(a, Color::rgb(0.0, 0.0, 0.0)), (b, Color::rgb(1.0, 0.0, 0.0))] {
+            s.edit("t", |d, _| {
+                d.node_mut(id).unwrap().appearance = Appearance::basic(Paint::solid(Color::rgb(0.0, 0.0, 1.0)), Paint::solid(c), 3.0).into();
+                Ok(())
+            })
+            .unwrap();
+        }
+        s.execute("select.set", &json!({"ids": [a.0, b.0]})).unwrap();
+        let r = ids(&s.execute(&format!("object.pathfinder.{op}"), &json!({})).unwrap());
+        let g = node(&s, r[0]);
+        let pieces = g.children().unwrap();
+        assert!(!pieces.is_empty(), "{op}");
+        assert!(pieces.iter().all(|c| c.appearance.stroke_width() == 0.0 && c.appearance.fill().is_some()), "{op} keeps a stroke");
+        if op == "merge" {
+            assert_eq!(pieces.len(), 1, "same fill, different strokes: merged");
+        }
+    }
+}
+
+/// #1590: an inset larger than the shape leaves nothing, and the error says so rather than asking
+/// for paths that are selected.
+#[test]
+fn offset_path_that_leaves_nothing_says_so() {
+    let mut s = session();
+    let a = rect(&mut s, 0.0, 0.0, 10.0, 10.0);
+    s.execute("select.set", &json!({"ids": [a.0]})).unwrap();
+    let e = s.execute("object.path.offsetPath", &json!({"offset": -20})).unwrap_err().to_string();
+    assert!(e.contains("leaves nothing") && !e.contains("select paths"), "{e}");
+}

crates/engine/src/tests_rasterfilters.rs

@@ -106,10 +106,19 @@ fn listed_applied_edited_and_undone() {
             assert_eq!((&e["raster"], &e["menu"]), (&json!(true), &json!(["Effect", menu])), "{id}");
         }
     }
-    // Junk parameters are stored as given and read clamped; the canvas still draws.
+    // Numbers far out of range are stored as given and read clamped; the canvas still draws.
     for (id, _) in EFFECTS {
-        s.execute("effect.apply", &json!({"effect": id, "ids": [g], "params": {"amount": 1e308, "radius": -1e308, "threshold": "x", "quality": 7}}))
-            .unwrap();
+        let defaults = vectorcraft_render::effects::default_params(id).unwrap();
+        let junk: serde_json::Map<String, Value> = defaults
+            .as_object()
+            .unwrap()
+            .iter()
+            .filter(|(_, v)| v.is_number())
+            .enumerate()
+            .map(|(i, (k, _))| (k.clone(), json!(if i % 2 == 0 { 1e308 } else { -1e308 })))
+            .collect();
+        assert!(!junk.is_empty(), "{id}");
+        s.execute("effect.apply", &json!({"effect": id, "ids": [g], "params": junk})).unwrap();
     }
     let _ = render(&s);
     let n = s.doc().unwrap().doc.node(NodeId(g)).unwrap().clone();

crates/engine/tests/param_keys.rs

@@ -22,6 +22,28 @@ fn a_journal_with_a_key_no_longer_read_still_replays() {
     assert_eq!((st.doc.artboards[0].rect.width(), st.doc.layers[0].children().unwrap().len()), (300.0, 1));
 }
 
+/// So do an effect's own parameters (#1592): a journal or a file with a key the effect doesn't
+/// take, or a value of another type, replays and opens; the effect reads what it knows, clamped.
+#[test]
+fn effect_params_no_longer_taken_still_replay_and_open() {
+    let mut s = Session::new();
+    s.execute("file.new", &json!({})).unwrap();
+    s.execute("shape.rectangle", &json!({"x": 10, "y": 10, "width": 50, "height": 40})).unwrap();
+    let old = [
+        ("effect.apply", json!({"effect": "blur.gaussian", "params": {"blurr": 3, "radius": "big"}})),
+        ("effect.setParams", json!({"index": 0, "params": {"amount": 1e308}})),
+    ];
+    for (id, params) in &old {
+        assert!(s.check_params(id, params).is_err(), "{id}");
+        s.execute(id, params).unwrap();
+    }
+    let doc = &s.active().unwrap().doc;
+    let back = vectorcraft_format::load(&vectorcraft_format::save(doc, false)).unwrap();
+    let stored = |d: &vectorcraft_doc::Document| d.layers[0].children().unwrap()[0].appearance.effects[0].params.clone();
+    assert_eq!(stored(&back), stored(doc));
+    assert_eq!(stored(&back)["blurr"], json!(3));
+}
+
 /// What a command adds to its own journal entry passes the check, so a recorded journal can be
 /// sent back through the control channel or MCP.
 #[test]

crates/eps/src/import/ai/paint.rs

@@ -158,8 +158,11 @@ impl GradientDef {
         if self.gradient.stops.is_empty() {
             return None;
         }
-        // Stops come last first: reversed, stops sharing a ramp point keep their order.
-        self.gradient.stops.reverse();
+        // Stops are listed along the ramp from either end: listed downwards they're reversed, so
+        // stops sharing a ramp point keep their order (and each its midpoint, to the next stop).
+        if self.gradient.stops.first().zip(self.gradient.stops.last()).is_some_and(|(first, last)| first.offset > last.offset) {
+            self.gradient.stops.reverse();
+        }
         self.gradient.stops.sort_by(|a, b| a.offset.total_cmp(&b.offset));
         Some((self.name, self.gradient))
     }

crates/eps/src/import/ai/tests.rs

@@ -410,6 +410,19 @@ fn stops_sharing_a_ramp_point_keep_their_order() {
     assert_eq!(colors, [Color::rgb(0.0, 0.0, 1.0), Color::rgb(0.0, 1.0, 0.0), Color::rgb(1.0, 0.0, 0.0)]);
 }
 
+#[test]
+fn stops_listed_upwards_keep_the_midpoint_of_the_one_that_starts_the_ramp() {
+    // GUARDS: reversing a list that runs upwards swaps two stops at 0, and the ramp to 100 takes the
+    // midpoint of the zero-length part between them.
+    let defs = "%AI5_BeginGradient: (U)\n(U) 0 3 Bd\n[\n<00FF>\n0\n%_0 0 0 0 1 1 1 2 1 6 50 0 Bs\n\
+                %_0 0 0 0 1 1 1 2 1 6 87 0 Bs\n%_0 0 0 0 0 0 0 2 1 6 50 100 Bs\nBD\n%AI5_EndGradient\n";
+    let art_ = format!("{}Bb\n1 (U) 0 0 0 1 1 0 0 1 0 0 1 Bg\n10 0 0 10 100 50 Xm\nf\n0 BB\n", rect_path(0.0, 0.0, 200.0, 100.0));
+    let doc = read_ok(&format!("{defs}{}", layer(&art_))).doc;
+    let Paint::Gradient(g) = fill(&art(&doc)[0]) else { panic!() };
+    let midpoints: Vec<_> = g.gradient.stops.iter().map(|s| s.midpoint).collect();
+    assert_eq!(midpoints, [0.5, 0.87, 0.5]);
+}
+
 #[test]
 fn per_anchor_data_reads() {
     let art_ = format!("{RED}{}f\n(00800080) Xt 0 XD\n%_(00004000) Xt 1 XD\n", rect_path(0.0, 0.0, 10.0, 10.0));

crates/eps/src/import/graphics.rs

@@ -366,9 +366,9 @@ impl Out {
     /// A new clip of `path` inside `clips`; `None` for a rectangle around the whole page, which
     /// clips nothing.
     fn clip(&mut self, path: BezPath, rule: FillRule) -> Option<Arc<Clip>> {
-        let lines = path.elements().iter().all(|e| !matches!(e, PathEl::QuadTo(..) | PathEl::CurveTo(..)));
-        let around = path.bounding_box().inflate(0.5, 0.5);
-        if lines && path.elements().len() <= 6 && around.contains(self.frame.origin()) && around.contains(Point::new(self.frame.x1, self.frame.y1)) {
+        // Only a polygon that really covers the page: a diamond touching its edges has the page as
+        // its bounding box but cuts its corners away (#1542).
+        if path.elements().len() <= 6 && vectorcraft_geom::hit::polygon_covers_rect(&path, self.frame, 0.5) {
             return None;
         }
         self.next_clip += 1;

crates/eps/src/import/tests.rs

@@ -248,6 +248,12 @@ fn clips_become_clipping_groups() {
     // eoclip of a path.
     let o = objects(&read("10 10 moveto 30 10 lineto 30 30 lineto closepath eoclip newpath 0 0 50 50 rectfill").document);
     assert!(matches!(o[0].kind, NodeKind::Group { clip: true, .. }));
+    // #1542: a diamond touching the page edges has the page as its bounding box but still clips.
+    let o = objects(&read("50 0 moveto 100 50 lineto 50 100 lineto 0 50 lineto closepath clip newpath 0 0 100 100 rectfill").document);
+    assert!(matches!(o[0].kind, NodeKind::Group { clip: true, .. }), "{:?}", o[0].kind);
+    // A turned square around the whole page clips nothing.
+    let o = objects(&read("50 -60 moveto 160 50 lineto 50 160 lineto -60 50 lineto closepath clip newpath 0 0 100 100 rectfill").document);
+    assert!(matches!(o[0].kind, NodeKind::Path { .. }), "{:?}", o[0].kind);
 }
 
 #[test]
@@ -467,6 +473,22 @@ fn the_bounding_box_comes_from_the_header_or_the_trailer() {
     assert!(r.warnings.iter().any(|w| w.contains("first of the file's 2 pages")), "{:?}", r.warnings);
 }
 
+/// #1552: a Type 42 font's glyph space is one unit an em, so its identity FontMatrix scaled to 12
+/// sets 12 pt type (a Type 1's 0.001 matrix needs the 1000-unit space).
+#[test]
+fn type_42_fonts_set_type_at_their_size() {
+    for (kind, matrix) in [(42, "[1 0 0 1 0 0]"), (1, "[0.001 0 0 0.001 0 0]")] {
+        let body = format!(
+            "/T 10 dict begin /FontName /T def /FontType {kind} def /FontMatrix {matrix} def /Encoding StandardEncoding def currentdict end /T exch definefont pop \
+             /T findfont 12 scalefont setfont 10 20 moveto (Hi) show"
+        );
+        let r = read(&body);
+        let NodeKind::Text(t) = &objects(&r.document)[0].kind else { panic!("{:?}", r.warnings) };
+        let size = t.runs[0].style.size * t.xf.determinant().abs().sqrt();
+        assert!((size - 12.0).abs() < 1e-6, "FontType {kind}: {size} pt");
+    }
+}
+
 #[test]
 fn embedded_font_programs_are_skipped() {
     let body = "/MyFont 10 dict begin /FontName /MyFont def /FontMatrix [0.001 0 0 0.001 0 0] def currentdict end currentfile eexec\n\

crates/eps/src/import/text.rs

@@ -403,7 +403,10 @@ impl Interp<'_> {
         let f = font.borrow();
         let name = f.get(&Key::name("FontName")).and_then(Obj::text).map_or_else(|| DEFAULT_FONT.to_string(), |n| n.to_string());
         let m = f.get(&Key::name("FontMatrix")).and_then(|o| o.items().and_then(|i| matrix_of(&i.borrow()))).unwrap_or(Affine::scale(0.001));
-        Ok((name, m * Affine::scale(1000.0)))
+        // Type 1 glyphs are in 1000-unit space; a Type 42 font's glyph space is one unit an em
+        // (its FontMatrix, usually the identity, is already the em's).
+        let units = if f.get(&Key::name("FontType")).and_then(Obj::as_num) == Some(42.0) { 1.0 } else { 1000.0 };
+        Ok((name, m * Affine::scale(units)))
     }
 
     /// `s` (read as Latin-1) set in the current font at user point `at`: point type placed there,

crates/geom/src/corners.rs

@@ -155,8 +155,8 @@ impl Corner {
         let (h_out, h_in) = match kind {
             // An arc tangent to both sides, turning by 180° less the angle between them there.
             CornerKind::Round => {
-                let h = radius * arc_handle(-cos);
-                (start - du * h, end - dv * h)
+                let (hu, hv) = self.round_handles(radius, (start, du), (end, dv));
+                (start - du * hu, end - dv * hv)
             }
             // An arc centred on the corner through both ends, spanning the angle.
             CornerKind::InvertedRound => {
@@ -169,6 +169,33 @@ impl Corner {
     }
 }
 
+impl Corner {
+    /// The handle lengths of a round cut of `radius` between `start` and `end` (each a point and
+    /// the direction its side runs on in there). Between straight sides they are the arc's. A
+    /// curved side has turned by the time the cut meets it, so the arc's handles would reach past
+    /// where the tangents at the cut's ends cross and the cut would stick out of the corner
+    /// (#1512): there each handle is the share an arc takes of its tangent, up to that crossing
+    /// (a third of the way to the other end where the tangents don't cross between them).
+    fn round_handles(&self, radius: f64, (start, du): (Point, Vec2), (end, dv): (Point, Vec2)) -> (f64, f64) {
+        let cos = du.dot(dv);
+        let arc = arc_handle(-cos);
+        if self.side_u.straight() && self.side_v.straight() {
+            return (radius * arc, radius * arc);
+        }
+        // start − du·a = end − dv·b is where the tangents cross.
+        let (cross, w) = (du.cross(dv), start - end);
+        let (a, b) = (w.cross(dv) / cross, w.cross(du) / cross);
+        if cross.abs() > MIN_SINE && a > EPS && b > EPS && a.is_finite() && b.is_finite() {
+            // An arc's handle over its tangent's length, radius · tan(turn / 2).
+            let share = arc * (1.0 - cos) / cross.abs();
+            (a * share, b * share)
+        } else {
+            let third = start.distance(end) / 3.0;
+            (third, third)
+        }
+    }
+}
+
 /// A corner cut: the parameters where it meets its sides (from the corner), its two new anchors
 /// and the handles between them.
 #[derive(Clone, Copy, Debug)]
@@ -401,6 +428,30 @@ mod tests {
         }
     }
 
+    /// A round cut next to a curve stays inside its corner, however large (#1512): its handles
+    /// stop short of where the tangents at its ends cross, so it doesn't stick out past the sides.
+    #[test]
+    fn a_round_cut_next_to_a_curve_stays_inside_its_corner() {
+        // A square whose top side arches up, meeting the upright sides at an angle.
+        let mut sp =
+            SubPath::polyline(&[Point::new(100.0, 150.0), Point::new(300.0, 150.0), Point::new(300.0, 300.0), Point::new(100.0, 300.0)], true);
+        sp.anchors[0].h_out = Point::new(120.0, 20.0);
+        sp.anchors[1].h_in = Point::new(280.0, 20.0);
+        let path = PathData::single(sp);
+        let bounds = path.bounds().unwrap().inflate(1e-6, 1e-6);
+        for radius in [10.0, 60.0, 200.0, 1e6] {
+            let (cut, _) = cut_corners(&path, &[radius, radius], &[]);
+            let b = cut.bounds().unwrap();
+            assert!(bounds.union(b) == bounds, "radius {radius}: {b:?} is outside {bounds:?}");
+            // Each cut's handles end before its tangents cross: the cut turns one way only.
+            let a = &cut.subpaths[0].anchors;
+            for (from, to) in [(a[a.len() - 1], a[0]), (a[1], a[2])] {
+                let (t0, t1, chord) = (from.h_out - from.p, to.p - to.h_in, to.p - from.p);
+                assert!(t0.cross(chord) * chord.cross(t1) > 0.0 && t0.cross(t1) * t0.cross(chord) > 0.0, "radius {radius}: {from:?} {to:?}");
+            }
+        }
+    }
+
     /// Inverted round and chamfer cuts end where the round one does, at any angle.
     #[test]
     fn kinds_share_their_ends() {

crates/geom/src/hit.rs

@@ -6,6 +6,47 @@ use kurbo::{BezPath, ParamCurveNearest, PathEl, Point, Rect, Shape};
 
 use crate::path::{FillRule, PathData};
 
+/// Does the filled area of `path` cover all of `r` shrunk by `tol` on every side? Answered for one
+/// convex polygon (a single subpath of straight segments), which covers the rect when it contains
+/// its four corners; any other path gives `false`, so a caller treats it as not covering.
+pub fn polygon_covers_rect(path: &BezPath, r: Rect, tol: f64) -> bool {
+    let mut pts: Vec<Point> = Vec::new();
+    for (i, el) in path.elements().iter().enumerate() {
+        match *el {
+            PathEl::MoveTo(p) if i == 0 => pts.push(p),
+            PathEl::LineTo(p) if i > 0 => pts.push(p),
+            PathEl::ClosePath if i > 0 => {}
+            _ => return false,
+        }
+    }
+    if pts.len() > 1 && pts.first() == pts.last() {
+        pts.pop();
+    }
+    if pts.len() < 3 {
+        return false;
+    }
+    // Convex: every turn goes the same way (straight runs allowed).
+    let n = pts.len();
+    let mut sign = 0.0f64;
+    for i in 0..n {
+        let (a, b, c) = (pts[i], pts[(i + 1) % n], pts[(i + 2) % n]);
+        let cross = (b - a).cross(c - b);
+        if cross.abs() <= 1e-9 {
+            continue;
+        }
+        if sign == 0.0 {
+            sign = cross.signum();
+        } else if cross.signum() != sign {
+            return false;
+        }
+    }
+    let inner = r.inflate(-tol, -tol);
+    sign != 0.0
+        && [Point::new(inner.x0, inner.y0), Point::new(inner.x1, inner.y0), Point::new(inner.x1, inner.y1), Point::new(inner.x0, inner.y1)]
+            .into_iter()
+            .all(|c| fill_contains(path, FillRule::NonZero, c))
+}
+
 /// Is `p` inside the filled area of `path` under `rule`? Open subpaths are implicitly closed (as when filled).
 pub fn fill_contains(path: &BezPath, rule: FillRule, p: Point) -> bool {
     let w = closed(path).winding(p);
@@ -94,6 +135,32 @@ mod tests {
     use super::*;
     use crate::shapes;
 
+    #[test]
+    fn polygon_covers_rect_only_for_convex_polygons_around_it() {
+        let page = Rect::new(0.0, 0.0, 100.0, 100.0);
+        let poly = |pts: &[(f64, f64)]| {
+            let mut b = BezPath::new();
+            b.move_to(pts[0]);
+            for &p in &pts[1..] {
+                b.line_to(p);
+            }
+            b.close_path();
+            b
+        };
+        assert!(polygon_covers_rect(&poly(&[(0.0, 0.0), (100.0, 0.0), (100.0, 100.0), (0.0, 100.0)]), page, 0.01));
+        assert!(polygon_covers_rect(&poly(&[(50.0, -60.0), (160.0, 50.0), (50.0, 160.0), (-60.0, 50.0)]), page, 0.01), "turned, around it");
+        // The page's bounding box, but its corners are cut away.
+        assert!(!polygon_covers_rect(&poly(&[(50.0, 0.0), (100.0, 50.0), (50.0, 100.0), (0.0, 50.0)]), page, 0.01));
+        // Contains the corners but notches into the page: not convex.
+        assert!(!polygon_covers_rect(&poly(&[(-1.0, -1.0), (101.0, -1.0), (101.0, 101.0), (50.0, 40.0), (-1.0, 101.0)]), page, 0.01));
+        // Curves and several subpaths aren't judged.
+        assert!(!polygon_covers_rect(&kurbo::Circle::new((50.0, 50.0), 200.0).to_path(0.1), page, 0.01));
+        let mut two = poly(&[(0.0, 0.0), (100.0, 0.0), (100.0, 100.0), (0.0, 100.0)]);
+        two.extend(poly(&[(10.0, 10.0), (20.0, 10.0), (20.0, 20.0)]));
+        assert!(!polygon_covers_rect(&two, page, 0.01));
+        assert!(!polygon_covers_rect(&BezPath::new(), page, 0.01));
+    }
+
     #[test]
     fn fill_and_stroke() {
         let p = shapes::rectangle(Rect::new(0.0, 0.0, 10.0, 10.0)).to_bezpath();

crates/mcp/src/headless.rs

@@ -128,7 +128,7 @@ impl Headless {
         // A key the command's description doesn't name is an error, not a default (#1442).
         match HOST_COMMANDS.iter().find(|c| c.0 == id) {
             Some((_, _, doc)) => vectorcraft_engine::check_keys(id, doc, params),
-            None => vectorcraft_engine::check_params(id, params),
+            None => self.session.check_params(id, params),
         }
         .map_err(|e| e.to_string())?;
         match id {

crates/pdf/src/import.rs

@@ -26,6 +26,8 @@ use crate::import_shading::{clipped, extend_clip, fold_stop_opacity, gradient_sh
 use crate::import_text::{Families, LineFacts, Look, Placement, TextLine, Upright};
 use crate::{CropTo, ImportOptions, ImportReport, PdfError, TextAs};
 
+/// Mixed into an image's cache key when it is read white inside an alpha soft mask.
+const WHITE_KEY: u128 = 0x7717_e000_a1fa;
 /// The name of the paths text imports as.
 const TEXT_OUTLINES: &str = "<Text Outlines>";
 /// A page whose overprint (ISO 32000-1 §8.6.7) is left out rather than given to the wrong objects.
@@ -197,6 +199,8 @@ pub fn import_with_report(bytes: &[u8], opts: &ImportOptions) -> Result<ImportRe
     b.colors.uncalibrated_rgb = opts.uncalibrated_rgb && picked.iter().filter_map(|&n| pages.get(n)).any(crate::pages::has_private_data);
     let cache = InterpreterCache::new();
     let mut x = 0.0;
+    // Where the next page's art may begin (a `.ai` page's art reaches past its artboard).
+    let mut clear = f64::NEG_INFINITY;
     // Every page only text over private data: a file saved without its PDF part shows a notice
     // there, not its art. A page that states where its art is isn't that notice.
     let (mut only_text, mut art_boxes) = (true, false);
@@ -220,6 +224,8 @@ pub fn import_with_report(bytes: &[u8], opts: &ImportOptions) -> Result<ImportRe
         let xf = Affine::translate((x - frame.x0, -frame.y0)) * init;
         let mut ctx = Context::new(xf, ab, &cache, pdf.xref(), settings.clone());
         b.page = ab;
+        // The first id of this page's art.
+        let first_id = b.next;
         let scan = scan_page(page, &mut ocgs, all_on, &mut b.fonts);
         if route {
             let mut seen = HashSet::new();
@@ -267,6 +273,33 @@ pub fn import_with_report(bytes: &[u8], opts: &ImportOptions) -> Result<ImportRe
         if clipped {
             b.warn(PAST_PAGE_NOTE);
         }
+        // A `.ai` page keeps its art past the artboard edge, unclipped (#646), so a page whose art
+        // reaches far to the left would lay it over the page before it in the row: there it would
+        // be taken for that page's art (by the check against the editing data, which then finds
+        // art its layers don't have there, and by `place_pages`). Such a page moves right until its
+        // art clears the art before it.
+        let mut art_right = f64::NEG_INFINITY;
+        if ai && let Some(art) = parts.iter().flat_map(|(_, v)| v.iter()).filter_map(|n| n.visual_bounds()).reduce(|a, b| a.union(b)) {
+            // Art at a coordinate that isn't a number (a damaged file) moves nothing.
+            let dx = Some((clear - art.x0).max(0.0)).filter(|dx| dx.is_finite()).unwrap_or(0.0);
+            if dx > 0.0 {
+                let shift = Affine::translate((dx, 0.0));
+                for (_, v) in &mut parts {
+                    for n in v.iter_mut() {
+                        Arc::make_mut(n).transform(shift, false);
+                    }
+                }
+                // What the page's lines of type were is told where their glyphs are (the outlines
+                // stroked on them are looked for there), so that moves with them.
+                for facts in b.lines.iter_mut().filter(|(id, _)| id.0 >= first_id).map(|(_, facts)| facts) {
+                    for ink in &mut facts.ink {
+                        *ink = *ink + kurbo::Vec2::new(dx, 0.0);
+                    }
+                }
+                ab = Rect::new(ab.x0 + dx, ab.y0, ab.x1 + dx, ab.y1);
+            }
+            art_right = art.x1 + dx;
+        }
         let children: Vec<Arc<Node>> = parts.iter().flat_map(|(_, v)| v.iter().cloned()).collect();
         only_text &= ai && is_only_text(&children);
         art_boxes |= crate::pages::states_art(page);
@@ -278,6 +311,7 @@ pub fn import_with_report(bytes: &[u8], opts: &ImportOptions) -> Result<ImportRe
             ab = art;
         }
         x = right + opts.artboard_gap;
+        clear = right.max(art_right) + opts.artboard_gap;
         doc.artboards.push(Artboard {
             id: i as u32 + 1,
             name: format!("Artboard {}", i + 1),
@@ -756,6 +790,10 @@ struct Builder<'p> {
     /// A transparency group was just pushed: a form's (whose flags come next) or an image's.
     pending: bool,
     nested: u32,
+    /// Reading an alpha soft mask's art: images are read white with their own alpha, so the
+    /// mask's luminance is their alpha, as whitened vector art's is (cairo, and so Inkscape,
+    /// rasterizes masks into such images).
+    white_images: bool,
     /// The last filled path: its node and its outline (a stroke of the same outline joins it).
     last_fill: Option<(NodeId, BezPath)>,
     /// What each line of type made tells beyond its text object ([`crate::import_lines`]).
@@ -898,6 +936,7 @@ impl<'p> Builder<'p> {
             marked: vec![],
             pending: false,
             nested: 0,
+            white_images: false,
             last_fill: None,
             lines: HashMap::new(),
         }
@@ -1202,11 +1241,50 @@ impl<'p> Builder<'p> {
     }
 
     fn flush_text(&mut self) {
-        let Some((t, opacity, facts)) = self.text.take().and_then(TextLine::finish) else { return };
-        let mut n = Node::new(self.id(), NodeKind::Text(Box::new(t)));
-        n.opacity = opacity;
-        self.lines.insert(n.id, facts);
-        self.push_node(n);
+        let Some(mut line) = self.text.take() else { return };
+        let held = std::mem::take(&mut line.held);
+        if let Some((t, opacity, facts)) = line.finish() {
+            let mut n = Node::new(self.id(), NodeKind::Text(Box::new(t)));
+            n.opacity = opacity;
+            self.lines.insert(n.id, facts);
+            self.push_node(n);
+        }
+        // The strokes of its glyphs' outlines, right after it ([`import_lines`] makes them its stroke).
+        for n in held {
+            self.push_node(n);
+        }
+    }
+
+    /// A stroke of the outline of the glyph just drawn, in the glyph's own paint, while every glyph
+    /// before it on the open line was stroked so too, is held with the line instead of ending it
+    /// (an editor writes type on a path glyph by glyph, each followed by the stroke added to the
+    /// type). `false`: it isn't one.
+    fn hold_glyph_stroke(&mut self, path: &BezPath, transform: Affine, paint: &hayro_interpret::Paint<'_>, draw_mode: &PathDrawMode) -> bool {
+        let PathDrawMode::Stroke(props) = draw_mode else { return false };
+        if self.mask.is_some() || self.blend != BlendMode::Normal || matches!(paint, hayro_interpret::Paint::Pattern(_)) {
+            return false;
+        }
+        let (p, opacity) = self.paint(paint, true);
+        let Some(line) = &self.text else { return false };
+        let Some(ink) = line.ink.last() else { return false };
+        if line.held.len() + 1 != line.ink.len() || opacity < 0.999 || !line.last_fill().is_some_and(|f| *f == p) {
+            return false;
+        }
+        let mut bp = path.clone();
+        bp.apply_affine(transform);
+        let b = bp.bounding_box();
+        let tol = 0.01 * (ink.width() + ink.height()) + 0.01;
+        if ![(b.x0, ink.x0), (b.y0, ink.y0), (b.x1, ink.x1), (b.y1, ink.y1)].iter().all(|(a, c)| (a - c).abs() <= tol) {
+            return false;
+        }
+        let mut st = stroke_layer(p, opacity, props, mean_scale(transform));
+        // Every painted path takes its turn in the scan's overprint list, a held one too.
+        st.overprint = self.path_overprint();
+        let n = Node::path(self.id(), PathData::from_bezpath(&bp), Appearance { items: vec![AppearanceItem::Stroke(st)], ..Default::default() });
+        if let Some(line) = &mut self.text {
+            line.held.push(n);
+        }
+        true
     }
 
     /// Convert a hayro paint to a VectorCraft paint and opacity (`stroke`: for a stroke).
@@ -1267,7 +1345,10 @@ impl<'p> Builder<'p> {
             return s.clone();
         }
         let page = self.page;
-        let spec = match self.nested(page, |b| m.interpret(b)) {
+        let saved = std::mem::replace(&mut self.white_images, m.mask_type() == MaskType::Alpha);
+        let art = self.nested(page, |b| m.interpret(b));
+        self.white_images = saved;
+        let spec = match art {
             Some(art) => {
                 let [r, g, b, _] = m.background_color().to_rgba().components();
                 let backdrop = luminance(&Color::rgb(r, g, b));
@@ -1298,10 +1379,15 @@ impl<'p> Builder<'p> {
         {
             return Some(Paint::Pattern { pattern: name.clone(), xf });
         }
+        // A swatch is shared with uses outside an alpha mask, and pattern paints keep their
+        // colours there: its images are read as they are.
+        let white = std::mem::take(&mut self.white_images);
         let art = self.nested(Rect::ZERO, |b| {
             // A cell whose content can't be decoded is empty.
             let _ = t.interpret(b, Affine::IDENTITY, stroke);
-        })?;
+        });
+        self.white_images = white;
+        let art = art?;
         let sig = paints(&art);
         let entry = self.pattern_keys.entry(key).or_default();
         entry.0 += 1;
@@ -1620,6 +1706,10 @@ impl<'a> Device<'a> for Builder<'_> {
 
     fn draw_path(&mut self, path: &BezPath, transform: Affine, paint: &hayro_interpret::Paint<'a>, draw_mode: &PathDrawMode) {
         self.flush_glyphs();
+        if self.hold_glyph_stroke(path, transform, paint, draw_mode) {
+            self.pending = false;
+            return;
+        }
         self.flush_text();
         self.pending = false;
         let overprint = self.path_overprint();
@@ -1722,14 +1812,12 @@ impl<'a> Device<'a> for Builder<'_> {
                 (*isolate, *knockout) = (i, k);
             }
         }
-        let bb = clip_path.path.bounding_box();
-        // Clips that contain the whole page do nothing visible; don't create groups for them.
+        // Clips that contain the whole page do nothing visible; don't create groups for them. Only
+        // a polygon that really covers it counts: a diamond touching the page edges has the page
+        // as its bounding box but cuts its corners away (#1542).
         let redundant = clip_path.path.elements().len() <= 6
-            && bb.x0 <= self.page.x0 + 0.01
-            && bb.y0 <= self.page.y0 + 0.01
-            && bb.x1 >= self.page.x1 - 0.01
-            && bb.y1 >= self.page.y1 - 0.01
-            && self.page.area() > 0.0;
+            && self.page.area() > 0.0
+            && vectorcraft_geom::hit::polygon_covers_rect(&clip_path.path, self.page, 0.01);
         let kind = if redundant { FrameKind::Skip } else { FrameKind::Clip(Box::new(self.clip_node(&clip_path.path, fill_rule(clip_path.fill)))) };
         self.stack.push(Frame::new(kind));
     }
@@ -1802,12 +1890,14 @@ impl<'a> Device<'a> for Builder<'_> {
         self.pending = false;
         match image {
             Image::Raster(r) => {
-                let key = hayro_interpret::CacheKey::cache_key(&r);
+                let white = self.white_images;
+                // Inside an alpha mask the same image is read again, white (its own cache key).
+                let key = hayro_interpret::CacheKey::cache_key(&r) ^ if white { WHITE_KEY } else { 0 };
                 let st = r.stream();
                 let (w, h) = (r.width(), r.height());
                 // CMYK images keep their samples (read once per image).
-                let known = self.cmyk_keys.contains(&key);
-                let cmyk = if known {
+                let known = !white && self.cmyk_keys.contains(&key);
+                let cmyk = if known || white {
                     None
                 } else {
                     crate::import_image::cmyk(st, w, h).unwrap_or_else(|why| {
@@ -1826,7 +1916,8 @@ impl<'a> Device<'a> for Builder<'_> {
                 let dict = st.dict();
                 let filters = st.filters();
                 let cs_ok = dict.get::<Name<'_>>(b"ColorSpace").is_some_and(|n| matches!(n.as_ref(), b"DeviceRGB" | b"DeviceGray"));
-                let jpeg = filters.len() == 1
+                let jpeg = !white
+                    && filters.len() == 1
                     && matches!(filters[0], hayro_syntax::Filter::DctDecode)
                     && cs_ok
                     && !dict.contains_key(b"SMask")
@@ -1843,6 +1934,7 @@ impl<'a> Device<'a> for Builder<'_> {
                         let (w, h, sf) = (img.width(), img.height(), img.scale_factors());
                         let a = alpha.map(|a| resize_alpha(&a, w, h)).unwrap_or_else(|| vec![255; (w * h) as usize]);
                         let rgba: Vec<u8> = match img {
+                            _ if white => a.into_iter().flat_map(|a| [255, 255, 255, a]).collect(),
                             ImageData::Rgb(d) => d.data.as_chunks::<3>().0.iter().zip(a).flat_map(|(c, a)| [c[0], c[1], c[2], a]).collect(),
                             ImageData::Luma(d) => d.data.iter().zip(a).flat_map(|(g, a)| [*g, *g, *g, a]).collect(),
                         };
@@ -1858,11 +1950,13 @@ impl<'a> Device<'a> for Builder<'_> {
                 self.add_image(key, || rgba_png(rgba, w, h).map(|png| (ImageBlob::new("image/png", png), w, h)), xf);
             }
             Image::Stencil(s) => {
-                let key = hayro_interpret::CacheKey::cache_key(&s);
+                let white = self.white_images;
+                let key = hayro_interpret::CacheKey::cache_key(&s) ^ if white { WHITE_KEY } else { 0 };
                 let mut decoded: Option<Decoded> = None;
                 s.with_stencil(
                     |luma, paint| {
                         let rgb = match paint {
+                            _ if white => [255, 255, 255, 255],
                             hayro_interpret::Paint::Color(c) => c.to_rgba().to_rgba8(),
                             _ => [0, 0, 0, 255],
                         };

crates/pdf/src/import_text.rs

@@ -11,7 +11,7 @@ use std::collections::HashMap;
 
 use kurbo::{Affine, BezPath, Point, Rect, Vec2};
 use vectorcraft_color::Paint;
-use vectorcraft_doc::{CharStyle, ParaDirection, TextKind, TextObject, TextRun};
+use vectorcraft_doc::{CharStyle, Node, ParaDirection, TextKind, TextObject, TextRun};
 use vectorcraft_text::TextLayout;
 
 /// One glyph's placement: its baseline origin, advance direction, size and horizontal scale.
@@ -144,6 +144,9 @@ pub(crate) struct TextLine {
     gaps: Vec<(usize, f64)>,
     /// Each glyph's advance in the file's font (points), with [`Self::baseline`].
     advances: Vec<f64>,
+    /// The strokes of its glyphs' outlines drawn between them, one per glyph with ink so far
+    /// (written right after the line).
+    pub held: Vec<Node>,
 }
 
 /// What a finished line of type tells beyond its text object (see [`crate::import_lines`]).
@@ -177,9 +180,15 @@ impl TextLine {
             ink: vec![],
             gaps: vec![],
             advances: vec![],
+            held: vec![],
         }
     }
 
+    /// The paint the last glyph is filled with.
+    pub fn last_fill(&self) -> Option<&Paint> {
+        self.runs.last()?.0.fill.as_ref()
+    }
+
     /// Add glyph `text` set vertically (`upright`) if it continues this column (or makes this
     /// line's single glyph a column): below the last one, in the same column. `false`: it starts
     /// another line.
@@ -350,6 +359,20 @@ impl TextLine {
             t.runs = tracked_each(std::mem::take(&mut t.runs), own, self.at.size);
         }
         if let Some(path) = path {
+            // Evenly spaced type keeps its length along the path: the path runs through the
+            // glyphs' origins, one curve each, to the end of the last glyph, and tracking makes up
+            // the difference from the advances.
+            if own.is_none() {
+                let length: f64 = path.segments().take(self.baseline.len()).map(|seg| kurbo::ParamCurveArclen::arclen(&seg, 1e-3)).sum();
+                let laid = vectorcraft_text::layout(db, &t);
+                let natural: f64 = laid.glyphs.iter().map(|g| g.advance).sum();
+                let chars: usize = t.runs.iter().map(|r| r.text.chars().count()).sum();
+                let size = self.at.size;
+                if chars > 1 && length.is_finite() && (length - natural).abs() > size * 0.01 {
+                    let (tracking, spaces) = spacing(&laid, &[], length - natural, chars, size);
+                    t.runs = tracked(std::mem::take(&mut t.runs), tracking, &spaces);
+                }
+            }
             t.kind = TextKind::OnPath { path: vectorcraft_geom::PathData::from_bezpath(&path), start: 0.0, end: None };
             t.xf = Affine::IDENTITY;
             t.cached_bounds = Some(vectorcraft_text::layout(db, &t).bounds);

crates/pdf/src/tests_import_fidelity.rs

@@ -78,6 +78,58 @@ fn the_mask(d: &Document) -> (Node, OpacityMask) {
     (n, m)
 }
 
+/// The two pixels of the image a soft mask of kind `s` draws: black, opaque on the left and clear
+/// on the right (its own `/SMask`).
+fn mask_image_pixels(s: &str) -> [[u8; 4]; 2] {
+    let g = first_extra(1);
+    let group = stream(
+        &format!(
+            "/Type /XObject /Subtype /Form /BBox [0 0 100 100] /Group << /S /Transparency /CS /DeviceRGB >> /Resources << /XObject << /Im0 {} 0 R >> >>",
+            g + 1
+        ),
+        "q 100 0 0 100 0 0 cm /Im0 Do Q",
+    );
+    let image = stream(
+        &format!(
+            "/Type /XObject /Subtype /Image /Width 2 /Height 1 /ColorSpace /DeviceRGB /BitsPerComponent 8 /Filter /ASCIIHexDecode /SMask {} 0 R",
+            g + 2
+        ),
+        "000000000000>",
+    );
+    let smask =
+        stream("/Type /XObject /Subtype /Image /Width 2 /Height 1 /ColorSpace /DeviceGray /BitsPerComponent 8 /Filter /ASCIIHexDecode", "FF00>");
+    let bytes = one_page(
+        "/GS0 gs 1 0 0 rg 0 0 100 100 re f",
+        &format!("/ExtGState << /GS0 << /SMask << /Type /Mask /S /{s} /G {g} 0 R >> >> >>"),
+        &[&group, &image, &smask],
+    );
+    let d = open(&bytes);
+    let (_, m) = the_mask(&d);
+    let mut keys = vec![];
+    m.art.walk(&mut |n| {
+        if let NodeKind::Image(im) = &n.kind {
+            keys.push(im.key.clone());
+        }
+    });
+    let [key] = keys.as_slice() else { panic!("one image in the mask art: {keys:?}") };
+    let px = image::load_from_memory(&d.images[key].bytes).unwrap().to_rgba8();
+    [px.get_pixel(0, 0).0, px.get_pixel(1, 0).0]
+}
+
+/// An alpha soft mask whose art is an image with its own alpha (some PDF writers rasterize masks
+/// so): the image is read white with that alpha, so the mask's luminance is the alpha, not the
+/// image's colour (ISO 32000-1 11.5.2: an alpha mask takes the group's alpha, not its colour).
+#[test]
+fn an_alpha_soft_mask_of_an_image_uses_the_images_alpha() {
+    assert_eq!(mask_image_pixels("Alpha"), [[255, 255, 255, 255], [255, 255, 255, 0]]);
+}
+
+/// A luminosity soft mask takes the group's colour (ISO 32000-1 11.5.3): its image stays black.
+#[test]
+fn a_luminosity_soft_mask_of_an_image_keeps_the_images_colour() {
+    assert_eq!(mask_image_pixels("Luminosity"), [[0, 0, 0, 255], [0, 0, 0, 0]]);
+}
+
 #[test]
 fn a_luminosity_soft_mask_becomes_an_opacity_mask() {
     let d = open(&masked("/S /Luminosity", "1 1 1 rg 0 0 50 100 re f"));
@@ -544,3 +596,16 @@ fn glyphs_closed_up_by_half_an_em_stay_one_line() {
     assert_eq!(t.len(), 1, "one line: {:?}", t.iter().map(|t| t.plain_text()).collect::<Vec<_>>());
     assert_eq!(t[0].plain_text(), "Tight");
 }
+
+/// #1542: a clip only counts as covering the page when it does; a diamond whose bounding box is
+/// the page still clips, a page rectangle or a turned square around it doesn't make a group.
+#[test]
+fn clips_with_the_page_as_bounding_box_still_clip() {
+    let clipped = |clip: &str| {
+        let d = open(&one_page(&format!("q {clip} W n 1 0.5 0 rg 0 0 100 100 re f Q"), "", &[]));
+        all(&d).iter().any(|n| matches!(n.kind, NodeKind::Group { clip: true, .. }))
+    };
+    assert!(clipped("50 0 m 100 50 l 50 100 l 0 50 l h"), "diamond");
+    assert!(!clipped("0 0 100 100 re"), "the page");
+    assert!(!clipped("50 -60 m 160 50 l 50 160 l -60 50 l h"), "a turned square around the page");
+}

crates/pdf/src/tests_import_lines.rs

@@ -131,6 +131,47 @@ fn a_stroke_written_as_stroked_glyph_outlines_is_the_types_stroke() {
     assert_eq!(d.layers[0].children().unwrap().len(), 2);
 }
 
