Merge #283: fix(engine): Alt-drag copies snap to their original; Cmd+D repeats the step (#256) (@Nael-Nathanael)

crates/engine/src/cmd/edit.rs

@@ -18,7 +18,7 @@ pub fn specs() -> Vec<CommandSpec> {
         spec!(
             "edit.duplicate",
             "Duplicate",
-            "{ids?, dx?, dy? (offset; default 0 for frames-in-place... Figma offsets top-level frames to the right)}",
+            "{ids?, dx?, dy? (page offset; default: the offset of the last duplicate when ids are its copies, still selected; else top-level frames to the right with a 100 gap, everything else in place)}",
             true,
             duplicate
         ),
@@ -412,13 +412,48 @@ fn delete(s: &mut Session, p: &Value) -> Result<Value> {
     Ok(json!({"deleted": ids}))
 }
 
+/// Layers duplicated last (Duplicate or Alt-drag) and their copies, in the same order. While the
+/// copies are the selection, Duplicate places the next copies as far from them as they are from
+/// their sources, measured then: so moving the copies first sets the step.
+#[derive(Clone, Debug)]
+pub struct Duplicated {
+    pub sources: Vec<NodeId>,
+    pub copies: Vec<NodeId>,
+}
+
+impl Duplicated {
+    pub fn is_selection(&self, sel: &[NodeId]) -> bool {
+        let set = |v: &[NodeId]| v.iter().copied().collect::<BTreeSet<_>>();
+        !self.copies.is_empty() && set(&self.copies) == set(sel)
+    }
+
+    /// The page offset from the sources to the copies, if both are still there and the copies move
+    /// freely (an auto layout places its own).
+    fn offset(&self, doc: &Document) -> Option<(f64, f64)> {
+        let free = self
+            .copies
+            .iter()
+            .all(|c| doc.node(*c).is_some_and(|n| n.child_layout.absolute || n.parent.and_then(|p| doc.node(p)).is_none_or(|p| p.layout.is_none())));
+        if !free || self.sources.iter().chain(&self.copies).any(|i| !doc.contains(*i)) {
+            return None;
+        }
+        let (a, b) = (doc.bounds_of(&self.sources)?, doc.bounds_of(&self.copies)?);
+        let d = (b.x0 - a.x0, b.y0 - a.y0);
+        (d.0.is_finite() && d.1.is_finite() && (d.0 != 0.0 || d.1 != 0.0)).then_some(d)
+    }
+}
+
 fn duplicate(s: &mut Session, p: &Value) -> Result<Value> {
     let ids = req_targets("edit.duplicate", s, p)?;
     let rename = s.prefs.rename_duplicates;
+    let explicit = num(p, "dx").is_some() || num(p, "dy").is_some();
+    let ds = s.ds()?;
+    let roots_now = z_sorted(&ds.doc, &roots(&ds.doc, &ids));
+    let repeat = ds.last_duplicate.as_ref().filter(|d| !explicit && d.is_selection(&roots_now)).and_then(|d| d.offset(&ds.doc));
     let doc = s.doc_mut()?;
-    let ids = z_sorted(doc, &roots(doc, &ids));
+    let ids = roots_now;
     let mut out = Vec::new();
-    for i in ids {
+    for i in ids.iter().copied() {
         let n = doc.get(i)?;
         let parent = n.parent.ok_or_else(|| bad("edit.duplicate", "pages are duplicated with page.duplicate"))?;
         let top_frame = doc.node(parent).is_some_and(Node::is_page) && n.kind.is_frame_like();
@@ -432,14 +467,21 @@ fn duplicate(s: &mut Session, p: &Value) -> Result<Value> {
             _ if top_frame => (w + 100.0, 0.0),
             _ => (0.0, 0.0),
         };
-        let nn = doc.get_mut(nid)?;
-        nn.transform = Affine::translate((dx, dy)) * nn.transform;
+        match repeat {
+            Some((rx, ry)) => super::arrange::move_world(doc, nid, rx, ry)?,
+            None => {
+                let nn = doc.get_mut(nid)?;
+                nn.transform = Affine::translate((dx, dy)) * nn.transform;
+            }
+        }
         if rename {
+            let nn = doc.get_mut(nid)?;
             nn.name = bump_name(&nn.name);
         }
         out.push(nid);
     }
     s.set_selection(out.clone());
+    s.ds_mut()?.last_duplicate = Some(Duplicated { sources: ids, copies: out.clone() });
     Ok(json!({"ids": out}))
 }
 

