Use the new pushImageFilter offset parameter to fix the transform of the children (flutter#113673) (flutter#115884)

Author: flar

packages/flutter/lib/src/rendering/layer.dart

@@ -1816,13 +1816,14 @@ class ColorFilterLayer extends ContainerLayer {
 }
 
 /// A composite layer that applies an [ImageFilter] to its children.
-class ImageFilterLayer extends ContainerLayer {
+class ImageFilterLayer extends OffsetLayer {
   /// Creates a layer that applies an [ImageFilter] to its children.
   ///
   /// The [imageFilter] property must be non-null before the compositing phase
   /// of the pipeline.
   ImageFilterLayer({
     ui.ImageFilter? imageFilter,
+    super.offset,
   }) : _imageFilter = imageFilter;
 
   /// The image filter to apply to children.
@@ -1844,6 +1845,7 @@ class ImageFilterLayer extends ContainerLayer {
     assert(imageFilter != null);
     engineLayer = builder.pushImageFilter(
       imageFilter!,
+      offset: offset,
       oldLayer: _engineLayer as ui.ImageFilterEngineLayer?,
     );
     addChildrenToScene(builder);

packages/flutter/lib/src/widgets/image_filter.dart

@@ -105,12 +105,13 @@ class _ImageFilterRenderObject extends RenderProxyBox {
     }
 
     if (layer == null) {
-      layer = ImageFilterLayer(imageFilter: imageFilter);
+      layer = ImageFilterLayer(imageFilter: imageFilter, offset: offset);
     } else {
       final ImageFilterLayer filterLayer = layer! as ImageFilterLayer;
       filterLayer.imageFilter = imageFilter;
+      filterLayer.offset = offset;
     }
-    context.pushLayer(layer!, super.paint, offset);
+    context.pushLayer(layer!, super.paint, Offset.zero);
     assert(() {
       layer!.debugCreator = debugCreator;
       return true;

packages/flutter/test/widgets/image_filter_test.dart

@@ -6,6 +6,7 @@
 // machines.
 @Tags(<String>['reduced-test-set'])
 
+import 'dart:math';
 import 'dart:ui';
 
 import 'package:flutter/foundation.dart';
@@ -29,6 +30,24 @@ void main() {
     );
   });
 
+  testWidgets('Image filter - blur with offset', (WidgetTester tester) async {
+    await tester.pumpWidget(
+      RepaintBoundary(
+        child: Transform.translate(
+          offset: const Offset(50, 50),
+          child: ImageFiltered(
+            imageFilter: ImageFilter.blur(sigmaX: 3.0, sigmaY: 3.0),
+            child: const Placeholder(),
+          ),
+        ),
+      ),
+    );
+    await expectLater(
+      find.byType(ImageFiltered),
+      matchesGoldenFile('image_filter_blur_offset.png'),
+    );
+  });
+
   testWidgets('Image filter - dilate', (WidgetTester tester) async {
     await tester.pumpWidget(
       RepaintBoundary(
@@ -97,6 +116,42 @@ void main() {
     );
   });
 
+  testWidgets('Image filter - matrix with offset', (WidgetTester tester) async {
+    final Matrix4 matrix = Matrix4.rotationZ(pi / 18);
+    final ImageFilter matrixFilter = ImageFilter.matrix(matrix.storage);
+    await tester.pumpWidget(
+      RepaintBoundary(
+        child: Transform.translate(
+          offset: const Offset(50, 50),
+          child: ImageFiltered(
+            imageFilter: matrixFilter,
+            child: MaterialApp(
+              title: 'Flutter Demo',
+              theme: ThemeData(primarySwatch: Colors.blue),
+              home: Scaffold(
+                appBar: AppBar(
+                  title: const Text('Matrix ImageFilter Test'),
+                ),
+                body: const Center(
+                  child:Text('Hooray!'),
+                ),
+                floatingActionButton: FloatingActionButton(
+                  onPressed: () { },
+                  tooltip: 'Increment',
+                  child: const Icon(Icons.add),
+                ),
+              ),
+            ),
+          ),
+        ),
+      ),
+    );
+    await expectLater(
+      find.byType(ImageFiltered),
+      matchesGoldenFile('image_filter_matrix_offset.png'),
+    );
+  });
+
   testWidgets('Image filter - reuses its layer', (WidgetTester tester) async {
     Future<void> pumpWithSigma(double sigma) async {
       await tester.pumpWidget(