+/// A `.ai` page moved right in the row, so its art past the artboard clears the page before it
+/// (#1528), still has the stroke drawn on its type's glyphs read as the type's stroke.
+#[test]
+fn a_stroke_on_the_type_of_a_moved_ai_page_is_still_the_types_stroke() {
+    let ai = "/PieceInfo << /Illustrator << /Private << /AIPrivateData1 7 /NumBlock 1 >> >> >>";
+    let content = format!(
+        "0 g -70 10 80 20 re f BT 1 0 0 rg /F1 24 Tf 10 50 Td (Hi) Tj ET 0 0 1 RG 0.5 w {}{}",
+        outline('H', 10.0),
+        outline('i', 10.0 + 0.722 * 24.0)
+    );
+    let pages = [("0 g 10 10 20 20 re f", String::new()), (content.as_str(), HELVETICA.to_string())].map(|(c, resources)| PdfPage {
+        entries: ai.into(),
+        resources,
+        ..PdfPage::new(100.0, 100.0, c)
+    });
+    let d = import(&vectorcraft_testkit::pdf::pdf(&pages, None)).unwrap();
+    assert!(d.artboards[1].rect.x0 > d.artboards[0].rect.x1 + 36.0 + 1.0, "page 2 moved: {:?}", d.artboards);
+    let art = d.layers[1].children().unwrap();
+    assert_eq!(art.len(), 2, "the note and the type: {art:?}");
+    assert!(matches!(art[1].appearance.items.as_slice(), [AppearanceItem::Stroke(_)]), "{:?}", art[1].appearance);
+}
+
+#[test]
+fn glyphs_each_followed_by_their_stroked_outline_stay_one_object() {
+    // Type on a path is written glyph by glyph: each glyph, then its outline stroked in the same
+    // colour (a shadow under the type).
+    let glyph = |c: char, x: f64, stroke: &str| format!("BT 0 0 1 rg /F1 24 Tf {x} 50 Td ({c}) Tj ET {stroke} 0.5 w {}", outline(c, x));
+    let i_at = 10.0 + 0.722 * 24.0;
+    let d = import(&page(&(glyph('H', 10.0, "0 0 1 RG") + &glyph('i', i_at, "0 0 1 RG")))).unwrap();
+    let art = d.layers[0].children().unwrap();
+    assert_eq!(art.len(), 1, "one object: {art:?}");
+    let NodeKind::Text(t) = &art[0].kind else { panic!("{:?}", art[0].kind) };
+    assert_eq!(t.plain_text(), "Hi");
+    let [AppearanceItem::Stroke(st)] = art[0].appearance.items.as_slice() else { panic!("{:?}", art[0].appearance) };
+    assert_eq!(st.paint.color(), Some(Color::rgb(0.0, 0.0, 1.0)));
+    // A stroke of another colour drawn over each glyph in turn would also cover the next one's
+    // neighbour as one object's stroke: the glyphs stay as the file draws them.
+    let d = import(&page(&(glyph('H', 10.0, "1 1 1 RG") + &glyph('i', i_at, "1 1 1 RG")))).unwrap();
+    assert_eq!(texts(&d).len(), 2);
+}
+
 /// A 300 × 200 pt page with `lines` of (x, y from the top, size, text) in Source Sans 3.
 fn source_sans(lines: &[(f32, f32, f32, &str)]) -> Vec<u8> {
     crate::tests_live_text::text_pdf(lines, false)

crates/pdf/src/tests_import_options.rs

@@ -158,6 +158,27 @@ fn art_of_neighbouring_artboards_off_a_page_is_left_to_its_own_page() {
     assert_eq!(d.layers[0].children().map_or(0, |c| c.len()), 2);
 }
 
+/// A `.ai` keeps its art past the artboard edge (#646): a note mostly left of artboard 2 (as notes
+/// for a design are put beside it) doesn't lie over artboard 1 in the row, where it would be taken
+/// for that page's art: page 2 moves right until its art clears page 1's.
+#[test]
+fn art_of_an_ai_page_reaching_left_does_not_lie_over_the_page_before() {
+    let ai = "/PieceInfo << /Illustrator << /Private << /AIPrivateData1 7 /NumBlock 1 >> >> >>";
+    let page = |content: &str| PdfPage { entries: ai.into(), ..PdfPage::new(100.0, 100.0, content) };
+    // Page 2's note runs from 70 points left of its box to 10 points into it.
+    let pages = [page("0 g 10 10 20 20 re f"), page("1 1 1 rg 1 0 0 RG -70 10 80 60 re B")];
+    let d = open(&pdf(&pages, None), ImportOptions::default());
+    let (a, b) = (d.artboards[0].rect, d.artboards[1].rect);
+    let note = d.layers[1].children().unwrap()[0].visual_bounds().unwrap();
+    assert!(note.x0 >= a.x1 + 36.0, "the note clears artboard 1: {note:?} {a:?}");
+    assert!((b.x0 - note.x0 - 70.0).abs() < 1.0, "and keeps its place by artboard 2: {note:?} {b:?}");
+    assert_eq!((b.width(), b.height()), (100.0, 100.0));
+    // A plain PDF clips its art to the page: its pages stay 36 points apart.
+    let plain = [PdfPage::new(100.0, 100.0, "0 g 10 10 20 20 re f"), PdfPage::new(100.0, 100.0, "1 0 0 RG -70 10 80 60 re S")];
+    let d = open(&pdf(&plain, None), ImportOptions::default());
+    assert_eq!(d.artboards[1].rect.x0, d.artboards[0].rect.x1 + 36.0);
+}
+
 #[test]
 fn an_encrypted_pdf_opens_with_its_password_only() {
     let bytes = pdf(&[PdfPage::new(200.0, 100.0, "1 0 0 rg 10 10 50 50 re f")], Some("secret"));

crates/pdf/src/tests_realtext.rs

@@ -424,3 +424,22 @@ fn glyphs_spaced_each_their_own_way_keep_their_place() {
         }
     });
 }
+
+/// Evenly tracked type on a path comes back with its tracking: each glyph where it was along the
+/// curve, not closed up to the font's advances.
+#[test]
+fn evenly_tracked_type_on_a_path_keeps_its_length() {
+    let mut arc = BezPath::new();
+    arc.move_to((40.0, 200.0));
+    arc.curve_to((100.0, 80.0), (260.0, 80.0), (320.0, 200.0));
+    let mut t = TextObject::point(Point::ORIGIN, "ARCHING TYPE", CharStyle { tracking: 80.0, ..style(24.0) });
+    t.kind = TextKind::OnPath { path: PathData::from_bezpath(&arc), start: 0.0, end: None };
+    let d = doc(vec![t]);
+    let want = origins(&d);
+    let back = import_as(&pdf(&d, false).bytes, TextAs::default());
+    let got = origins(&back);
+    assert_eq!(got.len(), want.len(), "{:?}", texts(&back));
+    for (g, w) in got.iter().zip(&want) {
+        assert!(g.distance(*w) < 0.3, "{got:?}\nvs {want:?}");
+    }
+}

crates/render/src/encode/quantize.rs

@@ -341,9 +341,11 @@ fn median_cut(colors: impl Iterator<Item = [u8; 3]>, k: usize, r: Reduction) ->
     let mut palette: Vec<[f32; 3]> = boxes.iter().map(|&(a, b, ..)| mean(&cells[a..b])).collect();
     // k-means: move each entry to the mean of the cells nearest to it.
     for _ in 0..3 {
+        // Centres move between passes, not within one: build the spatial index once per pass.
+        let index = PaletteIndex::new(&palette, w);
         let mut sums = vec![([0f64; 3], 0f64); palette.len()];
         for c in &cells {
-            let i = nearest(&palette, c.mean, w);
+            let i = index.nearest(c.mean);
             for ch in 0..3 {
                 sums[i].0[ch] += c.mean[ch] as f64 * c.count as f64;
             }
@@ -371,8 +373,137 @@ fn median_cut(colors: impl Iterator<Item = [u8; 3]>, k: usize, r: Reduction) ->
     out
 }
 
-fn nearest(palette: &[[f32; 3]], c: [f32; 3], w: [f32; 3]) -> usize {
-    palette.iter().enumerate().min_by(|a, b| dist(*a.1, c, w).total_cmp(&dist(*b.1, c, w))).map_or(0, |(i, _)| i)
+/// An exact 3-D nearest-neighbour index for the weighted RGB distance used by palette export.
+///
+/// Balanced at the weighted widest axis. Every subtree carries tight channel bounds, so a
+/// branch-and-bound search skips it when even its nearest *possible* colour is farther than the
+/// best one found. Equal distances still choose the earliest palette index (as a linear scan did).
+/// For very small palettes a scan is cheaper than traversing the tree.
+struct PaletteNode {
+    index: usize,
+    lo: [f32; 3],
+    hi: [f32; 3],
+    left: Option<usize>,
+    right: Option<usize>,
+}
+
+struct PaletteIndex<'a> {
+    colors: &'a [[f32; 3]],
+    weights: [f32; 3],
+    nodes: Vec<PaletteNode>,
+    root: Option<usize>,
+}
+
+impl<'a> PaletteIndex<'a> {
+    const SCAN_CUTOFF: usize = 12;
+
+    fn new(colors: &'a [[f32; 3]], weights: [f32; 3]) -> Self {
+        let mut nodes = if colors.len() <= Self::SCAN_CUTOFF { Vec::new() } else { Vec::with_capacity(colors.len()) };
+        let root = if colors.len() <= Self::SCAN_CUTOFF {
+            None
+        } else {
+            let mut indices: Vec<usize> = (0..colors.len()).collect();
+            Self::build(colors, weights, &mut indices, &mut nodes)
+        };
+        Self { colors, weights, nodes, root }
+    }
+
+    // Median partitioning takes O(k log k) time and space for k palette entries.
+    fn build(colors: &[[f32; 3]], w: [f32; 3], ids: &mut [usize], nodes: &mut Vec<PaletteNode>) -> Option<usize> {
+        if ids.is_empty() {
+            return None;
+        }
+        let (mut lo, mut hi) = ([f32::INFINITY; 3], [f32::NEG_INFINITY; 3]);
+        for &id in ids.iter() {
+            let Some(c) = colors.get(id) else { continue };
+            for axis in 0..3 {
+                lo[axis] = lo[axis].min(c[axis]);
+                hi[axis] = hi[axis].max(c[axis]);
+            }
+        }
+        let axis = (0..3).max_by(|&a, &b| (w[a] * (hi[a] - lo[a])).total_cmp(&(w[b] * (hi[b] - lo[b])))).unwrap_or(0);
+        let mid = ids.len() / 2;
+        ids.select_nth_unstable_by(mid, |&a, &b| {
+            let ac = colors.get(a).map_or(0.0, |c| c[axis]);
+            let bc = colors.get(b).map_or(0.0, |c| c[axis]);
+            ac.total_cmp(&bc).then(a.cmp(&b))
+        });
+        let (before, rest) = ids.split_at_mut(mid);
+        let (pivot, after) = rest.split_first_mut()?;
+        let at = nodes.len();
+        nodes.push(PaletteNode { index: *pivot, lo, hi, left: None, right: None });
+        let left = Self::build(colors, w, before, nodes);
+        let right = Self::build(colors, w, after, nodes);
+        if let Some(n) = nodes.get_mut(at) {
+            n.left = left;
+            n.right = right;
+        }
+        Some(at)
+    }
+
+    // Lower bound on *the same f32 weighted squared distance* as `dist`: avoid transforming
+    // coordinates, which would change rounding and potentially break identical-palette ties.
+    fn lower_bound(&self, id: usize, c: [f32; 3]) -> f32 {
+        let Some(n) = self.nodes.get(id) else { return f32::INFINITY };
+        (0..3)
+            .map(|i| {
+                let gap = if c[i] < n.lo[i] {
+                    n.lo[i] - c[i]
+                } else if c[i] > n.hi[i] {
+                    c[i] - n.hi[i]
+                } else {
+                    0.0
+                };
+                (self.weights[i] * gap).powi(2)
+            })
+            .sum()
+    }
+
+    fn search(&self, at: usize, c: [f32; 3], best: &mut (f32, usize)) {
+        let Some(n) = self.nodes.get(at) else { return };
+        let Some(&p) = self.colors.get(n.index) else { return };
+        let d = dist(p, c, self.weights);
+        if d < best.0 || (d == best.0 && n.index < best.1) {
+            *best = (d, n.index);
+        }
+        // Search the more promising box first, tightening the bound for the second box.
+        let left = n.left.map(|id| (id, self.lower_bound(id, c)));
+        let right = n.right.map(|id| (id, self.lower_bound(id, c)));
+        match (left, right) {
+            (Some(a), Some(b)) => {
+                let (first, second) = if a.1 <= b.1 { (a, b) } else { (b, a) };
+                if first.1 <= best.0 {
+                    self.search(first.0, c, best);
+                }
+                // `<=` is essential: an equal-distance colour may have an earlier index.
+                if second.1 <= best.0 {
+                    self.search(second.0, c, best);
+                }
+            }
+            (Some(a), None) | (None, Some(a)) => {
+                if a.1 <= best.0 {
+                    self.search(a.0, c, best);
+                }
+            }
+            (None, None) => {}
+        }
+    }
+
+    fn nearest(&self, c: [f32; 3]) -> usize {
+        if self.colors.len() <= Self::SCAN_CUTOFF {
+            return self
+                .colors
+                .iter()
+                .enumerate()
+                .min_by(|a, b| dist(*a.1, c, self.weights).total_cmp(&dist(*b.1, c, self.weights)))
+                .map_or(0, |(i, _)| i);
+        }
+        let mut best = (f32::INFINITY, 0);
+        if let Some(root) = self.root {
+            self.search(root, c, &mut best);
+        }
+        best.1
+    }
 }
 
 /// The 8×8 ordered-dither threshold at (x, y), in 0..1.
@@ -398,19 +529,20 @@ fn noise(x: usize, y: usize) -> f32 {
 /// names (transparent) get index 0 and take no diffused error.
 fn map(colors: &[[u8; 3]], width: usize, palette: &[[u8; 3]], w: [f32; 3], dither: Dither, amount: f32, skip: impl Fn(usize) -> bool) -> Vec<u8> {
     let pal: Vec<[f32; 3]> = palette.iter().map(|c| c.map(f32::from)).collect();
+    let index = PaletteIndex::new(&pal, w);
     // Nearest entries by colour: exact colours without dithering, a 6-bit grid with it.
     let mut exact: HashMap<[u8; 3], u8> = HashMap::new();
     let mut grid = vec![u16::MAX; if dither == Dither::None { 0 } else { 1 << 18 }];
     let mut lookup = |c: [f32; 3]| -> u8 {
         let q = c.map(|v| v.round().clamp(0.0, 255.0) as u8);
         if grid.is_empty() {
-            return *exact.entry(q).or_insert_with(|| nearest(&pal, c, w) as u8);
+            return *exact.entry(q).or_insert_with(|| index.nearest(c) as u8);
         }
         let key = (q[0] as usize >> 2) << 12 | (q[1] as usize >> 2) << 6 | q[2] as usize >> 2;
         match grid.get(key) {
             Some(&v) if v != u16::MAX => v as u8,
             _ => {
-                let i = nearest(&pal, c, w) as u8;
+                let i = index.nearest(c) as u8;
                 if let Some(g) = grid.get_mut(key) {
                     *g = i as u16;
                 }
@@ -466,3 +598,83 @@ fn map(colors: &[[u8; 3]], width: usize, palette: &[[u8; 3]], w: [f32; 3], dithe
     }
     out
 }
+
+#[cfg(test)]
+mod nearest_tests {
+    use super::*;
+
+    // The original definition, retained only as a parity oracle for the spatial index.
+    fn linear(colors: &[[f32; 3]], c: [f32; 3], w: [f32; 3]) -> usize {
+        colors.iter().enumerate().min_by(|a, b| dist(*a.1, c, w).total_cmp(&dist(*b.1, c, w))).map_or(0, |(i, _)| i)
+    }
+
+    fn next(seed: &mut u32) -> u32 {
+        *seed ^= *seed << 13;
+        *seed ^= *seed >> 17;
+        *seed ^= *seed << 5;
+        *seed
+    }
+
+    #[test]
+    fn exact_nearest_matches_linear_for_palette_sizes_and_weights() {
+        let mut seed = 0x2ab4_1017;
+        for w in [[1.0; 3], [0.55, 0.77, 0.34], [0.1, 1.0, 0.01]] {
+            for size in [0, 1, 2, 8, 12, 13, 16, 17, 32, 64, 128, 256] {
+                // Include duplicated colours, close k-means-style floating-point centres,
+                // and a wide colour gamut. Query points are fractional, as with dithering.
+                let colors: Vec<[f32; 3]> =
+                    (0..size)
+                        .map(|i| {
+                            if i % 11 == 0 {
+                                [127.0, 127.0, 127.0]
+                            } else {
+                                [0, 1, 2].map(|_| (next(&mut seed) % 65_536) as f32 * (255.0 / 65_535.0))
+                            }
+                        })
+                        .collect();
+                let index = PaletteIndex::new(&colors, w);
+                for _ in 0..500 {
+                    let c = [0, 1, 2].map(|_| (next(&mut seed) % 65_536) as f32 * (255.0 / 65_535.0));
+                    assert_eq!(index.nearest(c), linear(&colors, c, w), "size {size}, weights {w:?}, query {c:?}");
+                }
+            }
+        }
+    }
+
+    #[test]
+    fn equal_distance_always_chooses_first_palette_entry() {
+        // Enough entries to exercise the tree, even when they share one bounding box.
+        let mut colors = vec![[128.0, 128.0, 128.0]; 256];
+        colors[0] = [0.0, 128.0, 128.0];
+        colors[255] = [2.0, 128.0, 128.0];
+        let index = PaletteIndex::new(&colors, [1.0; 3]);
+        assert_eq!(index.nearest([1.0, 128.0, 128.0]), 0, "equal distance to indices 0 and 255");
+        assert_eq!(index.nearest([128.0; 3]), 1, "equal among 254 identical colours");
+        let colors = vec![[10.0, 10.0, 10.0]; 256];
+        assert_eq!(PaletteIndex::new(&colors, [0.55, 0.77, 0.34]).nearest([10.0; 3]), 0);
+    }
+
+    /// Opt-in microbenchmark: compares the same nearest-neighbour queries, without image IO.
+    #[test]
+    #[ignore = "run with cargo test -p vectorcraft-render nearest_palette_benchmark --release -- --ignored --nocapture"]
+    fn nearest_palette_benchmark() {
+        use std::time::Instant;
+
+        let mut seed = 0x87bb_7641;
+        let colors: Vec<[f32; 3]> = (0..256).map(|_| [0, 1, 2].map(|_| (next(&mut seed) % 256) as f32)).collect();
+        let queries: Vec<[f32; 3]> = (0..100_000).map(|_| [0, 1, 2].map(|_| (next(&mut seed) % 65_536) as f32 * (255.0 / 65_535.0))).collect();
+        let w = [0.55, 0.77, 0.34];
+        let start = Instant::now();
+        let baseline: Vec<_> = queries.iter().map(|&c| linear(&colors, c, w)).collect();
+        let old = start.elapsed();
+        let start = Instant::now();
+        let index = PaletteIndex::new(&colors, w);
+        let improved: Vec<_> = queries.iter().map(|&c| index.nearest(c)).collect();
+        let new = start.elapsed();
+        assert_eq!(baseline, improved);
+        eprintln!(
+            "100k nearest-colour queries, 256 entries: linear {old:?}, spatial index {new:?}, speedup {:.2}x",
+            old.as_secs_f64() / new.as_secs_f64()
+        );
+    }
+}

crates/render/src/fx.rs

@@ -274,6 +274,9 @@ fn draw_scaled(ctx: &mut RenderContext, image: std::sync::Arc<vello_cpu::Pixmap>
     // On whole pixels at full size the cheapest sampler is exact.
     let quality = if k < 1.0 { peniko::ImageQuality::Medium } else { peniko::ImageQuality::Low };
     let sampler = peniko::ImageSampler { quality, ..Default::default() };
+    // The raster maps 1:1 onto the rect: a paint transform left by an earlier fill (a pattern,
+    // radial or freeform gradient) would resample it (#1536).
+    ctx.reset_paint_transform();
     ctx.set_paint(vello_cpu::Image { image: vello_cpu::ImageSource::Pixmap(image), sampler });
     ctx.fill_rect(&Rect::new(0.0, 0.0, w, h));
     ctx.set_transform(Affine::IDENTITY);
@@ -617,6 +620,7 @@ impl Renderer {
         ctx.set_transform(Affine::translate((x, y)));
         ctx.set_blend_mode(blend_mode(mode));
         let sampler = peniko::ImageSampler { quality: peniko::ImageQuality::Low, ..Default::default() };
+        ctx.reset_paint_transform();
         ctx.set_paint(vello_cpu::Image { image: vello_cpu::ImageSource::Pixmap(image), sampler });
         ctx.fill_rect(&Rect::new(0.0, 0.0, w, h));
         ctx.set_blend_mode(blend_mode(vectorcraft_doc::color::BlendMode::Normal));

crates/render/src/lib.rs

@@ -96,6 +96,9 @@ pub struct RenderOptions {
     /// Pattern editing mode's tile edge and swatch bounds colour (Object → Pattern → Tile Edge
     /// Color), RGB.
     pub tile_edge: [u8; 3],
+    /// Colour and style of the paths made into guides (Preferences › Guides & Grid, as the ruler
+    /// guides the UI draws): RGB, and whether they are dotted.
+    pub guide: ([u8; 3], bool),
     /// View Opacity Mask (Alt-click the mask thumbnail): instead of the artwork, show this object's
     /// opacity mask alone as its coverage in greyscale (white = opaque, black = transparent).
     pub mask_view: Option<NodeId>,
@@ -201,6 +204,7 @@ impl Default for RenderOptions {
             trim: false,
             skip_templates: false,
             tile_edge: vectorcraft_doc::LAYER_COLORS[0].1,
+            guide: ([0x4a, 0xd8, 0xff], false),
             mask_view: None,
             highlight_substitutions: false,
             anti_alias: AntiAlias::Art,
@@ -1158,7 +1162,17 @@ impl Renderer {
             NodeKind::Path { path, rule, guide, .. } => {
                 let bp = path.to_bezpath();
                 if *guide {
-                    self.hairline(ctx, f, &bp, [0x4a, 0xd8, 0xff, 255]);
+                    let ([r, g, b], dots) = f.opts.guide;
+                    if dots {
+                        let mut screen = bp.clone();
+                        screen.apply_affine(f.view);
+                        ctx.set_transform(Affine::IDENTITY);
+                        ctx.set_stroke(kurbo::Stroke::new(1.5).with_dashes(0.0, [1.5, 2.5]));
+                        ctx.set_paint(f.ink.fixed([r, g, b, 255]));
+                        ctx.stroke_path(&screen);
+                    } else {
+                        self.hairline(ctx, f, &bp, [r, g, b, 255]);
+                    }
                 } else {
                     self.draw_shape(ctx, f, n, &bp, *rule);
                 }

crates/render/src/pattern.rs

@@ -274,6 +274,58 @@ mod tests {
         p[0] > 200 && p[1] > 200 && p[2] > 200
     }
 
+    /// #1536: a raster effect drawn after a pattern fill is the same as without the pattern (the
+    /// pattern's paint transform must not resample the effect's raster).
+    #[test]
+    fn effects_after_a_pattern_fill_keep_their_place_and_size() {
+        let fx = |id: &str, params: serde_json::Value| vectorcraft_doc::Effect { id: id.into(), params, visible: true };
+        for effect in [
+            fx("blur.gaussian", serde_json::json!({"radius": 4.0})),
+            fx("stylize.dropShadow", serde_json::json!({"x": 6, "y": 6, "blur": 3, "opacity": 100})),
+        ] {
+            let make = |with_pattern: bool| {
+                let mut d = doc_with_pattern(TileType::Grid);
+                let l = d.layers[0].id;
+                let filled = d.children(Some(l)).unwrap()[0].id;
+                d.remove(filled).unwrap();
+                if with_pattern {
+                    let id = d.alloc_id();
+                    let n = Node::path(
+                        id,
+                        shapes::rectangle(Rect::new(0.0, 0.0, 80.0, 80.0)),
+                        Appearance::basic(pattern_paint("Checks"), Paint::None, 0.0),
+                    );
+                    d.insert(Some(l), 0, n).unwrap();
+                }
+                let id = d.alloc_id();
+                let mut n = Node::path(
+                    id,
+                    shapes::ellipse(Rect::new(120.0, 110.0, 180.0, 170.0)),
+                    Appearance::basic(Paint::solid(Color::rgb(0.5, 0.5, 0.5)), Paint::None, 0.0),
+                );
+                n.appearance.effects.push(effect.clone());
+                let at = d.children(Some(l)).map_or(0, Vec::len);
+                d.insert(Some(l), at, n).unwrap();
+                d
+            };
+            // Supersampled, as raster exports draw.
+            let one = |d: &Document| {
+                let mut r = Renderer::new();
+                r.render(
+                    d,
+                    200,
+                    200,
+                    Affine::IDENTITY,
+                    &RenderOptions { background: Some([255, 255, 255, 255]), supersample: true, ..Default::default() },
+                )
+            };
+            let (with, without) = (one(&make(true)), one(&make(false)));
+            for (x, y) in [(150, 140), (125, 140), (176, 160), (150, 172), (184, 176)] {
+                assert_eq!(with.pixel(x, y), without.pixel(x, y), "{} at ({x}, {y})", effect.id);
+            }
+        }
+    }
+
     #[test]
     fn pattern_fill_is_periodic() {
         let d = doc_with_pattern(TileType::Grid);

crates/render/src/tests_tileedge.rs

@@ -67,3 +67,31 @@ fn swatch_bounds_outline_the_period_dashed() {
     let off = render(&editing(tt, false, false), Some([0, 200, 0]));
     assert!((51..70).all(|x| is_white(off.pixel(x, 90))));
 }
+
+/// #1534: a path made into a guide is drawn in the guide colour and style (Preferences › Guides &
+/// Grid), as ruler guides are: a line, or dots with gaps between them.
+#[test]
+fn guide_paths_take_the_guide_color_and_style() {
+    let mut d = Document::new(200.0, 200.0);
+    let (layer, id) = (d.layers[0].id, d.alloc_id());
+    let mut n = Node::path(id, shapes::rectangle(Rect::new(0.0, 0.0, 60.0, 60.0)), Appearance::basic(Paint::None, Paint::None, 0.0));
+    if let NodeKind::Path { guide, .. } = &mut n.kind {
+        *guide = true;
+    }
+    d.insert(Some(layer), 0, n).unwrap();
+    let draw = |guide| {
+        let opts = RenderOptions { background: Some([255; 4]), guide, ..Default::default() };
+        Renderer::new().render(&d, 120, 120, Affine::translate((50.5, 50.5)), &opts)
+    };
+    // Along the top edge of the square (y = 50), between its corners: the pixels the red covers.
+    let inked = |r: &Rendered| (55..105).filter(|x| r.pixel(*x, 50)[1] < 64).count();
+    let line = draw(([200, 0, 0], false));
+    let p = line.pixel(80, 50);
+    assert!(p[0] > 150 && p[1] < 100 && p[2] < 100, "{p:?}");
+    assert_eq!(inked(&line), 50);
+    let dotted = draw(([200, 0, 0], true));
+    let dots = inked(&dotted);
+    assert!((10..40).contains(&dots), "{dots}: {:?}", (45..70).map(|x| dotted.pixel(x, 50)[1]).collect::<Vec<_>>());
+    let default = draw(RenderOptions::default().guide);
+    assert!((55..105).all(|x| !is_white(default.pixel(x, 50))), "a line by default");
+}

crates/svg/src/export.rs

@@ -50,6 +50,7 @@ fn write(doc: &Document, opts: &ExportOptions, native: Option<&[u8]>, id_prefix:
         body: String::new(),
         defs: String::new(),
         classes: Vec::new(),
+        class_ids: HashMap::new(),
         used_ids: HashSet::new(),
         names: HashMap::new(),
         depth: 1,
@@ -259,8 +260,10 @@ struct Writer<'a> {
     xf: Affine,
     body: String,
     defs: String,
-    /// Unique CSS declaration blocks; class name is `cls-{index + 1}`.
+    /// Unique CSS declaration blocks, in first-use order (used for deterministic output).
     classes: Vec<String>,
+    /// 1-based class/entity number by declaration; avoids a linear scan for each style.
+    class_ids: HashMap<String, usize>,
     used_ids: HashSet<String>,
     names: HashMap<NodeId, String>,
     depth: usize,
@@ -657,13 +660,13 @@ impl Writer<'_> {
 
     /// The 1-based number of a distinct declaration block (a CSS class or a style entity).
     fn class(&mut self, decl: String) -> usize {
-        match self.classes.iter().position(|c| *c == decl) {
-            Some(i) => i + 1,
-            None => {
-                self.classes.push(decl);
-                self.classes.len()
-            }
+        if let Some(&i) = self.class_ids.get(decl.as_str()) {
+            return i;
         }
+        let i = self.classes.len() + 1;
+        self.class_ids.insert(decl.clone(), i);
+        self.classes.push(decl);
+        i
     }
 
     /// `<metadata>`: the Dublin Core terms of File Info ([`ExportOptions::metadata`]) and the

crates/svg/src/import.rs

@@ -21,9 +21,11 @@ use text::TextSlots;
 pub(crate) use fx::BLEND;
 
 mod css;
+mod css_transform;
 mod files;
 mod fx;
 mod spread;
+mod symbol_units;
 mod text;
 mod vector_effect;
 
@@ -464,11 +466,15 @@ impl Edits {
 /// * undisplayed objects (`display: none`, as Save writes hidden layers) are shown and recorded,
 ///   to come back hidden; one something links to (a `<use>` template) stays as it is;
 /// * shapes with a non-scaling stroke get an id when they have none, recorded ([`vector_effect`]);
-/// * linked files are read ([`files`]).
+/// * linked files are read ([`files`]);
+/// * percentage lengths in a `<symbol>` with a `viewBox` become numbers ([`symbol_units`]).
 fn prepass<'s>(svg: &'s str, opts: &ImportOptions) -> (Cow<'s, str>, Found) {
     let mut found = Found::default();
     // (`:` for prefixed elements such as `<svg:image>`.)
-    if !["<a", "display", "<use", ":use", "<image", ":image", vector_effect::NON_SCALING, "data-", "groupmode"].iter().any(|t| svg.contains(t)) {
+    let css_transform = has_css_transform(svg);
+    if !css_transform
+        && !["<a", "display", "<use", ":use", "<image", ":image", vector_effect::NON_SCALING, "data-", "groupmode"].iter().any(|t| svg.contains(t))
+    {
         return (svg.into(), found);
     }
     let Ok(xml) = roxmltree::Document::parse_with_options(svg, roxmltree::ParsingOptions { allow_dtd: true, ..Default::default() }) else {
@@ -507,9 +513,20 @@ fn prepass<'s>(svg: &'s str, opts: &ImportOptions) -> (Cow<'s, str>, Found) {
         }
     }
     found.files = files::Files::read(svg, &xml, opts, &mut edits, &mut found.warnings);
+    if !symbols.is_empty() && svg.contains('%') {
+        edits.list.extend(symbol_units::rewrites(&xml));
+    }
+    if css_transform {
+        edits.list.extend(css_transform::rewrites(svg, &xml));
+    }
     (edits.apply(svg), found)
 }
 
+/// Is there a `transform` CSS declaration in `svg` (`transform` followed by `:`)?
+fn has_css_transform(svg: &str) -> bool {
+    svg.match_indices("transform").any(|(i, t)| svg.get(i + t.len()..).is_some_and(|s| s.trim_start().starts_with(':')))
+}
+
 /// The elements that are objects (what [`hidden_objects`] shows).
 const OBJECTS: &[&str] = &["g", "a", "path", "rect", "circle", "ellipse", "line", "polyline", "polygon", "image", "text", "use"];
 

crates/svg/src/import/css.rs

@@ -15,7 +15,8 @@ use usvg::roxmltree;
 
 pub(super) type XNode<'a, 'i> = roxmltree::Node<'a, 'i>;
 
-/// `name: value` declarations of a block or `style` attribute, with their `!important` flag.
+/// `name: value` declarations of a block or `style` attribute, with their `!important` flag. The
+/// `font` shorthand becomes its longhands, as usvg reads it for the rest of the drawing (#1557).
 fn parse_decls(s: &str) -> Vec<(String, String, bool)> {
     s.split(';')
         .filter_map(|d| {
@@ -27,9 +28,28 @@ fn parse_decls(s: &str) -> Vec<(String, String, bool)> {
             };
             Some((k.trim().to_ascii_lowercase(), v.to_string(), important))
         })
+        .flat_map(|(k, v, important)| match k.as_str() {
+            "font" => font_longhands(&v).into_iter().map(|(k, v)| (k.to_string(), v, important)).collect(),
+            _ => vec![(k, v, important)],
+        })
         .collect()
 }
 
+/// The longhands of a `font` shorthand: those it leaves out back to their initial values. None
+/// when it doesn't parse (it is then ignored, as in CSS).
+fn font_longhands(v: &str) -> Vec<(&'static str, String)> {
+    let Ok(f) = svgtypes::FontShorthand::from_str(v) else { return Vec::new() };
+    let or = |o: Option<&str>| o.unwrap_or("normal").to_string();
+    vec![
+        ("font-style", or(f.font_style)),
+        ("font-variant", or(f.font_variant)),
+        ("font-weight", or(f.font_weight)),
+        ("font-stretch", or(f.font_stretch)),
+        ("font-size", f.font_size.to_string()),
+        ("font-family", f.font_family.to_string()),
+    ]
+}
+
 /// One compound selector (`text.a.b#c[x=y]`).
 #[derive(Debug, Default)]
 struct Compound {
@@ -343,6 +363,19 @@ mod tests {
         );
     }
 
+    #[test]
+    fn the_font_shorthand_sets_its_longhands() {
+        let d = parse_decls("fill: red; font: italic bold 30px 'DejaVu Sans' ; font-weight: 300 !important; font: nonsense");
+        let get = |k: &str| d.iter().filter(|(n, ..)| n == k).map(|(_, v, i)| (v.as_str(), *i)).collect::<Vec<_>>();
+        assert_eq!(get("font-style"), [("italic", false)]);
+        assert_eq!(get("font-weight"), [("bold", false), ("300", true)]);
+        assert_eq!(get("font-size"), [("30px", false)]);
+        assert_eq!(get("font-family"), [("'DejaVu Sans'", false)]);
+        assert_eq!(get("font-variant"), [("normal", false)]);
+        assert_eq!(get("fill"), [("red", false)]);
+        assert!(get("font").is_empty(), "the shorthand itself is not kept");
+    }
+
     #[test]
     fn unsupported_selectors_are_dropped() {
         for s in ["a + b", "a ~ b", "a:hover", "svg|text", "> a", "a >", ""] {

crates/svg/src/import/css_transform.rs

@@ -0,0 +1,151 @@
+//! CSS `transform` declarations in SVG syntax, for usvg.
+//!
+//! usvg takes the `transform` property (from a `style` attribute or a `<style>` rule) as a
+//! presentation attribute that overrides the element's `transform` attribute, but reads its value
+//! as SVG, without CSS units: `translate(100px, 0)` or `rotate(45deg)` fails, and the element is
+//! left with no transform at all (#1557). Before usvg runs, such values are rewritten in SVG
+//! syntax: lengths in `px` (or unitless), angles in `deg`, `rad`, `grad` or `turn`, and the CSS
+//! functions SVG lacks (`translateX`, `scaleY`, `skew`…) spelled with SVG's. A value that can't be
+//! (percentages, `em`, 3D functions) is left as it is.
+
+use std::f64::consts::PI;
+use std::ops::Range;
+
+use usvg::roxmltree;
+
+use super::css::XNode;
+
+/// The CSS transform `value` in SVG syntax; `None` when it has nothing to rewrite or can't be.
+pub(super) fn to_svg(value: &str) -> Option<String> {
+    let v = value.trim();
+    if v.eq_ignore_ascii_case("none") {
+        return Some("matrix(1 0 0 1 0 0)".into());
+    }
+    let mut out = Vec::new();
+    let mut rest = v;
+    while !rest.trim_start().is_empty() {
+        rest = rest.trim_start();
+        let open = rest.find('(')?;
+        let close = rest.find(')')?;
+        let name = rest.get(..open)?.trim().to_ascii_lowercase();
+        let args: Vec<&str> = rest.get(open + 1..close)?.split(|c: char| c == ',' || c.is_whitespace()).filter(|a| !a.is_empty()).collect();
+        let len = |i: usize| args.get(i).and_then(|a| length(a));
+        let ang = |i: usize| args.get(i).and_then(|a| angle(a));
+        let num = |i: usize| args.get(i).and_then(|a| a.parse::<f64>().ok()).filter(|n| n.is_finite());
+        let f = match (name.as_str(), args.len()) {
+            ("matrix", 6) => format!("matrix({} {} {} {} {} {})", num(0)?, num(1)?, num(2)?, num(3)?, len(4)?, len(5)?),
+            ("translate", 1) => format!("translate({} 0)", len(0)?),
+            ("translate", 2) => format!("translate({} {})", len(0)?, len(1)?),
+            ("translatex", 1) => format!("translate({} 0)", len(0)?),
+            ("translatey", 1) => format!("translate(0 {})", len(0)?),
+            ("scale", 1) => format!("scale({})", num(0)?),
+            ("scale", 2) => format!("scale({} {})", num(0)?, num(1)?),
+            ("scalex", 1) => format!("scale({} 1)", num(0)?),
+            ("scaley", 1) => format!("scale(1 {})", num(0)?),
+            ("rotate", 1) => format!("rotate({})", ang(0)?),
+            ("skewx", 1) => format!("skewX({})", ang(0)?),
+            ("skewy", 1) => format!("skewY({})", ang(0)?),
+            ("skew", 1) => format!("skewX({})", ang(0)?),
+            ("skew", 2) => format!("matrix(1 {} {} 1 0 0)", ang(1)?.to_radians().tan(), ang(0)?.to_radians().tan()),
+            _ => return None,
+        };
+        out.push(f);
+        rest = rest.get(close + 1..)?;
+    }
+    let svg = out.join(" ");
+    (!out.is_empty() && svg != v).then_some(svg)
+}
+
+/// A length in user units: `px` or unitless.
+fn length(a: &str) -> Option<f64> {
+    let n = a.strip_suffix("px").unwrap_or(a).parse::<f64>().ok()?;
+    n.is_finite().then_some(n)
+}
+
+/// An angle in degrees.
+fn angle(a: &str) -> Option<f64> {
+    let a = a.to_ascii_lowercase();
+    let (n, k) = if let Some(n) = a.strip_suffix("deg") {
+        (n, 1.0)
+    } else if let Some(n) = a.strip_suffix("grad") {
+        (n, 0.9)
+    } else if let Some(n) = a.strip_suffix("rad") {
+        (n, 180.0 / PI)
+    } else if let Some(n) = a.strip_suffix("turn") {
+        (n, 360.0)
+    } else {
+        (a.as_str(), 1.0)
+    };
+    let d = n.parse::<f64>().ok()? * k;
+    d.is_finite().then_some(d)
+}
+
+/// Where CSS can be in `svg`: `style` attribute values and `<style>` contents.
+fn css_ranges(xml: &roxmltree::Document) -> Vec<Range<usize>> {
+    let mut out = Vec::new();
+    for n in xml.descendants().filter(XNode::is_element) {
+        if let Some(a) = n.attributes().find(|a| a.name() == "style" && a.namespace().is_none()) {
+            out.push(a.range_value());
+        }
+        if n.tag_name().name() == "style" {
+            out.extend(n.children().filter(XNode::is_text).map(|t| t.range()));
+        }
+    }
+    out
+}
+
+/// The `transform` declarations in CSS in `svg`, each as (value range, value in SVG syntax).
+pub(super) fn rewrites(svg: &str, xml: &roxmltree::Document) -> Vec<(Range<usize>, String)> {
+    let mut out = Vec::new();
+    for r in css_ranges(xml) {
+        let Some(css) = svg.get(r.clone()) else { continue };
+        let mut from = 0;
+        while let Some(i) = css.get(from..).and_then(|s| s.find("transform")).map(|i| i + from) {
+            from = i + "transform".len();
+            let before = css.get(..i).and_then(|s| s.chars().next_back());
+            if before.is_some_and(|c| c.is_ascii_alphanumeric() || c == '-' || c == '_') {
+                continue;
+            }
+            let after = css.get(from..).unwrap_or("");
+            let Some(colon) = after.find(|c: char| !c.is_whitespace()).filter(|&k| after.get(k..).is_some_and(|s| s.starts_with(':'))) else {
+                continue;
+            };
+            let start = from + colon + 1;
+            let len = css.get(start..).and_then(|s| s.find([';', '}', '!', '"', '\'', '<'])).unwrap_or(css.len() - start);
+            let Some(value) = css.get(start..start + len) else { continue };
+            if let Some(svg_value) = to_svg(value) {
+                out.push((r.start + start..r.start + start + len, format!(" {svg_value}")));
+            }
+        }
+    }
+    out
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn css_transforms_become_svg() {
+        assert_eq!(to_svg("translate(100px, 100px)").as_deref(), Some("translate(100 100)"));
+        assert_eq!(to_svg(" translateX(5px) rotate(0.25turn) ").as_deref(), Some("translate(5 0) rotate(90)"));
+        assert_eq!(to_svg("rotate(1.5707963267948966rad) scaleY(2)").as_deref(), Some("rotate(90) scale(1 2)"));
+        assert_eq!(to_svg("skew(45deg)").as_deref(), Some("skewX(45)"));
+        assert_eq!(to_svg("matrix(1, 0, 0, 1, 10px, 20px)").as_deref(), Some("matrix(1 0 0 1 10 20)"));
+        assert_eq!(to_svg("none").as_deref(), Some("matrix(1 0 0 1 0 0)"));
+        // Already SVG, or not expressible: left alone.
+        assert_eq!(to_svg("translate(10 20)"), None);
+        assert_eq!(to_svg("translate(50%, 0)"), None);
+        assert_eq!(to_svg("rotate3d(1, 0, 0, 45deg)"), None);
+        assert_eq!(to_svg("translate(1px"), None);
+    }
+
+    #[test]
+    fn only_css_is_rewritten() {
+        let svg = r#"<svg xmlns="http://www.w3.org/2000/svg"><style>.a { fill: red; transform: rotate(45deg) } .b{-webkit-transform:rotate(1deg)}</style><rect class="a" transform="translate(1 2)" style="transform:translate(3px,4px);fill:blue"/><text>transform: rotate(9deg)</text></svg>"#;
+        let xml = roxmltree::Document::parse(svg).unwrap();
+        let found = rewrites(svg, &xml);
+        let r: Vec<(&str, &str)> = found.iter().map(|(r, v)| (&svg[r.clone()], v.as_str())).collect();
+        assert_eq!(r, vec![(" rotate(45deg) ", " rotate(45)"), ("translate(3px,4px)", " translate(3 4)")]);
+    }
+}

