Symbols: Reset Transformation's enabled check does not measure the symbol's art

crates/engine/src/cmd.rs

@@ -722,9 +722,9 @@ pub use pathops::shape_count;
 /// The gaps View › Show Live Paint Gaps shows on a Live Paint group.
 pub use buildcmds::live_paint_gaps;
 
-/// The transform Reset Transformation gives a symbol instance (the Symbols panel menu and the
-/// Control bar enable it when there is one).
-pub use brushsym::reset_transformation;
+/// Whether Reset Transformation changes a symbol instance (the Symbols panel menu and the
+/// Control bar enable it when it changes one).
+pub use brushsym::reset_transformation_changes;
 
 /// Command ids kept only so older scripts keep working: `(alias, the command it duplicates)`.
 /// They run as before but the command palette leaves them out (it lists the command once).

crates/engine/src/cmd/brushsym.rs

@@ -24,8 +24,8 @@ use super::{
 };
 use crate::EngineError;
 
-/// The transform Reset Transformation gives a symbol instance.
-pub use symbols::reset_transformation;
+/// Whether Reset Transformation changes a symbol instance.
+pub use symbols::reset_transformation_changes;
 
 mod brushes;
 mod dynamic;

crates/engine/src/cmd/brushsym/symbols.rs

@@ -702,22 +702,32 @@ const RESET_TOLERANCE: f64 = 1e-9;
 
 /// The transform Reset Transformation gives instance `n` of the document of `boxes`: its symbol's
 /// own scale, without rotation, shear or reflection, with the center of its art's bounding box
-/// where it is. `None` when `n` is not an instance of a symbol the document holds, is in
-/// perspective, or already has that transform.
-pub fn reset_transformation(boxes: &vectorcraft_doc::SymbolBoxes, n: &Node) -> Option<Affine> {
+/// where it is. `None` when [`reset_transformation_changes`] is false for `n`.
+fn reset_transformation(boxes: &vectorcraft_doc::SymbolBoxes, n: &Node) -> Option<Affine> {
     let d = boxes.document();
-    let NodeKind::SymbolInstance { symbol, xf } = &n.kind else { return None };
-    if n.extras().perspective.is_some() || !d.symbols.iter().any(|s| s.name == *symbol) {
+    if !reset_transformation_changes(d, n) {
         return None;
     }
-    // The symbol's stored natural size, or the art unscaled when that size is not positive and finite.
+    let NodeKind::SymbolInstance { symbol, xf } = &n.kind else { return None };
     let scale = d.symbol_natural_xf(symbol);
     // The art's box in symbol space (the ±HALF square when the art cannot be measured): its
     // center keeps its place on the page.
     let art = boxes.art_bounds(symbol).unwrap_or_else(|| vectorcraft_geom::Rect::new(-HALF, -HALF, HALF, HALF));
     let center = xf.transform_rect_bbox(art).center();
-    let new = Affine::translate(center - scale * art.center()) * scale;
-    xf.as_coeffs().iter().zip(new.as_coeffs()).any(|(a, b)| (a - b).abs() > RESET_TOLERANCE).then_some(new)
+    Some(Affine::translate(center - scale * art.center()) * scale)
+}
+
+/// Does Reset Transformation change `n`? True for an instance of a symbol `d` holds, not in
+/// perspective, whose scale, rotation, shear or reflection differs from the symbol's own scale
+/// (its stored natural size, or the art unscaled when that size is not positive and finite).
+/// It does not measure the art.
+pub fn reset_transformation_changes(d: &Document, n: &Node) -> bool {
+    let NodeKind::SymbolInstance { symbol, xf } = &n.kind else { return false };
+    if n.extras().perspective.is_some() || !d.symbols.iter().any(|s| s.name == *symbol) {
+        return false;
+    }
+    let natural = d.symbol_natural_xf(symbol).as_coeffs();
+    xf.as_coeffs()[..4].iter().zip(&natural[..4]).any(|(a, b)| (a - b).abs() > RESET_TOLERANCE)
 }
 
 pub(super) fn symbol_instance_reset_transform(s: &mut Session, p: &Value) -> Result<Value> {

crates/ui-egui/src/panels/symbols.rs

@@ -164,8 +164,7 @@ pub(crate) fn changed_instances_selected(app: &VectorcraftApp) -> bool {
 /// symbol's, which Reset Transformation restores?
 fn transformed_instances_selected(app: &VectorcraftApp) -> bool {
     let Some(doc) = app.session.active().map(|st| st.doc.clone()) else { return false };
-    let boxes = doc.symbol_boxes();
-    instance_selected(app, |c| vectorcraft_engine::cmd::reset_transformation(&boxes, c).is_some())
+    instance_selected(app, |c| vectorcraft_engine::cmd::reset_transformation_changes(&doc, c))
 }
 
 /// The symbols of the selected objects when every one is a symbol instance; `None` otherwise.