crates/engine/src/duplicate_spacing_tests.rs

@@ -0,0 +1,159 @@
+//! Duplicating at a spacing: a copy Alt-dragged off a layer snaps to that layer too (its edges,
+//! centres and equal spacing), and Duplicate repeats the last duplicate's offset while its copies
+//! are selected, so Alt-drag (or Duplicate and move) then Cmd+D steps out evenly spaced copies.
+
+use serde_json::{Value, json};
+
+use crate::Session;
+use crate::params::id_of;
+use crate::tools::{PointerEvent, PointerKind};
+use figcraft_doc::NodeId;
+
+fn ex(s: &mut Session, cmd: &str, p: Value) -> Value {
+    s.execute(cmd, &p).unwrap_or_else(|e| panic!("{cmd}: {e}"))
+}
+
+fn rect(s: &mut Session, x: f64, y: f64) -> NodeId {
+    id_of(&ex(s, "shape.rectangle", json!({"x": x, "y": y, "width": 100, "height": 100}))["id"]).unwrap()
+}
+
+/// Alt-drag from `from` to `to`: returns the copy (the selection afterwards).
+fn alt_drag(s: &mut Session, from: (f64, f64), to: (f64, f64)) -> NodeId {
+    let ev = |kind, (x, y): (f64, f64)| PointerEvent { alt: true, ..PointerEvent::at(kind, x, y, 1.0) };
+    s.pointer(&ev(PointerKind::Down, from)).unwrap();
+    for k in 1..=4 {
+        let t = f64::from(k) / 4.0;
+        s.pointer(&ev(PointerKind::Move, (from.0 + (to.0 - from.0) * t, from.1 + (to.1 - from.1) * t))).unwrap();
+    }
+    s.pointer(&ev(PointerKind::Up, to)).unwrap();
+    let sel = s.selection();
+    assert_eq!(sel.len(), 1, "one copy selected");
+    sel[0]
+}
+
+/// Duplicate the selection: the copy.
+fn cmd_d(s: &mut Session) -> NodeId {
+    let out = ex(s, "edit.duplicate", json!({}));
+    id_of(&out["ids"][0]).unwrap()
+}
+
+fn at(s: &Session, id: NodeId) -> (f64, f64) {
+    let b = s.doc().unwrap().world_bounds(id).unwrap();
+    (b.x0, b.y0)
+}
+
+#[test]
+fn an_alt_dragged_copy_snaps_to_the_layer_it_came_from() {
+    let mut s = Session::new();
+    let a = rect(&mut s, 0.0, 0.0);
+    // 2 px below the original's top edge: within the snap distance.
+    let copy = alt_drag(&mut s, (50.0, 50.0), (250.0, 52.0));
+    assert_ne!(copy, a);
+    assert_eq!(at(&s, copy), (200.0, 0.0), "the copy's top lines up with the original's");
+    assert_eq!(at(&s, a), (0.0, 0.0), "the original stays");
+}
+
+#[test]
+fn an_alt_dragged_copy_spaces_equally_with_the_layer_it_came_from() {
+    let mut s = Session::new();
+    rect(&mut s, 0.0, 0.0);
+    rect(&mut s, 200.0, 0.0);
+    // B's copy dropped 2 px short of the 100 gap that A and B have.
+    let copy = alt_drag(&mut s, (250.0, 50.0), (448.0, 50.0));
+    assert_eq!(at(&s, copy), (400.0, 0.0));
+}
+
+#[test]
+fn duplicate_repeats_the_step_set_by_moving_the_copy() {
+    let mut s = Session::new();
+    let a = rect(&mut s, 0.0, 0.0);
+    ex(&mut s, "select.set", json!({"ids": [a]}));
+    let c1 = cmd_d(&mut s);
+    assert_eq!(at(&s, c1), (0.0, 0.0), "the first copy lands in place");
+    ex(&mut s, "node.set", json!({"ids": [c1], "props": {"x": 150, "y": 20}}));
+    let c2 = cmd_d(&mut s);
+    assert_eq!(at(&s, c2), (300.0, 40.0), "the next one as far again");
+    let c3 = cmd_d(&mut s);
+    assert_eq!(at(&s, c3), (450.0, 60.0), "and again");
+}
+
+#[test]
+fn duplicate_after_an_alt_drag_repeats_its_step() {
+    let mut s = Session::new();
+    rect(&mut s, 0.0, 0.0);
+    let copy = alt_drag(&mut s, (50.0, 50.0), (180.0, 50.0));
+    assert_eq!(at(&s, copy), (130.0, 0.0));
+    let next = cmd_d(&mut s);
+    assert_eq!(at(&s, next), (260.0, 0.0));
