#1063: return the text animator property a script asked for

addProperty("ADBE Text Tracking Amount") returned the first property added to the animator, which is
the Tracking Type companion, so the script changed the wrong value. The engine now reports the
requested property's position in the Properties group, and the script returns that property. An
animator's Properties group also finds its properties by their After Effects names, such as
ADBE Text Tracking Amount, which the name table already had in the other direction. A regression
test checks the property returned, its value, and the lookup by name.

Not covered: the Advanced and Wiggly selector children and the Expression amount, which still keep
their own names.

Co-Authored-By: Claude Haiku 5.5 <noreply@anthropic.com>

crates/engine/src/commands/text_anim.rs

@@ -139,6 +139,7 @@ fn add_animator_prop(s: &mut Session, p: &Value) -> Result<Value> {
     }
     let layer = s.project.comp(cid).and_then(|c| c.layer(lid)).cloned().ok_or_else(|| bad(C, "no layer"))?;
     let auid = animator_uid(s, &layer, p, C)?;
+    let mut index = 0;
     s.edit("Add Text Animator Property", None, |proj, _| {
         let mut next = proj.next_id;
         let mut ids = Ids(&mut next);
@@ -148,10 +149,13 @@ fn add_animator_prop(s: &mut Session, p: &Value) -> Result<Value> {
         for k in &kinds {
             add_props(&mut ids, anim, k, three);
         }
+        // The requested property's 1-based position in the Properties group. A companion (such as
+        // Tracking Type) is added before it, so the first new child is not always the one asked for.
+        index = kinds.first().and_then(|k| anim.sub("properties")?.children.iter().position(|n| n.match_id() == k.as_str())).map_or(0, |i| i + 1);
         proj.next_id = next;
         Ok(())
     })?;
-    Ok(json!({"animator": auid}))
+    Ok(json!({"animator": auid, "index": index}))
 }
 
 pub(crate) fn add_selector(s: &mut Session, p: &Value) -> Result<Value> {

crates/script/src/model.rs

@@ -415,11 +415,14 @@ fn find_child<'a>(l: &'a Layer, g: &'a PropGroup, k: &str, depth: u8) -> Option<
         matchnames::node(&ch)
     };
     let lk = loose(k);
+    // An animator's Properties group also answers to the After Effects names of its properties.
+    let animator_props = g.match_id == "properties";
     g.children
         .iter()
         .find(|n| chain_of(n) == k)
         .or_else(|| g.children.iter().find(|n| n.name() == k))
         .or_else(|| g.children.iter().find(|n| n.match_id() == k))
+        .or_else(|| g.children.iter().find(|n| animator_props && animator_property_match_name(n.match_id()) == Some(k)))
         .or_else(|| g.children.iter().find(|n| n.name().eq_ignore_ascii_case(k)))
         .or_else(|| g.children.iter().find(|n| loose(n.name()) == lk || loose(n.match_id()) == lk))
         .or_else(|| alias(&lk).and_then(|m| g.children.iter().find(|n| n.match_id() == m)))
@@ -671,10 +674,9 @@ fn resolve_add(s: &Session, a: &J) -> R {
     })
 }
 
-/// A text animator property (`layer.addTextAnimatorProperty` key) from an After Effects match
-/// name or a display name.
-fn text_animator_property(name: &str) -> Option<&'static str> {
-    const AE: &[(&str, &str)] = &[
+/// The After Effects match name and key of each text animator property.
+fn animator_property_table() -> &'static [(&'static str, &'static str)] {
+    &[
         ("ADBE Text Anchor Point 3D", "anchor"),
         ("ADBE Text Position 3D", "position"),
         ("ADBE Text Scale 3D", "scale"),
@@ -698,12 +700,24 @@ fn text_animator_property(name: &str) -> Option<&'static str> {
         ("ADBE Text Character Offset", "characterOffset"),
         ("ADBE Text Character Replace", "characterValue"),
         ("ADBE Text Blur", "blur"),
-    ];
-    if let Some((_, k)) = AE.iter().find(|(m, _)| m.eq_ignore_ascii_case(name)) {
+    ]
+}
+
+/// A text animator property (`layer.addTextAnimatorProperty` key) from an After Effects match
+/// name or a display name.
+fn text_animator_property(name: &str) -> Option<&'static str> {
+    let table = animator_property_table();
+    if let Some((_, k)) = table.iter().find(|(m, _)| m.eq_ignore_ascii_case(name)) {
         return Some(k);
     }
     let n = loose(name);
-    AE.iter().map(|(_, k)| *k).find(|k| loose(k) == n || (n == "anchorpoint" && *k == "anchor") || (n == "trackingamount" && *k == "tracking"))
+    table.iter().map(|(_, k)| *k).find(|k| loose(k) == n || (n == "anchorpoint" && *k == "anchor") || (n == "trackingamount" && *k == "tracking"))
+}
+
+/// The After Effects match name of a text animator property key (`tracking` is
+/// `ADBE Text Tracking Amount`), for scripts that look a property up by that name (#1063).
+fn animator_property_match_name(key: &str) -> Option<&'static str> {
+    animator_property_table().iter().find(|(_, k)| *k == key).map(|(m, _)| *m)
 }
 
 /// `app.findMenuCommandId(name)`: 1-based index of the command whose label matches (menu items

crates/script/src/prelude.js

@@ -718,9 +718,8 @@ PropertyGroup.prototype.addProperty = function (name) {
   } else if (r.kind === "animator") {
     uid = __call("layer.addTextAnimator", { comp: L.__comp, layer: L.__id, properties: [] }).animator;
   } else if (r.kind === "animatorProperty") {
-    var before = this.numProperties;
-    __call("layer.addTextAnimatorProperty", { comp: L.__comp, layer: L.__id, animator: r.animator, property: r.property });
-    return this.property(before + 1);
+    var added = __call("layer.addTextAnimatorProperty", { comp: L.__comp, layer: L.__id, animator: r.animator, property: r.property });
+    return this.property(added.index);
   } else if (r.kind === "selector") {
     var n0 = this.numProperties;
     __call("layer.addTextSelector", { comp: L.__comp, layer: L.__id, animator: r.animator, kind: r.selector });

crates/script/src/tests.rs

@@ -1028,3 +1028,23 @@ fn scripted_levels_alpha_controls_resolve_from_the_effect() {
     );
     assert_eq!(o.result, json!([0.5, 0.5]));
 }
+
+/// A text animator property added by its After Effects name is the one asked for, not its Tracking
+/// Type companion, and it can be found again by that name (#1063).
+#[test]
+fn scripted_text_animator_property_is_the_one_asked_for() {
+    let mut s = session();
+    let o = ok(
+        &mut s,
+        r#"
+        var c = app.project.items.addComp("Track", 960, 300, 1, 3, 30);
+        var t = c.layers.addText("MOVARA");
+        var a = t.property("ADBE Text Properties").property("ADBE Text Animators").addProperty("ADBE Text Animator");
+        var props = a.property("ADBE Text Animator Properties");
+        var added = props.addProperty("ADBE Text Tracking Amount");
+        added.setValue(20);
+        [added.name, props.property("ADBE Text Tracking Amount").value, props.property("ADBE Text Tracking Amount").name]
+        "#,
+    );
+    assert_eq!(o.result, json!(["Tracking Amount", 20, "Tracking Amount"]));
+}