Re-land "Custom compositor layers must take into account the device pixel ratio."

This reverts commit 6c2381da and applies iOS fixes.

flow/embedded_views.h

@@ -208,7 +208,9 @@ class ExternalViewEmbedder {
   // sets the stage for the next pre-roll.
   virtual void CancelFrame() = 0;
 
-  virtual void BeginFrame(SkISize frame_size, GrContext* context) = 0;
+  virtual void BeginFrame(SkISize frame_size,
+                          GrContext* context,
+                          double device_pixel_ratio) = 0;
 
   virtual void PrerollCompositeEmbeddedView(
       int view_id,

flow/layers/layer_tree.h

@@ -71,8 +71,15 @@ class LayerTree {
     checkerboard_offscreen_layers_ = checkerboard;
   }
 
+  void set_device_pixel_ratio(double device_pixel_ratio) {
+    device_pixel_ratio_ = device_pixel_ratio;
+  }
+
+  double device_pixel_ratio() const { return device_pixel_ratio_; }
+
  private:
   SkISize frame_size_ = SkISize::MakeEmpty();  // Physical pixels.
+  double device_pixel_ratio_ = 1.0;
   std::shared_ptr<Layer> root_layer_;
   fml::TimePoint build_start_;
   fml::TimePoint build_finish_;

shell/common/engine.cc

@@ -438,6 +438,7 @@ void Engine::Render(std::unique_ptr<flutter::LayerTree> layer_tree) {
     return;
 
   layer_tree->set_frame_size(frame_size);
+  layer_tree->set_device_pixel_ratio(viewport_metrics_.device_pixel_ratio);
   animator_->Render(std::move(layer_tree));
 }
 

shell/common/rasterizer.cc

@@ -230,7 +230,8 @@ RasterStatus Rasterizer::DrawToSurface(flutter::LayerTree& layer_tree) {
 
   if (external_view_embedder != nullptr) {
     external_view_embedder->BeginFrame(layer_tree.frame_size(),
-                                       surface_->GetContext());
+                                       surface_->GetContext(),
+                                       layer_tree.device_pixel_ratio());
     embedder_root_surface = external_view_embedder->GetRootSurface();
   }
 

shell/platform/darwin/ios/ios_surface_gl.h

@@ -60,7 +60,7 @@ class IOSSurfaceGL final : public IOSSurface,
   void CancelFrame() override;
 
   // |ExternalViewEmbedder|
-  void BeginFrame(SkISize frame_size, GrContext* context) override;
+  void BeginFrame(SkISize frame_size, GrContext* context, double device_pixel_ratio) override;
 
   // |ExternalViewEmbedder|
   void PrerollCompositeEmbeddedView(int view_id,

shell/platform/darwin/ios/ios_surface_gl.mm

@@ -100,7 +100,7 @@ void IOSSurfaceGL::CancelFrame() {
 }
 
 // |ExternalViewEmbedder|
-void IOSSurfaceGL::BeginFrame(SkISize frame_size, GrContext* context) {
+void IOSSurfaceGL::BeginFrame(SkISize frame_size, GrContext* context, double device_pixel_ratio) {
   FlutterPlatformViewsController* platform_views_controller = GetPlatformViewsController();
   FML_CHECK(platform_views_controller != nullptr);
   platform_views_controller->SetFrameSize(frame_size);

shell/platform/darwin/ios/ios_surface_metal.h

@@ -48,7 +48,7 @@ class IOSSurfaceMetal final : public IOSSurface,
   void CancelFrame() override;
 
   // |ExternalViewEmbedder|
-  void BeginFrame(SkISize frame_size, GrContext* context) override;
+  void BeginFrame(SkISize frame_size, GrContext* context, double device_pixel_ratio) override;
 
   // |ExternalViewEmbedder|
   void PrerollCompositeEmbeddedView(int view_id,

shell/platform/darwin/ios/ios_surface_metal.mm

@@ -61,7 +61,9 @@ void IOSSurfaceMetal::CancelFrame() {
   [CATransaction commit];
 }
 
-void IOSSurfaceMetal::BeginFrame(SkISize frame_size, GrContext* context) {
+void IOSSurfaceMetal::BeginFrame(SkISize frame_size,
+                                 GrContext* context,
+                                 double device_pixel_ratio) {
   FlutterPlatformViewsController* platform_views_controller = GetPlatformViewsController();
   FML_CHECK(platform_views_controller != nullptr);
   platform_views_controller->SetFrameSize(frame_size);

shell/platform/darwin/ios/ios_surface_software.h

@@ -52,7 +52,7 @@ class IOSSurfaceSoftware final : public IOSSurface,
   void CancelFrame() override;
 
   // |ExternalViewEmbedder|
-  void BeginFrame(SkISize frame_size, GrContext* context) override;
+  void BeginFrame(SkISize frame_size, GrContext* context, double device_pixel_ratio) override;
 
