#2817: Closed fits short tangent lists like mask.setClosed

crates/engine/src/cmd/paths/closed.rs

@@ -120,6 +120,8 @@ pub(super) fn toggle_closed(s: &mut Session, _: &Value) -> Result<Value> {
             if path.closed == closed {
                 continue;
             }
+            // As `mask.setClosed`: a path read from a file may have fewer tangents than vertices (#1250).
+            path.fit_tangents();
             path.closed = closed;
             if roto {
                 super::roto_smooth(&mut path);

crates/engine/src/tests/viewer.rs

@@ -527,6 +527,25 @@ fn toggle_closed_recomputes_roto_bezier_tangents() {
     assert_eq!(path(&s), closed, "reclosing restores the closed RotoBezier tangents");
 }
 
+#[test]
+fn toggle_closed_fits_short_tangent_lists_like_set_closed() {
+    let mut s = comp();
+    let lid = s.execute("layer.newSolid", json!({})).unwrap()["layer"].as_u64().unwrap();
+    let uid = s.execute("mask.new", json!({"layer": lid, "vertices": [[0, 0], [100, 0], [100, 100]], "closed": true})).unwrap()["mask"].as_u64().unwrap();
+    let cid = s.active_comp_id().unwrap();
+    let layer_mut = std::sync::Arc::make_mut(&mut s.project).comp_mut(cid).unwrap().layer_mut(LayerId(lid)).unwrap();
+    let prop = layer_mut.props.find_group_mut(uid).unwrap().get_mut("path").unwrap();
+    let KV::Path(path) = &mut prop.value else { panic!("not a path") };
+    // A file can store fewer tangents than vertices (#1250).
+    path.in_tangents.clear();
+    path.out_tangents.truncate(1);
+    s.state.selected_props = vec![(LayerId(lid), uid)];
+    s.execute("path.toggleClosed", json!({})).unwrap();
+    let path = layer(&s, lid).props.find_group(uid).unwrap().get("path").unwrap().value.as_path().unwrap().clone();
+    assert!(!path.closed);
+    assert_eq!((path.in_tangents.len(), path.out_tangents.len()), (3, 3));
+}
+
 #[test]
 fn toggle_closed_edits_layer_time_and_roundtrips() {
     use effectcraft_keyframe::Keyframe;