+}
+
+#[test]
+fn duplicate_only_repeats_for_the_last_copies() {
+    let mut s = Session::new();
+    let a = rect(&mut s, 0.0, 0.0);
+    ex(&mut s, "select.set", json!({"ids": [a]}));
+    let c1 = cmd_d(&mut s);
+    ex(&mut s, "node.set", json!({"ids": [c1], "props": {"x": 150}}));
+    // Another selection forgets it: the original duplicates in place.
+    ex(&mut s, "select.set", json!({"ids": [a]}));
+    ex(&mut s, "select.set", json!({"ids": [c1]}));
+    let c2 = cmd_d(&mut s);
+    assert_eq!(at(&s, c2), (150.0, 0.0), "the step was forgotten when the selection changed");
+    // An offset given explicitly wins over a remembered one.
+    ex(&mut s, "node.set", json!({"ids": [c2], "props": {"x": 300}}));
+    let out = ex(&mut s, "edit.duplicate", json!({"dx": 10}));
+    let c3 = id_of(&out["ids"][0]).unwrap();
+    assert_eq!(at(&s, c3), (310.0, 0.0));
+}
+
+#[test]
+fn undo_doesnt_let_a_new_layer_take_a_remembered_step() {
+    let mut s = Session::new();
+    let a = rect(&mut s, 0.0, 0.0);
+    ex(&mut s, "select.set", json!({"ids": [a]}));
+    let c1 = cmd_d(&mut s);
+    ex(&mut s, "node.set", json!({"ids": [c1], "props": {"x": 150}}));
+    ex(&mut s, "edit.undo", json!({}));
+    ex(&mut s, "edit.undo", json!({}));
+    assert!(!s.doc().unwrap().contains(c1));
+    // Undo gives ids back: the new rectangle may well get the undone copy's.
+    let r = rect(&mut s, 500.0, 500.0);
+    ex(&mut s, "select.set", json!({"ids": [r]}));
+    let c = cmd_d(&mut s);
+    assert_eq!(at(&s, c), (500.0, 500.0), "a plain duplicate, in place");
+}
+
+#[test]
+fn the_step_is_measured_in_page_space_inside_a_rotated_frame() {
+    let mut s = Session::new();
+    let f = id_of(&ex(&mut s, "frame.create", json!({"x": 0, "y": 0, "width": 600, "height": 600}))["id"]).unwrap();
+    ex(&mut s, "node.set", json!({"ids": [f], "props": {"rotation": 30}}));
+    let a = id_of(&ex(&mut s, "shape.rectangle", json!({"x": 50, "y": 50, "width": 40, "height": 40, "parent": f}))["id"]).unwrap();
+    ex(&mut s, "select.set", json!({"ids": [a]}));
+    let c1 = cmd_d(&mut s);
+    ex(&mut s, "node.set", json!({"ids": [c1], "props": {"x": 150}}));
+    let (p0, p1) = (at(&s, a), at(&s, c1));
+    let c2 = cmd_d(&mut s);
+    let p2 = at(&s, c2);
+    let close = |a: f64, b: f64| (a - b).abs() < 1e-6;
+    assert!(close(p2.0 - p1.0, p1.0 - p0.0) && close(p2.1 - p1.1, p1.1 - p0.1), "{p0:?} {p1:?} {p2:?}");
+}
+
+#[test]
+fn an_alt_drag_into_auto_layout_sets_no_step() {
+    let mut s = Session::new();
+    let f = id_of(&ex(&mut s, "frame.create", json!({"x": 0, "y": 0, "width": 400, "height": 100}))["id"]).unwrap();
+    for i in 0..2 {
+        ex(&mut s, "shape.rectangle", json!({"x": i * 60, "y": 0, "width": 50, "height": 30, "parent": f}));
+    }
+    ex(&mut s, "layout.add", json!({"ids": [f]}));
+    ex(&mut s, "select.none", json!({}));
+    let kids = s.doc().unwrap().node(f).unwrap().children.clone();
+    let b = s.doc().unwrap().world_bounds(kids[0]).unwrap();
+    let from = (b.center().x, b.center().y);
+    alt_drag(&mut s, from, (from.0 + 70.0, from.1));
+    assert!(s.ds().unwrap().last_duplicate.is_none(), "the layout placed the copy: no step to repeat");
+    let n = s.doc().unwrap().node(f).unwrap().children.len();
+    cmd_d(&mut s);
+    assert_eq!(s.doc().unwrap().node(f).unwrap().children.len(), n + 1, "Duplicate still adds one to the flow");
+}

