Recolor: count left-out art by the colors of nested pattern tiles too

A left-out object whose pattern's tile uses another pattern showed the inner tile's colors
without them being compared, so a group rewrite that recolored the inner tile still counted the
object as left unchanged. The comparison now follows the patterns tiles use, each once.

crates/engine/src/cmd/recolor.rs

@@ -119,24 +119,35 @@ fn used_colors(d: &Document, ids: &[NodeId], only: Option<&BTreeSet<NodeId>>) ->
 }
 
 /// The colors `n` shows, in paint order ([`node_colors`]), then the colors of the tiles of the
-/// patterns it uses as fills or strokes.
-fn shown_colors(d: &Document, n: &Node) -> Vec<Color> {
+/// patterns it uses as fills or strokes, and of the patterns those tiles use (each pattern once).
+fn shown_colors<'a>(d: &'a Document, n: &'a Node) -> Vec<Color> {
     let mut colors = vec![];
     node_colors(n, &mut |c, _| colors.push(*c));
     let mut patterns: Vec<&str> = vec![];
+    pattern_names(n, &mut patterns);
+    let mut next = 0;
+    while let Some(&name) = patterns.get(next) {
+        next += 1;
+        for a in d.pattern(name).map(|def| def.art.as_slice()).unwrap_or_default() {
+            node_colors(a, &mut |c, _| colors.push(*c));
+            pattern_names(a, &mut patterns);
+        }
+    }
+    colors
+}
+
+/// Adds the names of the patterns `n` and the objects inside it use as fills or strokes to `names`,
+/// leaving out names already there.
+fn pattern_names<'a>(n: &'a Node, names: &mut Vec<&'a str>) {
     n.walk(&mut |m| {
         for p in node_paints(m) {
             if let Paint::Pattern { pattern, .. } = p
-                && !patterns.contains(&pattern.as_str())
+                && !names.contains(&pattern.as_str())
             {
-                patterns.push(pattern);
+                names.push(pattern);
             }
         }
     });
-    for def in patterns.iter().filter_map(|p| d.pattern(p)) {
-        def.art.iter().for_each(|a| node_colors(a, &mut |c, _| colors.push(*c)));
-    }
-    colors
 }
 
 /// The objects whose colors `recolor.colors` and `recolor.reduce` read, for [`used_colors`]: `ids`

crates/engine/src/tests/recolor.rs

@@ -659,6 +659,39 @@ fn recolor_of_everything_does_not_count_locked_art_whose_pattern_the_group_rewri
     assert_eq!(r["notChanged"], json!({"locked": 0, "hidden": 0}), "{r}");
 }
 
+#[test]
+fn recolor_of_everything_does_not_count_locked_art_whose_nested_pattern_the_group_rewrite_recolors() {
+    let mut s = session();
+    run(&mut s, "swatch.newGroup", json!({"name": "Brand", "colors": ["#2878f0", "#ff0000"]}));
+    let names: Vec<String> =
+        s.doc().unwrap().doc.swatch_groups.iter().find(|g| g.name == "Brand").unwrap().swatches.iter().map(|w| w.name.clone()).collect();
+    for name in &names {
+        run(&mut s, "swatch.edit", json!({"name": name, "global": true}));
+    }
+    // "Dots": a tile linked to the group's second swatch; "Rings": a tile filled with "Dots".
+    let tile = rect(&mut s, json!("#000000"));
+    run(&mut s, "paint.setFill", json!({"ids": [tile.0], "swatch": names[1]}));
+    run(&mut s, "select.set", json!({"ids": [tile.0]}));
+    run(&mut s, "object.pattern.make", json!({"name": "Dots", "width": 20, "height": 20}));
+    run(&mut s, "object.pattern.done", json!({}));
+    let outer = rect(&mut s, json!("#000000"));
+    run(&mut s, "paint.setFill", json!({"ids": [outer.0], "swatch": "Dots"}));
+    run(&mut s, "select.set", json!({"ids": [outer.0]}));
+    run(&mut s, "object.pattern.make", json!({"name": "Rings", "width": 40, "height": 40}));
+    run(&mut s, "object.pattern.done", json!({}));
+    let tile_hex = |s: &Session| s.doc().unwrap().doc.pattern("Dots").unwrap().art[0].appearance.fill_paint().color().unwrap().to_hex();
+    let locked = rect(&mut s, json!("#000000"));
+    run(&mut s, "paint.setFill", json!({"ids": [locked.0], "swatch": "Rings"}));
+    set_props(&mut s, &[locked], json!({"locked": true}));
+    let open = rect(&mut s, json!("#000000"));
+    run(&mut s, "paint.setFill", json!({"ids": [open.0], "swatch": names[1]}));
+    select_all(&mut s);
+    // The rewrite recolors the inner tile, which the locked art shows through "Rings".
+    let r = run(&mut s, "recolor.apply", json!({"map": {"#ff0000": "#00ff00"}, "group": "Brand", "groupColors": ["#2878f0", "#00ff00"]}));
+    assert_eq!(tile_hex(&s), "#00ff00", "{r}");
+    assert_eq!(r["notChanged"], json!({"locked": 0, "hidden": 0}), "{r}");
+}
+
 #[test]
 fn recolor_of_everything_does_not_count_locked_art_that_would_only_take_a_swatch_link() {
     let mut s = session();