Scripting: a stroke's Dashes use After Effects' match names (#815)

Dashes reported its children as `dash`, `gap`, `offset`, so
`property("ADBE Vector Stroke Dash 1")` was null and addProperty threw.
They now report ADBE Vector Stroke Dash 1-3 / Gap 1-3 / Offset.
addProperty with one of those names returns the existing property
(EffectCraft's Dashes always holds Dash 1, Gap 1 and Offset) or adds the
Dash/Gap 2 or 3 pair through shape.dashes.add. Lookups by the old ids
still work.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

crates/script/src/matchnames.rs

@@ -72,6 +72,22 @@ const TEXT_PATH_OPTIONS: &[(&str, &str)] = &[
     ("lastMargin", "ADBE Text Last Margin"),
 ];
 
+// A stroke's Dashes, as After Effects' scripting API names them (#815).
+const STROKE_DASHES: &[(&str, &str)] = &[
+    ("dash", "ADBE Vector Stroke Dash 1"),
+    ("gap", "ADBE Vector Stroke Gap 1"),
+    ("dash2", "ADBE Vector Stroke Dash 2"),
+    ("gap2", "ADBE Vector Stroke Gap 2"),
+    ("dash3", "ADBE Vector Stroke Dash 3"),
+    ("gap3", "ADBE Vector Stroke Gap 3"),
+    ("offset", "ADBE Vector Stroke Offset"),
+];
+
+/// The Dashes child id (`dash`, `gap2`, `offset`…) for an After Effects match name.
+pub fn stroke_dash(name: &str) -> Option<&'static str> {
+    STROKE_DASHES.iter().find(|(_, m)| *m == name).map(|(id, _)| *id)
+}
+
 const TEXT_ANIMATOR: &[(&str, &str)] = &[("selectors", "ADBE Text Selectors"), ("properties", "ADBE Text Animator Properties")];
 
 const TEXT_SELECTORS: &[(&str, &str)] =
@@ -447,6 +463,9 @@ pub fn node(chain: &[&Node]) -> String {
             if let Some((_, _, m)) = SHAPE_PROPS.iter().find(|(item, prop, _)| *item == pid && *prop == id) {
                 return m.to_string();
             }
+            if pid == "dashes" {
+                return find(STROKE_DASHES, id).map(str::to_string).unwrap_or_else(own);
+            }
             own()
         }
         _ => own(),

crates/script/src/model.rs

@@ -626,6 +626,15 @@ fn resolve_add(s: &Session, a: &J) -> R {
             }
         }
         "animators" => json!({"kind": "animator"}),
+        // A stroke always holds Dash 1, Gap 1 and Offset (Dash 0 draws no dashes); adding one of
+        // them returns it, Dash/Gap 2 and 3 are added as a pair (`shape.dashes.add`) (#815).
+        "dashes" if in_group => match matchnames::stroke_dash(name) {
+            Some(id) => match g.children.iter().find(|n| n.match_id() == id) {
+                Some(n) => json!({"kind": "existing", "uid": n.uid()}),
+                None => json!({"kind": "dash", "id": id, "stroke": l.props.parent_of(g.uid).map(|p| p.uid)}),
+            },
+            None => json!({"error": format!("Can not add \"{name}\" to Dashes")}),
+        },
         _ if in_contents && in_group => match matchnames::shape_kind(name) {
             Some(k) => {
                 json!({"kind": "shape", "shape": k, "group": if l.props.sub("contents").is_some_and(|c| c.uid == g.uid) { J::Null } else { json!(g.uid) }})

crates/script/src/prelude.js

@@ -715,6 +715,15 @@ PropertyGroup.prototype.addProperty = function (name) {
     var p = { comp: L.__comp, layer: L.__id, kind: r.shape };
     if (r.group !== null && r.group !== undefined) p.group = r.group;
     uid = __call("layer.addShapeItem", p).uid;
+  } else if (r.kind === "existing") {
+    uid = r.uid;
+  } else if (r.kind === "dash") {
+    // Dash/Gap 2 and 3 come as a pair: add pairs until the one asked for exists.
+    var dp = { comp: L.__comp, layer: L.__id, prop: r.stroke };
+    for (var n = 0; n < 3 && !this.property(name); n++) __call("shape.dashes.add", dp);
+    var added = this.property(name);
+    if (!added) throw __err("Can not add \"" + name + "\" to Dashes");
+    return added;
   } else if (r.kind === "animator") {
     uid = __call("layer.addTextAnimator", { comp: L.__comp, layer: L.__id, properties: [] }).animator;
   } else if (r.kind === "animatorProperty") {

crates/script/src/tests.rs

@@ -828,6 +828,37 @@ fn script_remove_keys_batches_a_range_as_one_edit() {
     assert!(invalid.error.is_some());
 }
 
+/// #815: a stroke's Dashes use After Effects' match names, and addProperty with them returns
+/// Dash 1 / Gap 1 / Offset or adds the Dash 2 / Gap 2 pair.
+#[test]
+fn script_stroke_dashes_use_after_effects_match_names() {
+    let mut s = session();
+    let o = ok(
+        &mut s,
+        "function names(g) { var a = []; for (var i = 1; i <= g.numProperties; i++) a.push(g.property(i).matchName); return a.join(','); }\
+         var comp = app.project.items.addComp('Names', 100, 100, 1, 10, 25);\
+         var contents = comp.layers.addShape().property('ADBE Root Vectors Group'); contents.addProperty('ADBE Vector Shape - Rect');\
+         var d = contents.addProperty('ADBE Vector Graphic - Stroke').property('ADBE Vector Stroke Dashes');\
+         var before = names(d);\
+         var dash1 = d.addProperty('ADBE Vector Stroke Dash 1'); dash1.setValue(12);\
+         var gap2 = d.addProperty('ADBE Vector Stroke Gap 2');\
+         var err = ''; try { d.addProperty('ADBE Vector Stroke Dash 9'); } catch (e) { err = e.message; }\
+         [before, dash1.matchName, d.property('ADBE Vector Stroke Dash 1').value, d.property('ADBE Vector Stroke Offset').matchName, gap2.matchName, names(d), err]",
+    );
+    assert_eq!(
+        o.result,
+        json!([
+            "ADBE Vector Stroke Dash 1,ADBE Vector Stroke Gap 1,ADBE Vector Stroke Offset",
+            "ADBE Vector Stroke Dash 1",
+            12,
+            "ADBE Vector Stroke Offset",
+            "ADBE Vector Stroke Gap 2",
+            "ADBE Vector Stroke Dash 1,ADBE Vector Stroke Gap 1,ADBE Vector Stroke Dash 2,ADBE Vector Stroke Gap 2,ADBE Vector Stroke Offset",
+            "Can not add \"ADBE Vector Stroke Dash 9\" to Dashes"
+        ])
+    );
+}
+
 #[test]
 fn script_layer_comment_and_unnamed_marker_params_round_trip() {
     let mut s = session();