crates/engine/src/lib.rs

@@ -328,6 +328,9 @@ pub struct DocState {
     pub guide: Option<(NodeId, usize)>,
     /// The selection's rotation origin, when moved or shown (see [`rotation_origin`]; not saved).
     pub(crate) rotation_origin: Option<rotation_origin::RotationOrigin>,
+    /// The last duplicate while its copies are the selection: Duplicate repeats its offset (see
+    /// [`cmd::edit::Duplicated`]; not saved).
+    pub(crate) last_duplicate: Option<cmd::edit::Duplicated>,
 }
 
 /// A version shown on the canvas in place of the document: read-only until it's restored or the
@@ -383,6 +386,7 @@ impl DocState {
             focus: None,
             guide: None,
             rotation_origin: None,
+            last_duplicate: None,
         };
         st.zoom_to_fit();
         st
@@ -538,6 +542,10 @@ impl DocState {
         if self.rotation_origin.as_ref().is_some_and(|o| o.ids != self.selection) {
             self.rotation_origin = None;
         }
+        // So does the last duplicate (undo reuses ids: a new layer could take a copy's).
+        if self.last_duplicate.as_ref().is_some_and(|d| !d.is_selection(&self.selection)) {
+            self.last_duplicate = None;
+        }
     }
 }
 
@@ -1441,6 +1449,8 @@ mod double_click_tests;
 #[cfg(test)]
 mod draw_tools_tests;
 #[cfg(test)]
+mod duplicate_spacing_tests;
+#[cfg(test)]
 mod effects_tests;
 #[cfg(test)]
 mod export_behaviour_tests;

crates/engine/src/measure_tests.rs

@@ -196,16 +196,17 @@ fn alt_drag_shows_live_distances_to_the_neighbours() {
         e
     };
     s.pointer(&ev(PointerKind::Down, 30.0)).unwrap();
-    // Alt duplicates: the copy moves to 110..160, between the original and the other layer.
+    // Alt duplicates: the copy, dragged to 110..160, snaps to equal spacing between the original
+    // and the other layer (105..155).
     s.pointer(&ev(PointerKind::Move, 130.0)).unwrap();
     let g = s.tool.overlay.guides.clone();
     assert_eq!(
         labelled(&g),
         vec![
-            ("30".into(), [135, 0, 135, 30]),
-            ("30".into(), [135, 70, 135, 100]),
-            ("40".into(), [160, 50, 200, 50]),
-            ("50".into(), [60, 50, 110, 50])
+            ("30".into(), [130, 0, 130, 30]),
+            ("30".into(), [130, 70, 130, 100]),
+            ("45".into(), [60, 50, 105, 50]),
+            ("45".into(), [155, 50, 200, 50])
         ]
     );
     s.pointer(&ev(PointerKind::Up, 130.0)).unwrap();

crates/engine/src/snap.rs

@@ -74,15 +74,6 @@ impl Targets {
         // A layer's box in snap space.
         let bbox = |id: NodeId| doc.node(id).map(|n| transform_rect_bbox(to * doc.world_transform(id), n.local_rect())).filter(|b| b.is_finite());
         let mut t = Targets { space, moving: moving.iter().filter_map(|m| bbox(*m)).reduce(|a, b| a.union(b)), ..Default::default() };
-        let push = |r: Rect, t: &mut Targets| {
-            for x in [r.x0, r.center().x, r.x1] {
-                t.xs.push((x, r.y0, r.y1));
-            }
-            for y in [r.y0, r.center().y, r.y1] {
-                t.ys.push((y, r.x0, r.x1));
-            }
-            t.boxes.push(r);
-        };
         let parent = parent_of(doc, page, moving);
         // The parent frame's own box (and its layout grids).
         if parent != page
@@ -109,7 +100,7 @@ impl Targets {
                     continue;
                 }
                 if let Some(b) = bbox(*c) {
-                    push(b, &mut t);
+                    t.add_box(b);
                 }
             }
         }
@@ -136,6 +127,17 @@ impl Targets {
         t
     }
 
