Fix embedder mutation order

shell/platform/embedder/embedder_layers.cc

@@ -112,20 +112,6 @@ void EmbedderLayers::PushPlatformViewLayer(
 
     std::vector<const FlutterPlatformViewMutation*> mutations_array;
 
-    if (std::distance(mutators.Bottom(), mutators.Top()) > 0) {
-      // If there are going to be any mutations, they must first take into
-      // account the transformation for the device pixel ratio and root surface
-      // transformation.
-      auto base_xformation =
-          SkMatrix::Concat(root_surface_transformation_,
-                           SkMatrix::MakeScale(device_pixel_ratio_));
-      if (!base_xformation.isIdentity()) {
-        mutations_array.push_back(
-            mutations_referenced_.emplace_back(ConvertMutation(base_xformation))
-                .get());
-      }
-    }
-
     for (auto i = mutators.Bottom(); i != mutators.Top(); ++i) {
       const auto& mutator = *i;
       switch (mutator->GetType()) {
@@ -164,10 +150,19 @@ void EmbedderLayers::PushPlatformViewLayer(
       }
     }
 
-    if (mutations_array.size() > 0) {
+    if (!mutations_array.empty()) {
+      // If there are going to be any mutations, they must first take into
+      // account the root surface transformation.
+      if (!root_surface_transformation_.isIdentity()) {
+        mutations_array.push_back(
+            mutations_referenced_
+                .emplace_back(ConvertMutation(root_surface_transformation_))
+                .get());
+      }
+
       auto mutations =
           std::make_unique<std::vector<const FlutterPlatformViewMutation*>>(
-              mutations_array);
+              mutations_array.rbegin(), mutations_array.rend());
       mutations_arrays_referenced_.emplace_back(std::move(mutations));
 
       view.mutations_count = mutations_array.size();

shell/platform/embedder/fixtures/main.dart

@@ -662,6 +662,23 @@ void scene_builder_with_clips() {
   window.scheduleFrame();
 }
 
+@pragma('vm:entry-point')
+void scene_builder_with_complex_clips() {
+  window.onBeginFrame = (Duration duration) {
+    SceneBuilder builder = SceneBuilder();
+
+    builder.pushClipRect(Rect.fromLTRB(0.0, 0.0, 1024.0, 600.0));
+    builder.pushOffset(512.0, 0.0);
+    builder.pushClipRect(Rect.fromLTRB(0.0, 0.0, 512.0, 600.0));
+    builder.pushOffset(-256.0, 0.0);
+    builder.pushClipRect(Rect.fromLTRB(0.0, 0.0, 1024.0, 600.0));
+    builder.addPlatformView(42, width: 1024.0, height: 600.0);
+
+    builder.addPicture(Offset(0.0, 0.0), CreateGradientBox(Size(1024.0, 600.0)));
+    window.render(builder.build());
+  };
+  window.scheduleFrame();
+}
 
 void sendObjectToNativeCode(dynamic object) native 'SendObjectToNativeCode';
 

shell/platform/embedder/tests/embedder_unittests.cc

@@ -3234,7 +3234,7 @@ TEST_F(EmbedderTest, PlatformViewMutatorsAreValidWithPixelRatio) {
           FlutterPlatformView platform_view = *layers[1]->platform_view;
           platform_view.struct_size = sizeof(platform_view);
           platform_view.identifier = 42;
-          platform_view.mutations_count = 4;
+          platform_view.mutations_count = 3;
 
           FlutterLayer layer = {};
           layer.struct_size = sizeof(layer);
@@ -3369,8 +3369,7 @@ TEST_F(EmbedderTest,
               case kFlutterPlatformViewMutationTypeTransformation:
                 mutation.type = kFlutterPlatformViewMutationTypeTransformation;
                 mutation.transformation =
-                    FlutterTransformationMake(SkMatrix::Concat(
-                        root_surface_transformation, SkMatrix::MakeScale(2.0)));
+                    FlutterTransformationMake(root_surface_transformation);
 
                 break;
             }
@@ -3606,6 +3605,88 @@ TEST_F(EmbedderTest, ClipsAreCorrectlyCalculated) {
   latch.Wait();
 }
 