crates/svg/src/import/symbol_units.rs

@@ -0,0 +1,72 @@
+//! Percentage lengths inside a `<symbol>` with a `viewBox`, as numbers, for usvg.
+//!
+//! A percentage is of the nearest viewport's size in user units, and a symbol's `viewBox` sets
+//! that size for its content as a nested `<svg>`'s does (SVG 2, 8.9 Units; 5.6 The `use` element).
+//! usvg takes the percentages of the `<use>`'s width and height instead and then scales the art by
+//! the `viewBox`, so it comes out too large and out of place (#1561). Before usvg runs, the
+//! percentages of the shapes' geometry are rewritten in the `viewBox`'s units.
+
+use std::ops::Range;
+use std::str::FromStr;
+
+use usvg::roxmltree;
+
+/// The elements whose geometry attributes are rewritten.
+const SHAPES: &[&str] = &["rect", "circle", "ellipse", "line", "image", "use", "text"];
+/// The elements whose content has lengths of its own kind (or a viewport of its own).
+const SCOPES: &[&str] = &["symbol", "svg", "pattern", "mask", "clipPath", "marker"];
+
+/// What a percentage of attribute `name` is of, in a viewport of `w` × `h`: its width, its height,
+/// or (a radius) its diagonal over √2.
+fn basis(name: &str, w: f64, h: f64) -> Option<f64> {
+    match name {
+        "x" | "x1" | "x2" | "cx" | "width" | "rx" => Some(w),
+        "y" | "y1" | "y2" | "cy" | "height" | "ry" => Some(h),
+        "r" => Some(((w * w + h * h) / 2.0).sqrt()),
+        _ => None,
+    }
+}
+
+/// The percentage geometry of shapes in symbols with a `viewBox`, each as (value range, number).
+pub(super) fn rewrites(xml: &roxmltree::Document) -> Vec<(Range<usize>, String)> {
+    let mut out = Vec::new();
+    for n in xml.descendants().filter(|n| n.is_element() && SHAPES.contains(&n.tag_name().name())) {
+        let Some(scope) = n.ancestors().skip(1).find(|a| SCOPES.contains(&a.tag_name().name())) else { continue };
+        let Some(vb) = Some(scope)
+            .filter(|s| s.tag_name().name() == "symbol")
+            .and_then(|s| s.attribute("viewBox"))
+            .and_then(|v| svgtypes::ViewBox::from_str(v).ok())
+        else {
+            continue;
+        };
+        if !(vb.w > 0.0 && vb.h > 0.0 && vb.w.is_finite() && vb.h.is_finite()) {
+            continue;
+        }
+        for a in n.attributes().filter(|a| a.namespace().is_none()) {
+            let percent = a.value().trim().strip_suffix('%').and_then(|v| v.trim().parse::<f64>().ok()).filter(|v| v.is_finite());
+            if let (Some(p), Some(of)) = (percent, basis(a.name(), vb.w, vb.h)) {
+                out.push((a.range_value(), (p / 100.0 * of).to_string()));
+            }
+        }
+    }
+    out
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn percentages_in_a_symbol_are_of_its_view_box() {
+        let svg = r##"<svg xmlns="http://www.w3.org/2000/svg"><rect width="50%"/>
+            <symbol id="a" viewBox="0 0 200 100"><rect x="10%" y="10%" width="100%" height="50%" rx="5"/><circle cx="50%" r="100%"/>
+              <linearGradient x2="100%"/><pattern><rect width="100%"/></pattern><g><line x2="25%" y2=" 25% "/></g></symbol>
+            <symbol id="b"><rect width="100%"/></symbol><use href="#a" width="30%"/></svg>"##;
+        let xml = roxmltree::Document::parse(svg).unwrap();
+        let found: Vec<(&str, String)> = rewrites(&xml).into_iter().map(|(r, v)| (&svg[r], v)).collect();
+        let r = (200.0f64 * 200.0 / 2.0 + 100.0 * 100.0 / 2.0).sqrt().to_string();
+        let expected =
+            [("10%", "20"), ("10%", "10"), ("100%", "200"), ("50%", "50"), ("50%", "100"), ("100%", r.as_str()), ("25%", "50"), (" 25% ", "25")];
+        assert_eq!(found.iter().map(|(a, b)| (*a, b.as_str())).collect::<Vec<_>>(), expected);
+    }
+}

crates/svg/src/import/text.rs

@@ -175,7 +175,8 @@ pub(super) fn prepare<'s>(svg: &'s str, xml: &roxmltree::Document, dpi: f64, war
     let cx = Ctx::new(xml, dpi);
     let mut out = String::new();
     let mut copied = 0;
-    for t in xml.descendants().filter(|n| n.is_element() && n.tag_name().name() == "text" && n.tag_name().namespace() == Some(SVG_NS)) {
+    let is_text = |n: &XNode| n.is_element() && matches!(n.tag_name().name(), "text" | "flowRoot") && n.tag_name().namespace() == Some(SVG_NS);
+    for t in xml.descendants().filter(is_text) {
         let label = t.attribute("id").map_or_else(|| "a text".to_string(), |id| format!("text '{id}'"));
         if t.ancestors().skip(1).any(|a| a.is_element() && a.tag_name().name() == "clipPath") {
             warnings.push(format!("{label} in a clip path ignored"));
@@ -191,11 +192,13 @@ pub(super) fn prepare<'s>(svg: &'s str, xml: &roxmltree::Document, dpi: f64, war
         else {
             continue;
         };
-        let Some(q) = qname.strip_suffix("text").filter(|q| q.is_empty() || q.ends_with(':')) else { continue };
+        let flowed = t.tag_name().name() == "flowRoot";
+        let Some(q) = qname.strip_suffix(t.tag_name().name()).filter(|q| q.is_empty() || q.ends_with(':')) else { continue };
         if cx.css.own(t, "display").as_deref() == Some("none") || r.start < copied {
             continue;
         }
-        let Some((text, paints)) = cx.build(xml, t, &label, warnings) else { continue };
+        let built = if flowed { cx.build_flow(t, &label, warnings) } else { cx.build(xml, t, &label, warnings) };
+        let Some((text, paints)) = built else { continue };
         out.push_str(&svg[copied..r.start]);
         placeholder(&mut out, q, &cx.css, t, &slots.prefix, slots.texts.len(), text.marker, &paints);
         copied = r.end;
@@ -468,10 +471,11 @@ impl Ctx {
             None => {
                 let id = href(tp)?.trim().strip_prefix('#')?;
                 let el = xml.descendants().find(|n| n.is_element() && n.attribute("id") == Some(id))?;
-                if el.tag_name().name() != "path" {
-                    return None;
-                }
-                let mut bp = BezPath::from_svg(el.attribute("d")?).ok()?;
+                let d = match el.tag_name().name() {
+                    "path" => el.attribute("d")?.to_string(),
+                    _ => self.shape_path(el)?,
+                };
+                let mut bp = BezPath::from_svg(&d).ok()?;
                 bp.apply_affine(parse_transform(el.attribute("transform")));
                 bp
             }
@@ -483,6 +487,123 @@ impl Ctx {
         usable.then_some(bp)
     }
 
+    /// The equivalent path of a basic shape (SVG 2 › Basic Shapes), as path data: what a
+    /// `<textPath>` that points at it follows. Circles and ellipses start at 3 o'clock and rounded
+    /// rects at the end of the top-left corner, all running clockwise; lines and polylines follow
+    /// their points. `None` for other elements and for shapes that render nothing.
+    fn shape_path(&self, el: XNode) -> Option<String> {
+        let (vw, vh) = self.viewport;
+        let len = |a: &str, pct: f64| el.attribute(a).and_then(|v| self.length(v, DEFAULT_FONT_SIZE, pct));
+        let x = |a: &str| len(a, vw).unwrap_or(0.0);
+        let y = |a: &str| len(a, vh).unwrap_or(0.0);
+        let points = || -> Vec<f64> { el.attribute("points").map(|v| list(v).map_while(|t| t.parse().ok()).collect()).unwrap_or_default() };
+        let ellipse = |cx: f64, cy: f64, rx: f64, ry: f64| {
+            (rx > 0.0 && ry > 0.0).then(|| {
+                format!(
+                    "M{} {} A{rx} {ry} 0 0 1 {cx} {} A{rx} {ry} 0 0 1 {} {cy} A{rx} {ry} 0 0 1 {cx} {} A{rx} {ry} 0 0 1 {} {cy}Z",
+                    cx + rx,
+                    cy,
+                    cy + ry,
+                    cx - rx,
+                    cy - ry,
+                    cx + rx
+                )
+            })
+        };
+        match el.tag_name().name() {
+            "circle" => {
+                let r = len("r", ((vw * vw + vh * vh) / 2.0).sqrt())?;
+                ellipse(x("cx"), y("cy"), r, r)
+            }
+            "ellipse" => {
+                let (rx, ry) = (len("rx", vw), len("ry", vh));
+                let (rx, ry) = (rx.or(ry)?, ry.or(rx)?);
+                ellipse(x("cx"), y("cy"), rx, ry)
+            }
+            "rect" => {
+                let (x0, y0, w, h) = (x("x"), y("y"), len("width", vw)?, len("height", vh)?);
+                if w <= 0.0 || h <= 0.0 {
+                    return None;
+                }
+                let (rx, ry) = (len("rx", vw).filter(|v| *v > 0.0), len("ry", vh).filter(|v| *v > 0.0));
+                let (rx, ry) = (rx.or(ry).unwrap_or(0.0).min(w / 2.0), ry.or(rx).unwrap_or(0.0).min(h / 2.0));
+                if rx <= 0.0 || ry <= 0.0 {
+                    return Some(format!("M{x0} {y0} H{} V{} H{x0}Z", x0 + w, y0 + h));
+                }
+                let (x1, y1) = (x0 + w, y0 + h);
+                Some(format!(
+                    "M{} {y0} H{} A{rx} {ry} 0 0 1 {x1} {} V{} A{rx} {ry} 0 0 1 {} {y1} H{} A{rx} {ry} 0 0 1 {x0} {} V{} A{rx} {ry} 0 0 1 {} {y0}Z",
+                    x0 + rx,
+                    x1 - rx,
+                    y0 + ry,
+                    y1 - ry,
+                    x1 - rx,
+                    x0 + rx,
+                    y1 - ry,
+                    y0 + ry,
+                    x0 + rx
+                ))
+            }
+            "line" => Some(format!("M{} {} L{} {}", x("x1"), y("y1"), x("x2"), y("y2"))),
+            tag @ ("polyline" | "polygon") => {
+                let pts = points();
+                let mut d = String::new();
+                for (i, [x, y]) in pts.as_chunks::<2>().0.iter().enumerate() {
+                    let _ = write!(d, "{}{x} {y} ", if i == 0 { 'M' } else { 'L' });
+                }
+                if d.is_empty() {
+                    return None;
+                }
+                if tag == "polygon" {
+                    d.push('Z');
+                }
+                Some(d)
+            }
+            _ => None,
+        }
+    }
+
+    /// Read one Inkscape `<flowRoot>` (SVG 1.2 flowed text, which browsers don't draw but
+    /// Inkscape writes) as area type: its frame the first `<rect>` of its `<flowRegion>`, a
+    /// paragraph per `<flowPara>`, styled as `<text>` is. Other regions are left out with a warning.
+    fn build_flow(&self, t: XNode, label: &str, warnings: &mut Vec<String>) -> Option<(PendingText, Vec<String>)> {
+        let (vw, vh) = self.viewport;
+        let region = t.children().find(|c| c.is_element() && c.tag_name().name() == "flowRegion");
+        let rect = region.and_then(|r| r.children().find(|c| c.is_element() && c.tag_name().name() == "rect"));
+        let size = |n: XNode, a: &str, pct: f64| n.attribute(a).and_then(|v| self.length(v, DEFAULT_FONT_SIZE, pct));
+        let frame = rect.and_then(|r| {
+            let (w, h) = (size(r, "width", vw)?, size(r, "height", vh)?);
+            (w > 0.0 && h > 0.0).then(|| (r, Rect::new(0.0, 0.0, w, h)))
+        });
+        let Some((r, frame)) = frame else {
+            warnings.push(format!("{label}: flowed text (flowRoot) without a rectangle region was left out"));
+            return None;
+        };
+        let origin = Affine::translate((size(r, "x", vw).unwrap_or(0.0), size(r, "y", vh).unwrap_or(0.0)));
+        let paras: Vec<XNode> = t.descendants().filter(|n| n.is_element() && n.tag_name().name() == "flowPara").collect();
+        let collapse = |n: XNode| {
+            n.descendants().filter(XNode::is_text).filter_map(|c| c.text()).collect::<String>().split_whitespace().collect::<Vec<_>>().join(" ")
+        };
+        let text = paras.iter().map(|p| collapse(*p)).collect::<Vec<_>>().join("\n");
+        if text.trim().is_empty() {
+            return None;
+        }
+        let style = self.elem(paras.first().copied().unwrap_or(t)).style.clone();
+        let mut obj = TextObject::point(Point::ZERO, &text, style);
+        obj.kind = TextKind::Area { frame: vectorcraft_geom::shapes::rectangle(frame) };
+        obj.xf = parse_transform(r.attribute("transform")) * origin;
+        let servers = vec![(None, None); obj.runs.len()];
+        let b = obj.xf.transform_rect_bbox(frame);
+        // A size, place or transform past what numbers hold (`width="1e999"`) has no frame to set type in.
+        if ![b.x0, b.y0, b.x1, b.y1].iter().all(|v| v.is_finite()) {
+            warnings.push(format!("{label}: flowed text (flowRoot) with a region too large to place was left out"));
+            return None;
+        }
+        let marker = Rect::new(b.x0, b.y0, b.x1.max(b.x0 + 1.0), b.y1.max(b.y0 + 1.0));
+        let name = t.attribute("id").unwrap_or("").to_string();
+        Some((PendingText { name, obj, servers, paints: 0, non_scaling: false, under: None, marker }, Vec::new()))
+    }
+
     /// Read one `<text>`: the pending text and its `url(#…)` paints.
     fn build(&self, xml: &roxmltree::Document, t: XNode, label: &str, warnings: &mut Vec<String>) -> Option<(PendingText, Vec<String>)> {
         let preserve = t.ancestors().filter(|a| a.is_element()).find_map(|a| a.attribute((roxmltree::NS_XML_URI, "space"))) == Some("preserve");

crates/svg/tests/import_details.rs

@@ -181,3 +181,38 @@ fn reflect_and_repeat_match_resvg() {
         assert_similar(&render_artboard(&d), &resvg_render(&svg(&body), 200, 120), 24.0, 0.01);
     }
 }
+
+/// #1557: `transform` as a CSS property, in CSS syntax, moves the object (and wins over the
+/// attribute, as in CSS), from a `style` attribute or a `<style>` rule.
+#[test]
+fn css_transforms_move_objects() {
+    let d = import_with(
+        &svg(r#"<style>.r { transform: rotate(90deg) }</style>
+            <rect id="a" x="0" y="0" width="50" height="50" fill="red" style="transform: translate(100px, 100px)"/>
+            <rect id="b" x="0" y="0" width="50" height="50" fill="blue" transform="translate(0 100)" style="transform: translateX(100px)"/>
+            <rect id="c" class="r" x="0" y="0" width="50" height="20" fill="green"/>"#),
+        &ImportOptions::default(),
+    )
+    .unwrap()
+    .0;
+    let b: Vec<Rect> = art(&d).iter().map(|n| n.geometric_bounds().unwrap()).collect();
+    let near =
+        |r: Rect, x0: f64, y0: f64, x1: f64, y1: f64| [(r.x0, x0), (r.y0, y0), (r.x1, x1), (r.y1, y1)].iter().all(|(a, b)| (a - b).abs() < 1e-6);
+    assert!(near(b[0], 100.0, 100.0, 150.0, 150.0), "{:?}", b[0]);
+    assert!(near(b[1], 100.0, 0.0, 150.0, 50.0), "{:?}", b[1]);
+    assert!(near(b[2], -20.0, 0.0, 0.0, 50.0), "{:?}", b[2]);
+}
+
+/// #1561: percentages in a `<symbol>` with a `viewBox` are of the `viewBox`, so the symbol draws as
+/// the same one written with numbers.
+#[test]
+fn percentages_in_a_symbol_are_of_its_view_box() {
+    let drawing = |w: &str, h: &str, cx: &str, cy: &str| {
+        let s = svg(&format!(
+            r##"<defs><symbol id="s" viewBox="0 0 100 50"><rect width="{w}" height="{h}" fill="red"/><circle cx="{cx}" cy="{cy}" r="20" fill="blue"/></symbol></defs>
+            <use xlink:href="#s" x="20" y="10" width="160" height="100"/>"##
+        ));
+        render_artboard(&import_with(&s, &ImportOptions::default()).unwrap().0)
+    };
+    assert_similar(&drawing("100%", "100%", "25%", "50%"), &drawing("100", "50", "25", "25"), 24.0, 0.001);
+}

crates/svg/tests/import_text.rs

@@ -518,3 +518,114 @@ fn gradients_on_scaled_text_stay_in_place() {
     let (start, end) = (t.xf * geom.start, t.xf * geom.end);
     assert!(start.distance(Point::new(40.0, 0.0)) < 1e-6 && end.distance(Point::new(240.0, 0.0)) < 1e-6, "{start:?} {end:?}");
 }
+
+/// The start of a type-on-a-path object's path and a point a little way along it, in document
+/// space.
+fn path_start(t: &TextObject) -> (Point, Point) {
+    use vectorcraft_geom::kurbo::{ParamCurve, PathEl};
+    let TextKind::OnPath { path, .. } = &t.kind else { panic!("{:?}", t.kind) };
+    let mut bp = path.to_bezpath();
+    bp.apply_affine(t.xf);
+    let PathEl::MoveTo(p0) = bp.elements()[0] else { panic!("{bp:?}") };
+    let next = bp.segments().next().unwrap().eval(0.05);
+    (p0, next)
+}
+
+#[test]
+fn text_path_follows_basic_shapes_as_their_equivalent_paths() {
+    let (d, w) = import_with_report(&svg(r##"<circle id="c" cx="150" cy="150" r="100"/>
+        <ellipse id="e" cx="150" cy="150" rx="80" ry="40" transform="translate(10 0)"/>
+        <rect id="r" x="20" y="30" width="100" height="60" rx="10"/>
+        <rect id="s" x="20" y="30" width="100" height="60"/>
+        <line id="l" x1="10" y1="200" x2="210" y2="200"/>
+        <polyline id="pl" points="10,10 110,10 110,60"/>
+        <polygon id="pg" points="10 10, 60 10, 35 50"/>
+        <text font-size="10"><textPath xlink:href="#c">TEXT ON A CIRCLE</textPath></text>
+        <text font-size="10"><textPath href="#e">Ellipse</textPath></text>
+        <text font-size="10"><textPath href="#r">Rounded</textPath></text>
+        <text font-size="10"><textPath href="#s">Square</textPath></text>
+        <text font-size="10"><textPath href="#l">Line</textPath></text>
+        <text font-size="10"><textPath href="#pl">Polyline</textPath></text>
+        <text font-size="10"><textPath href="#pg">Polygon</textPath></text>"##))
+    .unwrap();
+    assert!(!w.iter().any(|w| w.contains("textPath")), "{w:?}");
+    let t = texts(&d);
+    assert_eq!(t.len(), 7);
+    assert!(t.iter().all(|t| matches!(t.kind, TextKind::OnPath { .. })), "{:?}", t.iter().map(|t| &t.kind).collect::<Vec<_>>());
+    let near = |a: Point, b: Point| (a - b).hypot() < 1e-6;
+    // Circle: starts at 3 o'clock and runs clockwise (down first, y pointing down), around the circle.
+    let (p0, next) = path_start(t[0]);
+    assert!(near(p0, Point::new(250.0, 150.0)) && next.y > p0.y && next.x < p0.x, "{p0:?} {next:?}");
+    let TextKind::OnPath { path, .. } = &t[0].kind else { panic!("not on a path") };
+    let b = t[0].xf.transform_rect_bbox(path.bounds().unwrap());
+    assert!(close(b.x0, 50.0, 1e-6) && close(b.y0, 50.0, 1e-6) && close(b.x1, 250.0, 1e-6) && close(b.y1, 250.0, 1e-6), "{b:?}");
+    assert!(path.is_closed());
+    // Ellipse, with the shape's own transform.
+    let (p0, next) = path_start(t[1]);
+    assert!(near(p0, Point::new(240.0, 150.0)) && next.y > p0.y, "{p0:?} {next:?}");
+    // Rounded rect: after the top-left corner, along the top edge to the right.
+    let (p0, next) = path_start(t[2]);
+    assert!(near(p0, Point::new(30.0, 30.0)) && next.x > p0.x && close(next.y, 30.0, 1e-9), "{p0:?} {next:?}");
+    let (p0, next) = path_start(t[3]);
+    assert!(near(p0, Point::new(20.0, 30.0)) && next.x > p0.x, "{p0:?} {next:?}");
+    // Line, polyline and polygon follow their points.
+    assert!(near(path_start(t[4]).0, Point::new(10.0, 200.0)));
+    assert!(near(path_start(t[5]).0, Point::new(10.0, 10.0)));
+    let TextKind::OnPath { path, .. } = &t[6].kind else { panic!("not on a path") };
+    assert!(path.is_closed() && near(path_start(t[6]).0, Point::new(10.0, 10.0)));
+    assert_eq!(t[0].plain_text(), "TEXT ON A CIRCLE");
+}
+
+#[test]
+fn text_path_to_an_empty_shape_still_falls_back_to_point_type() {
+    let (d, w) =
+        import_with_report(&svg(r##"<circle id="c" cx="5" cy="5" r="0"/><text x="5" y="10"><textPath href="#c">Zero</textPath></text>"##)).unwrap();
+    assert!(matches!(only_text(&d).kind, TextKind::Point));
+    assert!(w.iter().any(|w| w.contains("textPath")), "{w:?}");
+}
+
+/// #1557: the `font` shorthand sets the type's size, weight and style.
+#[test]
+fn the_font_shorthand_styles_type() {
+    let d = open(r#"<text x="10" y="40" style="font: italic bold 30px sans-serif">Deco</text>"#);
+    let t = only_text(&d);
+    let st = &t.runs[0].style;
+    assert!(close(st.size * t.xf.determinant().abs().sqrt(), 30.0, 1e-6), "{}", st.size);
+    let style = st.font_style.to_ascii_lowercase();
+    assert!(style.contains("bold") && style.contains("italic"), "{style}");
+}
+
+/// Inkscape's flowed text (`<flowRoot>`) becomes area type in its region's rectangle, a paragraph
+/// per `<flowPara>`; another kind of region is left out with a warning, not silently.
+#[test]
+fn flowed_text_becomes_area_type() {
+    let (d, w) = import_with_report(&svg(
+        r#"<flowRoot style="font-size:16px;font-family:sans-serif"><flowRegion><rect x="20" y="30" width="100" height="160"/></flowRegion><flowPara>This is   flowed text</flowPara><flowPara>Second <flowSpan>one</flowSpan></flowPara></flowRoot>
+        <flowRoot><flowRegion><path d="M0 0 L10 0 L5 10 Z"/></flowRegion><flowPara>Lost</flowPara></flowRoot>"#,
+    ))
+    .unwrap();
+    let t = only_text(&d);
+    assert_eq!(t.plain_text(), "This is flowed text\nSecond one");
+    let TextKind::Area { frame } = &t.kind else { panic!("{:?}", t.kind) };
+    let b = t.xf.transform_rect_bbox(frame.bounds().unwrap());
+    assert!(close(b.x0, 20.0, 1e-6) && close(b.y0, 30.0, 1e-6) && close(b.x1, 120.0, 1e-6) && close(b.y1, 190.0, 1e-6), "{b:?}");
+    assert!(close(t.runs[0].style.size * t.xf.determinant().abs().sqrt(), 16.0, 1e-6));
+    assert!(w.iter().any(|w| w.contains("flowRoot")), "{w:?}");
+}
+
+/// Flowed text that can't be read is left out with a warning each, and never stops the import: no
+/// region, a region too large for numbers, a flowRoot inside a flowRoot (read once, as the outer one).
+#[test]
+fn flowed_text_that_cannot_be_read_is_reported() {
+    let (d, w) = import_with_report(&svg(
+        r#"<flowRoot id="none"><flowPara>No region</flowPara></flowRoot>
+        <flowRoot id="huge"><flowRegion><rect width="1e999" height="10"/></flowRegion><flowPara>Huge</flowPara></flowRoot>
+        <flowRoot id="far"><flowRegion><rect x="1e308" width="1e308" height="10" transform="scale(1e308)"/></flowRegion><flowPara>Far</flowPara></flowRoot>
+        <flowRoot id="outer"><flowRegion><rect width="50" height="50"/></flowRegion><flowPara>Outer</flowPara><flowRoot><flowRegion><rect width="5" height="5"/></flowRegion><flowPara>inner</flowPara></flowRoot></flowRoot>"#,
+    ))
+    .unwrap();
+    assert_eq!(only_text(&d).plain_text(), "Outer\ninner");
+    for id in ["none", "huge", "far"] {
+        assert!(w.iter().any(|w| w.contains(id) && w.contains("flowRoot")), "{id}: {w:?}");
+    }
+}

crates/svg/tests/options.rs

@@ -29,6 +29,33 @@ fn doc() -> Document {
     d
 }
 
+/// A large palette should create one class per distinct declaration, preserving first-use
+/// numbers even when earlier styles recur after hundreds of others.
+#[test]
+fn many_css_styles_preserve_first_use_numbers() {
+    let mut d = Document::new(300.0, 10.0);
+    let layer = d.layers[0].id;
+    let colors = (0u16..256).chain([0, 128, 255]);
+    for (x, color) in colors.enumerate() {
+        let x = x as f64;
+        let appearance = Appearance::basic(Paint::solid(Color::rgb8(color as u8, 31, 63)), Paint::None, 0.0);
+        let n = Node::path(d.alloc_id(), shapes::rectangle(Rect::new(x, 0.0, x + 0.5, 1.0)), appearance);
+        d.insert(Some(layer), usize::MAX, n).unwrap();
+    }
+
+    for (styling, definition_marker) in [(Styling::InternalCss, ".cls-"), (Styling::StyleEntities, "<!ENTITY st")] {
+        let svg = export(&d, &ExportOptions { styling, ..Default::default() });
+        let paths: Vec<_> = svg.lines().filter(|line| line.contains("<path ")).collect();
+        assert_eq!(paths.len(), 259, "{styling:?}");
+        for (i, path) in paths.iter().enumerate() {
+            let number = if i < 256 { i + 1 } else { [1, 129, 256][i - 256] };
+            let expected = if styling == Styling::InternalCss { format!("class=\"cls-{number}\"") } else { format!("style=\"&st{number};\"") };
+            assert!(path.contains(&expected), "path {i} should reference {expected}: {path}");
+        }
+        assert_eq!(svg.matches(definition_marker).count(), 256, "{styling:?}");
+    }
+}
+
 #[test]
 fn every_combination_reads_back() {
     let d = doc();

crates/text/src/fontconfig.rs

@@ -0,0 +1,253 @@
+//! The font folders fontconfig is set up with (Linux and the other Unix desktops): the `<dir>`
+//! entries of its configuration, `/etc/fonts/fonts.conf` and what that includes (`conf.d`, the
+//! user's own files). Distributions and packages add folders outside the usual ones there: TeX
+//! fonts under `/usr/share/texmf/fonts`, say, which `fc-list` and other apps then show (#1529).
+//!
+//! The format is fontconfig's documented one
+//! (<https://www.freedesktop.org/software/fontconfig/fontconfig-user.html>, "Configuration file
+//! format"): `<dir prefix="…">` and `<include prefix="…">` are all that is read here. The files are
+//! read as they are: fontconfig itself (a library, or `fc-list`) isn't asked.
+
+use std::collections::HashSet;
+use std::path::{Path, PathBuf};
+
+/// The most configuration files read, and the largest one (they are a few kilobytes each).
+const MAX_FILES: usize = 512;
+const MAX_FILE_BYTES: u64 = 1 << 20;
+/// The most folders taken, and how deep files may include files.
+const MAX_DIRS: usize = 256;
+const MAX_DEPTH: usize = 8;
+
+/// A `<dir>` (a font folder) or an `<include>` (another configuration file, or a folder of them)
+/// with its `prefix` attribute and its text.
+#[derive(Debug, PartialEq)]
+struct Entry {
+    include: bool,
+    prefix: String,
+    path: String,
+}
+
+/// The `<dir>` and `<include>` elements of a configuration file, in order. Anything that isn't
+/// one of them, comments included, is skipped; a file that isn't well formed gives what was read
+/// before the damage.
+fn entries(xml: &str) -> Vec<Entry> {
+    let mut out = vec![];
+    let mut rest = xml;
+    while let Some(at) = rest.find('<') {
+        rest = rest.get(at + 1..).unwrap_or_default();
+        if let Some(comment) = rest.strip_prefix("!--") {
+            rest = comment.split_once("-->").map_or("", |(_, after)| after);
+            continue;
+        }
+        let Some((tag, after)) = rest.split_once('>') else { break };
+        let name = tag.split_whitespace().next().unwrap_or_default();
+        if !matches!(name, "dir" | "include") || tag.ends_with('/') {
+            continue;
+        }
+        let Some((text, after)) = after.split_once("</") else { break };
+        rest = after;
+        // No element is inside these: text with a tag in it isn't a path.
+        if text.contains('<') {
+            continue;
+        }
+        let path = text.trim().replace("&amp;", "&").replace("&lt;", "<").replace("&gt;", ">").replace("&quot;", "\"").replace("&apos;", "'");
+        if !path.is_empty() {
+            out.push(Entry { include: name == "include", prefix: attribute(tag, "prefix").unwrap_or_default().to_string(), path });
+        }
+    }
+    out
+}
+
+/// The value of attribute `name` in a start tag's text.
+fn attribute<'a>(tag: &'a str, name: &str) -> Option<&'a str> {
+    let mut rest = tag;
+    while let Some(at) = rest.find(name) {
+        let before_ok = rest.get(..at).is_some_and(|b| b.ends_with(char::is_whitespace));
+        rest = rest.get(at + name.len()..)?;
+        let Some(value) = rest.trim_start().strip_prefix('=') else { continue };
+        let value = value.trim_start();
+        let quote = value.chars().next().filter(|q| matches!(q, '"' | '\''))?;
+        let (value, _) = value.get(1..)?.split_once(quote)?;
+        if before_ok {
+            return Some(value);
+        }
+    }
+    None
+}
+
+/// Where the user's files are: the home folder and the XDG data and configuration folders.
+#[derive(Clone, Debug, Default)]
+pub(crate) struct Places {
+    pub home: Option<PathBuf>,
+    pub data_home: Option<PathBuf>,
+    pub config_home: Option<PathBuf>,
+}
+
+impl Places {
+    /// The path an entry of the file `from` names: `~` is the home folder, `prefix="xdg"` the XDG
+    /// data folder (a `<dir>`) or configuration folder (an `<include>`), `prefix="relative"` the
+    /// file's own folder, as is an `<include>` that isn't a full path. A `<dir>` relative to the
+    /// folder the app was started in is none.
+    fn resolve(&self, e: &Entry, from: &Path) -> Option<PathBuf> {
+        // `~` alone or before a `/`: another user's home (`~name`) isn't looked up.
+        if let Some(rest) = e.path.strip_prefix('~').filter(|rest| rest.is_empty() || rest.starts_with('/')) {
+            return Some(self.home.as_ref()?.join(rest.trim_start_matches('/')));
+        }
+        let path = Path::new(&e.path);
+        let base = match e.prefix.as_str() {
+            "xdg" if e.include => self.config_home.as_deref(),
+            "xdg" => self.data_home.as_deref(),
+            _ if path.is_absolute() => return Some(path.to_path_buf()),
+            "relative" => from.parent(),
+            _ if e.include => from.parent(),
+            _ => None,
+        };
+        Some(base?.join(path)).filter(|p| p.is_absolute())
+    }
+}
+
+/// The font folders the configuration file `root` and the files it includes list, in order, each
+/// once. Files that are missing or can't be read list none.
+pub(crate) fn font_dirs(root: &Path, places: &Places) -> Vec<PathBuf> {
+    let mut read = Reader { places, files: HashSet::new(), dirs: vec![] };
+    read.file(root, 0);
+    read.dirs
+}
+
+struct Reader<'a> {
+    places: &'a Places,
+    /// The files read so far (a file including itself is read once).
+    files: HashSet<PathBuf>,
+    dirs: Vec<PathBuf>,
+}
+
+impl Reader<'_> {
+    fn file(&mut self, path: &Path, depth: usize) {
+        if depth > MAX_DEPTH || self.files.len() >= MAX_FILES || !self.files.insert(path.to_path_buf()) {
+            return;
+        }
+        // A folder of configuration files: those named as fontconfig reads them (a digit first,
+        // `.conf` last), in name order.
+        if let Ok(list) = std::fs::read_dir(path) {
+            let mut files: Vec<PathBuf> = list
+                .flatten()
+                .take(MAX_FILES)
+                .filter(|e| {
+                    let name = e.file_name();
+                    let name = name.to_string_lossy();
+                    name.starts_with(|c: char| c.is_ascii_digit()) && name.ends_with(".conf")
+                })
+                .map(|e| e.path())
+                .collect();
+            files.sort();
+            for f in files {
+                self.file(&f, depth + 1);
+            }
+            return;
+        }
+        // A file that is missing, too large or not text lists nothing.
+        if !std::fs::metadata(path).is_ok_and(|m| m.is_file() && m.len() <= MAX_FILE_BYTES) {
+            return;
+        }
+        let Ok(text) = std::fs::read_to_string(path) else { return };
+        for e in entries(&text) {
+            let Some(to) = self.places.resolve(&e, path) else { continue };
+            if e.include {
+                self.file(&to, depth + 1);
+            } else if self.dirs.len() < MAX_DIRS && !self.dirs.contains(&to) {
+                self.dirs.push(to);
+            }
+        }
+    }
+}
+
+/// The configuration file fontconfig starts from: `FONTCONFIG_FILE`, else `fonts.conf` in
+/// `FONTCONFIG_PATH`, else `/etc/fonts/fonts.conf`.
+pub(crate) fn root() -> PathBuf {
+    let var = |name| std::env::var_os(name).map(PathBuf::from).filter(|p| p.is_absolute());
+    var("FONTCONFIG_FILE").or_else(|| var("FONTCONFIG_PATH").map(|d| d.join("fonts.conf"))).unwrap_or_else(|| "/etc/fonts/fonts.conf".into())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn entry(include: bool, prefix: &str, path: &str) -> Entry {
+        Entry { include, prefix: prefix.into(), path: path.into() }
+    }
+
+    #[test]
+    fn dirs_and_includes_are_read_and_the_rest_is_skipped() {
+        let xml = r#"<?xml version="1.0"?>
+<!DOCTYPE fontconfig SYSTEM "urn:fontconfig:fonts.dtd">
+<fontconfig>
+  <description>Default configuration file</description>
+  <!-- <dir>/commented/out</dir> -->
+  <dir>/usr/share/fonts</dir>
+  <dir prefix="xdg">fonts</dir>
+  <dir prefix = 'relative' salt="x"> more &amp; more </dir>
+  <dir>~/.fonts</dir>
+  <dir></dir>
+  <cachedir>/var/cache/fontconfig</cachedir>
+  <match target="pattern"><test qual="any" name="family"><string>mono</string></test></match>
+  <include ignore_missing="yes">conf.d</include>
+  <include ignore_missing="yes" prefix="xdg">fontconfig/fonts.conf</include>
+  <dir>/cut/off"#;
+        assert_eq!(
+            entries(xml),
+            [
+                entry(false, "", "/usr/share/fonts"),
+                entry(false, "xdg", "fonts"),
+                entry(false, "relative", "more & more"),
+                entry(false, "", "~/.fonts"),
+                entry(true, "", "conf.d"),
+                entry(true, "xdg", "fontconfig/fonts.conf"),
+            ]
+        );
+        // Damaged files and files that aren't XML read as nothing, without a panic.
+        for junk in
+            ["", "<", "<dir", "<dir>", "<dir><dir></dir>", "</dir>", "<!--", "<dir prefix=>x</dir", "\u{0}<dir prefix=\"", "<dir prefix='é>ü</dir>"]
+        {
+            let _ = entries(junk);
+        }
+        assert_eq!(attribute("dir notprefix=\"a\" prefix=\"b\"", "prefix"), Some("b"));
+    }
+
+    /// A configuration as distributions lay it out: the main file lists the usual folders and
+    /// includes `conf.d`, where a package's file adds its own folder (TeX fonts, #1529) and
+    /// another includes the user's files.
+    #[test]
+    fn folders_of_included_files_are_listed_once_in_order() {
+        let tmp = std::env::temp_dir().join(format!("vc-fontconfig-{}", std::process::id()));
+        let _ = std::fs::remove_dir_all(&tmp);
+        let (etc, home) = (tmp.join("etc/fonts"), tmp.join("home"));
+        let write = |path: PathBuf, body: &str| {
+            std::fs::create_dir_all(path.parent().unwrap()).unwrap();
+            std::fs::write(path, format!("<fontconfig>{body}</fontconfig>")).unwrap();
+        };
+        let texmf = tmp.join("usr/share/texmf/fonts/opentype");
+        write(
+            etc.join("fonts.conf"),
+            &format!(
+                "<dir>{}</dir><dir prefix=\"xdg\">fonts</dir><dir>~/.fonts</dir><dir>fonts-of-the-working-folder</dir>\
+                 <include ignore_missing=\"yes\">conf.d</include><include>{}</include><include>fonts.conf</include>",
+                tmp.join("usr/share/fonts").display(),
+                etc.join("missing.conf").display()
+            ),
+        );
+        write(etc.join("conf.d/09-texlive.conf"), &format!("<dir>{}</dir>", texmf.display()));
+        write(etc.join("conf.d/50-user.conf"), "<include ignore_missing=\"yes\" prefix=\"xdg\">fontconfig/fonts.conf</include>");
+        write(etc.join("conf.d/README"), "<dir>/not/a/conf/file</dir>");
+        write(etc.join("conf.d/user.conf"), "<dir>/no/digit/first</dir>");
+        write(home.join(".config/fontconfig/fonts.conf"), &format!("<dir prefix=\"relative\">mine</dir><dir>{}</dir>", texmf.display()));
+        let places = Places { home: Some(home.clone()), data_home: Some(home.join(".local/share")), config_home: Some(home.join(".config")) };
+        assert_eq!(
+            font_dirs(&etc.join("fonts.conf"), &places),
+            [tmp.join("usr/share/fonts"), home.join(".local/share/fonts"), home.join(".fonts"), texmf, home.join(".config/fontconfig/mine")]
+        );
+        // Without a home folder, what needs one is left out; a missing file lists nothing.
+        assert_eq!(font_dirs(&etc.join("fonts.conf"), &Places::default()).len(), 2);
+        assert!(font_dirs(&tmp.join("none.conf"), &places).is_empty());
+        let _ = std::fs::remove_dir_all(&tmp);
+    }
+}

crates/text/src/fontdb.rs

@@ -1269,12 +1269,21 @@ pub fn system_font_dirs() -> Vec<PathBuf> {
         // list their own data folders), relative paths ignored as the XDG spec says.
         let xdg = |var| std::env::var_os(var).map(|v| std::env::split_paths(&v).filter(|p| p.is_absolute()).collect::<Vec<_>>()).unwrap_or_default();
         let data_home = xdg("XDG_DATA_HOME").into_iter().next().or_else(|| home.as_ref().map(|h| h.join(".local/share")));
-        dirs.extend(data_home.into_iter().chain(xdg("XDG_DATA_DIRS")).map(|d| d.join("fonts")));
+        dirs.extend(data_home.iter().cloned().chain(xdg("XDG_DATA_DIRS")).map(|d| d.join("fonts")));
         if let Some(h) = &home {
             dirs.push(h.join(".fonts"));
         }
         // In a Flatpak sandbox, the host's fonts (system, local and the user's).
         dirs.extend(["/run/host/fonts", "/run/host/local-fonts", "/run/host/user-fonts"].map(Into::into));
+        // The folders fontconfig is set up with outside those: packages add their own (TeX fonts
+        // under `/usr/share/texmf/fonts`, #1529), and `fc-list` and other apps show their fonts.
+        let config_home = xdg("XDG_CONFIG_HOME").into_iter().next().or_else(|| home.as_ref().map(|h| h.join(".config")));
+        let places = crate::fontconfig::Places { home: home.clone(), data_home, config_home };
+        for dir in crate::fontconfig::font_dirs(&crate::fontconfig::root(), &places) {
+            if !dirs.iter().any(|known| dir.starts_with(known)) {
+                dirs.push(dir);
+            }
+        }
     }
     dirs.extend(app_font_dir().map(Path::to_path_buf));
     #[cfg(not(target_arch = "wasm32"))]

crates/text/src/lib.rs

@@ -14,6 +14,7 @@ pub mod craft_fonts;
 pub mod edit;
 pub mod embed;
 mod features;
+mod fontconfig;
 mod fontdb;
 pub mod hyphen;
 mod layout;

crates/tools/src/guides.rs

@@ -384,6 +384,12 @@ impl Targets {
         self
     }
 
+    /// The ruler guides alone ([`Self::with_rulers`]): what a dragged selection's grabbed point
+    /// still snaps to with View → Snap to Point when Smart Guides line the selection up.
+    pub(crate) fn rulers(cx: &ToolContext) -> Self {
+        Self::default().styled(cx).with_rulers(cx)
+    }
+
     /// What a dragged selection's grabbed point snaps to with View → Snap to Point and Smart
     /// Guides off: the anchors of the art but `exclude` and the ruler guides.
     pub fn snap_to_point(cx: &ToolContext, exclude: &[NodeId]) -> Option<Self> {

crates/tools/src/select.rs

@@ -90,6 +90,9 @@ pub(crate) struct MoveSnap {
     /// original.
     copy_targets: Option<Targets>,
     copy_points: Option<Targets>,
+    /// With Smart Guides on, the ruler guides View › Snap to Point still pulls the grabbed point
+    /// onto (#1534); `points` holds them with Smart Guides off.
+    rulers: Option<Targets>,
 }
 
 impl MoveSnap {
@@ -102,6 +105,7 @@ impl MoveSnap {
             points: points(&cx.selection.objects),
             copy_targets: guides.then(|| Targets::for_move(cx, &[])),
             copy_points: points(&[]),
+            rulers: (guides && cx.snap_to_point).then(|| Targets::rulers(cx)),
         }
     }
 