+    /// A box to snap to (in snap space): its edges and centre lines, and equal spacing with it.
+    pub fn add_box(&mut self, r: Rect) {
+        for x in [r.x0, r.center().x, r.x1] {
+            self.xs.push((x, r.y0, r.y1));
+        }
+        for y in [r.y0, r.center().y, r.y1] {
+            self.ys.push((y, r.x0, r.x1));
+        }
+        self.boxes.push(r);
+    }
+
     /// A point to snap onto (a vector point, a segment midpoint): lines through it on both axes,
     /// and a marker when a moving point lands on it.
     pub fn add_point(&mut self, p: Point) {

crates/engine/src/tools.rs

@@ -1196,7 +1196,13 @@ impl Session {
                 if ids.is_empty() {
                     return Ok(());
                 }
-                let targets = Targets::gather(&doc, page, &ids);
+                let mut targets = Targets::gather(&doc, page, &ids);
+                // A copy dragged out with Alt snaps to the layers it came from too (they stay put).
+                if ev.alt
+                    && let Some(b) = targets.moving
+                {
+                    targets.add_box(b);
+                }
                 self.begin_interaction(if ev.alt { "Duplicate" } else { "Move" })?;
                 self.tool.gesture = Gesture::Move { start: ev.p(), ids, targets, duplicate: ev.alt, moved: false };
                 self.tool.overlay.cursor = if ev.alt { Cursor::Copy } else { Cursor::Default };
@@ -1707,6 +1713,7 @@ impl Session {
                     // dropped; layers in an auto layout frame already sit in their slot.
                     let page = self.page()?;
                     let sel = self.selection();
+                    let sources = if duplicate { ids.clone() } else { Vec::new() };
                     let moving = if duplicate { sel } else { ids };
                     let doc = self.doc()?.clone();
                     let in_al =
@@ -1735,6 +1742,10 @@ impl Session {
                         self.cancel_interaction()?;
                     } else {
                         self.commit_interaction()?;
+                        // Duplicate repeats a free Alt-drag's step (an auto layout places its own).
+                        if duplicate && !in_al && moving.len() == sources.len() {
+                            self.ds_mut()?.last_duplicate = Some(crate::cmd::edit::Duplicated { sources, copies: moving });
+                        }
                     }
                 } else {
                     self.cancel_interaction()?;

docs/mcp.md

@@ -1406,6 +1406,12 @@ turned off 0°.
   With `pointer`, `alt: true` hovers measure (add `cmd` for nested layers, `shift` for padding) and
   `alt` drags show live distances to the neighbours; `inspect_ui` reports them under
   `tool.overlay` (`guides`, and `measure_box` for the box measured to).
+- **Duplicating at a spacing**: a copy Alt-dragged off a layer with `pointer` snaps to that layer
+  too (its edges, centres and equal spacing). `edit.duplicate {ids?, dx?, dy?}` without `dx`/`dy`
+  repeats the last duplicate's page offset while its copies are what it duplicates (and still the
+  selection), measured when it runs: Alt-drag or duplicate and move a copy, then each
+  `edit.duplicate` steps out the next one as far again. Copies placed by an auto layout set no
+  step; explicit `dx`/`dy` always win.
 - **Scale tool** (`tool.scale`, K): dragging a selection handle with `pointer` scales everything by
   one factor (sizes and positions whatever the constraints, strokes, effects, corner radii, auto
   layout spacing, min/max sizes, layout grids, guides, tiled images, text), one undo step per drag,

docs/ui-parity.md

@@ -55,7 +55,7 @@ interaction feel not yet compared.
 | Flip, rotate 90° | done | |
 | Rotation origin (Alt+R) | done | a handle at the selection's centre to drag (snaps to the box's corners, edge middles and centre), double-click puts it back, Escape or Alt+R hides it; the corner handles, the rotation field, Rotate 90°/180° and `transform.rotate` turn about it; it follows the layers and lasts as long as the selection, not saved (the documentation doesn't say; pinned) |
 | Enter with a shape or frame tool chosen | done | places what a click makes (100×100, lines 100 long, sections 400×300) in the middle of the view, selected (`tool.place`); from the toolbar, Enter on the chosen tool. No crosshair to move with the arrows first |
-| Alt-drag duplicate | done | |
+| Alt-drag duplicate | done | the copy snaps to the layer it came from too (edges, centres, equal spacing); Duplicate (Cmd+D) then repeats the copy's offset, also after a Duplicate whose copy was moved, as long as the copies stay selected (the documentation doesn't say; pinned from community answers) |
 | Drag threshold; double-click into groups and text | done | a press moves or resizes only once the pointer has travelled 3 px on screen, so a click or double-click made with an unsteady hand drags nothing; a double-click goes one level into a group and the next one edits the text under it, wherever on the text it lands, with all of it selected (a double-click in the text being edited selects the word) (`double_click_tests`); Enter on a selected text does the same (all of it selected, typing replaces it) and Escape leaves editing with the layer still selected (`text_enter_tests`) |
 | Scale tool (K): handles about an anchor, live factor, panel | done | |
 | Nudge 1 / Shift 10 (preference), Cmd+arrows resize | done | arrows reorder auto layout children |