From 36a5a0f55f2a71eeac9f91dcafe497e99fd6fc6b Mon Sep 17 00:00:00 2001
From: Dan Field <dnfield@google.com>
Date: Mon, 19 Sep 2022 13:11:47 -0700
Subject: [PATCH] Avoid sending zero transform semantic nodes to the engine
 (#111843)

---
 .../flutter/lib/src/rendering/object.dart     |  2 +-
 .../flutter/test/widgets/semantics_test.dart  | 27 +++++++++++++++++++
 2 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/packages/flutter/lib/src/rendering/object.dart b/packages/flutter/lib/src/rendering/object.dart
index 7f9dda15a55..f61aeb21fcf 100644
--- a/packages/flutter/lib/src/rendering/object.dart
+++ b/packages/flutter/lib/src/rendering/object.dart
@@ -4433,7 +4433,7 @@ class _SemanticsGeometry {
   /// by this object can be dropped from the semantics tree without losing
   /// semantics information.
   bool get dropFromTree {
-    return _rect.isEmpty;
+    return _rect.isEmpty || _transform.isZero();
   }
 
   /// Whether the [SemanticsNode] annotated with the geometric information
diff --git a/packages/flutter/test/widgets/semantics_test.dart b/packages/flutter/test/widgets/semantics_test.dart
index bdadfee6b96..fa84dce6849 100644
--- a/packages/flutter/test/widgets/semantics_test.dart
+++ b/packages/flutter/test/widgets/semantics_test.dart
@@ -1632,6 +1632,33 @@ void main() {
       textDirection: TextDirection.ltr,
     ));
   });
+
+  testWidgets('Semantics with zero transform gets dropped', (WidgetTester tester) async {
+    // Regression test for https://github.com/flutter/flutter/issues/110671.
+    // Construct a widget tree that will end up with a fitted box that applies
+    // a zero transform because it does not actually draw its children.
+    // Assert that this subtree gets dropped (the root node has no children).
+    await tester.pumpWidget(Column(
+      children: <Widget>[
+        SizedBox(
+          height: 0,
+          width: 500,
+          child: FittedBox(
+            child: SizedBox(
+              height: 55,
+              width: 266,
+              child: SingleChildScrollView(child: Column()),
+            ),
+          ),
+        ),
+      ],
+    ));
+
+    final SemanticsNode node = RendererBinding.instance.renderView.debugSemantics!;
+
+    expect(node.transform, null); // Make sure the zero transform didn't end up on the root somehow.
+    expect(node.childrenCount, 0);
+  });
 }
 
 class CustomSortKey extends OrdinalSortKey {