+TEST_F(EmbedderTest, ComplexClipsAreCorrectlyCalculated) {
+  auto& context = GetEmbedderContext();
+
+  EmbedderConfigBuilder builder(context);
+  builder.SetOpenGLRendererConfig(SkISize::Make(1024, 600));
+  builder.SetCompositor();
+  builder.SetDartEntrypoint("scene_builder_with_complex_clips");
+
+  const auto root_surface_transformation =
+      SkMatrix().preTranslate(0, 1024).preRotate(-90, 0, 0);
+
+  context.SetRootSurfaceTransformation(root_surface_transformation);
+
+  fml::AutoResetWaitableEvent latch;
+  context.GetCompositor().SetNextPresentCallback(
+      [&](const FlutterLayer** layers, size_t layers_count) {
+        ASSERT_EQ(layers_count, 3u);
+
+        {
+          FlutterPlatformView platform_view = *layers[1]->platform_view;
+          platform_view.struct_size = sizeof(platform_view);
+          platform_view.identifier = 42;
+
+          FlutterLayer layer = {};
+          layer.struct_size = sizeof(layer);
+          layer.type = kFlutterLayerContentTypePlatformView;
+          layer.platform_view = &platform_view;
+          layer.size = FlutterSizeMake(600.0, 1024.0);
+          layer.offset = FlutterPointMake(0.0, -256.0);
+
+          ASSERT_EQ(*layers[1], layer);
+
+          const auto** mutations = platform_view.mutations;
+
+          ASSERT_EQ(mutations[0]->type,
+                    kFlutterPlatformViewMutationTypeTransformation);
+          ASSERT_EQ(SkMatrixMake(mutations[0]->transformation),
+                    root_surface_transformation);
+
+          ASSERT_EQ(mutations[1]->type,
+                    kFlutterPlatformViewMutationTypeClipRect);
+          ASSERT_EQ(SkRectMake(mutations[1]->clip_rect),
+                    SkRect::MakeLTRB(0.0, 0.0, 1024.0, 600.0));
+
+          ASSERT_EQ(mutations[2]->type,
+                    kFlutterPlatformViewMutationTypeTransformation);
+          ASSERT_EQ(SkMatrixMake(mutations[2]->transformation),
+                    SkMatrix::MakeTrans(512.0, 0.0));
+
+          ASSERT_EQ(mutations[3]->type,
+                    kFlutterPlatformViewMutationTypeClipRect);
+          ASSERT_EQ(SkRectMake(mutations[3]->clip_rect),
+                    SkRect::MakeLTRB(0.0, 0.0, 512.0, 600.0));
+
+          ASSERT_EQ(mutations[4]->type,
+                    kFlutterPlatformViewMutationTypeTransformation);
+          ASSERT_EQ(SkMatrixMake(mutations[4]->transformation),
+                    SkMatrix::MakeTrans(-256.0, 0.0));
+
+          ASSERT_EQ(mutations[5]->type,
+                    kFlutterPlatformViewMutationTypeClipRect);
+          ASSERT_EQ(SkRectMake(mutations[5]->clip_rect),
+                    SkRect::MakeLTRB(0.0, 0.0, 1024.0, 600.0));
+        }
+
+        latch.Signal();
+      });
+
+  auto engine = builder.LaunchEngine();
+  ASSERT_TRUE(engine.is_valid());
+
+  FlutterWindowMetricsEvent event = {};
+  event.struct_size = sizeof(event);
+  event.width = 400;
+  event.height = 300;
+  event.pixel_ratio = 1.0;
+  ASSERT_EQ(FlutterEngineSendWindowMetricsEvent(engine.get(), &event),
+            kSuccess);
+
+  latch.Wait();
+}
+
 TEST_F(EmbedderTest, ObjectsCanBePostedViaPorts) {
   auto& context = GetEmbedderContext();
   EmbedderConfigBuilder builder(context);