From df13bef195ecdc9a9409aa3c8531e181f389fbfd Mon Sep 17 00:00:00 2001
From: Jackson Gardner <jacksongardner@google.com>
Date: Fri, 23 Feb 2024 14:52:02 -0800
Subject: [PATCH] Correctly offset the cull rect of the opacity layer.

This fixes https://github.com/flutter/flutter/issues/140999.
---
 lib/web_ui/lib/src/engine/layers.dart      | 1 +
 lib/web_ui/test/ui/scene_builder_test.dart | 6 +++---
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/lib/web_ui/lib/src/engine/layers.dart b/lib/web_ui/lib/src/engine/layers.dart
index e5b52f762779a..7d6940be76be5 100644
--- a/lib/web_ui/lib/src/engine/layers.dart
+++ b/lib/web_ui/lib/src/engine/layers.dart
@@ -283,6 +283,7 @@ class OpacityOperation implements LayerOperation {
     if (offset != ui.Offset.zero) {
       canvas.save();
       canvas.translate(offset.dx, offset.dy);
+      cullRect = cullRect.shift(-offset);
     }
     canvas.saveLayer(
       cullRect,
diff --git a/lib/web_ui/test/ui/scene_builder_test.dart b/lib/web_ui/test/ui/scene_builder_test.dart
index 7bd8463c5ced0..fee4e87e6b74a 100644
--- a/lib/web_ui/test/ui/scene_builder_test.dart
+++ b/lib/web_ui/test/ui/scene_builder_test.dart
@@ -124,16 +124,16 @@ Future<void> testMain() async {
         );
       }));
 
-      sceneBuilder.pushOpacity(0x7F);
+      sceneBuilder.pushOpacity(0x7F, offset: const ui.Offset(150, 150));
       sceneBuilder.addPicture(ui.Offset.zero, drawPicture((ui.Canvas canvas) {
         final ui.Paint paint = ui.Paint()..color = const ui.Color(0xFFFF0000);
         canvas.drawCircle(
-          const ui.Offset(125, 150),
+          const ui.Offset(-25, 0),
           50,
           paint
         );
         canvas.drawCircle(
-          const ui.Offset(175, 150),
+          const ui.Offset(25, 0),
           50,
           paint
         );