From 05190d6b591dab0187edcbe8f54c1c83d9276278 Mon Sep 17 00:00:00 2001
From: Daniel McNab <36049421+DJMcNab@users.noreply.github.com>
Date: Fri, 17 Jan 2025 16:26:40 +0000
Subject: [PATCH] Expose `transform_has_changed` and use that instead

---
 masonry/src/contexts.rs     | 9 +++++++++
 xilem/src/view/transform.rs | 6 ++----
 2 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/masonry/src/contexts.rs b/masonry/src/contexts.rs
index 1a4d8efd4..3d9dbcfc0 100644
--- a/masonry/src/contexts.rs
+++ b/masonry/src/contexts.rs
@@ -236,6 +236,15 @@ impl MutateCtx<'_> {
             widget_children: self.widget_children.reborrow_mut(),
         }
     }
+
+    /// Whether the (local) transform of this widget has been modified since
+    /// the last time this widget's transformation was resolved.
+    ///
+    /// This is exposed for Xilem, and is more likely to change or be removed
+    /// in major releases of Masonry.
+    pub fn transform_has_changed(&self) -> bool {
+        self.widget_state.transform_changed
+    }
 }
 
 // --- MARK: WIDGET_REF ---
diff --git a/xilem/src/view/transform.rs b/xilem/src/view/transform.rs
index 5af650f86..8a2e974eb 100644
--- a/xilem/src/view/transform.rs
+++ b/xilem/src/view/transform.rs
@@ -115,16 +115,14 @@ where
         ctx: &mut ViewCtx,
         mut element: xilem_core::Mut<'_, Self::Element>,
     ) {
-        let initial_transform = element.ctx.transform();
         self.child.rebuild(
             &prev.child,
             &mut view_state.child,
             ctx,
             element.reborrow_mut(),
         );
-        let transform_changed = element.ctx.transform() != initial_transform;
-        // We detect a child view changing the transform by comparing the
-        // resulting transform before and after the child view runs.
+        let transform_changed = element.ctx.transform_has_changed();
+        // If the child view changed the transform, we know we're out of date.
         if transform_changed {
             // If it has changed the transform, then we know that it will only be due to effects
             // "below us" (that is, it will have restarted from scratch).