@@ -133,6 +137,14 @@ impl MoveSnap {
                 guides = ov;
             }
         }
+        // A ruler guide within reach of the grabbed point wins over lining the bounds up.
+        if let Some(t) = &self.rulers {
+            let (q, ov) = t.snap_point(start + d, cx.tol(cx.snap_tolerance));
+            if q != start + d {
+                d = q - start;
+                guides = ov;
+            }
+        }
         if cx.snap_to_pixel
             && let Some(b) = self.bounds
         {
@@ -733,6 +745,29 @@ mod tests {
         assert_eq!(a, vec![Action::Commit]);
     }
 
+    /// #1534: with Smart Guides on (the default), the point a selection is dragged by still snaps
+    /// to a ruler guide within the Snap to Point distance; not with Snap to Point off.
+    #[test]
+    fn a_move_snaps_the_grabbed_point_to_a_ruler_guide_with_smart_guides_on() {
+        let (mut d, id) = doc_with_rect();
+        d.guides = vec![vectorcraft_doc::Guide::new(true, 173.4)];
+        let mut s = Selection::default();
+        s.add(id);
+        let p = paint();
+        let dx = |c: &ToolContext, to: f64| {
+            let mut t = SelectionTool::default();
+            t.pointer(c, &ev(PointerKind::Down, 150.0, 150.0));
+            let a = t.pointer(c, &ev(PointerKind::Drag, to, 150.0));
+            let Some(Action::Preview(_, v)) = a.last() else { panic!("{a:?}") };
+            v["matrix"][4].as_f64().unwrap()
+        };
+        let c = cx(&d, &s, &p);
+        assert!(c.smart_guides && c.snap_to_point);
+        assert!((dx(&c, 172.0) - 23.4).abs() < 1e-9, "onto the guide");
+        assert_eq!(dx(&c, 165.0), 15.0, "out of reach");
+        assert_eq!(dx(&ToolContext { snap_to_point: false, ..cx(&d, &s, &p) }, 172.0), 22.0);
+    }
+
     /// Alt pressed during a move makes a copy, which snaps to the original it leaves behind (as
     /// gathered before the previews moved it); released, the move doesn't.
     #[test]

crates/trace/Cargo.toml

@@ -10,7 +10,6 @@ workspace = true
 
 [dependencies]
 vectorcraft-geom = { workspace = true }
-vectorcraft-pathops = { workspace = true }
 kurbo = { workspace = true }
 image = { workspace = true }
 serde = { workspace = true }

crates/trace/src/centerline.rs

@@ -12,14 +12,23 @@
 //!    merged into one point) become polylines through the pixel centres; rings without ends
 //!    become closed ones. Short spurs that thinning leaves at junctions are pruned and the runs
 //!    on either side of a junction left with two of them are joined.
-//! 5. **Curves**: each polyline is fitted like an outline ([`fit::fit_polyline`]); the stroke
-//!    width is the line's mean width (its pixel count over its length).
+//! 5. **Ink**: the skeleton is right to a pixel only, so each of its points is moved to the middle
+//!    of the line's ink, read from the image: across the line (along the pixel column or row most
+//!    nearly square to it) each pixel is as much ink as its colour is the line's rather than the
+//!    paper's, and the ink's centroid is the line's middle there and its sum the line's width (an
+//!    anti-aliased or blurred line says both to a fraction of a pixel). The stroke width is the
+//!    median of those widths, and each end is put where the ink ends, less the half width a round
+//!    cap adds.
+//! 6. **Curves**: each polyline is fitted as outlines are ([`fit::fit_piece`]): a straight line
+//!    is two anchors, corners stay corners, the rest is as few curves as Paths allows.
 
 use std::collections::HashSet;
 
 use vectorcraft_geom::{PathData, Point};
 
-use crate::fit::{self, FitOptions};
+use crate::Raster;
+use crate::fit;
+use crate::logo::Style;
 
 /// One line of a colour layer: its centre lines and the width to stroke them with.
 pub(crate) struct Line {
@@ -31,7 +40,19 @@ pub(crate) struct Line {
 
 /// The lines of colour `label` in `labels` (`w` × `h`, row-major) no wider than `max_width`
 /// pixels, and which pixels they cover (to leave out of the filled areas).
-pub(crate) fn lines(labels: &[u16], label: u16, w: usize, h: usize, max_width: f64, o: &FitOptions) -> (Vec<bool>, Vec<Line>) {
+/// `ink` is the colour of the layer's ink in `img` (its palette colour; in Black and White the
+/// image's own black), which the lines' middles and widths are read against.
+#[allow(clippy::too_many_arguments)]
+pub(crate) fn lines(
+    labels: &[u16],
+    label: u16,
+    w: usize,
+    h: usize,
+    max_width: f64,
+    img: &Raster,
+    ink: [f64; 3],
+    style: &Style,
+) -> (Vec<bool>, Vec<Line>) {
     let mut thin = vec![false; labels.len()];
     let mut out = vec![];
     if w == 0 || h == 0 || labels.len() != w * h {
@@ -61,7 +82,7 @@ pub(crate) fn lines(labels: &[u16], label: u16, w: usize, h: usize, max_width: f
         if widest > max_width {
             continue;
         }
-        let Some(line) = trace_line(&comp, w, max_width, o) else { continue };
+        let Some(line) = trace_line(&comp, w, max_width, img, ink, style) else { continue };
         for &i in &comp {
             thin[i] = true;
         }
@@ -221,7 +242,7 @@ impl Run {
 }
 
 /// The centre lines of one line component (pixel indices of the `w`-wide image).
-fn trace_line(comp: &[usize], w: usize, max_width: f64, o: &FitOptions) -> Option<Line> {
+fn trace_line(comp: &[usize], w: usize, max_width: f64, img: &Raster, ink: [f64; 3], style: &Style) -> Option<Line> {
     let xs = comp.iter().map(|&i| i % w);
     let ys = comp.iter().map(|&i| i / w);
     let (x0, x1, y0, y1) = (xs.clone().min()?, xs.max()?, ys.clone().min()?, ys.max()?);
@@ -312,14 +333,168 @@ fn trace_line(comp: &[usize], w: usize, max_width: f64, o: &FitOptions) -> Optio
     };
     let spur = width(&runs);
     let runs = join(prune(runs, centres.len(), spur), centres.len());
-    let width = width(&runs);
-    let subs: Vec<_> = runs.iter().filter_map(|r| fit::fit_polyline(&r.pts, r.closed, o)).collect();
+    let mut runs = runs;
+    let coarse = width(&runs);
+    let ink = Ink { img, color: ink, reach: (max_width / 2.0).ceil().clamp(1.0, 64.0) as i64 + 2 };
+    // How many runs end at each node: one is an end of the line.
+    let mut meet = vec![0usize; centres.len()];
+    for e in runs.iter().flat_map(|r| r.ends.iter().flatten()) {
+        meet[*e] += 1;
+    }
+    let (mut widths, mut soft, mut read) = (vec![], 0usize, 0usize);
+    for r in &mut runs {
+        let n = r.pts.len();
+        let old = r.pts.clone();
+        for i in 0..n {
+            // A junction stays where its pixels put it.
+            let end = if i == 0 {
+                r.ends[0]
+            } else if i + 1 == n {
+                r.ends[1]
+            } else {
+                None
+            };
+            if end.is_some_and(|e| meet[e] > 1) {
+                continue;
+            }
+            let (a, b) = if r.closed { (old[(i + n - 2 % n) % n], old[(i + 2) % n]) } else { (old[i.saturating_sub(2)], old[(i + 2).min(n - 1)]) };
+            let d = b - a;
+            if d.hypot() < 1e-9 {
+                continue;
+            }
+            let upright = d.x.abs() >= d.y.abs();
+            let Some(across) = ink.across(old[i], upright) else { continue };
+            r.pts[i] = old[i] + if upright { kurbo::Vec2::new(0.0, across.middle) } else { kurbo::Vec2::new(across.middle, 0.0) };
+            widths.push(across.width * if upright { d.x.abs() } else { d.y.abs() } / d.hypot());
+            read += 1;
+            soft += usize::from(across.soft);
+        }
+    }
+    // The stroke is as wide as the ink at the line's middle point (where no ink could be read, as
+    // wide as its pixels make it).
+    widths.sort_by(f64::total_cmp);
+    let width = widths.get(widths.len() / 2).copied().unwrap_or(coarse).clamp(0.25, max_width.max(1.0));
+    // Each end goes where the ink ends, less the half width its round cap adds.
+    for r in runs.iter_mut().filter(|r| !r.closed && r.pts.len() >= 2) {
+        for k in 0..2 {
+            if r.ends[k].is_some_and(|e| meet[e] > 1) {
+                continue;
+            }
+            let n = r.pts.len();
+            let (tip, inner) = if k == 0 { (r.pts[0], r.pts[3.min(n - 1)]) } else { (r.pts[n - 1], r.pts[n - 1 - 3.min(n - 1)]) };
+            let d = tip - inner;
+            if d.hypot() < 1e-9 {
+                continue;
+            }
+            let more = ink.beyond(tip, d / d.hypot()) - width / 2.0;
+            if more.abs() > 0.05 && more > -1.0 {
+                let to = tip + d / d.hypot() * more;
+                if k == 0 { r.pts[0] = to } else { r.pts[n - 1] = to }
+            }
+        }
+    }
+    let mut style = *style;
+    if read > 0 && soft * 4 < read {
+        // Hard pixels: the middle is only known to about half a pixel (as for outlines).
+        style.tol *= 2.5;
+        style.line_tol *= 2.5;
+        style.sigma = 1.5;
+    }
+    let subs: Vec<_> = runs
+        .iter()
+        .filter_map(|r| {
+            if r.closed { fit::subpath(&fit::fit_closed(&r.pts, &style)?, true) } else { fit::subpath(&fit::fit_piece(&r.pts, &style, false), false) }
+        })
+        .collect();
     if subs.is_empty() {
         return None;
     }
     Some(Line { path: PathData::new(subs), width, pixels: comp.len() })
 }
 
+/// What the image says of a line's ink.
+struct Ink<'a> {
+    img: &'a Raster,
+    /// The line's colour.
+    color: [f64; 3],
+    /// How far (pixels) from the skeleton the ink is looked for.
+    reach: i64,
+}
+
+/// The ink across a line at one point: where its middle lies from the point, how wide it is, and
+/// whether its edges are soft (some pixel is part ink, part paper).
+struct Across {
+    middle: f64,
+    width: f64,
+    soft: bool,
+}
+
+impl Ink<'_> {
+    /// How far the colour of pixel `(x, y)` is from the line's (`None` off the image).
+    fn far(&self, x: i64, y: i64) -> Option<f64> {
+        let (w, h) = (i64::from(self.img.width), i64::from(self.img.height));
+        if x < 0 || y < 0 || x >= w || y >= h {
+            return None;
+        }
+        let at = (y * w + x) as usize * 4;
+        let p = self.img.rgba.get(at..at + 3)?;
+        Some((0..3).map(|k| (f64::from(p[k]) - self.color[k]).powi(2)).sum::<f64>().sqrt())
+    }
+    /// How far the paper's colour is from the line's around pixel `(x, y)`: the farthest colour
+    /// within reach, along its row and its column.
+    fn paper(&self, x: i64, y: i64) -> f64 {
+        (-self.reach..=self.reach).flat_map(|k| [self.far(x + k, y), self.far(x, y + k)]).flatten().fold(0.0, f64::max)
+    }
+    /// The ink across the line through the pixel `p` lies in: along its column (`upright`) or row.
+    fn across(&self, p: Point, upright: bool) -> Option<Across> {
+        let (x, y) = (p.x.floor() as i64, p.y.floor() as i64);
+        let paper = self.paper(x, y);
+        // Paper too like the ink says nothing.
+        if paper < 24.0 {
+            return None;
+        }
+        let tone = |k: i64| (if upright { self.far(x, y + k) } else { self.far(x + k, y) }).map_or(0.0, |d| (1.0 - d / paper).clamp(0.0, 1.0));
+        // From the pixel with most ink near the skeleton's (thinning leaves it up to a pixel or two
+        // off the line's darkest row) out to where the ink ends, or rises again (another line).
+        let peak = [0, -1, 1, -2, 2].into_iter().fold(0, |best, k| if tone(k) > tone(best) + 1e-9 { k } else { best });
+        let here = tone(peak);
+        let (mut sum, mut moment, mut soft) = (here, here * peak as f64, here > 0.1 && here < 0.9);
+        for side in [-1, 1] {
+            let mut last = here;
+            for k in 1..=self.reach {
+                let t = tone(peak + side * k);
+                if t < 0.04 || t > last + 0.1 {
+                    break;
+                }
+                sum += t;
+                moment += t * (peak + side * k) as f64;
+                soft |= t > 0.1 && t < 0.9;
+                last = t;
+            }
+        }
+        // The pixel's centre is at `p`'s own half-pixel; the middle is measured from `p`.
+        let centre = if upright { y as f64 + 0.5 - p.y } else { x as f64 + 0.5 - p.x };
+        (sum > 0.0).then(|| Across { middle: centre + moment / sum, width: sum, soft })
+    }
+    /// How much ink (pixels) lies beyond `tip`, going `dir` (a unit vector).
+    fn beyond(&self, tip: Point, dir: kurbo::Vec2) -> f64 {
+        let paper = self.paper(tip.x.floor() as i64, tip.y.floor() as i64);
+        if paper < 24.0 {
+            return 0.0;
+        }
+        let mut sum = 0.0;
+        for step in 1..=4 * (self.reach + 2) {
+            let q = tip + dir * (step as f64 * 0.25);
+            let t = self.far(q.x.floor() as i64, q.y.floor() as i64).map_or(0.0, |d| (1.0 - d / paper).clamp(0.0, 1.0));
+            if t < 0.04 {
+                break;
+            }
+            sum += 0.25 * t;
+        }
+        sum
+    }
+}
+
 /// The runs without the spurs thinning leaves: runs shorter than the line's `width` from a line end
 /// to a junction that keeps at least two other runs.
 fn prune(runs: Vec<Run>, nodes: usize, width: f64) -> Vec<Run> {

crates/trace/src/contour.rs

@@ -51,7 +51,8 @@ fn step(d: u8) -> (i32, i32) {
 fn label(mask: &[bool], w: usize, h: usize) -> (Vec<u32>, Vec<usize>) {
     let mut comp = vec![u32::MAX; w * h];
     let mut sizes = Vec::new();
-    let mut stack = Vec::new();
+    // (Indices as `u32`: a mask has at most 64 million pixels, and this stack can hold them all.)
+    let mut stack: Vec<u32> = Vec::new();
     for s in 0..w * h {
         if !mask[s] || comp[s] != u32::MAX {
             continue;
@@ -59,14 +60,15 @@ fn label(mask: &[bool], w: usize, h: usize) -> (Vec<u32>, Vec<usize>) {
         let id = sizes.len() as u32;
         let mut n = 0usize;
         comp[s] = id;
-        stack.push(s);
+        stack.push(s as u32);
         while let Some(i) = stack.pop() {
+            let i = i as usize;
             n += 1;
             let (x, y) = (i % w, i / w);
             let mut go = |j: usize| {
                 if mask[j] && comp[j] == u32::MAX {
                     comp[j] = id;
-                    stack.push(j);
+                    stack.push(j as u32);
                 }
             };
             if x > 0 {

crates/trace/src/fit.rs

@@ -1,20 +1,11 @@
-//! Loop → Bézier curves, and centre line → Bézier curves.
+//! Loop → Bézier curves, and the pieces of that which centre lines use too.
 
-use vectorcraft_geom::{Anchor, AnchorKind, CubicBez, ParamCurve, PathData, Point, SubPath};
-use vectorcraft_pathops::{SimplifyOptions, simplify_with};
+use vectorcraft_geom::{Anchor, AnchorKind, Point, SubPath};
 
 use crate::contour::Loop;
 use crate::logo::{Cubic, Stats, Style, all_within, fit_open, fit_outline, resample_closed, resample_open, sample_cubics};
 use crate::subpixel::{self, Crack};
 
-#[derive(Clone, Copy, Debug)]
-pub(crate) struct FitOptions {
-    pub polygon_tol: f64,
-    pub fit_tol: f64,
-    pub corner_angle: f64,
-    pub snap_lines: bool,
-}
-
 fn seg_dist(p: Point, a: Point, b: Point) -> f64 {
     let ab = b - a;
     let l2 = ab.hypot2();
@@ -60,10 +51,78 @@ fn before(a: Point, b: Point) -> std::cmp::Ordering {
     a.x.total_cmp(&b.x).then(a.y.total_cmp(&b.y))
 }
 
+/// Lines within this of level or upright are made exactly so (the tangent of 2.5°).
+const NEARLY_UPRIGHT: f64 = 0.0437;
+
+/// The farthest (px) levelling a line may move either of its ends.
+const LEVEL_REACH: f64 = 1.6;
+
+/// Snap Curves To Lines: the straight pieces of `segs` (a chain; `closed` when its end joins its
+/// start) that are within 2.5° of level or upright and at least 2 px long are made exactly level
+/// or upright (unless that moves an end by more than [`LEVEL_REACH`]), by moving their ends
+/// across them: both to their mean, or, in an open chain, the
+/// free end to the end that is fixed (with `fixed_ends`, a chain's own ends stay where they are:
+/// they are junctions other regions share). The pieces next to a moved end follow it.
+fn snap_upright(segs: &mut [Cubic], closed: bool, fixed_ends: bool) {
+    let n = segs.len();
+    let straight = |c: &Cubic| seg_dist(c[1], c[0], c[3]) < 1e-6 && seg_dist(c[2], c[0], c[3]) < 1e-6;
+    let lines: Vec<bool> = segs.iter().map(straight).collect();
+    // Anchor `i` starts piece `i`; an open chain has one more, at its end.
+    let fixed = |i: usize| !closed && fixed_ends && (i == 0 || i == n);
+    let at = |segs: &[Cubic], i: usize| if i < n { segs[i][0] } else { segs[n - 1][3] };
+    let put = |segs: &mut [Cubic], i: usize, p: Point| {
+        let i = if closed { i % n } else { i };
+        let d = p - at(segs, i);
+        if i < n {
+            segs[i][0] = p;
+            segs[i][1] += d;
+        }
+        if let Some(before) = if i > 0 { Some(i - 1) } else { closed.then_some(n - 1) } {
+            segs[before][3] = p;
+            segs[before][2] += d;
+        }
+    };
+    for (i, &line) in lines.iter().enumerate() {
+        let (ia, ib) = (i, if closed { (i + 1) % n } else { i + 1 });
+        let (a, b) = (at(segs, ia), at(segs, ib));
+        let d = b - a;
+        if !line || d.hypot() < 2.0 || ia == ib {
+            continue;
+        }
+        let level = d.y.abs() <= NEARLY_UPRIGHT * d.x.abs();
+        if !level && d.x.abs() > NEARLY_UPRIGHT * d.y.abs() {
+            continue;
+        }
+        let pick = |p: Point| if level { p.y } else { p.x };
+        let to = match (fixed(ia), fixed(ib)) {
+            (true, true) => continue,
+            (true, false) => pick(a),
+            (false, true) => pick(b),
+            (false, false) => (pick(a) + pick(b)) / 2.0,
+        };
+        // Not when an end would go farther than a pixel and a half or so from where the image has it: a long line a
+        // degree or two off is that line, not a level one drawn badly.
+        if (pick(a) - to).abs().max((pick(b) - to).abs()) > LEVEL_REACH {
+            continue;
+        }
+        let moved = |p: Point| if level { Point::new(p.x, to) } else { Point::new(to, p.y) };
+        if !fixed(ia) {
+            put(segs, ia, moved(a));
+        }
+        if !fixed(ib) {
+            put(segs, ib, moved(b));
+        }
+    }
+    // A straight piece has its handles on it.
+    for (c, _) in segs.iter_mut().zip(&lines).filter(|(_, line)| **line) {
+        *c = [c[0], c[0] + (c[3] - c[0]) / 3.0, c[0] + (c[3] - c[0]) * (2.0 / 3.0), c[3]];
+    }
+}
+
 /// A whole loop fitted. The same loop gives the same curves whichever way it runs and wherever it
 /// starts (it is fitted clockwise from its leftmost point): the outline of a shape and the hole it
 /// leaves in the shape around it are one curve.
-fn fit_closed(pts: &[Point], style: &Style) -> Option<Vec<Cubic>> {
+pub(crate) fn fit_closed(pts: &[Point], style: &Style) -> Option<Vec<Cubic>> {
     let n = pts.len();
     let area2: f64 = (0..n).map(|i| pts[i].x * pts[(i + 1) % n].y - pts[(i + 1) % n].x * pts[i].y).sum();
     let flip = area2 < 0.0;
@@ -80,13 +139,17 @@ fn fit_closed(pts: &[Point], style: &Style) -> Option<Vec<Cubic>> {
     if stats.reverted > 0 && !all_within(&sample_cubics(&segs, 0.25), &resample_closed(&pts, 0.5).map_or_else(|| pts.clone(), |(p, _)| p), 1.5) {
         segs = polygon(&pts, style.tol);
     }
+    if style.upright {
+        snap_upright(&mut segs, true, false);
+    }
     Some(if flip { reversed(segs) } else { segs })
 }
 
 /// A piece of a loop between two junctions fitted, from its first point to its last. The same
 /// piece gives the same curve whichever way it runs (it is fitted from its end further left): the
-/// edge two regions share is one curve.
-fn fit_piece(pts: &[Point], style: &Style) -> Vec<Cubic> {
+/// edge two regions share is one curve. `fixed_ends`: its ends are junctions and stay put (a centre
+/// line's ends are its own).
+pub(crate) fn fit_piece(pts: &[Point], style: &Style, fixed_ends: bool) -> Vec<Cubic> {
     let n = pts.len();
     let (Some(&first), Some(&last)) = (pts.first(), pts.last()) else { return vec![] };
     let flip = match before(first, last) {
@@ -107,6 +170,9 @@ fn fit_piece(pts: &[Point], style: &Style) -> Vec<Cubic> {
         let kept: Vec<Point> = (0..n).filter(|&i| keep[i]).map(|i| pts[i]).collect();
         segs = kept.windows(2).filter(|p| p[0] != p[1]).map(|p| [p[0], p[0], p[1], p[1]]).collect();
     }
+    if style.upright {
+        snap_upright(&mut segs, false, fixed_ends);
+    }
     if flip { reversed(segs) } else { segs }
 }
 
@@ -137,22 +203,30 @@ pub(crate) fn fit_loop(
         if piece.closed {
             segs = fit_closed(&piece.pts, &style)?;
         } else {
-            segs.extend(fit_piece(&piece.pts, &style));
+            segs.extend(fit_piece(&piece.pts, &style, true));
         }
     }
+    subpath(&segs, true)
+}
+
+/// A chain of cubics as a subpath: closed (its end joins its start) or open. A straight piece has
+/// no handles; an anchor whose two handles line up is smooth.
+pub(crate) fn subpath(segs: &[Cubic], closed: bool) -> Option<SubPath> {
     let n = segs.len();
-    // A straight piece has no handles.
     let straight = |c: &Cubic| seg_dist(c[1], c[0], c[3]) < 1e-6 && seg_dist(c[2], c[0], c[3]) < 1e-6;
-    let mut anchors = Vec::with_capacity(n);
-    for (i, cur) in segs.iter().enumerate() {
-        let before = segs.get((i + n - 1) % n)?;
-        let p = cur[0];
-        let (h_in, h_out) = (if straight(before) { p } else { before[2] }, if straight(cur) { p } else { cur[1] });
+    let mut anchors = Vec::with_capacity(n + 1);
+    for i in 0..if closed { n } else { n + 1 } {
+        // The piece that arrives at this anchor and the one that leaves it.
+        let before = if i > 0 { segs.get(i - 1) } else { closed.then(|| segs.last()).flatten() };
+        let after = segs.get(i);
+        let p = after.map(|c| c[0]).or(before.map(|c| c[3]))?;
+        let h_in = before.filter(|c| !straight(c)).map_or(p, |c| c[2]);
+        let h_out = after.filter(|c| !straight(c)).map_or(p, |c| c[1]);
         let (vi, vo) = (p - h_in, h_out - p);
         let smooth = vi.hypot() > 1e-9 && vo.hypot() > 1e-9 && vi.cross(vo).abs() < 0.07 * vi.hypot() * vo.hypot() && vi.dot(vo) > 0.0;
         anchors.push(Anchor { p, h_in, h_out, kind: if smooth { AnchorKind::Smooth } else { AnchorKind::Corner } });
     }
-    (n >= 2).then(|| SubPath::new(anchors, true))
+    (n >= if closed { 2 } else { 1 }).then(|| SubPath::new(anchors, closed))
 }
 
 /// The closed outline `pts` as straight pieces within `tol` of it (Douglas–Peucker).
@@ -170,68 +244,3 @@ fn polygon(pts: &[Point], tol: f64) -> Vec<Cubic> {
     let kept: Vec<Point> = (0..n).filter(|&i| keep[i]).map(|i| pts[i]).collect();
     (0..kept.len()).map(|i| [kept[i], kept[i], kept[(i + 1) % kept.len()], kept[(i + 1) % kept.len()]]).collect()
 }
-
-/// Fit a centre line through `pts` (pixel-centre points in order) into a Bézier subpath: the
-/// points within `polygon_tol` of it are dropped (Douglas–Peucker), then curves are fitted. A
-/// `closed` line runs back to its first point.
-pub(crate) fn fit_polyline(pts: &[Point], closed: bool, o: &FitOptions) -> Option<SubPath> {
-    let n = pts.len();
-    let first = *pts.first()?;
-    if n < 2 {
-        return None;
-    }
-    let mut ext = pts.to_vec();
-    let mut keep = vec![false; n + 1];
-    keep[0] = true;
-    if closed {
-        // Split the ring at its first point and the point farthest from it.
-        ext.push(first);
-        let far = (1..n).max_by(|&i, &j| pts[i].distance_squared(first).total_cmp(&pts[j].distance_squared(first))).unwrap_or(n / 2);
-        keep[far] = true;
-        rdp(&ext, 0, far, o.polygon_tol, &mut keep);
-        rdp(&ext, far, n, o.polygon_tol, &mut keep);
-    } else {
-        keep[n - 1] = true;
-        rdp(&ext, 0, n - 1, o.polygon_tol, &mut keep);
-    }
-    let mut poly: Vec<Point> = (0..n).filter(|&i| keep[i]).map(|i| pts[i]).collect();
-    if closed && poly.len() < 3 {
-        poly = pts.to_vec();
-    }
-    if poly.len() < if closed { 3 } else { 2 } {
-        return None;
-    }
-    let sp = SubPath::polyline(&poly, closed);
-    let fitted =
-        simplify_with(&PathData::single(sp), &SimplifyOptions { tolerance: o.fit_tol, corner_angle_deg: o.corner_angle, straight_lines: false });
-    let mut sp = fitted.subpaths.into_iter().next()?;
-    if sp.anchors.len() < 2 {
-        return None;
-    }
-    if o.snap_lines {
-        snap_to_lines(&mut sp, (o.fit_tol * 2.0).max(1.5));
-    }
-    Some(sp)
-}
-
-/// Retract the handles of curves that stay within `tol` of their chord.
-fn snap_to_lines(sp: &mut SubPath, tol: f64) {
-    let n = sp.anchors.len();
-    for i in 0..sp.segment_count() {
-        let j = (i + 1) % n;
-        let (a, b) = (sp.anchors[i], sp.anchors[j]);
-        if !a.has_out() && !b.has_in() {
-            continue;
-        }
-        let c = CubicBez::new(a.p, a.h_out, b.h_in, b.p);
-        if (1..8).all(|k| seg_dist(c.eval(k as f64 / 8.0), a.p, b.p) <= tol) {
-            sp.anchors[i].h_out = a.p;
-            sp.anchors[j].h_in = b.p;
-        }
-    }
-    for a in &mut sp.anchors {
-        if !a.has_in() || !a.has_out() {
-            a.kind = AnchorKind::Corner;
-        }
-    }
-}

crates/trace/src/gradient.rs

@@ -0,0 +1,437 @@
+//! Gradients: areas whose colour changes evenly along one direction are found before the image is
+//! reduced to its palette, and each is traced as one path filled with a linear gradient instead of
+//! as bands of flat colour.
+//!
+//! An area is a connected run of pixels that each differ little from their neighbours. It is a
+//! gradient when a plane fits each of its colour channels with all three sloping the same way, the
+//! colours along that way are a few stops with even ramps between them, and painting those stops
+//! back gives the area's own pixels. Anything else (a flat area, a photo's sky lit two ways, two
+//! flats with a soft edge between them) is left to be traced as before.
+
+use crate::Raster;
+use crate::quantize::TRANSPARENT;
+use kurbo::{Point, Vec2};
+
+/// The largest step (levels of a channel) between neighbouring pixels of one smooth area.
+const STEP: i32 = 8;
+/// The fewest pixels a gradient has, and the least length (px) along its direction.
+const MIN_PIXELS: usize = 400;
+const MIN_LENGTH: f64 = 16.0;
+/// The least change (levels of a channel) from one stop to another: less is a flat colour.
+const MIN_CHANGE: f64 = 24.0;
+/// The most stops, and the least distance between two (as a share of the length): closer stops are
+/// an edge, not a ramp.
+const MAX_STOPS: usize = 6;
+const MIN_SPACING: f64 = 0.08;
+/// How far (levels) the stops may be from the colours along the gradient.
+const STOP_TOLERANCE: f64 = 2.0;
+
+/// A linear gradient a traced path is filled with.
+#[derive(Clone, Debug, PartialEq)]
+pub struct TracedGradient {
+    /// The gradient's line, in pixel coordinates: the first stop's colour is at `start` and before
+    /// it, the last one's at `end` and beyond.
+    pub start: Point,
+    pub end: Point,
+    /// The stops: how far along the line (0 to 1, ascending, the first 0 and the last 1) and the colour.
+    pub stops: Vec<(f64, [u8; 3])>,
+}
+
+impl TracedGradient {
+    /// The gradient's colour at `p`.
+    pub fn color_at(&self, p: Point) -> [f64; 3] {
+        let d = self.end - self.start;
+        let t = if d.hypot2() > 0.0 { ((p - self.start).dot(d) / d.hypot2()).clamp(0.0, 1.0) } else { 0.0 };
+        let color = |i: usize| self.stops.get(i).map_or([0.0; 3], |s| s.1.map(f64::from));
+        let after = self.stops.iter().position(|s| s.0 >= t).unwrap_or(self.stops.len().saturating_sub(1));
+        let Some(before) = after.checked_sub(1) else { return color(after) };
+        let (ta, tb) = (self.stops.get(before).map_or(0.0, |s| s.0), self.stops.get(after).map_or(1.0, |s| s.0));
+        let k = if tb > ta { (t - ta) / (tb - ta) } else { 1.0 };
+        let (a, b) = (color(before), color(after));
+        [0, 1, 2].map(|c| a[c] + (b[c] - a[c]) * k)
+    }
+}
+
+/// The gradients of `img`: for each pixel the gradient it is part of (an index into the list, or
+/// `u32::MAX`), and the list.
+pub(crate) fn detect(img: &Raster) -> (Vec<u32>, Vec<TracedGradient>) {
+    let (w, h) = (img.width as usize, img.height as usize);
+    let px = |i: usize| img.rgba.get(i * 4..i * 4 + 4).filter(|p| p[3] >= 128).map(|p| [i32::from(p[0]), i32::from(p[1]), i32::from(p[2])]);
+    let near = |a: [i32; 3], b: Option<[i32; 3]>| b.is_some_and(|b| (0..3).all(|k| (a[k] - b[k]).abs() <= STEP));
+    // Smooth: an opaque pixel that differs little from each neighbour it has.
+    let smooth: Vec<bool> = (0..w * h)
+        .map(|i| {
+            let (x, y) = (i % w, i / w);
+            px(i).is_some_and(|c| {
+                (x == 0 || near(c, px(i - 1)))
+                    && (x + 1 == w || near(c, px(i + 1)))
+                    && (y == 0 || near(c, px(i - w)))
+                    && (y + 1 == h || near(c, px(i + w)))
+            })
+        })
+        .collect();
+    // Sloping: smooth, and some pixel a little way off (a 32nd of the image: a gradient across a
+    // large image changes by less than a level from one pixel to the next) is another colour.
+    // Flat colour is no part of a gradient, and left out it does not join a gradient to the flat
+    // area beside it where the two are nearly one colour.
+    let far = (w.min(h) / 32).clamp(4, 64) as i64;
+    let around = [
+        (far, 0),
+        (-far, 0),
+        (0, far),
+        (0, -far),
+        (far * 3 / 4, far * 3 / 4),
+        (far * 3 / 4, -far * 3 / 4),
+        (-far * 3 / 4, far * 3 / 4),
+        (-far * 3 / 4, -far * 3 / 4),
+    ];
+    let sloping: Vec<bool> = (0..w * h)
+        .map(|i| {
+            let (x, y) = ((i % w) as i64, (i / w) as i64);
+            let differs = |(dx, dy): (i64, i64)| {
+                let (nx, ny) = (x + dx, y + dy);
+                let other = (nx >= 0 && ny >= 0 && nx < w as i64 && ny < h as i64).then(|| px(ny as usize * w + nx as usize)).flatten();
+                px(i).zip(other).is_some_and(|(a, b)| (0..3).any(|k| (a[k] - b[k]).abs() >= 2))
+            };
+            smooth.get(i).copied().unwrap_or(false) && around.into_iter().any(differs)
+        })
+        .collect();
+    drop(smooth);
+    let smooth = sloping;
+    let mut of = vec![u32::MAX; w * h];
+    let mut seen = vec![false; w * h];
+    let mut depth = vec![0u16; w * h];
+    let mut found = vec![];
+    let (mut members, mut stack) = (vec![], vec![]);
+    for seed in 0..w * h {
+        if seen.get(seed).copied().unwrap_or(true) || !smooth.get(seed).copied().unwrap_or(false) {
+            continue;
+        }
+        // The connected smooth pixels from here.
+        members.clear();
+        stack.push(seed);
+        if let Some(s) = seen.get_mut(seed) {
+            *s = true;
+        }
+        while let Some(i) = stack.pop() {
+            members.push(i);
+            let (x, y) = (i % w, i / w);
+            for j in [(x > 0).then(|| i - 1), (x + 1 < w).then(|| i + 1), (y > 0).then(|| i - w), (y + 1 < h).then(|| i + w)].into_iter().flatten() {
+                if smooth.get(j).copied().unwrap_or(false) && !seen.get(j).copied().unwrap_or(true) {
+                    if let Some(s) = seen.get_mut(j) {
+                        *s = true;
+                    }
+                    stack.push(j);
+                }
+            }
+        }
+        if members.len() < MIN_PIXELS || found.len() >= 1000 {
+            continue;
+        }
+        // The gradient is read from the area's inside, where there is one: the pixels at its rim
+        // may be a soft edge to the next area, joined to this one where the two are alike.
+        // (`depth`: how many pixels in from the rim each of the area's pixels is, counted inwards
+        // from the pixels that have a neighbour outside it, as far as matters.)
+        let rim = far as usize + 2;
+        let unknown = u16::MAX;
+        members.iter().for_each(|&i| depth[i] = unknown);
+        let beside = |i: usize| {
+            let (x, y) = (i % w, i / w);
+            [(x > 0).then(|| i - 1), (x + 1 < w).then(|| i + 1), (y > 0).then(|| i - w), (y + 1 < h).then(|| i + w)].into_iter().flatten()
+        };
+        let mut front: Vec<usize> = members.iter().copied().filter(|&i| beside(i).any(|j| depth.get(j).copied() == Some(0))).collect();
+        front.iter().for_each(|&i| depth[i] = 1);
+        for d in 2..=rim as u16 {
+            let mut next = vec![];
+            for &i in &front {
+                for j in beside(i) {
+                    if let Some(slot) = depth.get_mut(j).filter(|s| **s == unknown) {
+                        *slot = d;
+                        next.push(j);
+                    }
+                }
+            }
+            front = next;
+        }
+        let inside: Vec<usize> = members.iter().copied().filter(|&i| depth.get(i).copied() == Some(unknown)).collect();
+        let fitted = fit(img, w, if inside.len() >= MIN_PIXELS { &inside } else { &members }, &members, rim);
+        members.iter().for_each(|&i| depth[i] = 0);
+        if let Some((g, part)) = fitted {
+            for &i in &part {
+                if let Some(o) = of.get_mut(i) {
+                    *o = found.len() as u32;
+                }
+            }
+            found.push(g);
+        }
+    }
+    (of, found)
+}
+
+/// The linear gradient the pixels `members` of `img` (`w` wide) are, if they are one, and those of
+/// `all` (the whole area `members` are the inside of, `rim` pixels in) that have its colours.
+fn fit(img: &Raster, w: usize, members: &[usize], all: &[usize], rim: usize) -> Option<(TracedGradient, Vec<usize>)> {
+    let n = members.len() as f64;
+    let at = |i: usize| Point::new((i % w) as f64 + 0.5, (i / w) as f64 + 0.5);
+    let rgb = |i: usize| img.rgba.get(i * 4..i * 4 + 3).map_or([0.0; 3], |p| [f64::from(p[0]), f64::from(p[1]), f64::from(p[2])]);
+    let mut middle = Vec2::ZERO;
+    let mut mean = [0.0; 3];
+    for &i in members {
+        middle += at(i).to_vec2();
+        let c = rgb(i);
+        (0..3).for_each(|k| mean[k] += c[k]);
+    }
+    let middle = (middle / n).to_point();
+    let mean = mean.map(|v| v / n);
+    // A plane through each channel, by least squares about the middle.
+    let (mut sxx, mut sxy, mut syy) = (0.0, 0.0, 0.0);
+    let (mut scx, mut scy) = ([0.0; 3], [0.0; 3]);
+    for &i in members {
+        let (d, c) = (at(i) - middle, rgb(i));
+        sxx += d.x * d.x;
+        sxy += d.x * d.y;
+        syy += d.y * d.y;
+        for k in 0..3 {
+            scx[k] += d.x * (c[k] - mean[k]);
+            scy[k] += d.y * (c[k] - mean[k]);
+        }
+    }
+    let det = sxx * syy - sxy * sxy;
+    if det <= 1e-6 * sxx * syy || !det.is_finite() {
+        return None;
+    }
+    // Each channel's slope, and the one direction they share: the longer axis of the three
+    // together (the shorter is what they do not share, and must be next to nothing).
+    let slope = [0, 1, 2].map(|k| Vec2::new((scx[k] * syy - scy[k] * sxy) / det, (scy[k] * sxx - scx[k] * sxy) / det));
+    let (mxx, mxy, myy) = slope.iter().fold((0.0, 0.0, 0.0), |m, s| (m.0 + s.x * s.x, m.1 + s.x * s.y, m.2 + s.y * s.y));
+    let spread = ((mxx - myy) / 2.0).hypot(mxy);
+    let (major, minor) = ((mxx + myy) / 2.0 + spread, (mxx + myy) / 2.0 - spread);
+    if major <= 0.0 || minor > 0.03 * major {
+        return None;
+    }
+    let angle = 0.5 * (2.0 * mxy).atan2(mxx - myy);
+    let dir = Vec2::new(angle.cos(), angle.sin());
+    // The colours along it, a pixel's width at a time.
+    let along = |i: usize| (at(i) - middle).dot(dir);
+    let (t0, t1) = members.iter().fold((f64::INFINITY, f64::NEG_INFINITY), |m, &i| (m.0.min(along(i) - 0.5), m.1.max(along(i) + 0.5)));
+    let length = t1 - t0;
+    if !(MIN_LENGTH..1e6).contains(&length) {
+        return None;
+    }
+    let bins = length.ceil() as usize;
+    // (Each step's mean colour, at the mean place of its pixels: the few pixels at the tip of a
+    // round area are not at the middle of their step.)
+    let mut sums = vec![([0.0; 3], 0.0f64, 0.0f64); bins];
+    for &i in members {
+        let t = along(i) - t0;
+        if let Some(b) = sums.get_mut((t as usize).min(bins - 1)) {
+            let c = rgb(i);
+            (0..3).for_each(|k| b.0[k] += c[k]);
+            b.1 += 1.0;
+            b.2 += t;
+        }
+    }
+    let curve: Vec<(f64, [f64; 3])> = sums.iter().filter(|b| b.1 > 0.0).map(|b| (b.2 / b.1 / length, b.0.map(|v| v / b.1))).collect();
+    // The fewest stops whose ramps pass within tolerance of every colour along the way: the two
+    // ends, then again and again the colour farthest from the ramp it lies on.
+    let mut keep = vec![0, curve.len().checked_sub(1)?];
+    loop {
+        let mut worst = (STOP_TOLERANCE, 0);
+        for pair in keep.windows(2) {
+            let (Some(&(ta, a)), Some(&(tb, b))) = (curve.get(pair[0]), curve.get(pair[1])) else { return None };
+            for (j, &(t, c)) in curve.iter().enumerate().take(pair[1]).skip(pair[0] + 1) {
+                let k = (t - ta) / (tb - ta);
+                let off = (0..3).map(|ch| (c[ch] - (a[ch] + (b[ch] - a[ch]) * k)).abs()).fold(0.0, f64::max);
+                if off > worst.0 {
+                    worst = (off, j);
+                }
+            }
+        }
+        if worst.1 == 0 {
+            break;
+        }
+        // (More than are let stand: those close together become one below.)
+        if keep.len() >= 4 * MAX_STOPS {
+            return None;
+        }
+        keep.push(worst.1);
+        keep.sort_unstable();
+    }
+    // Two stops close together are one stop where the ramp turns (a turn is not sharp to the
+    // pixel, least of all in a blurred image), unless their colours are far apart: that is an
+    // edge, not a ramp.
+    let mut stops: Vec<(f64, [f64; 3])> = vec![];
+    for &(t, c) in keep.iter().filter_map(|&j| curve.get(j)) {
+        match stops.last_mut() {
+            Some(last) if t - last.0 < MIN_SPACING => {
+                if (0..3).any(|k| (c[k] - last.1[k]).abs() >= MIN_CHANGE) {
+                    return None;
+                }
+                *last = ((last.0 + t) / 2.0, [0, 1, 2].map(|k| (last.1[k] + c[k]) / 2.0));
+            }
+            _ => stops.push((t, c)),
+        }
+    }
+    let (first, last) = (stops.first()?.0, stops.last()?.0);
+    // A change of colour, not one colour.
+    let change =
+        stops.iter().flat_map(|a| stops.iter().map(move |b| (0..3).map(|k| (a.1[k] - b.1[k]).abs()).fold(0.0, f64::max))).fold(0.0, f64::max);
+    // And ramps most of the way: two flat colours with a soft edge between them are no gradient.
+    let level: f64 = stops.windows(2).filter(|s| (0..3).all(|k| (s[1].1[k] - s[0].1[k]).abs() < 4.0)).map(|s| s[1].0 - s[0].0).sum();
+    if !(2..=MAX_STOPS).contains(&stops.len()) || last - first < MIN_SPACING || change < MIN_CHANGE || level > 0.3 * (last - first) {
+        return None;
+    }
+    let gradient = TracedGradient {
+        start: middle + dir * (t0 + first * length),
+        end: middle + dir * (t0 + last * length),
+        stops: stops.iter().map(|&(t, c)| ((t - first) / (last - first), c.map(|v| v.round().clamp(0.0, 255.0) as u8))).collect(),
+    };
+    // Carried on to the ends of the whole area, each end ramp going on as it goes.
+    let d = gradient.end - gradient.start;
+    let place = |i: usize| (at(i) - gradient.start).dot(d) / d.hypot2();
+    let reach = rim as f64 * 1.5 / d.hypot();
+    let (u0, u1) = all.iter().fold((0.0f64, 1.0f64), |m, &i| (m.0.min(place(i)), m.1.max(place(i))));
+    let (u0, u1) = (u0.max(-reach), u1.min(1.0 + reach));
+    let ramp = |a: (f64, [u8; 3]), b: (f64, [u8; 3]), u: f64| {
+        [0, 1, 2].map(|k| (f64::from(a.1[k]) + (f64::from(b.1[k]) - f64::from(a.1[k])) * (u - a.0) / (b.0 - a.0)).round().clamp(0.0, 255.0) as u8)
+    };
+    let mut stops = gradient.stops.clone();
+    if let (&[a, b, ..], &[.., y, z]) = (stops.as_slice(), stops.as_slice()) {
+        if let Some(first) = stops.first_mut() {
+            *first = (u0, ramp(a, b, u0));
+        }
+        if let Some(last) = stops.last_mut() {
+            *last = (u1, ramp(y, z, u1));
+        }
+    }
+    let gradient = TracedGradient {
+        start: gradient.start + d * u0,
+        end: gradient.start + d * u1,
+        stops: stops.into_iter().map(|(u, c)| ((u - u0) / (u1 - u0), c)).collect(),
+    };
+    // Painted back, it is the area: most pixels of its inside within a few levels, and all that
+    // are (the rest: noise, a soft rim, the flat colour just beyond it) on average nearer still.
+    let off = |i: usize| {
+        let (c, g) = (rgb(i), gradient.color_at(at(i)));
+        (0..3).map(|k| (c[k] - g[k]).abs()).fold(0.0, f64::max)
+    };
+    let part: Vec<usize> = all.iter().copied().filter(|&i| off(i) <= 6.0).collect();
+    let mean = part.iter().map(|&i| off(i)).sum::<f64>() / part.len().max(1) as f64;
+    let inside = members.iter().filter(|&&i| off(i) <= 6.0).count();
+    (part.len() >= MIN_PIXELS && inside * 4 >= members.len() * 3 && mean <= 3.5).then_some((gradient, part))
+}
+
+/// Settles the pixels along the edge of each gradient (they are part gradient and part what lies
+/// beyond, and no part of the smooth area the gradient was found in): each joins the gradient
+/// (`of`) when more than half of it is the gradient's colour there, and else takes the label of
+/// what lies beyond. `labels` are the image's palette labels, the gradients' pixels not among them.
+pub(crate) fn settle_edges(img: &Raster, of: &mut [u32], gradients: &[TracedGradient], labels: &mut [u16]) {
+    let (w, h) = (img.width as usize, img.height as usize);
+    let rgb = |i: usize| img.rgba.get(i * 4..i * 4 + 4).filter(|p| p[3] >= 128).map(|p| [f64::from(p[0]), f64::from(p[1]), f64::from(p[2])]);
+    // Twice: a soft edge is two pixels wide.
+    for _ in 0..2 {
+        let mut joins: Vec<(usize, u32)> = vec![];
+        let mut takes: Vec<(usize, u16)> = vec![];
+        for i in 0..w * h {
+            if of.get(i).copied() != Some(u32::MAX) {
+                continue;
+            }
+            let Some(c) = rgb(i) else { continue };
+            let (x, y) = ((i % w) as i64, (i / w) as i64);
+            let index = |x: i64, y: i64| (x >= 0 && y >= 0 && x < w as i64 && y < h as i64).then(|| y as usize * w + x as usize);
+            // The gradient on one side, and what lies two pixels out on the other.
+            let Some((g, dx, dy)) = [(1, 0), (-1, 0), (0, 1), (0, -1)].into_iter().find_map(|(dx, dy)| {
+                let g = index(x + dx, y + dy).and_then(|j| of.get(j).copied()).filter(|&g| g != u32::MAX)?;
+                Some((g, dx, dy))
+            }) else {
+                continue;
+            };
+            let Some(gradient) = gradients.get(g as usize) else { continue };
+            let own = gradient.color_at(Point::new(x as f64 + 0.5, y as f64 + 0.5));
+            let off = (0..3).map(|k| (c[k] - own[k]).abs()).fold(0.0, f64::max);
+            let beyond = index(x - 2 * dx, y - 2 * dy).filter(|&j| of.get(j).copied() == Some(u32::MAX));
+            let other = beyond.and_then(|j| Some((rgb(j)?, labels.get(j).copied()?)));
+            match other {
+                Some((o, label)) if (0..3).map(|k| (o[k] - own[k]).abs()).fold(0.0, f64::max) > 16.0 => {
+                    // How much of the pixel is the other colour.
+                    let d = [0, 1, 2].map(|k| o[k] - own[k]);
+                    let share = (0..3).map(|k| (c[k] - own[k]) * d[k]).sum::<f64>() / d.iter().map(|v| v * v).sum::<f64>();
+                    if share < 0.5 {
+                        joins.push((i, g));
+                    } else if label != TRANSPARENT {
+                        takes.push((i, label));
+                    }
+                }
+                // Gradient beyond too, or nothing to tell it from: part of it if it has its colour.
+                _ if off <= 16.0 => joins.push((i, g)),
+                _ => {}
+            }
+        }
+        for (i, g) in joins {
+            if let Some(o) = of.get_mut(i) {
+                *o = g;
+            }
+        }
+        for (i, l) in takes {
+            if let Some(slot) = labels.get_mut(i) {
+                *slot = l;
+            }
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn ramp(w: u32, h: u32, f: impl Fn(f64, f64) -> [f64; 3]) -> Raster {
+        Raster::from_fn(w, h, |x, y| {
+            let c = f(f64::from(x) + 0.5, f64::from(y) + 0.5);
+            [c[0].round() as u8, c[1].round() as u8, c[2].round() as u8, 255]
+        })
+    }
+
+    #[test]
+    fn a_linear_ramp_is_one_gradient_with_its_direction_and_ends() {
+        // Dark blue to yellow, 30° down from level.
+        let dir = Vec2::new(30f64.to_radians().cos(), 30f64.to_radians().sin());
+        let reach = Vec2::new(120.0, 80.0).dot(dir);
+        let img = ramp(120, 80, |x, y| {
+            let t = Vec2::new(x, y).dot(dir) / reach;
+            [20.0 + 220.0 * t, 40.0 + 180.0 * t, 160.0 - 140.0 * t]
+        });
+        let (of, found) = detect(&img);
+        assert_eq!(found.len(), 1);
+        assert!(of.iter().all(|&g| g == 0));
+        let g = &found[0];
+        let d = g.end - g.start;
+        assert!((d.atan2().to_degrees() - 30.0).abs() < 1.0, "{d:?}");
+        assert_eq!(g.stops.len(), 2);
+        for (stop, truth) in g.stops.iter().zip([[20.0, 40.0, 160.0], [240.0, 220.0, 20.0]]) {
+            assert!((0..3).all(|k| (f64::from(stop.1[k]) - truth[k]).abs() < 6.0), "{:?}", g.stops);
+        }
+    }
+
+    #[test]
+    fn flat_colour_soft_edges_and_two_way_shading_are_no_gradient() {
+        // One colour.
+        assert!(detect(&ramp(64, 64, |_, _| [200.0, 30.0, 30.0])).1.is_empty());
+        // Two flat colours with a soft edge between them.
+        let soft = ramp(96, 64, |x, _| [100.0 + 30.0 / (1.0 + (-(x - 48.0)).exp()); 3]);
+        assert!(detect(&soft).1.is_empty());
+        // Red changing across and green changing down.
+        assert!(detect(&ramp(96, 96, |x, y| [40.0 + 2.0 * x, 40.0 + 2.0 * y, 90.0])).1.is_empty());
+    }
+
+    #[test]
+    fn three_stops_are_three_stops() {
+        let img = ramp(200, 40, |x, _| {
+            let t = x / 200.0;
+            if t < 0.5 { [255.0 - 400.0 * t, 40.0, 40.0 + 300.0 * t] } else { [55.0 + 300.0 * (t - 0.5), 40.0 + 400.0 * (t - 0.5), 190.0] }
+        });
+        let (_, found) = detect(&img);
+        assert_eq!(found.len(), 1);
+        assert_eq!(found[0].stops.len(), 3, "{:?}", found[0].stops);
+        assert!((found[0].stops[1].0 - 0.5).abs() < 0.03);
+    }
+}

