Preflight: a frame with states is looked at as PDF export draws it (review)

Flex Layout's convert turns a multi-state group into a frame that keeps
its states. PDF export draws every object pasted into a frame, but the
white overprint check walked only the active state, so a white
overprint in another state printed unreported. Which children export
draws is now one function, drawn_children, used by both.

crates/engine/src/cmd/preflight/white_overprint.rs

@@ -15,7 +15,7 @@ use designcraft_color::{Color, ColorType, SwatchValue, swatch};
 use designcraft_doc::cjk_settings::AdornmentOverprint;
 use designcraft_doc::{AnchoredObject, CharProps, Content, Document, Item, ItemId, SpreadRef, Story, StrokeType};
 use designcraft_geom::Affine;
-use designcraft_pdf::{item_exported, layer_exported, shown_parent_items};
+use designcraft_pdf::{drawn_children, item_exported, layer_exported, shown_parent_items};
 
 use super::{Issue, page_of};
 use crate::Session;
@@ -126,7 +126,7 @@ pub(super) fn printed(s: &Session, d: &Document) -> (Vec<Issue>, BTreeMap<ItemId
                 On::Page(page) => (page, on),
             };
             issues.extend(item_issue(d, it, page));
-            let children: Vec<_> = it.shown_children().map(|c| (Node::Item(c.clone()), inside, composed)).collect();
+            let children: Vec<_> = drawn_children(it).map(|c| (Node::Item(c.clone()), inside, composed)).collect();
             if let Content::Text(tf) = &it.content {
                 frames.entry(it.id).or_insert(page);
                 let cs = s.cache.get(d, tf.story, composed);

crates/engine/src/cmd/preflight/white_overprint/tests.rs

@@ -235,3 +235,22 @@ fn what_pdf_export_leaves_out_is_not_reported() {
     s.execute("object.hide", &json!({"ids": [group]})).unwrap();
     assert_eq!(white_overprints(&mut s), [(PAPER_KENTEN.to_string(), r["id"].as_u64())]);
 }
+
+/// A multi-state object prints its active state only, but a frame made from one (Flex Layout's
+/// convert keeps the states) prints every object in it, as PDF export draws a frame's pasted-in
+/// objects: the inactive state's white overprint was left out (noted in review).
+#[test]
+fn a_frame_with_states_is_looked_at_as_pdf_export_draws_it() {
+    let mut s = Session::new();
+    s.execute("file.new", &json!({})).unwrap();
+    let a = rect(&mut s, [72.0, 72.0, 200.0, 200.0]);
+    paper_overprint(&mut s, a);
+    let b = rect(&mut s, [300.0, 72.0, 400.0, 200.0]);
+    let ms = s.execute("states.create", &json!({"ids": [a, b]})).unwrap()["id"].as_u64().unwrap();
+    let at = s.doc().unwrap().doc.item(designcraft_doc::ItemId(ms)).unwrap().children().iter().position(|c| c.id.0 == a).unwrap();
+    s.execute("states.show", &json!({"id": ms, "index": 1 - at})).unwrap();
+    assert!(white_overprints(&mut s).is_empty(), "an inactive state doesn't print");
+    s.execute("flex.convert", &json!({"ids": [ms]})).unwrap();
+    assert!(!s.doc().unwrap().doc.item(designcraft_doc::ItemId(ms)).unwrap().states.is_empty(), "the frame keeps its states");
+    assert_eq!(white_overprints(&mut s), [(PAPER_FILL.to_string(), Some(a))]);
+}

crates/pdf/src/export.rs

@@ -46,7 +46,9 @@ pub(crate) use images::SRGB_ICC;
 use images::{CmykImage, GreyImage, ImageContentCache, RasterMode, SrgbImage, embedded_icc, is_grey, is_grey_icc};
 pub(crate) use metadata::civil;
 pub(crate) use pipeline::{MARK_LEN, Sheet, exported_items, mark_start};
-pub use pipeline::{export_pdf, export_pdf_with_report, item_exported, layer_exported, print_color, sheet_spreads, shown_parent_items};
+pub use pipeline::{
+    drawn_children, export_pdf, export_pdf_with_report, item_exported, layer_exported, print_color, sheet_spreads, shown_parent_items,
+};
 #[cfg(test)]
 impl std::hash::Hasher for ConstantImageHasher {
     fn finish(&self) -> u64 {

crates/pdf/src/export/pipeline.rs

@@ -30,6 +30,14 @@ pub fn item_exported(it: &Item) -> bool {
     !it.hidden && !it.nonprinting
 }
 
+/// The items PDF export draws inside `it`: every item pasted into a frame (a frame keeps the
+/// states of a multi-state group converted to it, and draws them all), or a group's shown
+/// children (only the active state of a multi-state object).
+pub fn drawn_children(it: &Item) -> impl Iterator<Item = &Arc<Item>> {
+    let nested = it.has_nested_items();
+    it.children().iter().filter(move |_| nested).chain(it.shown_children().filter(move |_| !nested))
+}
+
 /// The parent pages' items that page `pi` of spread `si` shows, on exported layers, each with the
 /// offset that moves it onto the page: the parent's bases first, then the parent. None when the
 /// page hides parent items; the items the page overrides are left out (their overrides are the

crates/pdf/src/export/walk.rs

@@ -1,6 +1,6 @@
 use super::common::{TagEntry, blend, norm, rects_overlap, solid_fill, tf, to_path};
 use super::graphics::draw_coverage;
-use super::pipeline::{item_exported, layer_exported, shown_parent_items};
+use super::pipeline::{drawn_children, item_exported, layer_exported, shown_parent_items};
 use super::*;
 
 impl Exporter<'_> {
@@ -249,7 +249,7 @@ impl Exporter<'_> {
         if let Some(c) = &clip {
             s.push_clip_path(c, &FillRule::NonZero);
         }
-        for child in it.children() {
+        for child in drawn_children(it) {
             self.item(s, child, xf, page);
         }
         if clip.is_some() {
@@ -269,7 +269,7 @@ impl Exporter<'_> {
 
     fn draw_group_children(&mut self, s: &mut Surface, it: &Item, xf: Affine, page: Option<usize>) {
         let pushes = Self::push_group(s, it.opacity, it.blend) + Self::push_isolation(s, it);
-        for child in it.shown_children() {
+        for child in drawn_children(it) {
             self.item(s, child, xf, page);
         }
         for _ in 0..pushes {

crates/pdf/src/lib.rs

@@ -49,8 +49,8 @@ mod pdfx;
 mod pdfx1a;
 mod transitions;
 pub use export::{
-    BookletKind, BookletOptions, booklet_pairs, export_booklet, export_pdf, export_pdf_with_report, item_exported, layer_exported, merge_pdfs,
-    print_color, sheet_spreads, shown_parent_items,
+    BookletKind, BookletOptions, booklet_pairs, drawn_children, export_booklet, export_pdf, export_pdf_with_report, item_exported, layer_exported,
+    merge_pdfs, print_color, sheet_spreads, shown_parent_items,
 };
 pub use pdfx::{check_pdfx4, has_rgb_groups, make_pdfx4, pdfx_version};
 pub use pdfx1a::check_pdfx1a;