crates/trace/src/group.rs

@@ -0,0 +1,188 @@
+//! Auto Grouping: which traced path lies inside which, so that a result can be grouped the way it
+//! is nested (a ring with what fills its hole, a face with its eyes).
+
+use crate::TracedPath;
+use kurbo::{PathEl, Point, Rect};
+
+/// How far (px) outside an outline a point may lie and still count as inside it: two paths that
+/// share an edge are each fitted on their own.
+const NEAR: f64 = 0.5;
+
+/// A path's outer contour as a polygon, and its box.
+struct Outer {
+    pts: Vec<Point>,
+    bbox: Rect,
+    /// A closed, filled contour: something can lie inside it.
+    holds: bool,
+    /// Where something can: for each pixel row from `bbox.y0 - NEAR` down, the edges (each from
+    /// the point of that index to the next) that pass through it or within [`NEAR`] of it. A
+    /// point is tested against the edges of its row, not all of a long outline's.
+    rows: Vec<Vec<u32>>,
+}
+
+fn outer(tp: &TracedPath) -> Option<Outer> {
+    let (mut pts, mut subpaths, mut closed) = (vec![], 0, false);
+    kurbo::flatten(tp.path.to_bezpath(), 0.2, |el| match el {
+        PathEl::MoveTo(p) => {
+            subpaths += 1;
+            if subpaths == 1 {
+                pts.push(p);
+            }
+        }
+        PathEl::LineTo(p) if subpaths == 1 => pts.push(p),
+        PathEl::ClosePath if subpaths == 1 => closed = true,
+        _ => {}
+    });
+    let first = *pts.first()?;
+    let bbox = pts.iter().fold(Rect::from_points(first, first), |b, p| b.union_pt(*p));
+    if !bbox.is_finite() {
+        return None;
+    }
+    let holds = closed && tp.stroke.is_none();
+    // (Traced paths lie in the image: a box taller than any image is nothing to hold things.)
+    let holds = holds && bbox.height() < 1e6 && u32::try_from(pts.len()).is_ok();
+    let mut rows = vec![];
+    if holds {
+        rows = vec![vec![]; (bbox.height() + 2.0 * NEAR) as usize + 1];
+        for (i, (a, b)) in pts.iter().zip(pts.iter().cycle().skip(1)).enumerate() {
+            let (top, bottom) = (a.y.min(b.y) - bbox.y0, a.y.max(b.y) - bbox.y0 + 2.0 * NEAR);
+            for row in rows.iter_mut().take(bottom as usize + 1).skip(top.max(0.0) as usize) {
+                row.push(i as u32);
+            }
+        }
+    }
+    Some(Outer { pts, bbox, holds, rows })
+}
+
+/// Whether `p` lies inside the closed outline of `o`, or within [`NEAR`] of its edge.
+fn inside_or_near(p: Point, o: &Outer) -> bool {
+    let row = p.y - (o.bbox.y0 - NEAR);
+    let Some(edges) = (row >= 0.0).then(|| o.rows.get(row as usize)).flatten() else { return false };
+    let mut inside = false;
+    for &i in edges {
+        let (Some(a), Some(b)) = (o.pts.get(i as usize), o.pts.get((i as usize + 1) % o.pts.len().max(1))) else { continue };
+        if (a.y > p.y) != (b.y > p.y) && p.x < a.x + (p.y - a.y) / (b.y - a.y) * (b.x - a.x) {
+            inside = !inside;
+        }
+        let d = *b - *a;
+        let t = if d.hypot2() > 0.0 { ((p - *a).dot(d) / d.hypot2()).clamp(0.0, 1.0) } else { 0.0 };
+        if (p - (*a + d * t)).hypot2() <= NEAR * NEAR {
+            return true;
+        }
+    }
+    inside
+}
+
+/// For each of `paths` (bottom-most first), the path it lies inside, if any: the smallest filled
+/// path whose outer contour holds all of its own. The path that covers the whole `w` × `h` image
+/// (the paper) is nobody's parent: everything would be inside it.
+///
+/// Drawing each path followed by those inside it paints the picture `paths` paints in its own
+/// order: where the paths can overlap (`stacked`), a path only gets a parent below it, and only
+/// if no path that would then come after it instead of before it shares any of its box.
+pub(crate) fn parents(paths: &[TracedPath], w: usize, h: usize, stacked: bool) -> Vec<Option<usize>> {
+    let outers: Vec<Option<Outer>> = paths.iter().map(outer).collect();
+    let paper = Rect::new(1.0, 1.0, w as f64 - 1.0, h as f64 - 1.0);
+    let mut parent: Vec<Option<usize>> = vec![None; paths.len()];
+    // How many paths each is inside of.
+    let mut depth = vec![0usize; paths.len()];
+    // The paths something can lie inside, by the area of their boxes.
+    let mut by_area: Vec<usize> = (0..paths.len()).filter(|&p| outers.get(p).and_then(Option::as_ref).is_some_and(|o| o.holds)).collect();
+    let area = |p: &usize| outers.get(*p).and_then(Option::as_ref).map_or(0.0, |o| o.bbox.area());
+    by_area.sort_by(|a, b| area(a).total_cmp(&area(b)));
+    for (x, ox) in outers.iter().enumerate() {
+        let Some(ox) = ox else { continue };
+        // The paths whose box holds its own, smallest first.
+        let mut holders = by_area.iter().filter_map(|&p| Some((p, outers.get(p)?.as_ref()?))).filter(|&(p, op)| {
+            let (o, i) = (op.bbox, ox.bbox);
+            o.x0 - NEAR <= i.x0
+                && o.y0 - NEAR <= i.y0
+                && o.x1 + NEAR >= i.x1
+                && o.y1 + NEAR >= i.y1
+                && o.area() > i.area()
+                && !(stacked && p > x)
+                && !(o.x0 <= paper.x0 && o.y0 <= paper.y0 && o.x1 >= paper.x1 && o.y1 >= paper.y1)
+        });
+        // The paths under `x` that share some of its box: it may not come to lie under any of them.
+        // (Found only once some path holds its first point: most paths are inside none.)
+        let under = std::cell::OnceCell::new();
+        let under = || {
+            under.get_or_init(|| {
+                (0..x)
+                    .filter(|&y| outers.get(y).and_then(Option::as_ref).is_some_and(|oy| oy.bbox.intersect(ox.bbox).area() > 0.0))
+                    .collect::<Vec<_>>()
+            })
+        };
+        let found = holders.find(|&(p, op)| {
+            ox.pts.first().is_some_and(|pt| inside_or_near(*pt, op))
+                && (!stacked || under().iter().all(|&y| !comes_after(&parent, &depth, y, p)))
+                && ox.pts.iter().all(|pt| inside_or_near(*pt, op))
+        });
+        if let (Some((p, _)), Some(slot)) = (found, parent.get_mut(x)) {
+            *slot = Some(p);
+            let deep = depth.get(p).copied().unwrap_or(0) + 1;
+            if let Some(d) = depth.get_mut(x) {
+                *d = deep;
+            }
+        }
+    }
+    parent
+}
+
+/// Whether `y` is drawn after `p` and all that is inside `p`: it is in another branch of the
+/// nesting, and that branch starts above the one `p` is in.
+fn comes_after(parent: &[Option<usize>], depth: &[usize], y: usize, p: usize) -> bool {
+    let up = |i: usize| parent.get(i).copied().flatten();
+    let deep = |i: usize| depth.get(i).copied().unwrap_or(0);
+    let (mut a, mut b) = (y, p);
+    while deep(a) > deep(b) {
+        let Some(q) = up(a) else { break };
+        a = q;
+    }
+    while deep(b) > deep(a) {
+        let Some(q) = up(b) else { break };
+        b = q;
+    }
+    // (Equal: one is the other, or inside it.)
+    while a != b && up(a) != up(b) {
+        let (Some(qa), Some(qb)) = (up(a), up(b)) else { break };
+        (a, b) = (qa, qb);
+    }
+    a > b
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use vectorcraft_geom::PathData;
+
+    fn disc(c: (f64, f64), r: f64, color: u8) -> TracedPath {
+        let path = PathData::from_bezpath(&kurbo::Shape::to_path(&kurbo::Circle::new(c, r), 0.01));
+        TracedPath { path, color: [color; 3], pixels: 1, stroke: None, shape: None, gradient: None }
+    }
+
+    #[test]
+    fn a_path_is_inside_the_smallest_path_that_holds_it() {
+        // The paper, a disc, a disc inside it, a dot inside that, and a disc beside them.
+        let paths = [
+            disc((50.0, 50.0), 80.0, 255),
+            disc((30.0, 50.0), 20.0, 0),
+            disc((30.0, 50.0), 10.0, 100),
+            disc((30.0, 50.0), 3.0, 0),
+            disc((75.0, 50.0), 10.0, 0),
+        ];
+        for stacked in [false, true] {
+            assert_eq!(parents(&paths, 100, 100, stacked), [None, None, Some(1), Some(2), None]);
+        }
+    }
+
+    #[test]
+    fn stacked_paths_are_not_reordered_where_they_overlap() {
+        // A dot over a disc, with a wider disc between them in the stack that covers the dot's
+        // place without holding the first disc: grouped with the first disc, the dot would go under it.
+        let paths = [disc((30.0, 50.0), 20.0, 0), disc((60.0, 50.0), 24.0, 100), disc((35.0, 50.0), 3.0, 200)];
+        assert_eq!(parents(&paths, 100, 100, true), [None, None, None]);
+        // Where paths cannot overlap, either order paints the same.
+        assert_eq!(parents(&paths, 100, 100, false), [None, None, Some(0)]);
+    }
+}

crates/trace/src/lib.rs

@@ -34,8 +34,9 @@
 //!    Lines also straightens slightly curved runs and makes arcs of parts of circles.
 //!
 //! With **Create: Strokes**, the parts of a colour layer no wider than the stroke width are traced
-//! as stroked centre lines instead (see `centerline`); without Fills, wider parts become stroked
-//! outlines.
+//! as stroked centre lines instead (see `centerline`): placed in the middle of their ink to a
+//! fraction of a pixel, as wide as their ink, and fitted as outlines are. Without Fills, wider
+//! parts become stroked outlines.
 //!
 //! Colour layers are traced either *abutting* (each colour's own area; shapes share edges) or
 //! *overlapping* (stacked: each layer also covers every layer above it, so no hairline gaps).
@@ -44,9 +45,12 @@
 mod centerline;
 mod contour;
 mod fit;
+mod gradient;
+mod group;
 mod logo;
 mod mosaic;
 mod quantize;
+mod shapes;
 mod smooth;
 mod subpixel;
 
@@ -56,8 +60,10 @@ use serde::{Deserialize, Serialize};
 use vectorcraft_geom::PathData;
 
 pub use contour::{Component, Loop, trace_mask};
+pub use gradient::TracedGradient;
 pub use mosaic::mosaic;
 pub use quantize::{FULL_TONE_MAX, Quantized, TRANSPARENT, denoise, quantize};
+pub use shapes::TracedShape;
 use subpixel::Crack;
 
 /// Errors decoding a raster.
@@ -269,11 +275,23 @@ pub struct TraceParams {
     /// `noise / 10` pixels of the source image.)
     pub noise: u32,
     pub method: Method,
-    /// Drop white areas (no white background shape).
+    /// Ignore Color: drop the areas of one colour (no background shape): white, unless
+    /// `ignore_color` names another.
     pub ignore_white: bool,
+    /// The colour Ignore Color leaves out (`#rrggbb`): the palette colours within about 30 levels
+    /// of it. `None` is white. (Flat Logo mode leaves out white only.)
+    pub ignore_color: Option<String>,
     /// Replace nearly-straight curves with straight lines. In Logo mode this also snaps tight arcs
     /// to true circles.
     pub snap_curves_to_lines: bool,
+    /// Shapes: a filled outline that is a circle, an ellipse, a rectangle (square or rounded
+    /// corners) or a regular polygon comes out as exactly that shape ([`TracedPath::shape`]).
+    pub shapes: bool,
+    /// Auto Grouping: say which path lies inside which ([`TraceResult::parents`]).
+    pub auto_grouping: bool,
+    /// Gradients (Grayscale and Color): an area whose colour changes evenly along one direction
+    /// is one path filled with a linear gradient ([`TracedPath::gradient`]), not bands of colour.
+    pub gradients: bool,
     /// Create: trace areas as filled shapes.
     pub fills: bool,
     /// Create: trace lines no wider than `stroke_width` as stroked centre lines.
@@ -302,7 +320,11 @@ impl Default for TraceParams {
             noise: 25,
             method: Method::Abutting,
             ignore_white: false,
+            ignore_color: None,
             snap_curves_to_lines: false,
+            shapes: false,
+            auto_grouping: false,
+            gradients: false,
             fills: true,
             strokes: false,
             stroke_width: 10.0,
@@ -312,20 +334,10 @@ impl Default for TraceParams {
 }
 
 impl TraceParams {
-    /// Maximum distance (px) of polygon vertices from the pixel boundary.
-    fn polygon_tolerance(&self) -> f64 {
-        let f = (self.paths / 100.0).clamp(0.0, 1.0);
-        0.55 + 0.75 * (1.0 - f)
-    }
-    /// Curve fitting tolerance (px).
-    fn fit_tolerance(&self) -> f64 {
-        let f = (self.paths / 100.0).clamp(0.0, 1.0);
-        0.2 + 1.6 * (1.0 - f)
-    }
     /// How outlines are fitted: Paths sets how closely the curves follow the edge (0.08 px at 100,
     /// 0.33 px at 50, 0.78 px at 0), Corners the turn that makes a corner (35° at 100, 90° at 0).
-    /// Straight edges are always lines; Snap Curves To Lines also straightens slightly curved ones
-    /// and makes parts of circles true arcs.
+    /// Straight edges are always lines; Snap Curves To Lines also straightens slightly curved ones,
+    /// makes parts of circles true arcs, and makes lines within 2.5° of level or upright exactly so.
     fn outline_style(&self) -> logo::Style {
         // Parameters come from users and agents: a NaN or infinity must not reach the geometry.
         let unit = |v: f64, default: f64| if v.is_finite() { (v / 100.0).clamp(0.0, 1.0) } else { default };
@@ -340,19 +352,16 @@ impl TraceParams {
             circle_tol: if snap { 0.3 } else { 0.15 },
             restore: Some(logo::RestoreParams::default()),
             check_step: 0.15,
+            upright: snap,
             ..logo::Style::default()
         }
     }
-    /// Turn angle (degrees) above which a polygon vertex stays a corner.
-    fn corner_angle(&self) -> f64 {
-        let c = (self.corners / 100.0).clamp(0.0, 1.0);
-        150.0 - 115.0 * c
-    }
 }
 
 /// Built-in preset names in panel order (our own parameter sets).
 pub const PRESET_NAMES: &[&str] = &[
     "Default",
+    "Auto Color",
     "High Fidelity Photo",
     "Low Fidelity Photo",
     "3 Colors",
@@ -364,6 +373,7 @@ pub const PRESET_NAMES: &[&str] = &[
     "Silhouettes",
     "Line Art",
     "Technical Drawing",
+    "Outline",
     "Flat Logo",
 ];
 
@@ -392,6 +402,10 @@ pub fn preset(name: &str) -> Option<TraceParams> {
     };
     Some(match key.as_str() {
         "default" => d,
+        // A posterised image of a photo or of artwork: its own colours where it is flat art, as
+        // many as its tones need where it is not.
+        // (Color detail 85: a colour on a hundredth of the picture is still one of its colours.)
+        "auto color" => TraceParams { palette: Palette::Automatic, color_detail: 85.0, ..color(6, 65.0, 60.0, 16, Method::Abutting) },
         "high fidelity photo" => color(64, 90.0, 25.0, 4, Method::Overlapping),
         "low fidelity photo" => color(20, 60.0, 50.0, 12, Method::Overlapping),
         "3 colors" => color(3, 60.0, 60.0, 20, Method::Abutting),
@@ -403,6 +417,8 @@ pub fn preset(name: &str) -> Option<TraceParams> {
         "silhouettes" => bw(200, 40.0, 60.0, 30, false),
         "line art" => bw(128, 80.0, 70.0, 10, false),
         "technical drawing" => bw(128, 95.0, 90.0, 4, true),
+        // Black outlines: lines as stroked centre lines, wider areas as stroked outlines.
+        "outline" => TraceParams { fills: false, strokes: true, ..bw(128, 80.0, 70.0, 10, false) },
         // Flat-colour logos: colours found automatically, edges placed to a fraction of a pixel.
         "flat logo" => TraceParams { mode: Mode::Logo, colors: 8, paths: 60.0, corners: 50.0, noise: 6, snap_curves_to_lines: true, ..d },
         _ => return None,
@@ -426,6 +442,10 @@ pub struct TracedPath {
     /// Create Strokes: the path is stroked this wide (px), not filled (centre lines, or the
     /// outlines of wider areas without Fills).
     pub stroke: Option<f64>,
+    /// Shapes: the shape the path is, exactly (`path` is that shape's outline).
+    pub shape: Option<TracedShape>,
+    /// Gradients: the linear gradient the path is filled with (`color` is its middle colour).
+    pub gradient: Option<TracedGradient>,
 }
 
 /// The traced result, bottom-most path first.
@@ -434,6 +454,9 @@ pub struct TraceResult {
     pub paths: Vec<TracedPath>,
     /// Colours actually used.
     pub palette: Vec<[u8; 3]>,
+    /// Auto Grouping: for each of `paths`, the path it lies inside, if any (empty without the
+    /// option). Each path drawn before those inside it paints what `paths` paints in its order.
+    pub parents: Vec<Option<usize>>,
 }
 
 impl TraceResult {
@@ -446,6 +469,14 @@ fn is_white(c: [u8; 3]) -> bool {
     c.iter().all(|&v| v >= 245)
 }
 
+/// Whether Ignore Color leaves palette colour `c` out: `target` is the colour picked (`None`: white).
+fn is_ignored(c: [u8; 3], target: Option<[u8; 3]>) -> bool {
+    match target {
+        None => is_white(c),
+        Some(t) => (0..3).map(|k| (f64::from(c[k]) - f64::from(t[k])).powi(2)).sum::<f64>() <= 30.0 * 30.0 || (is_white(t) && is_white(c)),
+    }
+}
+
 /// Trace `img` with `params`. Failures (an image Logo mode refuses, say) give an empty result: use
 /// [`trace_within`] to see why.
 pub fn trace(img: &Raster, params: &TraceParams) -> TraceResult {
@@ -461,19 +492,63 @@ pub fn trace_within(img: &Raster, params: &TraceParams, max_anchors: usize) -> R
     if w == 0 || h == 0 || img.rgba.len() != w * h * 4 {
         return Ok(TraceResult::default());
     }
+    let mut out = trace_paths(img, params, max_anchors)?;
+    if params.auto_grouping {
+        // Abutting areas cannot overlap; stacked layers, Logo's shapes and stroked lines can.
+        let stacked = params.method == Method::Overlapping || params.mode == Mode::Logo || params.strokes;
+        out.parents = group::parents(&out.paths, img.width as usize, img.height as usize, stacked);
+    }
+    Ok(out)
+}
+
+fn trace_paths(img: &Raster, params: &TraceParams, max_anchors: usize) -> Result<TraceResult, TraceError> {
+    let (w, h) = (img.width as usize, img.height as usize);
     if params.mode == Mode::Logo {
         return logo::trace_logo(img, params, max_anchors);
     }
+    // The colour Ignore Color leaves out, if not white.
+    let ignore = match &params.ignore_color {
+        Some(name) if params.ignore_white => Some(logo::parse_hex(name).ok_or_else(|| TraceError::BadPalette(name.clone()))?),
+        _ => None,
+    };
     // A photo is traced from a copy with its noise smoothed away (see `smooth`).
     let smoothed = (params.mode != Mode::BlackAndWhite && quantize::continuous_tone(img)).then(|| smooth::smoothed(img));
     let img = smoothed.as_ref().unwrap_or(img);
-    let mut q = quantize(img, params);
+    // Gradients are found first and kept out of the palette: no colour is spent on bands of them.
+    let found = (params.gradients && params.mode != Mode::BlackAndWhite).then(|| gradient::detect(img)).filter(|f| !f.1.is_empty());
+    let without = found.as_ref().map(|(of, _)| {
+        let mut rest = img.clone();
+        for (p, &g) in rest.rgba.as_chunks_mut::<4>().0.iter_mut().zip(of) {
+            if g != u32::MAX {
+                p[3] = 0;
+            }
+        }
+        rest
+    });
+    let mut q = quantize(without.as_ref().unwrap_or(img), params);
+    drop(without);
+    // Each gradient is a palette entry of its own (its colour: the gradient's middle).
+    let mut gradients: Vec<Option<TracedGradient>> = vec![None; q.palette.len()];
+    if let Some((mut of, found)) = found {
+        gradient::settle_edges(img, &mut of, &found, &mut q.labels);
+        let first = q.palette.len();
+        for (l, &g) in q.labels.iter_mut().zip(&of) {
+            if g != u32::MAX {
+                *l = u16::try_from(first + g as usize).unwrap_or(TRANSPARENT);
+            }
+        }
+        q.palette.extend(found.iter().map(|g| g.color_at(g.start.midpoint(g.end)).map(|v| v.round().clamp(0.0, 255.0) as u8)));
+        gradients.extend(found.into_iter().map(Some));
+    }
     denoise(&mut q.labels, w, h, params.noise as usize);
-    // Pixel count per palette entry.
+    // Pixel count per palette entry, and the box its pixels lie in.
     let mut counts = vec![0usize; q.palette.len()];
-    for &l in &q.labels {
-        if let Some(c) = counts.get_mut(l as usize) {
+    let mut boxes: Vec<Option<(usize, usize, usize, usize)>> = vec![None; q.palette.len()];
+    for (i, &l) in q.labels.iter().enumerate() {
+        if let (Some(c), Some(b)) = (counts.get_mut(l as usize), boxes.get_mut(l as usize)) {
             *c += 1;
+            let (x, y) = (i % w, i / w);
+            *b = Some(b.map_or((x, y, x + 1, y + 1), |b| (b.0.min(x), b.1.min(y), b.2.max(x + 1), b.3.max(y + 1))));
         }
     }
     // Layers bottom → top: largest area first.
@@ -497,27 +572,29 @@ pub fn trace_within(img: &Raster, params: &TraceParams, max_anchors: usize) -> R
         rank[i] = r;
     }
     let layers: Vec<(usize, usize)> =
-        order.iter().copied().enumerate().filter(|&(_, ci)| !(params.ignore_white && is_white(q.palette[ci]))).collect();
+        order.iter().copied().enumerate().filter(|&(_, ci)| !(params.ignore_white && is_ignored(q.palette[ci], ignore))).collect();
     let job = Layers {
         q: &q,
         rank: &rank,
         params,
         img,
+        ignore,
+        boxes,
+        gradients: &gradients,
         bw_tones: bw_tones(img, &q),
         style: params.outline_style(),
-        opts: fit::FitOptions {
-            polygon_tol: params.polygon_tolerance(),
-            fit_tol: params.fit_tolerance(),
-            corner_angle: params.corner_angle(),
-            snap_lines: params.snap_curves_to_lines,
-        },
         w,
         h,
         anchors: AtomicUsize::new(0),
         max_anchors,
     };
     let mut out = TraceResult::default();
-    for (paths, &(_, ci)) in parallel_map(&layers, |&(r, ci)| job.layer(r, ci)).into_iter().zip(&layers) {
+    // A layer takes about ten bytes a pixel of its box while it is traced (its mask, the labels
+    // of its components, the stack that fills them, its edges): as many layers at a time as fit
+    // in half a gigabyte, so that a large image is not traced at the cost of gigabytes.
+    let largest = job.boxes.iter().flatten().map(|b| (b.2 - b.0) * (b.3 - b.1)).max().unwrap_or(1).max(1);
+    let at_a_time = ((512 << 20) / (largest * 10)).max(1);
+    for (paths, &(_, ci)) in parallel_map_at_most(at_a_time, &layers, |&(r, ci)| job.layer(r, ci)).into_iter().zip(&layers) {
         out.paths.extend(paths.ok_or(TraceError::TooComplex { max: max_anchors })?);
         let color = q.palette[ci];
         if !out.palette.contains(&color) {
@@ -527,17 +604,32 @@ pub fn trace_within(img: &Raster, params: &TraceParams, max_anchors: usize) -> R
     Ok(out)
 }
 
-/// The mean luminance of the pixels labelled 0 (white) and 1 (black) of a Black and White
-/// quantisation: pure white and black where a side has no pixel.
+/// The luminance of white and of black in a Black and White quantisation: what its lightest
+/// white pixels and its darkest black ones have (the 98th and 2nd percentiles; pure white and
+/// black where a side has no pixel). Not the means: where the black is thin lines, blurred or
+/// scanned, most black pixels are part paper, their mean is a gray, and read against it the middle
+/// of every line would count as more than all ink, now more and now less as the line crosses the
+/// pixel rows, which put a ripple on its edges.
 fn bw_tones(img: &Raster, q: &Quantized) -> [f64; 2] {
-    let (mut sum, mut n) = ([0.0f64; 2], [0.0f64; 2]);
+    let mut hist = [[0u64; 256]; 2];
     for (p, &l) in img.rgba.as_chunks::<4>().0.iter().zip(&q.labels) {
-        if let (Some(s), Some(n)) = (sum.get_mut(l as usize), n.get_mut(l as usize)) {
-            *s += (f64::from(p[0]) * 299.0 + f64::from(p[1]) * 587.0 + f64::from(p[2]) * 114.0) / 1000.0;
-            *n += 1.0;
+        if let Some(h) = hist.get_mut(l as usize) {
+            h[((u32::from(p[0]) * 299 + u32::from(p[1]) * 587 + u32::from(p[2]) * 114 + 500) / 1000).min(255) as usize] += 1;
         }
     }
-    [if n[0] > 0.0 { sum[0] / n[0] } else { 255.0 }, if n[1] > 0.0 { sum[1] / n[1] } else { 0.0 }]
+    // The luminance a share `at` of the side's pixels are darker than.
+    let percentile = |h: &[u64; 256], at: f64, none: f64| {
+        let total: u64 = h.iter().sum();
+        let mut seen = 0;
+        for (v, n) in h.iter().enumerate() {
+            seen += n;
+            if total > 0 && seen as f64 >= at * total as f64 {
+                return v as f64;
+            }
+        }
+        none
+    };
+    [percentile(&hist[0], 0.98, 255.0), percentile(&hist[1], 0.02, 0.0)]
 }
 
 /// What tracing one colour layer needs.
@@ -547,12 +639,16 @@ struct Layers<'a> {
     rank: &'a [usize],
     params: &'a TraceParams,
     img: &'a Raster,
-    /// Black and White: the mean luminance of the white pixels and of the black ones.
+    /// The colour Ignore Color leaves out, if not white.
+    ignore: Option<[u8; 3]>,
+    /// The box each palette entry's pixels lie in: `(x0, y0, x1, y1)`, the far sides excluded.
+    boxes: Vec<Option<(usize, usize, usize, usize)>>,
+    /// Gradients: the gradient each palette entry is, if it is one.
+    gradients: &'a [Option<TracedGradient>],
+    /// Black and White: the luminance of white and of black (see `bw_tones`).
     bw_tones: [f64; 2],
-    /// How outlines are fitted.
+    /// How outlines and centre lines are fitted.
     style: logo::Style,
-    /// How centre lines are fitted.
-    opts: fit::FitOptions,
     w: usize,
     h: usize,
     /// Anchor points made so far, by every layer.
@@ -564,7 +660,7 @@ impl Layers<'_> {
     /// Ignore White: white is no part of any layer (stacked layers reach under the layers above
     /// them, and must not reach under white that is left out).
     fn ignored(&self, label: u16) -> bool {
-        self.params.ignore_white && self.q.palette.get(label as usize).is_some_and(|c| is_white(*c))
+        self.params.ignore_white && self.q.palette.get(label as usize).is_some_and(|c| is_ignored(*c, self.ignore))
     }
     /// The region across a crack, for cutting outlines at their junctions: the outside pixel's
     /// colour. Stacked layers end on many colours at once and share no edge: one neighbour.
@@ -609,7 +705,7 @@ impl Layers<'_> {
     /// How far the edge lies from a crack between two pixels, towards the outside one (−0.5 to 0.5).
     ///
     /// Each pixel of the column across the crack is read as a blend of the tones on its two sides
-    /// (the two pixels' palette colours; in Black and White the mean luminance of the black and of
+    /// (the two pixels' palette colours; in Black and White the luminance of the image's black and of
     /// the white pixels). The edge is where the blends, summed, put it: as far out as there is
     /// inside tone in the outside pixels, less the outside tone in the inside ones (two pixels each
     /// way, while they are on the same side and no more blended than the pixel before: more would be
@@ -630,12 +726,31 @@ impl Layers<'_> {
             return 0.0;
         }
         let bw = self.params.mode == Mode::BlackAndWhite;
+        // Black and White: black is the image's black; white is the lightest pixel within a few
+        // pixels of the crack, the paper as it is here (a scan's paper is darker in one corner than
+        // in another, and read against the image's lightest white it would count as part ink).
+        let black = self.bw_tones[1];
+        let white = if bw {
+            let light = (-3..=4)
+                .filter_map(|k| c.at(k).and_then(|i| self.img.rgba.get(i * 4..i * 4 + 3)))
+                .map(|p| (f64::from(p[0]) * 299.0 + f64::from(p[1]) * 587.0 + f64::from(p[2]) * 114.0) / 1000.0);
+            light.fold(f64::NEG_INFINITY, f64::max).clamp((black + 32.0).min(self.bw_tones[0]), self.bw_tones[0])
+        } else {
+            self.bw_tones[0]
+        };
         let (ca, cb) = if bw {
-            let tone = |l: u16| [self.bw_tones[usize::from(l == 1)]; 3];
+            let tone = |l: u16| [if l == 1 { black } else { white }; 3];
             (tone(la), tone(lb))
         } else {
-            let (Some(ca), Some(cb)) = (self.q.palette.get(la as usize), self.q.palette.get(lb as usize)) else { return 0.0 };
-            (ca.map(f64::from), cb.map(f64::from))
+            // A side's own colour: its palette entry's, or its gradient's colour here.
+            let own = |l: u16, k: i32| {
+                let flat = self.q.palette.get(l as usize)?.map(f64::from);
+                let Some(g) = self.gradients.get(l as usize).and_then(Option::as_ref) else { return Some(flat) };
+                let i = c.at(k)?;
+                Some(g.color_at(vectorcraft_geom::Point::new((i % self.w) as f64 + 0.5, (i / self.w) as f64 + 0.5)))
+            };
+            let (Some(ca), Some(cb)) = (own(la, 0), own(lb, 1)) else { return 0.0 };
+            (ca, cb)
         };
         let d = [0, 1, 2].map(|k| cb[k] - ca[k]);
         let len2: f64 = d.iter().map(|v| v * v).sum();
@@ -689,7 +804,6 @@ impl Layers<'_> {
         };
         if bw {
             // The share of black at which a pixel turns black.
-            let (white, black) = (self.bw_tones[0], self.bw_tones[1]);
             let turn = ((white - f64::from(self.params.threshold)) / (white - black).max(1.0)).clamp(0.02, 0.98);
             shift += if la == 1 { 1.0 } else { -1.0 } * (0.5 - turn) / steep;
         }
@@ -699,40 +813,59 @@ impl Layers<'_> {
     /// The paths of layer `r` (palette entry `ci`), or `None` once the anchors made pass the
     /// maximum.
     fn layer(&self, r: usize, ci: usize) -> Option<Vec<TracedPath>> {
-        let (params, opts) = (self.params, &self.opts);
+        let params = self.params;
         let color = *self.q.palette.get(ci)?;
         let overlapping = params.method == Method::Overlapping;
         let (w, h) = (self.w, self.h);
         // Create Strokes: this colour's lines, left out of its areas.
         let (thin, lines) = if params.strokes {
-            centerline::lines(&self.q.labels, u16::try_from(ci).unwrap_or(TRANSPARENT), w, h, params.stroke_width, opts)
+            // The ink the lines are read against: the layer's colour; Black and White's own black.
+            let ink = if params.mode == Mode::BlackAndWhite { [self.bw_tones[usize::from(ci == 1)]; 3] } else { color.map(f64::from) };
+            centerline::lines(&self.q.labels, u16::try_from(ci).unwrap_or(TRANSPARENT), w, h, params.stroke_width, self.img, ink, &self.style)
         } else {
             (vec![], vec![])
         };
-        let mask: Vec<bool> = self
-            .q
-            .labels
-            .iter()
-            .enumerate()
-            .map(|(i, &l)| {
-                l != TRANSPARENT
-                    && !thin.get(i).copied().unwrap_or(false)
-                    && if overlapping { self.rank.get(l as usize).is_some_and(|&lr| lr >= r) && !self.ignored(l) } else { l as usize == ci }
-            })
-            .collect();
+        // The layer is traced within the box its pixels lie in, not the whole image.
+        let part = |l: u16| if overlapping { self.rank.get(l as usize).is_some_and(|&lr| lr >= r) && !self.ignored(l) } else { l as usize == ci };
+        let (mut x0, mut y0, mut x1, mut y1) = (w, h, 0, 0);
+        for (l, b) in self.boxes.iter().enumerate() {
+            if let Some(b) = b.filter(|_| part(l as u16)) {
+                (x0, y0, x1, y1) = (x0.min(b.0), y0.min(b.1), x1.max(b.2), y1.max(b.3));
+            }
+        }
+        if x0 >= x1 || y0 >= y1 {
+            return Some(vec![]);
+        }
+        let (bw, bh) = (x1 - x0, y1 - y0);
+        let mut mask = Vec::with_capacity(bw * bh);
+        for y in y0..y1 {
+            let row = self.q.labels.get(y * w + x0..y * w + x1)?;
+            mask.extend(row.iter().enumerate().map(|(k, &l)| l != TRANSPARENT && !thin.get(y * w + x0 + k).copied().unwrap_or(false) && part(l)));
+        }
         // Without Fills, areas are outlined with a 1 px stroke.
         let area_stroke = (params.strokes && !params.fills).then_some(1.0);
         let min_hole = params.noise.max(1) as i64;
         let mut paths = vec![];
-        let mut add = |path: PathData, pixels: usize, stroke: Option<f64>| {
+        let mut add = |path: PathData, pixels: usize, stroke: Option<f64>, shape: Option<TracedShape>| {
             let n = path.anchor_count();
             if self.anchors.fetch_add(n, Ordering::Relaxed).saturating_add(n) > self.max_anchors {
                 return false;
             }
-            paths.push(TracedPath { path, color, pixels, stroke });
+            // (A gradient fills; a stroked line of it is its middle colour.)
+            let gradient = self.gradients.get(ci).cloned().flatten().filter(|_| stroke.is_none());
+            paths.push(TracedPath { path, color, pixels, stroke, shape, gradient });
             true
         };
-        for comp in trace_mask(&mask, w, h) {
+        let mut comps = trace_mask(&mask, bw, bh);
+        drop(mask);
+        for comp in &mut comps {
+            for l in std::iter::once(&mut comp.outer).chain(&mut comp.holes) {
+                for p in &mut l.pts {
+                    *p = (p.0 + x0 as i32, p.1 + y0 as i32);
+                }
+            }
+        }
+        for comp in comps {
             let fit = |l: &Loop| fit::fit_loop(l, w, h, &|c| (self.shift(c), self.neighbour(c)), &|x, y| self.junction(x, y), &self.style);
             let Some(outer) = fit(&comp.outer) else { continue };
             let mut subs = vec![outer];
@@ -742,12 +875,18 @@ impl Layers<'_> {
                 }
                 subs.extend(fit(hole));
             }
-            if !add(PathData::new(subs), comp.pixels, area_stroke) {
+            // Shapes: a filled outline without holes that is a shape becomes that shape.
+            let shape = match subs.as_slice() {
+                [only] if params.shapes && area_stroke.is_none() => shapes::recognise(only),
+                _ => None,
+            };
+            let path = shape.map_or_else(|| PathData::new(subs), |s| s.path());
+            if !add(path, comp.pixels, area_stroke, shape) {
                 return None;
             }
         }
         for line in lines {
-            if !add(line.path, line.pixels, Some(line.width)) {
+            if !add(line.path, line.pixels, Some(line.width), None) {
                 return None;
             }
         }
@@ -756,9 +895,14 @@ impl Layers<'_> {
 }
 
 /// `f` of each of `items`, in order, spread over the available cores.
-#[cfg(not(target_arch = "wasm32"))]
 fn parallel_map<T: Sync, R: Send>(items: &[T], f: impl Fn(&T) -> R + Sync) -> Vec<R> {
-    let threads = std::thread::available_parallelism().map_or(1, |n| n.get()).min(items.len());
+    parallel_map_at_most(usize::MAX, items, f)
+}
+
+/// `f` of each of `items`, in order, spread over the available cores, at most `at_a_time` at once.
+#[cfg(not(target_arch = "wasm32"))]
+fn parallel_map_at_most<T: Sync, R: Send>(at_a_time: usize, items: &[T], f: impl Fn(&T) -> R + Sync) -> Vec<R> {
+    let threads = std::thread::available_parallelism().map_or(1, |n| n.get()).min(items.len()).min(at_a_time);
     if threads <= 1 {
         return items.iter().map(f).collect();
     }
@@ -787,7 +931,7 @@ fn parallel_map<T: Sync, R: Send>(items: &[T], f: impl Fn(&T) -> R + Sync) -> Ve
 
 /// `f` of each of `items`, in order (no threads on the web).
 #[cfg(target_arch = "wasm32")]
-fn parallel_map<T: Sync, R: Send>(items: &[T], f: impl Fn(&T) -> R + Sync) -> Vec<R> {
+fn parallel_map_at_most<T: Sync, R: Send>(_: usize, items: &[T], f: impl Fn(&T) -> R + Sync) -> Vec<R> {
     items.iter().map(f).collect()
 }
 

crates/trace/src/logo/mod.rs

@@ -26,5 +26,6 @@ mod unmix;
 
 pub(crate) use geom::{Cubic, all_within, resample_closed, resample_open, sample_cubics};
 pub(crate) use outline::{Stats, Style, fit_open, fit_outline};
+pub(crate) use palette::parse_hex;
 pub(crate) use pipeline::trace_logo;
 pub(crate) use restore::RestoreParams;

crates/trace/src/logo/outline.rs

@@ -25,6 +25,9 @@ pub(crate) struct Style {
     pub max_dev: f64,
     /// Spacing of the points of the fit that this check looks at.
     pub check_step: f64,
+    /// Straight pieces within a few degrees of level or upright are made exactly so (by the
+    /// tracer's other modes; Flat Logo leaves them).
+    pub upright: bool,
 }
 
 impl Default for Style {
@@ -42,6 +45,7 @@ impl Default for Style {
             restore: Some(RestoreParams::default()),
             max_dev: 1.4,
             check_step: 0.03,
+            upright: false,
         }
     }
 }

crates/trace/src/logo/pipeline.rs

@@ -478,7 +478,14 @@ pub(crate) fn trace_logo(img: &Raster, params: &TraceParams, max_anchors: usize)
         if !out.palette.contains(&color) {
             out.palette.push(color);
         }
-        out.paths.push(TracedPath { path: PathData::new(subs), color, pixels: (s.area * (factor * factor) as f64) as usize, stroke: None });
+        out.paths.push(TracedPath {
+            path: PathData::new(subs),
+            color,
+            pixels: (s.area * (factor * factor) as f64) as usize,
+            stroke: None,
+            shape: None,
+            gradient: None,
+        });
     }
     Ok(out)
 }

crates/trace/src/shapes.rs

@@ -0,0 +1,240 @@
+//! Shapes: traced outlines that are a circle, an ellipse, a rectangle (its corners square or
+//! rounded) or a regular polygon are told so, and come out as exactly that shape.
+//!
+//! An outline is a shape when every point of it lies within a small tolerance of the shape that
+//! its own area, middle and extents describe: nothing is taken for a shape that it merely
+//! resembles.
+
+use vectorcraft_geom::{Affine, ParamCurve, PathData, Point, Rect, SubPath, shapes};
+
+/// A shape an outline was found to be (pixel coordinates; angles in degrees, clockwise on screen).
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub enum TracedShape {
+    /// A rectangle `width` × `height` about `center`, turned by `rotation`, its corners rounded
+    /// with `radius` (0: square corners).
+    Rectangle { center: Point, width: f64, height: f64, radius: f64, rotation: f64 },
+    /// An ellipse with radii `rx` and `ry` about `center`, turned by `rotation` (a circle: equal
+    /// radii, no rotation).
+    Ellipse { center: Point, rx: f64, ry: f64, rotation: f64 },
+    /// A regular polygon: its first corner `rotation` from straight up.
+    Polygon { center: Point, radius: f64, sides: u32, rotation: f64 },
+}
+
+impl TracedShape {
+    /// The shape's outline.
+    pub fn path(&self) -> PathData {
+        let turned = |p: PathData, c: Point, deg: f64| p.transformed(Affine::rotate_about(deg.to_radians(), c));
+        match *self {
+            TracedShape::Rectangle { center, width, height, radius, rotation } => {
+                let r = Rect::from_center_size(center, (width, height));
+                turned(if radius > 0.0 { shapes::rounded_rectangle(r, radius) } else { shapes::rectangle(r) }, center, rotation)
+            }
+            TracedShape::Ellipse { center, rx, ry, rotation } => {
+                turned(shapes::ellipse(Rect::from_center_size(center, (2.0 * rx, 2.0 * ry))), center, rotation)
+            }
+            TracedShape::Polygon { center, radius, sides, rotation } => shapes::polygon(center, radius, sides, rotation),
+        }
+    }
+}
+
+/// How far a point may lie from the shape: half a pixel, and for large shapes 0.2% of their size.
+fn tolerance(size: f64) -> f64 {
+    (0.002 * size).max(0.5)
+}
+
+/// The shape the closed outline `sp` is, if it is one (and at least 6 px across).
+pub(crate) fn recognise(sp: &SubPath) -> Option<TracedShape> {
+    if !sp.closed || sp.anchors.len() < 2 {
+        return None;
+    }
+    // Points all along the outline.
+    let pts: Vec<Point> = (0..sp.segment_count()).flat_map(|i| (0..24).map(move |k| sp.segment(i).eval(f64::from(k) / 24.0))).collect();
+    let n = pts.len();
+    if n < 8 || !pts.iter().all(|p| p.x.is_finite() && p.y.is_finite()) {
+        return None;
+    }
+    // Area, middle and second moments of the polygon through them.
+    let (mut area2, mut cx, mut cy) = (0.0, 0.0, 0.0);
+    for i in 0..n {
+        let (a, b) = (pts[i], pts[(i + 1) % n]);
+        let cross = a.x * b.y - b.x * a.y;
+        area2 += cross;
+        cx += (a.x + b.x) * cross;
+        cy += (a.y + b.y) * cross;
+    }
+    let area = area2.abs() / 2.0;
+    if area < 20.0 {
+        return None;
+    }
+    let c = Point::new(cx / (3.0 * area2), cy / (3.0 * area2));
+    let (mut ixx, mut iyy, mut ixy) = (0.0, 0.0, 0.0);
+    for i in 0..n {
+        let (a, b) = (pts[i] - c, pts[(i + 1) % n] - c);
+        let cross = a.x * b.y - b.x * a.y;
+        ixx += (a.x * a.x + a.x * b.x + b.x * b.x) * cross;
+        iyy += (a.y * a.y + a.y * b.y + b.y * b.y) * cross;
+        ixy += (a.x * b.y + 2.0 * a.x * a.y + 2.0 * b.x * b.y + b.x * a.y) * cross;
+    }
+    // Per unit of area: the variances of x and y and their covariance.
+    let (sxx, syy, sxy) = (ixx / (6.0 * area2), iyy / (6.0 * area2), ixy / (12.0 * area2));
+    let mean = (sxx + syy) / 2.0;
+    let spread = ((sxx - syy) / 2.0).hypot(sxy);
+    let (major, minor) = (mean + spread, (mean - spread).max(0.0));
+    // The direction of the longer axis (none when the shape is as wide every way).
+    let axis = if spread < 0.01 * mean { 0.0 } else { 0.5 * (2.0 * sxy).atan2(sxx - syy) };
+    let size = 4.0 * major.sqrt();
+    let tol = tolerance(size);
+    if size < 6.0 || !size.is_finite() {
+        return None;
+    }
+    let local = |p: Point, angle: f64| {
+        let d = p - c;
+        (d.x * angle.cos() + d.y * angle.sin(), d.y * angle.cos() - d.x * angle.sin())
+    };
+
+    // An ellipse: its radii are twice the roots of its variances.
+    let (rx, ry) = (2.0 * major.sqrt(), 2.0 * minor.sqrt());
+    if ry > 2.0 {
+        let off = pts.iter().map(|&p| {
+            let (x, y) = local(p, axis);
+            // Scaled to a circle: how far from it, in pixels of the larger radius (no nearer than
+            // that to the ellipse: a long thin bar is no flat ellipse).
+            ((x / rx).hypot(y / ry) - 1.0).abs() * rx
+        });
+        if off.fold(0.0, f64::max) <= tol {
+            // Radii this close are a circle's, of the outline's area: a circle without anti-aliasing
+            // is fitted a little wider one way than the other.
+            let circle = (rx - ry).abs() <= 2.0 * tol;
+            let (rx, ry) = if circle { ((rx * ry).sqrt(), (rx * ry).sqrt()) } else { (rx, ry) };
+            return Some(TracedShape::Ellipse { center: c, rx, ry, rotation: if circle { 0.0 } else { axis.to_degrees() } });
+        }
+    }
+
+    // A rectangle, along its longest straight side (a square has no longer axis to go by).
+    let side = (0..sp.segment_count())
+        .filter(|&i| sp.segment_is_line(i))
+        .map(|i| sp.segment(i))
+        .max_by(|a, b| a.p0.distance(a.p3).total_cmp(&b.p0.distance(b.p3)));
+    if let Some(side) = side {
+        let d = side.p3 - side.p0;
+        // Turned by under 45° either way: a rectangle is the same a quarter turn on.
+        let quarter = std::f64::consts::FRAC_PI_2;
+        let angle = d.y.atan2(d.x);
+        let angle = angle - quarter * (angle / quarter).round();
+        let xy: Vec<(f64, f64)> = pts.iter().map(|&p| local(p, angle)).collect();
+        let (hw, hh) = xy.iter().fold((0.0f64, 0.0f64), |m, p| (m.0.max(p.0.abs()), m.1.max(p.1.abs())));
+        // Square corners first; else rounded ones, which take (4 − π) r² off the area.
+        let rounded = ((4.0 * hw * hh - area) / (4.0 - std::f64::consts::PI)).max(0.0).sqrt().min(hw.min(hh));
+        for radius in [0.0, rounded] {
+            let off = xy.iter().map(|&(x, y)| {
+                // Distance to the rounded rectangle's edge.
+                let (qx, qy) = (x.abs() - hw + radius, y.abs() - hh + radius);
+                (qx.max(0.0).hypot(qy.max(0.0)) + qx.max(qy).min(0.0) - radius).abs()
+            });
+            if hw > 2.0 && hh > 2.0 && (radius == 0.0 || radius >= 0.75) && off.fold(0.0, f64::max) <= tol {
+                return Some(TracedShape::Rectangle { center: c, width: 2.0 * hw, height: 2.0 * hh, radius, rotation: angle.to_degrees() });
+            }
+        }
+    }
+
+    // A regular polygon: its corners evenly round the middle, its sides straight between them.
+    let sides = sp.anchors.len();
+    if (3..=12).contains(&sides) {
+        let radius = sp.anchors.iter().map(|a| a.p.distance(c)).sum::<f64>() / sides as f64;
+        let first = sp.anchors.first()?.p - c;
+        let rotation = (first.y.atan2(first.x).to_degrees() + 90.0).rem_euclid(360.0 / sides as f64);
+        let shape = TracedShape::Polygon { center: c, radius, sides: sides as u32, rotation };
+        let ideal: Vec<Point> = shape.path().subpaths.first()?.anchors.iter().map(|a| a.p).collect();
+        // Every corner of the polygon has one of the outline's on it, and every point of the
+        // outline lies on one of the polygon's sides.
+        let cornered = ideal.iter().all(|q| sp.anchors.iter().any(|a| q.distance(a.p) <= 1.5 * tol));
+        let on_a_side = |p: Point| {
+            (0..ideal.len()).any(|i| {
+                let (a, b) = (ideal[i], ideal[(i + 1) % ideal.len()]);
+                let t = ((p - a).dot(b - a) / (b - a).hypot2()).clamp(0.0, 1.0);
+                p.distance(a + (b - a) * t) <= tol
+            })
+        };
+        if cornered && pts.iter().all(|&p| on_a_side(p)) {
+            // Four equal sides are a square: a rectangle, its sides half a right angle from its corners.
+            let side = radius * std::f64::consts::SQRT_2;
+            let turned = (rotation + 45.0).rem_euclid(90.0);
+            let square = TracedShape::Rectangle {
+                center: c,
+                width: side,
+                height: side,
+                radius: 0.0,
+                rotation: if turned > 45.0 { turned - 90.0 } else { turned },
+            };
+            return Some(if sides == 4 { square } else { shape });
+        }
+    }
+    None
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn is(shape: TracedShape) -> Option<TracedShape> {
+        recognise(shape.path().subpaths.first().unwrap())
+    }
+
+    #[test]
+    fn each_shape_is_told_from_its_own_outline() {
+        let c = Point::new(60.3, 45.6);
+        match is(TracedShape::Ellipse { center: c, rx: 20.0, ry: 20.0, rotation: 0.0 }) {
+            Some(TracedShape::Ellipse { center, rx, ry, rotation }) => {
+                assert!(center.distance(c) < 0.05 && (rx - 20.0).abs() < 0.05 && rx == ry && rotation == 0.0, "{center:?} {rx} {ry}")
+            }
+            other => panic!("{other:?}"),
+        }
+        match is(TracedShape::Ellipse { center: c, rx: 30.0, ry: 12.0, rotation: 25.0 }) {
+            Some(TracedShape::Ellipse { rx, ry, rotation, .. }) => {
+                assert!((rx - 30.0).abs() < 0.3 && (ry - 12.0).abs() < 0.3 && (rotation - 25.0).abs() < 0.5, "{rx} {ry} {rotation}")
+            }
+            other => panic!("{other:?}"),
+        }
+        match is(TracedShape::Rectangle { center: c, width: 50.0, height: 20.0, radius: 0.0, rotation: 10.0 }) {
+            Some(TracedShape::Rectangle { width, height, radius, rotation, .. }) => {
+                assert!((width - 50.0).abs() < 0.1 && (height - 20.0).abs() < 0.1 && radius == 0.0 && (rotation - 10.0).abs() < 0.1)
+            }
+            other => panic!("{other:?}"),
+        }
+        match is(TracedShape::Rectangle { center: c, width: 50.0, height: 30.0, radius: 8.0, rotation: 0.0 }) {
+            Some(TracedShape::Rectangle { width, radius, .. }) => {
+                assert!((width - 50.0).abs() < 0.2 && (radius - 8.0).abs() < 0.5, "{width} {radius}")
+            }
+            other => panic!("{other:?}"),
+        }
+        for sides in [3, 5, 6, 8] {
+            match is(TracedShape::Polygon { center: c, radius: 25.0, sides, rotation: 7.0 }) {
+                Some(TracedShape::Polygon { radius, sides: n, rotation, .. }) => {
+                    assert!(n == sides && (radius - 25.0).abs() < 0.1 && (rotation - 7.0).abs() < 0.1, "{sides}: {radius} {rotation}")
+                }
+                other => panic!("{sides} sides: {other:?}"),
+            }
+        }
+    }
+
+    #[test]
+    fn what_only_resembles_a_shape_is_none() {
+        // A star, an L, a rectangle with one corner cut, an egg.
+        let star = shapes::star(Point::new(50.0, 50.0), 30.0, 12.0, 5, 0.0);
+        assert_eq!(recognise(&star.subpaths[0]), None);
+        let poly = |pts: &[(f64, f64)]| SubPath::polyline(&pts.iter().map(|&p| Point::from(p)).collect::<Vec<_>>(), true);
+        assert_eq!(recognise(&poly(&[(0.0, 0.0), (40.0, 0.0), (40.0, 15.0), (15.0, 15.0), (15.0, 40.0), (0.0, 40.0)])), None);
+        assert_eq!(recognise(&poly(&[(0.0, 0.0), (40.0, 0.0), (40.0, 22.0), (34.0, 30.0), (0.0, 30.0)])), None);
+        let mut egg = shapes::ellipse(Rect::new(10.0, 10.0, 70.0, 50.0));
+        egg.subpaths[0].anchors[2].p.x += 4.0;
+        assert_eq!(recognise(&egg.subpaths[0]), None);
+        // Too small to say, open, or not a number.
+        assert_eq!(is(TracedShape::Ellipse { center: Point::new(5.0, 5.0), rx: 2.0, ry: 2.0, rotation: 0.0 }), None);
+        let mut open = shapes::rectangle(Rect::new(0.0, 0.0, 30.0, 20.0)).subpaths[0].clone();
+        open.closed = false;
+        assert_eq!(recognise(&open), None);
+        let mut bad = shapes::rectangle(Rect::new(0.0, 0.0, 30.0, 20.0)).subpaths[0].clone();
+        bad.anchors[1].p.x = f64::NAN;
+        assert_eq!(recognise(&bad), None);
+    }
+}

crates/trace/src/subpixel.rs

@@ -173,6 +173,56 @@ pub(crate) fn outline(
     };
     let step: Vec<bool> = (0..n).map(|i| edges[i].len == 1 && turn(i) * turn(i + 1) < 0).collect();
     let outward = |d: (i32, i32)| Vec2::new(f64::from(d.1), f64::from(-d.0));
+    // The pixel at a corner of the shape lies on both of the corner's edges, and what it lacks of
+    // the inside's colour is the doing of both: read as one edge's alone it dents the corner. The
+    // crack of each edge on it takes the shift of the next crack along that edge instead (edges
+    // of three pixels or more: a shorter one has no pixel clear of its corners).
+    let shifts = {
+        let mut shifts = shifts;
+        for i in 0..n {
+            let (b, e) = ((i + n - 1) % n, i);
+            if step[b] || step[e] || turn(i) == 0 {
+                continue;
+            }
+            let (before, edge) = (&edges[b], &edges[e]);
+            if before.len >= 3 {
+                shifts[before.first + before.len - 1] = shifts[before.first + before.len - 2];
+            }
+            if edge.len >= 3 {
+                shifts[edge.first] = shifts[edge.first + 1];
+            }
+        }
+        shifts
+    };
+
+    // A sharp corner whose own pixel is less than half the inside's colour goes to the outside, and
+    // the loop cuts the corner in two steps (the same, turned round, where the corner pixel of a
+    // notch goes to the inside). Between two edges of three pixels or more, those two steps are
+    // that corner: it lies where the two edges, each moved by its shift, meet. `notch[i]` is, for
+    // the first of the two steps, the corner (`Some(Some(..))`), for the second nothing
+    // (`Some(None)`), for any other edge `None`.
+    let mut notch: Vec<Option<Option<Point>>> = vec![None; n];
+    for i in 0..n {
+        let (a, s1, s2, b) = ((i + n - 1) % n, i, (i + 1) % n, (i + 2) % n);
+        let free = |e: usize| junctions[edges[e].first].is_none();
+        if n >= 6
+            && step[s1]
+            && step[s2]
+            && edges[a].len >= 3
+            && edges[b].len >= 3
+            && edges[s1].dir == edges[b].dir
+            && edges[s2].dir == edges[a].dir
+            && free(s1)
+            && free(s2)
+            && free(b)
+        {
+            let (ea, eb) = (&edges[a], &edges[b]);
+            // Edge `a` carried on one pixel further meets edge `b` carried back one.
+            let meet = at(s1) + Vec2::new(f64::from(ea.dir.0), f64::from(ea.dir.1));
+            notch[s1] = Some(Some(meet + outward(ea.dir) * shifts[ea.first + ea.len - 1] + outward(eb.dir) * shifts[eb.first]));
+            notch[s2] = Some(None);
+        }
+    }
 
     let mut pieces: Vec<Piece> = Vec::new();
     let start = first.unwrap_or(0);
@@ -196,7 +246,10 @@ pub(crate) fn outline(
                 let before = &edges[(i + n - 1) % n];
                 pts.push(corner + outward(before.dir) * shifts[(crack + cracks - 1) % cracks] + outward(e.dir) * shifts[crack]);
             }
-            if step[i] || !hard {
+            if !hard && let Some(sharp) = notch[i] {
+                // A corner whose own pixel went to the other side: the corner, not the two steps.
+                pts.extend(sharp);
+            } else if step[i] || !hard {
                 pts.push(corner + Vec2::new(f64::from(e.dir.0), f64::from(e.dir.1)) * 0.5 + outward(e.dir) * shifts[crack]);
             }
         }

crates/trace/src/tests.rs

@@ -255,7 +255,7 @@ fn snap_curves_to_lines_straightens_near_lines() {
 
 #[test]
 fn presets_resolve() {
-    assert_eq!(presets().len(), 13);
+    assert_eq!(presets().len(), 15);
     for n in PRESET_NAMES {
         assert!(preset(n).is_some(), "{n}");
     }
@@ -608,7 +608,7 @@ fn create_strokes_survives_noise_and_tiny_images() {
             for noise in [0, 1, 4] {
                 let p = TraceParams { strokes: true, fills, stroke_width: width, noise, ..TraceParams::default() };
                 for t in trace(&img, &p).paths {
-                    assert!(t.stroke.is_none_or(|w| w.is_finite() && w >= 1.0), "{:?}", t.stroke);
+                    assert!(t.stroke.is_none_or(|w| w.is_finite() && w >= 0.25), "{:?}", t.stroke);
                 }
             }
         }
@@ -1037,3 +1037,231 @@ fn abutting_regions_share_one_curve_along_their_edge() {
     }
     assert!(shared >= 12, "{shared} shared curves");
 }
+
+#[test]
+fn layers_traced_a_few_at_a_time_come_out_the_same() {
+    let items: Vec<usize> = (0..40).collect();
+    for at_a_time in [1, 3, usize::MAX] {
+        assert_eq!(parallel_map_at_most(at_a_time, &items, |i| i * i), items.iter().map(|i| i * i).collect::<Vec<_>>());
+    }
+    // A layer is traced within the box of its pixels: a shape far from the image's origin stays there.
+    let img = Raster::from_fn(90, 70, |x, y| if (60..80).contains(&x) && (40..60).contains(&y) { BLACK } else { WHITE });
+    let b = trace(&img, &bw()).paths[0].path.bounds().unwrap();
+    assert!([(b.x0, 60.0), (b.y0, 40.0), (b.x1, 80.0), (b.y1, 60.0)].iter().all(|(got, want)| (got - want).abs() < 0.01), "{b:?}");
+}
+
+#[test]
+fn a_blurred_thin_line_on_unevenly_lit_paper_is_a_few_anchors() {
+    // A line 2 px wide a little off the pixel rows, blurred over three pixels, on paper that is a
+    // quarter darker at one end than at the other: nowhere is its ink pure black, or the paper white.
+    let img = Raster::from_fn(160, 40, |x, y| {
+        let (fx, fy) = (f64::from(x) + 0.5, f64::from(y) + 0.5);
+        let paper = 235.0 - 55.0 * fx / 160.0;
+        let centre = 17.3 + 0.06 * fx;
+        // The share of ink in the pixel, the line's edges blurred linearly over 1.5 px either way.
+        let ink = if (10.0..150.0).contains(&fx) { ((1.0 + 1.5 - (fy - centre).abs()) / 3.0).clamp(0.0, 1.0) } else { 0.0 };
+        let v = (paper * (1.0 - ink) + 40.0 * ink).round() as u8;
+        [v, v, v, 255]
+    });
+    let res = trace(&img, &preset("Line Art").unwrap());
+    assert_eq!(res.paths.len(), 1);
+    let path = &res.paths[0].path;
+    // Its two long edges are smooth: a ripple would take an anchor every few pixels.
+    assert!(path.anchor_count() <= 10, "{} anchors", path.anchor_count());
+    // And it lies along the line's middle, about as wide as its ink.
+    let off = along(path).iter().filter(|p| p.x > 14.0 && p.x < 146.0).map(|p| ((p.y - (17.3 + 0.06 * p.x)).abs() - 1.0).abs()).fold(0.0, f64::max);
+    assert!(off < 0.5, "edges {off} px from where the ink's width puts them");
+}
+
+#[test]
+fn ignore_color_leaves_out_the_colour_picked() {
+    // Navy field, yellow disc, green bar.
+    let img = three_colour_art(0.0);
+    let params = TraceParams { colors: 3, ignore_white: true, ..sixteen_colors() };
+    // White by default: nothing here is white.
+    assert_eq!(trace(&img, &params).paths.len(), 3);
+    // The navy picked a little off: the field goes, the disc and the bar stay.
+    let res = trace(&img, &TraceParams { ignore_color: Some("#18263c".replace("3c", "5e")), ..params.clone() });
+    assert_eq!(res.paths.len(), 2);
+    assert!(res.paths.iter().all(|p| p.color != [20, 40, 90]));
+    // Not ticked, the colour is not left out; and a colour that is none is refused.
+    assert_eq!(trace(&img, &TraceParams { ignore_white: false, ignore_color: Some("#14285a".into()), ..params.clone() }).paths.len(), 3);
+    let bad = trace_within(&img, &TraceParams { ignore_color: Some("navy".into()), ..params.clone() }, usize::MAX);
+    assert!(matches!(bad, Err(TraceError::BadPalette(_))));
+    // Old documents have no such setting: white.
+    let old: TraceParams = serde_json::from_str(r#"{"mode":"color","ignoreWhite":true}"#).unwrap();
+    assert_eq!(old.ignore_color, None);
+    assert_eq!(serde_json::to_value(&params).unwrap()["ignoreColor"], serde_json::Value::Null);
+}
+
+#[test]
+fn snap_curves_to_lines_levels_a_rectangle_a_degree_askew() {
+    // 120 × 60, turned 1.5° about its centre.
+    let (c, t) = (Point::new(100.3, 60.6), 1.5f64.to_radians());
+    let img = soft(200, 120, |x, y| {
+        let (dx, dy) = (x - c.x, y - c.y);
+        (dx * t.cos() + dy * t.sin()).abs() <= 60.0 && (dy * t.cos() - dx * t.sin()).abs() <= 30.0
+    });
+    let sides = |snap: bool| {
+        let res = trace(&img, &TraceParams { snap_curves_to_lines: snap, ..bw() });
+        let sp = res.paths[0].path.subpaths[0].clone();
+        assert_eq!(sp.anchors.len(), 4, "{sp:?}");
+        (0..4).map(|i| sp.segment(i)).map(|s| ((s.p3.x - s.p0.x).abs(), (s.p3.y - s.p0.y).abs())).collect::<Vec<_>>()
+    };
+    // Snapped, every side is exactly level or upright; left alone, it keeps its 1.5°.
+    assert!(sides(true).iter().all(|(dx, dy)| *dx == 0.0 || *dy == 0.0), "{:?}", sides(true));
+    assert!(sides(false).iter().all(|(dx, dy)| dx.min(*dy) > 0.5), "{:?}", sides(false));
+    // And it is still the rectangle: 120 by 60 about the same centre.
+    let b = trace(&img, &TraceParams { snap_curves_to_lines: true, ..bw() }).paths[0].path.bounds().unwrap();
+    assert!((b.width() - 120.0).abs() < 1.0 && (b.height() - 60.0).abs() < 1.0 && (b.center().x - c.x).abs() < 0.3, "{b:?}");
+    // A side 5° off is no slip of the scanner: it stays.
+    let t = 5f64.to_radians();
+    let img = soft(200, 120, |x, y| {
+        let (dx, dy) = (x - c.x, y - c.y);
+        (dx * t.cos() + dy * t.sin()).abs() <= 60.0 && (dy * t.cos() - dx * t.sin()).abs() <= 30.0
+    });
+    let sp = trace(&img, &TraceParams { snap_curves_to_lines: true, ..bw() }).paths[0].path.subpaths[0].clone();
+    assert!(
+        (0..sp.segment_count())
+            .all(|i| (sp.segment(i).p3.y - sp.segment(i).p0.y).abs() > 1.0 && (sp.segment(i).p3.x - sp.segment(i).p0.x).abs() > 1.0)
+    );
+}
+
+#[test]
+fn a_straight_anti_aliased_line_is_two_anchors_in_its_middle_as_wide_as_its_ink() {
+    // 2.6 px wide, from (20.3, 30.7) to (170.6, 52.2): a little off the pixel rows.
+    let (a, b) = (Point::new(20.3, 30.7), Point::new(170.6, 52.2));
+    let along_line = |p: Point| ((p - a).dot(b - a) / (b - a).hypot2()).clamp(0.0, 1.0);
+    let img = soft(190, 80, |x, y| {
+        let p = Point::new(x, y);
+        p.distance(a + (b - a) * along_line(p)) <= 1.3
+    });
+    for noisy in [false, true] {
+        // (With grain of ±6 levels too: the line stays two anchors.)
+        let img = Raster::from_fn(190, 80, |x, y| {
+            let v = f64::from(img.pixel(x, y)[0]) + if noisy { 6.0 * jitter(x, y, 3) } else { 0.0 };
+            let v = v.round().clamp(0.0, 255.0) as u8;
+            [v, v, v, 255]
+        });
+        let res = trace(&img, &preset("Outline").unwrap());
+        assert_eq!(res.paths.len(), 1);
+        let (path, width) = (&res.paths[0].path, res.paths[0].stroke.unwrap());
+        assert_eq!(path.anchor_count(), 2, "noisy {noisy}: {path:?}");
+        assert!((width - 2.6).abs() < 0.15, "noisy {noisy}: {width} px wide");
+        for end in [path.subpaths[0].anchors[0].p, path.subpaths[0].anchors[1].p] {
+            // On the line through the true ends, to a tenth of a pixel.
+            let off = (end - a).cross(b - a).abs() / (b - a).hypot();
+            assert!(off < 0.1, "noisy {noisy}: an end {off} px off the line's middle");
+            // And where the ink ends, less the half width its round cap adds (the line here has round ends).
+            assert!(end.distance(a).min(end.distance(b)) < 0.6, "noisy {noisy}: an end at {end:?}");
+        }
+    }
+}
+
+#[test]
+fn a_stroke_is_as_wide_as_its_ink_not_a_whole_number_of_pixels() {
+    // (Lines with a pixel that is all ink somewhere: a thinner one's ink is read against its own
+    // darkest pixel, and comes out a little wide.)
+    for want in [1.7, 2.4, 3.4] {
+        let img = soft(120, 40, |x, y| (10.0..110.0).contains(&x) && (y - 20.3).abs() <= want / 2.0);
+        let res = trace(&img, &preset("Outline").unwrap());
+        let width = res.paths[0].stroke.unwrap();
+        assert!((width - want).abs() < 0.08, "{width} for a line {want} px wide");
+    }
+}
+
+#[test]
+fn an_anti_aliased_rectangle_along_the_pixel_grid_is_four_anchors() {
+    // Its sides lie between pixel columns and rows: its corner pixels are part of two sides each.
+    let img = soft(140, 90, |x, y| (20.4..120.7).contains(&x) && (15.3..70.6).contains(&y));
+    let res = trace(&img, &bw());
+    let sp = &res.paths[0].path.subpaths[0];
+    assert_eq!(sp.anchors.len(), 4, "{sp:?}");
+    assert!((0..4).all(|i| sp.segment_is_line(i)));
+    let b = res.paths[0].path.bounds().unwrap();
+    // (To the eighth of a pixel the test picture is drawn to.)
+    assert!((b.x0 - 20.4).abs() < 0.07 && (b.x1 - 120.7).abs() < 0.07 && (b.y0 - 15.3).abs() < 0.07 && (b.y1 - 70.6).abs() < 0.07, "{b:?}");
+}
+
+#[test]
+fn shapes_come_out_as_shapes_when_asked_for() {
+    // A disc, a square along the pixel grid and a rectangle turned 20°, anti-aliased.
+    let turn = 20f64.to_radians();
+    let turned = |x: f64, y: f64| {
+        let (dx, dy) = (x - 180.4, y - 45.3);
+        (dx * turn.cos() + dy * turn.sin()).abs() <= 30.0 && (dy * turn.cos() - dx * turn.sin()).abs() <= 18.0
+    };
+    let img = soft(220, 90, |x, y| {
+        Point::new(x, y).distance(Point::new(40.3, 44.6)) <= 25.0 || ((80.4..130.7).contains(&x) && (20.3..70.6).contains(&y)) || turned(x, y)
+    });
+    let plain = trace(&img, &bw());
+    assert!(plain.paths.iter().all(|p| p.shape.is_none()));
+    let res = trace(&img, &TraceParams { shapes: true, ..bw() });
+    assert_eq!(res.paths.len(), 3);
+    let mut found = (false, false, false);
+    for p in &res.paths {
+        // The path is the shape's own outline.
+        assert_eq!(Some(&p.path), p.shape.map(|s| s.path()).as_ref());
+        match p.shape {
+            Some(TracedShape::Ellipse { center, rx, ry, .. }) => {
+                found.0 = center.distance(Point::new(40.3, 44.6)) < 0.15 && (rx - 25.0).abs() < 0.15 && rx == ry
+            }
+            Some(TracedShape::Rectangle { center, width, height, radius: 0.0, rotation }) if center.x < 150.0 => {
+                found.1 = center.distance(Point::new(105.55, 45.45)) < 0.15
+                    && (width - 50.3).abs() < 0.25
+                    && (height - 50.3).abs() < 0.25
+                    && rotation.abs() < 0.3
+            }
+            Some(TracedShape::Rectangle { center, width, height, radius: 0.0, rotation }) => {
+                found.2 = center.distance(Point::new(180.4, 45.3)) < 0.2
+                    && (width - 60.0).abs() < 0.3
+                    && (height - 36.0).abs() < 0.3
+                    && (rotation - 20.0).abs() < 0.3
+            }
+            other => panic!("{other:?}"),
+        }
+    }
+    assert_eq!(found, (true, true, true));
+    // A letter is no shape, and a ring is not a disc.
+    let ring = soft(100, 100, |x, y| (20.0..40.0).contains(&Point::new(x, y).distance(Point::new(50.0, 50.0))));
+    assert!(trace(&ring, &TraceParams { shapes: true, ..bw() }).paths.iter().all(|p| p.shape.is_none()));
+}
+
+#[test]
+fn a_corner_whose_pixel_is_mostly_outside_is_still_a_corner() {
+    // Each corner pixel is under half covered (0.6 × 0.7 and less) and traces as outside.
+    let img = soft(140, 90, |x, y| (20.4..120.6).contains(&x) && (15.3..70.7).contains(&y));
+    let res = trace(&img, &bw());
+    let sp = &res.paths[0].path.subpaths[0];
+    assert_eq!(sp.anchors.len(), 4, "{sp:?}");
+    assert!((0..4).all(|i| sp.segment_is_line(i)));
+    let b = res.paths[0].path.bounds().unwrap();
+    assert!((b.x0 - 20.4).abs() < 0.07 && (b.x1 - 120.6).abs() < 0.07 && (b.y0 - 15.3).abs() < 0.07 && (b.y1 - 70.7).abs() < 0.07, "{b:?}");
+}
+
+/// A circle without anti-aliasing is still a circle, not an ellipse a little wider than tall.
+#[test]
+fn a_hard_edged_circle_is_a_circle() {
+    let img = Raster::from_fn(100, 100, |x, y| {
+        let (dx, dy) = (x as f64 + 0.5 - 50.0, y as f64 + 0.5 - 50.0);
+        if dx * dx + dy * dy <= 900.0 { [0, 0, 0, 255] } else { [255, 255, 255, 255] }
+    });
+    let res = trace(&img, &TraceParams { shapes: true, ignore_white: true, ..Default::default() });
+    let [TracedPath { shape: Some(TracedShape::Ellipse { center, rx, ry, .. }), .. }] = res.paths.as_slice() else { panic!("{:?}", res.paths) };
+    assert!(rx == ry && (rx - 30.0).abs() < 0.3 && center.distance(Point::new(50.0, 50.0)) < 0.1, "{center:?} {rx} {ry}");
+}
+
+/// Levelling moves no end far: a long line two degrees off level stays where the image has it.
+#[test]
+fn a_long_line_two_degrees_askew_is_not_levelled() {
+    let slope = 2f64.to_radians().tan();
+    let img = Raster::from_fn(240, 40, |x, y| {
+        let top = 12.0 + slope * (f64::from(x) - 20.0);
+        let inside = (20..220).contains(&x) && (f64::from(y) + 0.5 - top - 4.0).abs() <= 4.0;
+        if inside { [0, 0, 0, 255] } else { [255, 255, 255, 255] }
+    });
+    let res = trace(&img, &TraceParams { ignore_white: true, snap_curves_to_lines: true, ..Default::default() });
+    let b = res.paths[0].path.bounds().unwrap();
+    // 200 px at 2° rises 7 px: levelled, the bar would be 8 px tall, not 15.
+    assert!(b.height() > 13.0, "{b:?}");
+}

crates/trace/tests/quality/inputs.rs

@@ -2,7 +2,7 @@
 //! sizes) and two continuous-tone images computed per pixel.
 
 use kurbo::{Affine, BezPath, Circle, Ellipse, Point, RoundedRect, Shape};
-use vectorcraft_trace::Raster;
+use vectorcraft_trace::{Raster, TracedShape};
 
 use crate::raster::{self, noise};
 
@@ -15,13 +15,20 @@ pub enum Class {
     Poly,
     /// Thin lines, 0.5 to 5 units wide.
     Lines,
+    /// Straight-edged shapes and lines a degree or two off level and upright, as a scan or a
+    /// screenshot taken a little askew has them.
+    Askew,
+    /// Plain shapes apart from each other: a circle, an ellipse, rectangles, a regular polygon.
+    Plain,
     /// Flat art in several colours, with regions that touch.
     Flat,
     /// Continuous tone: a gradient and a photo-like image.
     Tone,
+    /// Linear gradients whose line and stops are known: one over the whole image, one in a disc.
+    Ramp,
 }
 
-pub const CLASSES: [Class; 5] = [Class::Shape, Class::Poly, Class::Lines, Class::Flat, Class::Tone];
+pub const CLASSES: [Class; 8] = [Class::Shape, Class::Poly, Class::Lines, Class::Askew, Class::Plain, Class::Flat, Class::Tone, Class::Ramp];
 
 impl Class {
     pub fn name(self) -> &'static str {
@@ -29,8 +36,11 @@ impl Class {
             Class::Shape => "curved shapes",
             Class::Poly => "polygons",
             Class::Lines => "thin lines",
+            Class::Askew => "askew shapes",
+            Class::Plain => "plain shapes",
             Class::Flat => "flat colour art",
             Class::Tone => "gradient, photo",
+            Class::Ramp => "linear gradients",
         }
     }
 }
@@ -78,9 +88,69 @@ pub struct Input {
     pub anchors: usize,
     /// Its sharp corners.
     pub corners: Vec<Point>,
+    /// The plain shapes it is made of, where it is made of them.
+    pub plain: Vec<TracedShape>,
+    /// Its lines, where it is lines: each one's two ends and its width.
+    pub strokes: Vec<(Point, Point, f64)>,
+    /// The linear gradient it is, where it is one.
+    pub ramp: Option<Ramp>,
     tone: Option<Tone>,
 }
 
+/// A linear gradient: its line (256-unit coordinates) and its stops along it (0 to 1).
+#[derive(Clone)]
+pub struct Ramp {
+    pub start: Point,
+    pub end: Point,
+    pub stops: Vec<(f64, [f64; 3])>,
+}
+
+impl Ramp {
+    pub fn color_at(&self, p: Point) -> [f64; 3] {
+        let d = self.end - self.start;
+        let t = ((p - self.start).dot(d) / d.hypot2()).clamp(0.0, 1.0);
+        let after = self.stops.iter().position(|s| s.0 >= t).unwrap().max(1);
+        let (a, b) = (self.stops[after - 1], self.stops[after]);
+        let k = (t - a.0) / (b.0 - a.0);
+        [0, 1, 2].map(|c| a.1[c] + (b.1[c] - a.1[c]) * k)
+    }
+}
+
+/// Dark blue to yellow across the whole image, 25° down from level.
+fn two_stop_ramp() -> Ramp {
+    let dir = kurbo::Vec2::from_angle(25f64.to_radians());
+    let reach = kurbo::Vec2::new(128.0, 128.0).dot(dir);
+    let centre = Point::new(128.0, 128.0);
+    Ramp { start: centre - dir * reach, end: centre + dir * reach, stops: vec![(0.0, [24.0, 40.0, 150.0]), (1.0, [250.0, 215.0, 60.0])] }
+}
+
+/// Red through white to green across a disc, 110° from level.
+fn three_stop_ramp() -> Ramp {
+    let dir = kurbo::Vec2::from_angle(110f64.to_radians());
+    let centre = Point::new(128.0, 128.0);
+    Ramp {
+        start: centre - dir * DISC,
+        end: centre + dir * DISC,
+        stops: vec![(0.0, [200.0, 30.0, 40.0]), (0.4, [245.0, 240.0, 230.0]), (1.0, [20.0, 120.0, 70.0])],
+    }
+}
+
+/// The radius of the disc the three-stop gradient fills.
+const DISC: f64 = 90.0;
+
+fn two_stop(u: f64, v: f64, _: u32, _: u32) -> [f64; 3] {
+    two_stop_ramp().color_at(Point::new(u * 256.0, v * 256.0))
+}
+
+fn three_stop(u: f64, v: f64, x: u32, _: u32) -> [f64; 3] {
+    let p = Point::new(u * 256.0, v * 256.0);
+    let inside = three_stop_ramp().color_at(p);
+    // The disc's edge, anti-aliased: how much of the pixel (256 / size units wide) is in it.
+    let pixel = 256.0 * u / (f64::from(x) + 0.5);
+    let cover = (0.5 + (DISC - p.distance(Point::new(128.0, 128.0))) / pixel).clamp(0.0, 1.0);
+    [0, 1, 2].map(|c| 255.0 + (inside[c] - 255.0) * cover)
+}
+
 const WHITE: [u8; 3] = [255, 255, 255];
 const INK: [u8; 3] = [0, 0, 0];
 
@@ -166,9 +236,23 @@ pub fn inputs() -> Vec<Input> {
         bg: WHITE,
         anchors,
         corners,
+        strokes: vec![],
+        plain: vec![],
+        ramp: None,
         tone: None,
     };
-    let tone = |name, f: Tone| Input { name, class: Class::Tone, shapes: vec![], bg: WHITE, anchors: 0, corners: vec![], tone: Some(f) };
+    let tone = |name, f: Tone| Input {
+        name,
+        class: Class::Tone,
+        shapes: vec![],
+        bg: WHITE,
+        anchors: 0,
+        corners: vec![],
+        strokes: vec![],
+        plain: vec![],
+        ramp: None,
+        tone: Some(f),
+    };
     let ink = |p: BezPath| vec![(p, INK)];
 
     let mut ellipses = Ellipse::new((90.3, 99.6), (60.0, 30.0), 0.0).to_path(1e-3);
@@ -208,13 +292,51 @@ pub fn inputs() -> Vec<Input> {
 
     // Five lines 200 long, 0.5 to 5 wide, at small angles to the pixel grid.
     let mut lines = BezPath::new();
+    let mut strokes = vec![];
     for (i, (deg, width)) in [(0.0f64, 0.5), (6.0, 1.0), (-9.0, 2.0), (12.0, 3.0), (-4.0, 5.0)].into_iter().enumerate() {
         let (hw, hl) = (width / 2.0, 100.0);
         let mut strip = poly(&[(-hl, -hw), (hl, -hw), (hl, hw), (-hl, hw)]);
-        strip.apply_affine(Affine::translate((128.3, 36.4 + 46.0 * i as f64)) * Affine::rotate(deg.to_radians()));
+        let place = Affine::translate((128.3, 36.4 + 46.0 * i as f64)) * Affine::rotate(deg.to_radians());
+        strip.apply_affine(place);
+        strokes.push((place * Point::new(-hl, 0.0), place * Point::new(hl, 0.0), width));
         lines.extend(strip);
     }
 
+    // A rectangle 1.5° off level, a plus sign 1° off the other way, and two lines 1° and 2° off.
+    let turned = |p: BezPath, deg: f64, about: (f64, f64)| Affine::rotate_about(deg.to_radians(), Point::new(about.0, about.1)) * p;
+    let plus = [
+        (150.0, 150.0),
+        (170.0, 150.0),
+        (170.0, 180.0),
+        (200.0, 180.0),
+        (200.0, 200.0),
+        (170.0, 200.0),
+        (170.0, 230.0),
+        (150.0, 230.0),
+        (150.0, 200.0),
+        (120.0, 200.0),
+        (120.0, 180.0),
+        (150.0, 180.0),
+    ];
+    let mut askew = turned(poly(&[(40.3, 30.6), (200.7, 30.6), (200.7, 110.4), (40.3, 110.4)]), 1.5, (120.0, 70.0));
+    askew.extend(turned(poly(&plus), -1.0, (160.0, 190.0)));
+    askew.extend(turned(poly(&[(20.0, 150.3), (100.0, 150.3), (100.0, 153.3), (20.0, 153.3)]), 1.0, (60.0, 152.0)));
+    askew.extend(turned(poly(&[(60.4, 170.0), (62.4, 170.0), (62.4, 240.0), (60.4, 240.0)]), 2.0, (61.0, 205.0)));
+
+    // A circle, a rectangle, a square, a rounded rectangle, an ellipse and a hexagon.
+    let plain = vec![
+        TracedShape::Ellipse { center: Point::new(50.3, 50.6), rx: 30.0, ry: 30.0, rotation: 0.0 },
+        TracedShape::Rectangle { center: Point::new(170.4, 50.3), width: 110.0, height: 60.0, radius: 0.0, rotation: 0.0 },
+        TracedShape::Rectangle { center: Point::new(50.6, 140.4), width: 60.0, height: 60.0, radius: 0.0, rotation: 0.0 },
+        TracedShape::Rectangle { center: Point::new(170.3, 140.6), width: 100.0, height: 50.0, radius: 12.0, rotation: 0.0 },
+        TracedShape::Ellipse { center: Point::new(70.4, 220.3), rx: 45.0, ry: 18.0, rotation: 0.0 },
+        TracedShape::Polygon { center: Point::new(190.6, 215.4), radius: 30.0, sides: 6, rotation: 10.0 },
+    ];
+    let mut plain_art = BezPath::new();
+    for shape in &plain {
+        plain_art.extend(shape.path().to_bezpath());
+    }
+
     let centre = Point::new(128.4, 128.3);
     let touching = vec![(half_disc(centre, 90.0, true), [200, 40, 50]), (half_disc(centre, 90.0, false), [30, 90, 200])];
     let bar = [(60.3, 180.4), (196.6, 180.4), (196.6, 206.7), (60.3, 206.7)];
@@ -225,7 +347,7 @@ pub fn inputs() -> Vec<Input> {
         (poly(&bar), [40, 160, 90]),
     ];
 
-    vec![
+    let mut all = vec![
         art("circle", Class::Shape, ink(Circle::new((128.3, 127.6), 80.4).to_path(1e-3)), 4, vec![]),
         art("ellipses", Class::Shape, ink(ellipses), 8, vec![]),
         art("badge with a hole", Class::Shape, ink(badge), 12, vec![]),
@@ -234,11 +356,22 @@ pub fn inputs() -> Vec<Input> {
         art("star", Class::Poly, ink(poly(&star)), 10, points(&star)),
         art("letter A", Class::Poly, ink(with_holes(poly(&a_outer), &[poly(&a_counter)])), 10, points(&[&a_outer[..], &a_counter].concat())),
         art("lines", Class::Lines, ink(lines), 20, vec![]),
+        art("askew shapes and lines", Class::Askew, ink(askew), 24, vec![]),
+        art("plain shapes", Class::Plain, ink(plain_art), 30, vec![]),
         art("two touching halves", Class::Flat, touching, 6, vec![(centre.x, centre.y - 90.0).into(), (centre.x, centre.y + 90.0).into()]),
         art("four-colour badge", Class::Flat, multicolor, 20, points(&bar)),
         tone("gradient", gradient),
         tone("photo-like", photo),
-    ]
+        Input { class: Class::Ramp, ramp: Some(two_stop_ramp()), ..tone("two-stop gradient", two_stop) },
+        Input { class: Class::Ramp, ramp: Some(three_stop_ramp()), ..tone("three-stop gradient in a disc", three_stop) },
+    ];
+    if let Some(input) = all.iter_mut().find(|i| i.name == "plain shapes") {
+        input.plain = plain;
+    }
+    if let Some(input) = all.iter_mut().find(|i| i.name == "lines") {
+        input.strokes = strokes;
+    }
+    all
 }
 
 impl Input {
@@ -268,6 +401,16 @@ impl Input {
         let k = Affine::scale(f64::from(size) / 256.0);
         self.shapes.iter().map(|(p, c)| (k * p.clone(), *c)).collect()
     }
+    /// Its lines in the pixel coordinates of a `size`-pixel drawing.
+    pub fn scaled_strokes(&self, size: u32) -> Vec<(Point, Point, f64)> {
+        let k = f64::from(size) / 256.0;
+        self.strokes.iter().map(|(a, b, w)| ((a.to_vec2() * k).to_point(), (b.to_vec2() * k).to_point(), w * k)).collect()
+    }
+    /// Its plain shapes' outlines in the pixel coordinates of a `size`-pixel drawing.
+    pub fn scaled_plain(&self, size: u32) -> Vec<BezPath> {
+        let k = Affine::scale(f64::from(size) / 256.0);
+        self.plain.iter().map(|s| k * s.path().to_bezpath()).collect()
+    }
     pub fn scaled_corners(&self, size: u32) -> Vec<Point> {
         self.corners.iter().map(|p| (p.to_vec2() * (f64::from(size) / 256.0)).to_point()).collect()
     }

crates/trace/tests/quality/main.rs

@@ -65,14 +65,20 @@ static ALLOC: Counting = Counting;
 /// Whether `input` is what `preset` is meant for.
 fn target(preset: &str, input: &Input) -> bool {
     let classes: &[Class] = match preset {
-        "High Fidelity Photo" | "Low Fidelity Photo" | "Shades of Gray" => &[Class::Tone],
+        "High Fidelity Photo"
+        | "Low Fidelity Photo"
+        | "Shades of Gray"
+        | "Shades of Gray with Auto Grouping"
+        | "High Fidelity Photo with Auto Grouping" => &[Class::Tone],
         // Three colours cannot show the badge's five.
         "3 Colors" => return input.name == "two touching halves",
-        "6 Colors" | "16 Colors" | "Flat Logo" => &[Class::Flat],
+        "6 Colors" | "16 Colors" | "Flat Logo" | "Auto Color" | "6 Colors with Auto Grouping" => &[Class::Flat],
+        "Default with Shapes" | "6 Colors with Shapes" => &[Class::Plain],
+        name if name.ends_with("Gradients") => &[Class::Ramp],
         "Sketched Art" => &[Class::Shape, Class::Lines],
         "Silhouettes" => &[Class::Shape],
-        "Line Art" => &[Class::Lines],
-        "Technical Drawing" => &[Class::Lines, Class::Poly],
+        "Line Art" | "Outline" => &[Class::Lines],
+        "Technical Drawing" => &[Class::Lines, Class::Poly, Class::Askew],
         _ => &[Class::Shape, Class::Poly],
     };
     classes.contains(&input.class)
@@ -134,9 +140,16 @@ fn svg_trace(svg: &str) -> TraceResult {
                 _ => panic!("unread transform {t}"),
             });
         }
-        Some(TracedPath { path: vectorcraft_geom::PathData::from_bezpath(&path), color: [0; 3], pixels: 0, stroke: None })
+        Some(TracedPath {
+            path: vectorcraft_geom::PathData::from_bezpath(&path),
+            color: [0; 3],
+            pixels: 0,
+            stroke: None,
+            shape: None,
+            gradient: None,
+        })
     });
-    TraceResult { paths: paths.collect(), palette: vec![[0; 3]] }
+    TraceResult { paths: paths.collect(), palette: vec![[0; 3]], ..Default::default() }
 }
 
 fn run_all(presets: &[(&'static str, TraceParams)], drawn: &[Drawing]) -> Vec<Run> {
@@ -172,12 +185,12 @@ fn stat(runs: &[&Metrics], field: impl Fn(&Metrics) -> f64, max: bool, digits: u
     if x.is_finite() { format!("{:.digits$}", x + 0.0) } else { "all".into() }
 }
 
-const HEADER: &str = "| ΔE | edge ΔE | off mean | off max | missed max | paths | anchors | × art | lines % | corners % | kinks | odd colours | odd px | gap px | overlap px | specks | outside px |\n|--:|--:|--:|--:|--:|--:|--:|--:|--:|--:|--:|--:|--:|--:|--:|--:|--:|\n";
+const HEADER: &str = "| ΔE | edge ΔE | off mean | off max | missed max | paths | anchors | × art | lines % | upright % | corners % | kinks | odd colours | odd px | gap px | overlap px | specks | outside px | centre off | width off | anchors a stroke | shapes % | grouped % | gradient paths | found % | angle off | ramp off |\n|--:|--:|--:|--:|--:|--:|--:|--:|--:|--:|--:|--:|--:|--:|--:|--:|--:|--:|--:|--:|--:|--:|--:|--:|--:|--:|--:|\n";
 
 fn row(runs: &[&Run]) -> String {
     let m: Vec<&Metrics> = runs.iter().filter_map(|r| r.metrics.as_ref()).collect();
     if m.is_empty() {
-        return format!("| refused |{}", " |".repeat(16));
+        return format!("| refused |{}", " |".repeat(26));
     }
     let cells = [
         stat(&m, |m| m.delta, false, 2),
@@ -189,6 +202,7 @@ fn row(runs: &[&Run]) -> String {
         stat(&m, |m| m.anchors, false, 0),
         stat(&m, |m| m.anchor_ratio, false, 2),
         stat(&m, |m| m.lines, false, 0),
+        stat(&m, |m| m.upright, false, 0),
         stat(&m, |m| m.corners, false, 0),
         stat(&m, |m| m.kinks, false, 1),
         stat(&m, |m| m.slivers, false, 1),
@@ -197,6 +211,15 @@ fn row(runs: &[&Run]) -> String {
         stat(&m, |m| m.overlap, false, 1),
         stat(&m, |m| m.specks, false, 1),
         stat(&m, |m| m.outside, true, 1),
+        stat(&m, |m| m.centre_off, false, 3),
+        stat(&m, |m| m.width_off, false, 2),
+        stat(&m, |m| m.stroke_anchors, false, 1),
+        stat(&m, |m| m.shapes, false, 0),
+        stat(&m, |m| m.grouped, false, 0),
+        stat(&m, |m| m.gradients, false, 1),
+        stat(&m, |m| m.ramp_found, false, 0),
+        stat(&m, |m| m.ramp_angle, true, 1),
+        stat(&m, |m| m.ramp_off, true, 0),
     ];
     format!("| {} |", cells.join(" | "))
 }
@@ -220,10 +243,30 @@ fn cost(img: &Raster, params: &TraceParams) -> String {
 }
 
 fn report() -> String {
-    let presets = presets();
+    // The built-in presets, and some of them with the Shapes or the Auto Grouping option on.
+    let mut presets = presets();
+    for (name, base) in [("Default with Shapes", "Default"), ("6 Colors with Shapes", "6 Colors")] {
+        presets.push((name, TraceParams { shapes: true, ..vectorcraft_trace::preset(base).unwrap() }));
+    }
+    for (name, base) in [
+        ("6 Colors with Auto Grouping", "6 Colors"),
+        ("Shades of Gray with Auto Grouping", "Shades of Gray"),
+        ("High Fidelity Photo with Auto Grouping", "High Fidelity Photo"),
+    ] {
+        presets.push((name, TraceParams { auto_grouping: true, ..vectorcraft_trace::preset(base).unwrap() }));
+    }
+    // Gradients: on the inputs that are linear gradients, with the option and without it.
+    for (name, base, gradients) in [
+        ("6 Colors, no Gradients", "6 Colors", false),
+        ("6 Colors with Gradients", "6 Colors", true),
+        ("High Fidelity Photo, no Gradients", "High Fidelity Photo", false),
+        ("High Fidelity Photo with Gradients", "High Fidelity Photo", true),
+    ] {
+        presets.push((name, TraceParams { gradients, ..vectorcraft_trace::preset(base).unwrap() }));
+    }
     let inputs = inputs();
     let drawn = draw_all(&inputs);
-    let one_colour = |d: &&Drawing| matches!(d.0.class, Class::Shape | Class::Poly | Class::Lines);
+    let one_colour = |d: &&Drawing| matches!(d.0.class, Class::Shape | Class::Poly | Class::Lines | Class::Askew | Class::Plain);
     if let Ok(dir) = std::env::var("TRACE_QUALITY_IMAGES") {
         for (input, size, variant, img) in &drawn {
             std::fs::write(format!("{dir}/{}.png", stem(input, *size, *variant)), img.encode_png()).unwrap();
@@ -270,7 +313,7 @@ fn report() -> String {
             .collect();
         let _ = write!(md, "\n## 4. Yardstick\n\n{} traces by another tracer, measured the same way.\n\n| inputs | variant ", theirs.len());
         md += HEADER.replacen("\n|", "\n|:--|:--|", 1).as_str();
-        for class in [Class::Shape, Class::Poly, Class::Lines] {
+        for class in [Class::Shape, Class::Poly, Class::Lines, Class::Askew, Class::Plain] {
             for variant in VARIANTS {
                 let rows: Vec<&Run> = theirs.iter().filter(|r| r.class == class && r.variant == variant).collect();
                 let _ = writeln!(md, "| {} | {} {}", class.name(), variant.name(), row(&rows));
@@ -304,6 +347,15 @@ fn report() -> String {
 fn quality_report() {
     let md = report();
     println!("{md}");
+    // Gradients finds none in art that is flat colour, however it is degraded.
+    let inputs = inputs();
+    for (name, _) in presets().iter().filter(|(_, p)| p.mode != vectorcraft_trace::Mode::BlackAndWhite && p.mode != vectorcraft_trace::Mode::Logo) {
+        let params = TraceParams { gradients: true, ..vectorcraft_trace::preset(name).unwrap() };
+        for (input, size, variant, img) in draw_all(&inputs).iter().filter(|d| !matches!(d.0.class, Class::Tone | Class::Ramp)) {
+            let found = trace_within(img, &params, MAX_ANCHORS).map_or(0, |res| res.paths.iter().filter(|p| p.gradient.is_some()).count());
+            assert_eq!(found, 0, "{name} with Gradients on {} at {size} px, {variant:?}", input.name);
+        }
+    }
     if let Ok(path) = std::env::var("TRACE_QUALITY_REPORT") {
         std::fs::write(path, md).unwrap();
     }

crates/trace/tests/quality/measure.rs

@@ -4,10 +4,10 @@ use std::collections::HashMap;
 
 use kurbo::{BezPath, ParamCurveArclen, Point, Shape, Stroke, StrokeOpts};
 use vectorcraft_geom::SubPath;
-use vectorcraft_trace::{Method, Mode, Raster, TraceParams, TraceResult, TracedPath};
+use vectorcraft_trace::{Method, Mode, Raster, TraceParams, TraceResult, TracedGradient, TracedPath};
 
 use crate::inputs::{Class, Input, Variant};
-use crate::raster::{coverage_into, polylines, render};
+use crate::raster::{coverage_into, polylines, render_painted};
 
 /// sRGB to Oklab (Björn Ottosson, "A perceptual color space for image processing", 2020).
 pub fn oklab(c: [u8; 3]) -> [f64; 3] {
@@ -175,6 +175,8 @@ pub struct Metrics {
     pub anchor_ratio: f64,
     /// Share (%) of the outline length made of straight segments.
     pub lines: f64,
+    /// Share (%) of the outline length that is exactly level or upright.
+    pub upright: f64,
     /// Share (%) of the art's sharp corners that have a traced corner within 1.5 px.
     pub corners: f64,
     /// Anchors where the path turns by 10° or more away from any true corner.
@@ -185,17 +187,79 @@ pub struct Metrics {
     /// Area (px) no path covers, and area covered twice.
     pub gap: f64,
     pub overlap: f64,
+    /// Stroked centre lines: their mean distance (px) from the true line's centre line, the mean
+    /// error (px) of their widths, and anchors per stroked path.
+    pub centre_off: f64,
+    pub width_off: f64,
+    pub stroke_anchors: f64,
+    /// Share (%) of the art's plain shapes that came out as a shape lying within 0.6 px of it.
+    pub shapes: f64,
+    /// Auto Grouping: share (%) of the paths that lie inside another.
+    pub grouped: f64,
+    /// Gradients: paths filled with one; and where the input is a known gradient, whether one was
+    /// found (%), the angle (°) between its line and the largest traced gradient's, and the largest
+    /// difference (levels of a channel) between their colours along the true line.
+    pub gradients: f64,
+    pub ramp_found: f64,
+    pub ramp_angle: f64,
+    pub ramp_off: f64,
     /// Paths under 6 px of area.
     pub specks: f64,
     /// How far (px) the trace reaches outside the image: a stray curve.
     pub outside: f64,
 }
 
+/// The order a grouped result is painted in: each path, then those inside it.
+fn draw_order(res: &TraceResult) -> Vec<usize> {
+    let mut inside = vec![vec![]; res.paths.len()];
+    let mut stack = vec![];
+    for i in (0..res.paths.len()).rev() {
+        match res.parents.get(i).copied().flatten() {
+            Some(p) => inside[p].insert(0, i),
+            None => stack.push(i),
+        }
+    }
+    let mut order = vec![];
+    while let Some(i) = stack.pop() {
+        order.push(i);
+        stack.extend(inside[i].iter().rev());
+    }
+    order
+}
+
 /// Measure `res`, the trace of `src` (`input` drawn `size` px square as `variant`) with `params`.
 pub fn measure(input: &Input, variant: Variant, size: u32, src: &Raster, params: &TraceParams, res: &TraceResult) -> Metrics {
     let n = size as usize;
     let shapes: Vec<(BezPath, [u8; 3])> = res.paths.iter().map(|tp| (painted(tp), tp.color)).collect();
-    let (delta_mean, edge_delta) = fidelity(src, &render(&shapes, [255; 3], n, n));
+    // Painted as the result is grouped: each path, then those inside it.
+    let drawn: Vec<(BezPath, [u8; 3], Option<&TracedGradient>)> =
+        draw_order(res).into_iter().map(|i| (shapes[i].0.clone(), shapes[i].1, res.paths[i].gradient.as_ref())).collect();
+    let (delta_mean, edge_delta) = fidelity(src, &render_painted(&drawn, [255; 3], n, n));
+    // Gradients: how many paths have one; and the largest of them against the gradient the input
+    // is: the angle between their lines, and the largest difference of a channel between their
+    // colours at 17 points along the true line.
+    let gradients = res.paths.iter().filter(|tp| tp.gradient.is_some()).count() as f64;
+    let (mut ramp_found, mut ramp_angle, mut ramp_off) = (f64::NAN, f64::NAN, f64::NAN);
+    if let Some(ramp) = &input.ramp {
+        let k = f64::from(size) / 256.0;
+        let found = res.paths.iter().filter(|tp| tp.gradient.is_some()).max_by_key(|tp| tp.pixels).and_then(|tp| tp.gradient.as_ref());
+        ramp_found = if found.is_some() { 100.0 } else { 0.0 };
+        if let Some(g) = found {
+            let (truth, own) = (ramp.end - ramp.start, g.end - g.start);
+            let between = (truth.atan2() - own.atan2()).to_degrees().rem_euclid(180.0);
+            ramp_angle = between.min(180.0 - between);
+            ramp_off = (0..=16)
+                .map(|j| {
+                    let p = ramp.start + truth * (f64::from(j) / 16.0);
+                    // (The true colour as this variant shows it: a scan's are its own.)
+                    let a = variant.color(ramp.color_at(p).map(|v| v.round() as u8)).map(f64::from);
+                    let b = g.color_at((p.to_vec2() * k).to_point());
+                    (0..3).map(|c| (a[c] - b[c]).abs()).fold(0.0, f64::max)
+                })
+                .fold(0.0, f64::max);
+        }
+    }
+    let grouped = if res.parents.is_empty() { f64::NAN } else { 100.0 * res.parents.iter().flatten().count() as f64 / res.paths.len().max(1) as f64 };
 
     // The background's frame: a path as large as the image.
     let is_frame = |p: &BezPath| {
@@ -207,7 +271,7 @@ pub fn measure(input: &Input, variant: Variant, size: u32, src: &Raster, params:
 
     let nan = f64::NAN;
     let (mut geo_mean, mut geo_max, mut miss_max, mut corners, mut kinks, mut slivers, mut sliver_area) = (nan, nan, nan, nan, nan, nan, nan);
-    if input.class != Class::Tone {
+    if !matches!(input.class, Class::Tone | Class::Ramp) {
         let truth_shapes = input.scaled(size);
         let truth = Outline::new(truth_shapes.iter().map(|(p, _)| p), None);
         let traced = Outline::new(shapes.iter().map(|(p, _)| p), Some(f64::from(size)));
@@ -224,7 +288,7 @@ pub fn measure(input: &Input, variant: Variant, size: u32, src: &Raster, params:
             let kept = true_corners.iter().filter(|c| turns.iter().any(|(p, t)| *t >= 20.0 && p.distance(**c) <= 1.5)).count();
             corners = 100.0 * kept as f64 / true_corners.len() as f64;
         }
-        if input.class != Class::Lines {
+        if !matches!(input.class, Class::Lines | Class::Askew | Class::Plain) {
             kinks = turns.iter().filter(|(p, t)| *t >= 10.0 && true_corners.iter().all(|c| p.distance(*c) > 2.0)).count() as f64;
         }
         if params.mode != Mode::BlackAndWhite {
@@ -234,7 +298,7 @@ pub fn measure(input: &Input, variant: Variant, size: u32, src: &Raster, params:
         }
     }
 
-    let (mut length, mut straight) = (0.0, 0.0);
+    let (mut length, mut straight, mut upright) = (0.0, 0.0, 0.0);
     for sp in art.iter().flat_map(|(tp, _)| &tp.path.subpaths) {
         for i in 0..sp.segment_count() {
             let len = sp.segment(i).arclen(0.05);
@@ -243,6 +307,9 @@ pub fn measure(input: &Input, variant: Variant, size: u32, src: &Raster, params:
             let c = sp.segment(i);
             if seg_dist(c.p1, c.p0, c.p3) < 0.02 && seg_dist(c.p2, c.p0, c.p3) < 0.02 {
                 straight += len;
+                if (c.p0.x - c.p3.x).abs() < 1e-9 || (c.p0.y - c.p3.y).abs() < 1e-9 {
+                    upright += len;
+                }
             }
         }
     }
@@ -265,7 +332,55 @@ pub fn measure(input: &Input, variant: Variant, size: u32, src: &Raster, params:
         }
     }
 
+    // Stroked paths against the lines they trace: each against the true line nearest its middle.
+    let (mut centre_off, mut width_off, mut stroke_anchors) = (nan, nan, nan);
+    let truth = input.scaled_strokes(size);
+    let stroked: Vec<&TracedPath> = res.paths.iter().filter(|tp| tp.stroke.is_some()).collect();
+    if !truth.is_empty() && !stroked.is_empty() {
+        let (mut off, mut samples, mut width) = (0.0, 0.0, 0.0);
+        for tp in &stroked {
+            let line = Outline::new([&tp.path.to_bezpath()], None);
+            let Some(middle) = line.segs.get(line.segs.len() / 2).map(|s| s.0.midpoint(s.1)) else { continue };
+            let Some((a, b, w)) = truth.iter().copied().min_by(|p, q| seg_dist(middle, p.0, p.1).total_cmp(&seg_dist(middle, q.0, q.1))) else {
+                continue;
+            };
+            for s in &line.segs {
+                // The distance to the line through the true ends: a centre line may be shorter or
+                // longer than the true one by how its caps are drawn.
+                let d = b - a;
+                off += (s.0.midpoint(s.1) - a).cross(d).abs() / d.hypot().max(1e-9);
+                samples += 1.0;
+            }
+            width += (tp.stroke.unwrap_or(0.0) - w).abs();
+        }
+        if samples > 0.0 {
+            (centre_off, width_off) = (off / samples, width / stroked.len() as f64);
+            stroke_anchors = stroked.iter().map(|tp| tp.path.anchor_count()).sum::<usize>() as f64 / stroked.len() as f64;
+        }
+    }
+
+    // Plain shapes: each is found when some path that is a shape lies on it.
+    let plain = input.scaled_plain(size);
+    let mut shapes_found = nan;
+    if !plain.is_empty() {
+        let made: Vec<Outline> = res.paths.iter().filter(|tp| tp.shape.is_some()).map(|tp| Outline::new([&tp.path.to_bezpath()], None)).collect();
+        let found = plain.iter().filter(|p| {
+            let truth = Outline::new([*p], None);
+            made.iter().any(|m| m.distance_to(&truth).1 <= 0.6 && truth.distance_to(m).1 <= 0.6)
+        });
+        shapes_found = 100.0 * found.count() as f64 / plain.len() as f64;
+    }
+
     Metrics {
+        grouped,
+        gradients,
+        ramp_found,
+        ramp_angle,
+        ramp_off,
+        shapes: shapes_found,
+        centre_off,
+        width_off,
+        stroke_anchors,
         delta: delta_mean,
         edge_delta,
         geo_mean,
@@ -275,6 +390,7 @@ pub fn measure(input: &Input, variant: Variant, size: u32, src: &Raster, params:
         anchors: anchors as f64,
         anchor_ratio: if input.anchors > 0 { anchors as f64 / input.anchors as f64 } else { nan },
         lines: if length > 0.0 { 100.0 * straight / length } else { nan },
+        upright: if length > 0.0 { 100.0 * upright / length } else { nan },
         corners,
         kinks,
         slivers,

crates/trace/tests/quality/raster.rs

@@ -2,7 +2,7 @@
 //! from ground-truth vector shapes here, never loaded from files.
 
 use kurbo::{BezPath, PathEl, Point};
-use vectorcraft_trace::Raster;
+use vectorcraft_trace::{Raster, TracedGradient};
 
 /// The closed polylines of `path` (one per subpath), flattened within `tol`.
 pub fn polylines(path: &BezPath, tol: f64) -> Vec<Vec<Point>> {
@@ -78,15 +78,25 @@ pub fn coverage(path: &BezPath, w: usize, h: usize) -> Vec<f32> {
 
 /// Paints `scene` (bottom first) over `bg`, anti-aliased, the way a renderer shows a trace.
 pub fn render(scene: &[(BezPath, [u8; 3])], bg: [u8; 3], w: usize, h: usize) -> Raster {
+    let scene: Vec<(BezPath, [u8; 3], Option<&TracedGradient>)> = scene.iter().map(|(p, c)| (p.clone(), *c, None)).collect();
+    render_painted(&scene, bg, w, h)
+}
+
+/// [`render`], with the paths that have a gradient filled with it.
+pub fn render_painted(scene: &[(BezPath, [u8; 3], Option<&TracedGradient>)], bg: [u8; 3], w: usize, h: usize) -> Raster {
     let mut buf = vec![bg.map(f32::from); w * h];
     let mut cov = vec![0.0f32; w * h];
-    for (path, color) in scene {
+    for (path, color, gradient) in scene {
         let (r0, r1) = coverage_into(path, w, h, &mut cov);
         for i in r0 * w..r1 * w {
             let a = cov[i].min(1.0);
             if a > 0.0 {
+                let color = match gradient {
+                    Some(g) => g.color_at(Point::new((i % w) as f64 + 0.5, (i / w) as f64 + 0.5)).map(|v| v as f32),
+                    None => color.map(f32::from),
+                };
                 for ch in 0..3 {
-                    buf[i][ch] += (f32::from(color[ch]) - buf[i][ch]) * a;
+                    buf[i][ch] += (color[ch] - buf[i][ch]) * a;
                 }
                 cov[i] = 0.0;
             }

crates/ui-egui/src/canvas.rs

@@ -234,7 +234,10 @@ pub fn show(app: &mut VectorcraftApp, ui: &mut Ui) {
     // File Handling › Display Bitmaps as Anti-aliased Images in Pixel Preview: off, images show
     // their pixels as they rasterize, hard-edged.
     let smooth_images = pixel.is_none() || app.session.prefs.anti_aliased_bitmaps;
+    // Paths made into guides are drawn as the ruler guides are (Preferences › Guides & Grid).
+    let guide_look = LineLook::guides(&app.session.prefs, &t);
     let key = CacheKey {
+        guide: ([guide_look.color.r(), guide_look.color.g(), guide_look.color.b()], guide_look.dots),
         doc: st.uid as usize,
         revision: st.revision,
         interacting: st.interaction.is_some(),
@@ -297,6 +300,7 @@ pub fn show(app: &mut VectorcraftApp, ui: &mut Ui) {
                 let [r, g, b, _] = c.to_rgba8(1.0);
                 [r, g, b]
             }),
+            guide: key.guide,
             mask_view,
             highlight_substitutions: true,
             // General › Anti-aliased Artwork: off, edges are hard on screen (raster effects and

crates/ui-egui/src/control.rs

@@ -144,7 +144,7 @@ pub fn handle(app: &mut VectorcraftApp, ctx: &egui::Context, req: &ControlReques
             let params = p.get("params").cloned().unwrap_or(json!({}));
             let params = if params.is_null() { json!({}) } else { params };
             // A key the command's description doesn't name is an error, not a default (#1442).
-            if let Err(e) = crate::menus::check_params(id, &params) {
+            if let Err(e) = crate::menus::check_params(&app.session, id, &params) {
                 return err(e);
             }
             wrap(app.run(id, params))

crates/ui-egui/src/dialogs/mod.rs

@@ -84,6 +84,7 @@ pub mod spot_colors;
 pub(crate) mod svg_options;
 pub mod swatch_conflict;
 pub mod swatch_options;
+pub mod symbol_options;
 pub mod symbolism_options;
 mod text_export;
 pub mod text_import;
@@ -290,6 +291,7 @@ registry! {
     LiquifyOptions: [liquify::KIND] => liquify::SPEC,
     FreehandOptions: [freehand::KIND] => freehand::SPEC,
     FlareOptions: [flare_options::KIND] => flare_options::SPEC,
+    SymbolOptions: [symbol_options::KIND] => symbol_options::SPEC,
     SymbolismOptions: [symbolism_options::KIND] => symbolism_options::SPEC,
     PerspectiveGridPresets: [perspective_presets::KIND] => perspective_presets::SPEC,
     PerspectiveGridOptions: [perspective_options::KIND] => perspective_options::SPEC,

crates/ui-egui/src/dialogs/symbol_options.rs

@@ -0,0 +1,45 @@
+//! Symbol Options: the name of the symbol New Symbol makes from the selection (`symbol.new`), asked
+//! before the symbol is made, as the Symbols panel's New Symbol button and menu item do.
+//!
+//! Fields: `name`.
+
+use serde_json::{Value, json};
+
+use super::swatch_options::{grid, label};
+use super::{DialogSpec, form};
+use crate::VectorcraftApp;
+use crate::state::Dialog;
+
+/// The dialog kind of Symbol Options.
+pub const KIND: &str = "symbolOptions";
+
+pub(super) const SPEC: DialogSpec = DialogSpec { heading: |_| tl!("Symbol Options").into(), body, confirm, min_width: 320.0, ..DialogSpec::FORM };
+
+/// Open Symbol Options to name a new symbol made from the selection.
+pub fn open(app: &mut VectorcraftApp) -> Result<Value, String> {
+    let st = app.session.active().ok_or("no document open")?;
+    if st.selection.is_empty() {
+        return Err("nothing selected".into());
+    }
+    let name = st.doc.unique_symbol_name("New Symbol");
+    app.ui.dialog = Some(Dialog::new(KIND, json!({ "name": name })));
+    Ok(Value::Null)
+}
+
+fn body(_: &mut VectorcraftApp, ui: &mut egui::Ui, d: &mut Dialog) -> bool {
+    grid(ui, |ui| {
+        label(ui, tl!("Name:"));
+        form::text(ui, d, "name", 190.0);
+        ui.end_row();
+    });
+    false
+}
+
+/// OK: make the symbol from the selection with the name typed.
+fn confirm(app: &mut VectorcraftApp, d: &Dialog) -> Result<Value, String> {
+    let r = app.run("symbol.new", json!({ "name": d.str("name") }));
+    if r.is_ok() {
+        app.ui.dialog = None;
+    }
+    r
+}

crates/ui-egui/src/i18n/cs.tsv

@@ -621,6 +621,7 @@
 	VectorCraft on GitHub	VectorCraft na GitHubu
 	Search Commands…	Hledat příkazy…
 	VectorCraft Help…	Nápověda VectorCraft…
+	Auto Color	Automatická barva
 	Automatic	Automaticky
 	Isolate Selected Group	Izolovat vybranou skupinu
 	Exit Isolation Mode	Ukončit izolovaný režim
@@ -807,6 +808,8 @@ lighting	Light	Světlo
 	File Info Dialog	Dialogové okno Informace o souboru
 	Go to Artboard	Přejít na pracovní plochu
 	Graphic Style Options…	Možnosti grafického stylu…
+	Symbol Options	Možnosti symbolu
+	Symbol Options…	Možnosti symbolu…
 	Home	Domů
 	Import Keyboard Shortcuts…	Importovat klávesové zkratky…
 	Justify all lines	Do bloku včetně posledního řádku
@@ -1424,6 +1427,8 @@ lighting	Light	Světlo
 	Abutting	Sousedící
 	Black and White	Černobílé
 	Corners	Rohy
+	Auto Grouping	Automatické seskupení
+	Ignore Color	Ignorovat barvu
 	Ignore White	Ignorovat bílou
 	Palette:	Paleta:
 	Limited	Omezená
@@ -3660,6 +3665,7 @@ effect	Regular	Pravidelný
 	Stroke Pressure	Tlak tahu
 
 # Plurals: one|few|other
+imageTrace	Outline	Obrys
 @plural	{n} item|{n} items	{n} položka|{n} položky|{n} položek
 @plural	Color Table ({n} color)|Color Table ({n} colors)	Tabulka barev ({n} barva)|Tabulka barev ({n} barvy)|Tabulka barev ({n} barev)
 @plural	Delete this {n} graphic style?|Delete these {n} graphic styles?	Odstranit {n} grafický styl?|Odstranit {n} grafické styly?|Odstranit {n} grafických stylů?
@@ -3734,6 +3740,7 @@ effect	Regular	Pravidelný
 @msg	No saved selections (Select → Save Selection…)	Žádné uložené výběry (Výběr → Uložit výběr…)
 @msg	No saved views (View → New View…)	Žádná uložená zobrazení (Zobrazení → Nové zobrazení…)
 @msg	Offset Path: select paths	Odsadit cestu: vyberte cesty
+@msg	Offset Path: the offset leaves nothing of the selected paths (an inset larger than the shapes)	Odsadit cestu: po odsazení z vybraných cest nic nezbude (odsazení dovnitř větší než tvary)
 @msg	Opened with {_1} note(s): {_2}	Otevřeno, poznámky ({_1}): {_2}
 @msg	Opened {url}	Otevřeno {url}
 @msg	Outline Stroke: no stroked paths selected	Převést tah na obrys: nejsou vybrány žádné cesty s tahem

crates/ui-egui/src/i18n/de.tsv

@@ -229,6 +229,7 @@
 	Author Title:	Titel des Autors:
 	Author:	Autor:
 	Auto	Auto
+	Auto Color	Automatische Farbe
 	Automatic	Automatisch
 	Auto Size New Area Type	Größe von neuem Flächentext automatisch anpassen
 	Auto Spell Check	Automatische Rechtschreibprüfung
@@ -1127,6 +1128,8 @@
 	Graphic Style Library	Grafikstil-Bibliothek
 	Graphic Style Options	Grafikstiloptionen
 	Graphic Style Options…	Grafikstiloptionen…
+	Symbol Options	Symboloptionen
+	Symbol Options…	Symboloptionen…
 	Graphic Styles	Grafikstile
 	Graphic Styles Options	Optionen für Grafikstile
 	Graphics	Grafik
@@ -1226,6 +1229,8 @@
 	Identify Objects By	Objekte identifizieren nach
 	Ignore	Ignorieren
 	Ignore Artboards (all the art as one page)	Zeichenflächen ignorieren (gesamte Grafik als eine Seite)
+	Auto Grouping	Automatisch gruppieren
+	Ignore Color	Farbe ignorieren
 	Ignore White	Weiß ignorieren
 	Palette:	Palette:
 	Limited	Begrenzt
@@ -3135,6 +3140,7 @@ effect	Points	Punkte
 	{warning}: click to correct to the closest color ({hex})	{warning}: Klicken korrigiert auf die nächstliegende Farbe ({hex})
 	“{file}” is protected by a password.	„{file}“ ist durch ein Kennwort geschützt.
 	● Recording	● Aufzeichnung
+imageTrace	Outline	Kontur
 @plural	{n} item|{n} items	{n} Element|{n} Elemente
 @plural	Color Table ({n} color)|Color Table ({n} colors)	Farbtabelle ({n} Farbe)|Farbtabelle ({n} Farben)
 @plural	Delete this {n} graphic style?|Delete these {n} graphic styles?	Diesen {n} Grafikstil löschen?|Diese {n} Grafikstile löschen?
@@ -3335,6 +3341,7 @@ theme	Appearance	Erscheinungsbild
 @msg	No saved selections (Select → Save Selection…)	Keine gespeicherten Auswahlen (Auswahl → Auswahl speichern…)
 @msg	No saved views (View → New View…)	Keine gespeicherten Ansichten (Ansicht → Neue Ansicht…)
 @msg	Offset Path: select paths	Pfad verschieben: Wählen Sie Pfade aus
+@msg	Offset Path: the offset leaves nothing of the selected paths (an inset larger than the shapes)	Pfad verschieben: Der Versatz lässt von den ausgewählten Pfaden nichts übrig (ein Versatz nach innen, der größer ist als die Formen)
 @msg	Opened with {_1} note(s): {_2}	Mit {_1} Hinweis(en) geöffnet: {_2}
 @msg	Opened {url}	{url} geöffnet
 @msg	Outline Stroke: no stroked paths selected	Konturlinie: keine Pfade mit Kontur ausgewählt

crates/ui-egui/src/i18n/es.tsv

@@ -247,6 +247,7 @@
 	Author Title:	Cargo del autor:
 	Author:	Autor:
 	Auto	Auto
+	Auto Color	Color automático
 	Automatic	Automático
 	Auto Size New Area Type	Ajustar automáticamente el tamaño del nuevo texto de área
 	Auto Spell Check	Revisión ortográfica automática
@@ -1144,6 +1145,8 @@
 	Graphic Style Library	Biblioteca de estilos gráficos
 	Graphic Style Options	Opciones de estilo gráfico
 	Graphic Style Options…	Opciones de estilo gráfico…
+	Symbol Options	Opciones de símbolo
+	Symbol Options…	Opciones de símbolo…
 	Graphic Styles	Estilos gráficos
 	Graphic Styles Options	Opciones de estilos gráficos
 	Graphics	Gráficos
@@ -1244,6 +1247,8 @@
 	Identify Objects By	Identificar objetos por
 	Ignore	Ignorar
 	Ignore Artboards (all the art as one page)	Ignorar mesas de trabajo (toda la ilustración como una página)
+	Auto Grouping	Agrupación automática
+	Ignore Color	Ignorar color
 	Ignore White	Ignorar blanco
 	Palette:	Paleta:
 	Limited	Limitada
@@ -3236,6 +3241,7 @@
 	{warning}: click to correct to the closest color ({hex})	{warning}: clic para corregir al color más cercano ({hex})
 	“{file}” is protected by a password.	“{file}” está protegido con contraseña.
 	● Recording	● Grabando
+imageTrace	Outline	Contorno
 @plural	{n} item|{n} items	{n} elemento|{n} elementos
 @plural	Color Table ({n} color)|Color Table ({n} colors)	Tabla de colores ({n} color)|Tabla de colores ({n} colores)
 @plural	Delete this {n} graphic style?|Delete these {n} graphic styles?	¿Eliminar {n} estilo gráfico?|¿Eliminar estos {n} estilos gráficos?
@@ -3435,6 +3441,7 @@ axis	Both	Ambos
 @msg	No saved selections (Select → Save Selection…)	No hay selecciones guardadas (Selección → Guardar selección…)
 @msg	No saved views (View → New View…)	No hay vistas guardadas (Ver → Nueva vista…)
 @msg	Offset Path: select paths	Desplazar trazado: selecciona trazados
+@msg	Offset Path: the offset leaves nothing of the selected paths (an inset larger than the shapes)	Desplazar trazado: el desplazamiento no deja nada de los trazados seleccionados (un desplazamiento hacia dentro mayor que las formas)
 @msg	Opened with {_1} note(s): {_2}	Se abrió con {_1} nota(s): {_2}
 @msg	Opened {url}	Se abrió {url}
 @msg	Outline Stroke: no stroked paths selected	Contornear trazo: no hay trazados con trazo seleccionados

crates/ui-egui/src/i18n/fr.tsv

@@ -248,6 +248,7 @@
 	Author Title:	Fonction de l’auteur :
 	Author:	Auteur :
 	Auto	Auto
+	Auto Color	Couleur automatique
 	Automatic	Automatique
 	Auto Size New Area Type	Taille automatique du nouveau texte captif
 	Auto Spell Check	Vérification orthographique automatique
@@ -1143,6 +1144,8 @@
 	Graphic Style Library	Bibliothèque de styles graphiques
 	Graphic Style Options	Options de style graphique
 	Graphic Style Options…	Options de style graphique…
+	Symbol Options	Options de symbole
+	Symbol Options…	Options de symbole…
 	Graphic Styles	Styles graphiques
 	Graphic Styles Options	Options des styles graphiques
 	Graphics	Graphiques
@@ -1243,6 +1246,8 @@
 	Identify Objects By	Identifier les objets par
 	Ignore	Ignorer
 	Ignore Artboards (all the art as one page)	Ignorer les plans de travail (toute l’illustration sur une page)
+	Auto Grouping	Groupement automatique
+	Ignore Color	Ignorer la couleur
 	Ignore White	Ignorer le blanc
 	Palette:	Palette :
 	Limited	Limitée
@@ -3233,6 +3238,7 @@
 	{warning}: click to correct to the closest color ({hex})	{warning} : cliquez pour corriger avec la couleur la plus proche ({hex})
 	“{file}” is protected by a password.	« {file} » est protégé par un mot de passe.
 	● Recording	● Enregistrement
+imageTrace	Outline	Contour
 @plural	{n} item|{n} items	{n} élément|{n} éléments
 @plural	Color Table ({n} color)|Color Table ({n} colors)	Table des couleurs ({n} couleur)|Table des couleurs ({n} couleurs)
 @plural	Delete this {n} graphic style?|Delete these {n} graphic styles?	Supprimer {n} style graphique ?|Supprimer ces {n} styles graphiques ?
@@ -3432,6 +3438,7 @@ axis	Both	Les deux
 @msg	No saved selections (Select → Save Selection…)	Aucune sélection enregistrée (Sélection → Enregistrer la sélection…)
 @msg	No saved views (View → New View…)	Aucune vue enregistrée (Affichage → Nouvelle vue…)
 @msg	Offset Path: select paths	Décalage : sélectionnez des tracés
+@msg	Offset Path: the offset leaves nothing of the selected paths (an inset larger than the shapes)	Décalage : le décalage ne laisse rien des tracés sélectionnés (un décalage vers l’intérieur plus grand que les formes)
 @msg	Opened with {_1} note(s): {_2}	Ouvert avec {_1} remarque(s) : {_2}
 @msg	Opened {url}	{url} ouvert
 @msg	Outline Stroke: no stroked paths selected	Vectoriser le contour : aucun tracé avec contour sélectionné

crates/ui-egui/src/i18n/hu.tsv

@@ -360,6 +360,7 @@
 	Auto Spell Check	Automatikus helyesírás-ellenőrzés
 	Auto-Collapse Iconic Panels	Ikonpanelek automatikus becsukása
 	Auto-Rotate (turn the paper to each artboard)	Automatikus elforgatás (a papír igazodik minden rajztáblához)
+	Auto Color	Automatikus szín
 	Automatic	Automatikus
 	Automatic flatness	Automatikus simaság
 	Automatically	Automatikusan
@@ -1469,6 +1470,8 @@
 	Graphic Style Library	Grafikaistílus-könyvtár
 	Graphic Style Options	Grafikai stílus beállításai
 	Graphic Style Options…	Grafikai stílus beállításai…
+	Symbol Options	Szimbólum beállításai
+	Symbol Options…	Szimbólum beállításai…
 	Graphic Styles	Grafikai stílusok
 	Graphic Styles (4)	Grafikai stílusok (4)
 	Graphic Styles Options	Grafikai stílusok beállításai
@@ -1608,6 +1611,8 @@
 	Identify Objects By	Objektumok azonosítása
 	Ignore	Kihagy
 	Ignore Artboards (all the art as one page)	Rajztáblák figyelmen kívül hagyása (az összes grafika egy oldalon)
+	Auto Grouping	Automatikus csoportosítás
+	Ignore Color	Szín figyelmen kívül hagyása
 	Ignore White	Fehér figyelmen kívül hagyása
 	Image	Kép
 	Image Info	Kép adatai
@@ -3935,6 +3940,7 @@ lighting	Light	Fény
 theme	Appearance	Kinézet
 
 # Plurals: one|other
+imageTrace	Outline	Körvonal
 @plural	Color Table ({n} color)|Color Table ({n} colors)	Színtábla ({n} szín)
 @plural	Delete this {n} graphic style?|Delete these {n} graphic styles?	{n} grafikai stílus törlése?
 @plural	{n} area highlighted|{n} areas highlighted	Kiemelt terület: {n}
@@ -4333,6 +4339,7 @@ theme	Appearance	Kinézet
 @msg	object {id} is not a selected top-level object	az objektum nem kijelölt legfelső szintű objektum: {id}
 @msg	objects with several fills or strokes, effects or brushes came in as their drawn look ({_1}): their appearance isn't editable yet	a több kitöltésű vagy körvonalú, effektusos vagy ecsetes objektumok a megrajzolt kinézetükkel kerültek be ({_1}): a megjelenésük még nem szerkeszthető
 @msg	Offset Path: select paths	Útvonal eltolása: jelölj ki útvonalakat
+@msg	Offset Path: the offset leaves nothing of the selected paths (an inset larger than the shapes)	Útvonal eltolása: az eltolás után semmi sem marad a kijelölt útvonalakból (a befelé eltolás nagyobb az alakzatoknál)
 @msg	onto must name a floating panel	az onto egy lebegő panelt kell megnevezzen
 @msg	onto must name a panel floating in another group	az onto egy másik csoportban lebegő panelt kell megnevezzen
 @msg	Opened with {_1} note(s): {_2}	Megnyitva; megjegyzések: {_1}: {_2}

crates/ui-egui/src/i18n/it.tsv

@@ -247,6 +247,7 @@
 	Author Title:	Qualifica dell'autore:
 	Author:	Autore:
 	Auto	Auto
+	Auto Color	Colore automatico
 	Automatic	Automatico
 	Auto Size New Area Type	Dimensionamento automatico del nuovo testo in area
 	Auto Spell Check	Controllo ortografico automatico
@@ -1143,6 +1144,8 @@
 	Graphic Style Library	Libreria stili grafici
 	Graphic Style Options	Opzioni stile grafico
 	Graphic Style Options…	Opzioni stile grafico…
+	Symbol Options	Opzioni simbolo
+	Symbol Options…	Opzioni simbolo…
 	Graphic Styles	Stili grafici
 	Graphic Styles Options	Opzioni stili grafici
 	Graphics	Grafica
@@ -1243,6 +1246,8 @@
 	Identify Objects By	Identifica oggetti per
 	Ignore	Ignora
 	Ignore Artboards (all the art as one page)	Ignora tavole da disegno (tutta la grafica come una sola pagina)
+	Auto Grouping	Raggruppamento automatico
+	Ignore Color	Ignora colore
 	Ignore White	Ignora bianco
 	Palette:	Palette:
 	Limited	Limitata
@@ -3236,6 +3241,7 @@
 	{warning}: click to correct to the closest color ({hex})	{warning}: fai clic per correggere con il colore più vicino ({hex})
 	“{file}” is protected by a password.	“{file}” è protetto da password.
 	● Recording	● Registrazione in corso
+imageTrace	Outline	Contorno
 @plural	{n} item|{n} items	{n} elemento|{n} elementi
 @plural	Color Table ({n} color)|Color Table ({n} colors)	Tabella colori ({n} colore)|Tabella colori ({n} colori)
 @plural	Delete this {n} graphic style?|Delete these {n} graphic styles?	Eliminare {n} stile grafico?|Eliminare questi {n} stili grafici?
@@ -3435,6 +3441,7 @@ axis	Both	Entrambi
 @msg	No saved selections (Select → Save Selection…)	Nessuna selezione salvata (Selezione → Salva selezione…)
 @msg	No saved views (View → New View…)	Nessuna vista salvata (Visualizza → Nuova vista…)
 @msg	Offset Path: select paths	Sposta tracciato: seleziona tracciati
+@msg	Offset Path: the offset leaves nothing of the selected paths (an inset larger than the shapes)	Sposta tracciato: lo spostamento non lascia nulla dei tracciati selezionati (uno spostamento verso l’interno maggiore delle forme)
 @msg	Opened with {_1} note(s): {_2}	Aperto con {_1} nota/e: {_2}
 @msg	Opened {url}	Aperto {url}
 @msg	Outline Stroke: no stroked paths selected	Contorna traccia: nessun tracciato con traccia selezionato

crates/ui-egui/src/i18n/ja.tsv

@@ -666,6 +666,7 @@
 	Hide Print Tiling	プリント分割を隠す
 	Unlock Grid	グリッドをロック解除
 	Edit Envelope	エンベロープを編集
+	Auto Color	自動カラー
 	Automatic	自動
 	Isolate Selected Group	選択したグループを分離
 	Exit Isolation Mode	分離モードを終了
@@ -1421,6 +1422,8 @@
 	Graphic Style Library	グラフィックスタイルライブラリ
 	Graphic Style Options	グラフィックスタイルオプション
 	Graphic Style Options…	グラフィックスタイルオプション…
+	Symbol Options	シンボルオプション
+	Symbol Options…	シンボルオプション…
 	Graphic Styles Options	グラフィックスタイルオプション
 	Graphics Processor	グラフィックプロセッサー
 	Graphics: {adapter}	グラフィックス: {adapter}
@@ -1481,6 +1484,8 @@
 	Identify Objects By	オブジェクトの識別方法
 	Ignore	無視
 	Ignore Artboards (all the art as one page)	アートボードを無視 (すべてのアートを 1 ページとして扱う)
+	Auto Grouping	自動グループ化
+	Ignore Color	カラーを無視
 	Ignore White	白を無視
 	Palette:	パレット:
 	Limited	限定
@@ -3225,6 +3230,7 @@
 	Yellow	イエロー
 	[Normal Character Style]	[標準文字スタイル]
 	[Normal Paragraph Style]	[標準段落スタイル]
+imageTrace	Outline	アウトライン
 @plural	Color Table ({n} color)|Color Table ({n} colors)	カラーテーブル ({n} 色)
 @plural	Delete this {n} graphic style?|Delete these {n} graphic styles?	{n} 個のグラフィックスタイルを削除しますか？
 @plural	{n} Layer|{n} Layers	{n} レイヤー
@@ -3592,6 +3598,7 @@ theme	Appearance	外観
 @msg	Divide Objects Below: select a path	背面のオブジェクトで型抜き: パスを選択してください
 @msg	Divide Objects Below: select exactly one path	背面のオブジェクトで型抜き: パスを 1 つだけ選択してください
 @msg	Offset Path: select paths	パスのオフセット: パスを選択してください
+@msg	Offset Path: the offset leaves nothing of the selected paths (an inset larger than the shapes)	パスのオフセット: オフセットすると選択したパスが何も残りません (内側へのオフセットがシェイプより大きい)
 @msg	Outline Stroke: no stroked paths selected	パスのアウトライン: 線のあるパスが選択されていません
 @msg	Split Into Grid: select paths large enough for the grid	グリッドに分割: グリッドが収まる大きさのパスを選択してください
 @msg	empty cutter	型抜きに使うパスが空です

crates/ui-egui/src/i18n/ko.tsv

@@ -664,6 +664,7 @@
 	Hide Print Tiling	인쇄 타일링 숨기기
 	Unlock Grid	격자 잠금 해제
 	Edit Envelope	엔벨로프 편집
+	Auto Color	자동 색상
 	Automatic	자동
 	Isolate Selected Group	선택한 그룹 격리
 	Exit Isolation Mode	격리 모드 종료
@@ -1416,6 +1417,8 @@
 	Graphic Style Library	그래픽 스타일 라이브러리
 	Graphic Style Options	그래픽 스타일 옵션
 	Graphic Style Options…	그래픽 스타일 옵션…
+	Symbol Options	심볼 옵션
+	Symbol Options…	심볼 옵션…
 	Graphic Styles Options	그래픽 스타일 옵션
 	Graphics Processor	그래픽 프로세서
 	Graphics: {adapter}	그래픽: {adapter}
@@ -1476,6 +1479,8 @@
 	Identify Objects By	개체 식별 기준
 	Ignore	무시
 	Ignore Artboards (all the art as one page)	아트보드 무시 (모든 아트웍을 한 페이지로)
+	Auto Grouping	자동 그룹화
+	Ignore Color	색상 무시
 	Ignore White	흰색 무시
 	Palette:	팔레트:
 	Limited	제한
@@ -3218,6 +3223,7 @@
 	Yellow	노랑
 	[Normal Character Style]	[기본 문자 스타일]
 	[Normal Paragraph Style]	[기본 단락 스타일]
+imageTrace	Outline	윤곽선
 @plural	Color Table ({n} color)|Color Table ({n} colors)	색상 표 ({n}색)|색상 표 ({n}색)
 @plural	Delete this {n} graphic style?|Delete these {n} graphic styles?	그래픽 스타일 {n}개를 삭제하시겠습니까?|그래픽 스타일 {n}개를 삭제하시겠습니까?
 @plural	{n} Layer|{n} Layers	레이어 {n}개|레이어 {n}개
@@ -3570,6 +3576,7 @@ theme	Appearance	외관
 @msg	Divide Objects Below: select a path	아래 개체 분할: 패스를 선택하세요
 @msg	Divide Objects Below: select exactly one path	아래 개체 분할: 패스를 하나만 선택하세요
 @msg	Offset Path: select paths	패스 오프셋: 패스를 선택하세요
+@msg	Offset Path: the offset leaves nothing of the selected paths (an inset larger than the shapes)	패스 오프셋: 오프셋을 적용하면 선택한 패스가 남지 않습니다(안쪽 오프셋이 모양보다 큼)
 @msg	Outline Stroke: no stroked paths selected	선 윤곽선화: 선이 있는 패스가 선택되지 않았습니다
 @msg	Split Into Grid: select paths large enough for the grid	격자로 분할: 격자에 충분한 크기의 패스를 선택하세요
 @msg	empty cutter	빈 커터입니다

crates/ui-egui/src/i18n/pl.tsv

@@ -606,6 +606,7 @@
 	VectorCraft on GitHub	VectorCraft w serwisie GitHub
 	Search Commands…	Szukaj poleceń…
 	VectorCraft Help…	Pomoc VectorCraft…
+	Auto Color	Kolor automatyczny
 	Automatic	Automatycznie
 	Isolate Selected Group	Izoluj zaznaczoną grupę
 	Exit Isolation Mode	Wyjdź z trybu izolacji
@@ -781,6 +782,8 @@ lighting	Light	Światło
 	File Info Dialog	Okno informacji o pliku
 	Go to Artboard	Przejdź do obszaru kompozycji
 	Graphic Style Options…	Opcje stylu graficznego…
+	Symbol Options	Opcje symbolu
+	Symbol Options…	Opcje symbolu…
 	Home	Strona startowa
 	Import Keyboard Shortcuts…	Importuj skróty klawiaturowe…
 	Justify all lines	Justuj wszystkie wiersze
@@ -1374,6 +1377,8 @@ lighting	Light	Światło
 	Abutting	Stykające się
 	Black and White	Czarno-biały
 	Corners	Narożniki
+	Auto Grouping	Automatyczne grupowanie
+	Ignore Color	Ignoruj kolor
 	Ignore White	Ignoruj biel
 	Palette:	Paleta:
 	Limited	Ograniczona
@@ -3528,6 +3533,7 @@ effect	Regular	Normalny
 	Stroke Direction	Kierunek pociągnięć
 	Stroke Width	Szerokość pociągnięć
 	Stroke Pressure	Nacisk pociągnięć
+imageTrace	Outline	Kontur
 @plural	{n} item|{n} items	{n} element|{n} elementy|{n} elementów
 @plural	Color Table ({n} color)|Color Table ({n} colors)	Tablica kolorów ({n} kolor)|Tablica kolorów ({n} kolory)|Tablica kolorów ({n} kolorów)
 @plural	Delete this {n} graphic style?|Delete these {n} graphic styles?	Usunąć {n} styl graficzny?|Usunąć {n} style graficzne?|Usunąć {n} stylów graficznych?
@@ -3600,6 +3606,7 @@ effect	Regular	Normalny
 @msg	No saved selections (Select → Save Selection…)	Brak zapisanych zaznaczeń (Zaznacz → Zapisz zaznaczenie…)
 @msg	No saved views (View → New View…)	Brak zapisanych widoków (Widok → Nowy widok…)
 @msg	Offset Path: select paths	Odsuń ścieżkę: zaznacz ścieżki
+@msg	Offset Path: the offset leaves nothing of the selected paths (an inset larger than the shapes)	Odsuń ścieżkę: po odsunięciu nic nie zostaje z zaznaczonych ścieżek (odsunięcie do wewnątrz większe niż kształty)
 @msg	Opened with {_1} note(s): {_2}	Otwarto, uwagi ({_1}): {_2}
 @msg	Opened {url}	Otwarto {url}
 @msg	Outline Stroke: no stroked paths selected	Obrys konturu: nie zaznaczono ścieżek z obrysem

crates/ui-egui/src/i18n/pt-br.tsv

@@ -983,6 +983,8 @@
 	Graphic Style Library	Biblioteca de Estilos Gráficos
 	Graphic Style Options	Opções de Estilo Gráfico
 	Graphic Style Options…	Opções de Estilo Gráfico…
+	Symbol Options	Opções de Símbolo
+	Symbol Options…	Opções de Símbolo…
 	Graphic Styles	Estilos Gráficos
 	Graphic Styles Options	Opções de Estilos Gráficos
 	Graphics Processor	Processador Gráfico
@@ -1070,7 +1072,7 @@
 	Identify Objects By	Identificar Objetos Por
 	Ignore	Ignorar
 	Ignore Artboards (all the art as one page)	Ignorar Mesas de Trabalho (toda a arte como uma página)
-	Ignore White	Ignorar Branco
+	Ignore Color	Ignorar Cor
 	Image Info	Informações da Imagem
 	Image Map:	Mapa da Imagem:
 	Image Size	Tamanho da Imagem
@@ -2661,6 +2663,7 @@
 	{warning}: click to correct to the closest color ({hex})	{warning}: clique para corrigir para a cor mais próxima ({hex})
 	“{file}” is protected by a password.	“{file}” é protegido por uma senha.
 	● Recording	● Gravando
+imageTrace	Outline	Contorno
 @plural	{n} item|{n} items	{n} item|{n} itens
 @plural	Color Table ({n} color)|Color Table ({n} colors)	Tabela de Cores ({n} cor)|Tabela de Cores ({n} cores)
 @plural	Delete this {n} graphic style?|Delete these {n} graphic styles?	Excluir este {n} estilo gráfico?|Excluir estes {n} estilos gráficos?
@@ -3091,6 +3094,7 @@ axis	Both	Ambos
 @msg	No saved selections (Select → Save Selection…)	Nenhuma seleção salva (Selecionar → Salvar seleção…)
 @msg	No saved views (View → New View…)	Nenhuma vista salva (Exibir → Nova vista…)
 @msg	Offset Path: select paths	Deslocar traçado: selecione traçados
+@msg	Offset Path: the offset leaves nothing of the selected paths (an inset larger than the shapes)	Deslocar traçado: o deslocamento não deixa nada dos traçados selecionados (um deslocamento para dentro maior que as formas)
 @msg	Opened with {_1} note(s): {_2}	Aberto com {_1} observação(ões): {_2}
 @msg	Opened {url}	{url} aberto
 @msg	Outline Stroke: no stroked paths selected	Contornar traço: nenhum traçado com traço selecionado

crates/ui-egui/src/i18n/ru.tsv

@@ -245,6 +245,7 @@
 	Author Title:	Должность автора:
 	Author:	Автор:
 	Auto	Авто
+	Auto Color	Автоцвет
 	Automatic	Автоматически
 	Auto Size New Area Type	Автоматически подгонять размер нового текста в области
 	Auto Spell Check	Автоматическая проверка орфографии
@@ -1141,6 +1142,8 @@
 	Graphic Style Library	Библиотека графических стилей
 	Graphic Style Options	Параметры графического стиля
 	Graphic Style Options…	Параметры графического стиля…
+	Symbol Options	Параметры символа
+	Symbol Options…	Параметры символа…
 	Graphic Styles	Графические стили
 	Graphic Styles Options	Параметры графических стилей
 	Graphics	Графика
@@ -1241,6 +1244,8 @@
 	Identify Objects By	Определять объекты по
 	Ignore	Игнорировать
 	Ignore Artboards (all the art as one page)	Игнорировать монтажные области (весь рисунок как одна страница)
+	Auto Grouping	Автогруппировка
+	Ignore Color	Игнорировать цвет
 	Ignore White	Игнорировать белый
 	Palette:	Палитра:
 	Limited	Ограниченная
@@ -3232,6 +3237,7 @@
 	{warning}: click to correct to the closest color ({hex})	{warning}: щёлкните для исправления на ближайший цвет ({hex})
 	“{file}” is protected by a password.	«{file}» защищён паролем.
 	● Recording	● Запись
+imageTrace	Outline	Контур
 @plural	{n} item|{n} items	{n} элемент|{n} элемента|{n} элементов
 @plural	Color Table ({n} color)|Color Table ({n} colors)	Цветовая таблица ({n} цвет)|Цветовая таблица ({n} цвета)|Цветовая таблица ({n} цветов)
 @plural	Delete this {n} graphic style?|Delete these {n} graphic styles?	Удалить этот графический стиль ({n})?|Удалить эти графические стили ({n})?|Удалить эти графические стили ({n})?
@@ -3431,6 +3437,7 @@ axis	Both	Оба
 @msg	No saved selections (Select → Save Selection…)	Нет сохранённых выделений (Выделение → Сохранить выделение…)
 @msg	No saved views (View → New View…)	Нет сохранённых видов (Просмотр → Новый вид…)
 @msg	Offset Path: select paths	Смещение контура: выделите контуры
+@msg	Offset Path: the offset leaves nothing of the selected paths (an inset larger than the shapes)	Смещение контура: после смещения от выделенных контуров ничего не остаётся (смещение внутрь больше самих фигур)
 @msg	Opened with {_1} note(s): {_2}	Открыто с примечаниями ({_1}) : {_2}
 @msg	Opened {url}	Открыто {url}
 @msg	Outline Stroke: no stroked paths selected	Обводка контура: не выделены контуры с обводкой

crates/ui-egui/src/i18n/uk.tsv

@@ -241,6 +241,7 @@
 	Author Title:	Посада автора:
 	Author:	Автор:
 	Auto	Авто
+	Auto Color	Автоколір
 	Automatic	Автоматично
 	Auto Size New Area Type	Автоматично підганяти розмір нового тексту в області
 	Auto Spell Check	Автоматична перевірка орфографії
@@ -1137,6 +1138,8 @@
 	Graphic Style Library	Бібліотека графічних стилів
 	Graphic Style Options	Параметри графічного стилю
 	Graphic Style Options…	Параметри графічного стилю…
+	Symbol Options	Параметри символу
+	Symbol Options…	Параметри символу…
 	Graphic Styles	Графічні стилі
 	Graphic Styles Options	Параметри графічних стилів
 	Graphics	Графіка
@@ -1237,6 +1240,8 @@
 	Identify Objects By	Визначати об’єкти по
 	Ignore	Ігнорувати
 	Ignore Artboards (all the art as one page)	Ігнорувати монтажні області (весь малюнок як одна сторінка)
+	Auto Grouping	Автогрупування
+	Ignore Color	Ігнорувати колір
 	Ignore White	Ігнорувати білий
 	Palette:	Палітра:
 	Limited	Обмежена
@@ -3229,6 +3234,7 @@ effect	Points	Точки
 	{warning}: click to correct to the closest color ({hex})	{warning}: натисніть , щоб виправити найближчий колір ({hex})
 	“{file}” is protected by a password.	"{file}" захищений паролем.
 	● Recording	● Запис
+imageTrace	Outline	Контур
 @plural	{n} item|{n} items	{n} елемент|{n} елементи|{n} елементів
 @plural	Color Table ({n} color)|Color Table ({n} colors)	Таблиця кольорів ({n} колір)|Таблиця кольорів ({n} кольори)|Таблиця кольорів ({n} кольорів)
 @plural	Delete this {n} graphic style?|Delete these {n} graphic styles?	Видалити цей графічний стиль ({n})?|Видалити ці графічні стилі ({n})?|Видалити ці графічні стилі ({n})?
@@ -3419,6 +3425,7 @@ axis	Both	Обидві
 @msg	No saved selections (Select → Save Selection…)	Немає збережених виділень (Виділення → Зберегти виділення…)
 @msg	No saved views (View → New View…)	Немає збережених видів (Перегляд → Новий вид…)
 @msg	Offset Path: select paths	Зміщення контуру: виділіть контури
+@msg	Offset Path: the offset leaves nothing of the selected paths (an inset larger than the shapes)	Зміщення контуру: після зміщення від виділених контурів нічого не лишається (зміщення всередину більше за самі фігури)
 @msg	Opened with {_1} note(s): {_2}	Відкрито із примітками ({_1}) : {_2}
 @msg	Opened {url}	Відкрито {url}
 @msg	Outline Stroke: no stroked paths selected	Обведення контуру: не виділено контури з обведенням

crates/ui-egui/src/i18n/vi.tsv

@@ -288,6 +288,7 @@
 	Auto Spell Check	Kiểm tra chính tả tự động
 	Auto-Collapse Iconic Panels	Tự động thu gọn bảng dạng biểu tượng
 	Auto-Rotate (turn the paper to each artboard)	Tự động xoay (xoay trang cho mỗi bảng vẽ)
+	Auto Color	Màu tự động
 	Automatic	Tự động
 	Automatic flatness	Độ phẳng tự động
 	Automatically	Tự động
@@ -1322,6 +1323,8 @@
 	Graphic Style Library	Thư viện kiểu đồ họa
 	Graphic Style Options	Tùy chọn kiểu đồ họa
 	Graphic Style Options…	Tùy chọn kiểu đồ họa…
+	Symbol Options	Tùy chọn ký hiệu
+	Symbol Options…	Tùy chọn ký hiệu…
 	Graphic Styles	Kiểu đồ họa
 	Graphic Styles Options	Tùy chọn kiểu đồ họa
 	Graphics	Đồ họa
@@ -1437,6 +1440,8 @@
 	Identify Objects By	Nhận diện đối tượng theo
 	Ignore	Bỏ qua
 	Ignore Artboards (all the art as one page)	Bỏ qua bảng vẽ (toàn bộ bản vẽ thành một trang)
+	Auto Grouping	Tự động nhóm
+	Ignore Color	Bỏ qua màu
 	Ignore White	Bỏ qua màu trắng
 	Image	Hình ảnh
 	Image Info	Thông tin hình ảnh
@@ -3556,6 +3561,7 @@
 	{warning}: click to correct to the closest color ({hex})	{warning}: bấm để chỉnh sang màu gần nhất ({hex})
 	“{file}” is protected by a password.	“{file}” được bảo vệ bằng mật khẩu.
 	● Recording	● Đang ghi
+imageTrace	Outline	Đường viền
 @plural	Color Table ({n} color)|Color Table ({n} colors)	Bảng màu ({n} màu)
 @plural	Delete this {n} graphic style?|Delete these {n} graphic styles?	Xóa {n} kiểu đồ họa này?
 @plural	{n} area highlighted|{n} areas highlighted	{n} vùng được tô sáng
@@ -3962,6 +3968,7 @@ theme	Appearance	Giao diện
 @msg	object {id} is not a selected top-level object	đối tượng {id} không phải là đối tượng cấp cao nhất đã chọn
 @msg	objects with several fills or strokes, effects or brushes came in as their drawn look ({_1}): their appearance isn't editable yet	đối tượng có nhiều tô hoặc nét, hiệu ứng hoặc cọ đã vào dưới dạng bề ngoài ({_1}): diện mạo chưa thể chỉnh sửa
 @msg	Offset Path: select paths	Đường dẫn độ lệch: hãy chọn đường dẫn
+@msg	Offset Path: the offset leaves nothing of the selected paths (an inset larger than the shapes)	Đường dẫn độ lệch: độ lệch không để lại gì từ các đường dẫn đã chọn (độ lệch vào trong lớn hơn hình)
 @msg	onto must name a floating panel	onto phải đặt tên bảng đang thả nổi
 @msg	onto must name a panel floating in another group	onto phải đặt tên bảng đang thả nổi trong nhóm khác
 @msg	Opened with {_1} note(s): {_2}	Đã mở với {_1} ghi chú: {_2}

crates/ui-egui/src/i18n/zh-hans.tsv

@@ -205,6 +205,7 @@
 	Author Title:	作者职务：
 	Author:	作者：
 	Auto	自动
+	Auto Color	自动颜色
 	Automatic	自动
 	Auto Size New Area Type	自动调整新区域文字大小
 	Auto Spell Check	自动拼写检查
@@ -1094,6 +1095,8 @@
 	Graphic Style Library	图形样式库
 	Graphic Style Options	图形样式选项
 	Graphic Style Options…	图形样式选项…
+	Symbol Options	符号选项
+	Symbol Options…	符号选项…
 	Graphic Styles	图形样式
 	Graphic Styles Options	图形样式选项
 	Graphics	图形
@@ -1189,6 +1192,8 @@
 	Identify Objects By	对象识别方式
 	Ignore	忽略
 	Ignore Artboards (all the art as one page)	忽略画板 (所有图稿作为一页)
+	Auto Grouping	自动编组
+	Ignore Color	忽略颜色
 	Ignore White	忽略白色
 	Palette:	调板：
 	Limited	有限
@@ -3129,6 +3134,7 @@
 	{warning}: click to correct to the closest color ({hex})	{warning}：单击以修正为最接近的颜色 ({hex})
 	“{file}” is protected by a password.	“{file}”受密码保护。
 	● Recording	● 录制中
+imageTrace	Outline	轮廓
 @plural	{n} item|{n} items	{n} 个项目
 @plural	Color Table ({n} color)|Color Table ({n} colors)	颜色表 ({n} 色)
 @plural	Delete this {n} graphic style?|Delete these {n} graphic styles?	要删除这 {n} 个图形样式吗？

crates/ui-egui/src/i18n/zh-hant.tsv

@@ -216,6 +216,7 @@
 	Author Title:	作者職稱：
 	Author:	作者：
 	Auto	自動
+	Auto Color	自動顏色
 	Automatic	自動
 	Auto Size New Area Type	自動調整新區域文字大小
 	Auto Spell Check	自動拼字檢查
@@ -1118,6 +1119,8 @@
 	Graphic Style Library	繪圖樣式資料庫
 	Graphic Style Options	繪圖樣式選項
 	Graphic Style Options…	繪圖樣式選項…
+	Symbol Options	符號選項
+	Symbol Options…	符號選項…
 	Graphic Styles	繪圖樣式
 	Graphic Styles Options	繪圖樣式選項
 	Graphics	圖形
@@ -1219,6 +1222,8 @@
 	Identify Objects By	識別物件依據
 	Ignore	略過
 	Ignore Artboards (all the art as one page)	忽略工作區域 (所有圖稿視為單一頁面)
+	Auto Grouping	自動群組
+	Ignore Color	忽略顏色
 	Ignore White	忽略白色
 	Palette:	調色盤：
 	Limited	有限
@@ -3222,6 +3227,7 @@
 	{warning}: click to correct to the closest color ({hex})	{warning}：按一下以修正為最接近的顏色 ({hex})
 	“{file}” is protected by a password.	「{file}」受密碼保護。
 	● Recording	● 錄製中
+imageTrace	Outline	輪廓
 @plural	{n} item|{n} items	{n} 個項目
 @plural	Color Table ({n} color)|Color Table ({n} colors)	色彩表 ({n} 色)
 @plural	Delete this {n} graphic style?|Delete these {n} graphic styles?	要刪除這 {n} 個繪圖樣式嗎？

crates/ui-egui/src/lib.rs

@@ -321,6 +321,8 @@ pub struct CacheKey {
     /// Appearance of Black › On Screen › Display All Blacks as Rich Black
     /// ([`vectorcraft_render::RenderOptions::rich_black`]).
     pub rich_black: bool,
+    /// Colour and style of guide paths ([`vectorcraft_render::RenderOptions::guide`]).
+    pub guide: ([u8; 3], bool),
 }
 
 #[derive(Clone, Copy, Debug, Default)]
@@ -621,7 +623,7 @@ impl VectorcraftApp {
         // In debug builds the app's own calls are held to the params descriptions too (#1442): a
         // panel passing a key its command doesn't read shows up in the tests.
         if cfg!(debug_assertions) {
-            menus::check_params(id, &params)?;
+            menus::check_params(&self.session, id, &params)?;
         }
         if let Some(r) = menus::run_ui_command(self, id, &params) {
             return r;

crates/ui-egui/src/menus.rs

@@ -403,6 +403,12 @@ pub const UI_COMMANDS: &[(&str, &str, &str, &str)] = &[
         "",
         "{name?} open Graphic Style Options (dialog `graphicStyleOptions`, field `name`): for style `name` OK renames it (graphicStyle.rename); without, OK makes a new style of that name from the selection (graphicStyle.new)",
     ),
+    (
+        "ui.symbolOptions",
+        "Symbol Options…",
+        "",
+        "{} open Symbol Options for a new symbol made from the selection, what the Symbols panel's New Symbol opens (dialog `symbolOptions`, field `name`, default the first free \"New Symbol\"/\"New Symbol N\"); OK runs symbol.new {name}",
+    ),
     (
         "tool.options",
         "Tool Options…",
@@ -899,11 +905,11 @@ pub(crate) fn opt_bool(p: &Value, key: &str) -> Result<Option<bool>, String> {
 /// `params` has only keys the params description of engine command `id` names, or the parameter
 /// error naming the one it doesn't (#1442). The UI's own commands aren't checked yet: their
 /// descriptions haven't been audited against what they read.
-pub fn check_params(id: &str, params: &Value) -> Result<(), String> {
+pub fn check_params(session: &vectorcraft_engine::Session, id: &str, params: &Value) -> Result<(), String> {
     if UI_COMMANDS.iter().any(|c| c.0 == id) {
         return Ok(());
     }
-    vectorcraft_engine::check_params(id, params).map_err(|e| e.to_string())
+    session.check_params(id, params).map_err(|e| e.to_string())
 }
 
 pub fn run_ui_command(app: &mut VectorcraftApp, id: &str, p: &Value) -> Option<Result<Value, String>> {
@@ -1290,6 +1296,7 @@ pub fn run_ui_command(app: &mut VectorcraftApp, id: &str, p: &Value) -> Option<R
         }
         "ui.colorPicker" => crate::dialogs::open_color_picker(app, p),
         "ui.graphicStyleOptions" => crate::dialogs::graphic_style_options::open(app, s("name").as_deref()),
+        "ui.symbolOptions" => crate::dialogs::symbol_options::open(app),
         "ui.brushOptions" => crate::dialogs::brush_options::open(app, s("name").as_deref()),
         "tool.options" => crate::toolbar::open_options(app, &s("tool").unwrap_or_default()),
         "ui.colorGuideOptions" => {