   // |ExternalViewEmbedder|
   void PrerollCompositeEmbeddedView(int view_id,

shell/platform/darwin/ios/ios_surface_software.mm

@@ -150,7 +150,9 @@ void IOSSurfaceSoftware::CancelFrame() {
 }
 
 // |ExternalViewEmbedder|
-void IOSSurfaceSoftware::BeginFrame(SkISize frame_size, GrContext* context) {
+void IOSSurfaceSoftware::BeginFrame(SkISize frame_size,
+                                    GrContext* context,
+                                    double device_pixel_ratio) {
   FlutterPlatformViewsController* platform_views_controller = GetPlatformViewsController();
   FML_CHECK(platform_views_controller != nullptr);
   platform_views_controller->SetFrameSize(frame_size);

shell/platform/embedder/embedder.cc

@@ -984,6 +984,12 @@ FlutterEngineResult FlutterEngineSendWindowMetricsEvent(
   metrics.physical_height = SAFE_ACCESS(flutter_metrics, height, 0.0);
   metrics.device_pixel_ratio = SAFE_ACCESS(flutter_metrics, pixel_ratio, 1.0);
 
+  if (metrics.device_pixel_ratio <= 0.0) {
+    FML_LOG(ERROR) << "Device pixel ratio invalid: "
+                   << metrics.device_pixel_ratio;
+    return LOG_EMBEDDER_ERROR(kInvalidArguments);
+  }
+
   return reinterpret_cast<flutter::EmbedderEngine*>(engine)->SetViewportMetrics(
              std::move(metrics))
              ? kSuccess

shell/platform/embedder/embedder_external_view_embedder.cc

@@ -67,9 +67,12 @@ static SkISize TransformedSurfaceSize(const SkISize& size,
 
 // |ExternalViewEmbedder|
 void EmbedderExternalViewEmbedder::BeginFrame(SkISize frame_size,
-                                              GrContext* context) {
+                                              GrContext* context,
+                                              double device_pixel_ratio) {
   Reset();
+
   pending_frame_size_ = frame_size;
+  pending_device_pixel_ratio_ = device_pixel_ratio;
   pending_surface_transformation_ = GetSurfaceTransformation();
 
   const auto surface_size = TransformedSurfaceSize(
@@ -155,7 +158,8 @@ SkCanvas* EmbedderExternalViewEmbedder::CompositeEmbeddedView(int view_id) {
 static FlutterLayer MakeBackingStoreLayer(
     const SkISize& frame_size,
     const FlutterBackingStore* store,
-    const SkMatrix& surface_transformation) {
+    const SkMatrix& surface_transformation,
+    double device_pixel_ratio) {
   FlutterLayer layer = {};
 
   layer.struct_size = sizeof(layer);
@@ -166,7 +170,9 @@ static FlutterLayer MakeBackingStoreLayer(
       SkRect::MakeWH(frame_size.width(), frame_size.height());
 
   const auto transformed_layer_bounds =
-      surface_transformation.mapRect(layer_bounds);
+      SkMatrix::Concat(surface_transformation,
+                       SkMatrix::MakeScale(device_pixel_ratio))
+          .mapRect(layer_bounds);
 
   layer.offset.x = transformed_layer_bounds.x();
   layer.offset.y = transformed_layer_bounds.y();
@@ -190,7 +196,8 @@ static FlutterPlatformView MakePlatformView(
 static FlutterLayer MakePlatformViewLayer(
     const EmbeddedViewParams& params,
     const FlutterPlatformView& platform_view,
-    const SkMatrix& surface_transformation) {
+    const SkMatrix& surface_transformation,
+    double device_pixel_ratio) {
   FlutterLayer layer = {};
 
   layer.struct_size = sizeof(layer);
@@ -204,7 +211,9 @@ static FlutterLayer MakePlatformViewLayer(
   );
 
   const auto transformed_layer_bounds =
-      surface_transformation.mapRect(layer_bounds);
+      SkMatrix::Concat(surface_transformation,
+                       SkMatrix::MakeScale(device_pixel_ratio))
+          .mapRect(layer_bounds);
 
   layer.offset.x = transformed_layer_bounds.x();
   layer.offset.y = transformed_layer_bounds.y();
@@ -235,8 +244,11 @@ bool EmbedderExternalViewEmbedder::SubmitFrame(GrContext* context) {
   {
     // The root surface is expressed as a layer.
     presented_layers.push_back(MakeBackingStoreLayer(
-        pending_frame_size_, root_render_target_->GetBackingStore(),
-        pending_surface_transformation_));
+        pending_frame_size_,                     // frame size
+        root_render_target_->GetBackingStore(),  // backing store
+        pending_surface_transformation_,         // surface transformation
+        pending_device_pixel_ratio_              // device pixel ratio
+        ));
   }
 
   const auto surface_size = TransformedSurfaceSize(
@@ -262,9 +274,12 @@ bool EmbedderExternalViewEmbedder::SubmitFrame(GrContext* context) {
     // The layers presented to the embedder will contain a back pointer to this
     // struct. It is safe to deallocate when the embedder callback is done.
     presented_platform_views[view_id] = MakePlatformView(view_id);
-    presented_layers.push_back(
-        MakePlatformViewLayer(params, presented_platform_views.at(view_id),
-                              pending_surface_transformation_));
+    presented_layers.push_back(MakePlatformViewLayer(
+        params,                                // embedded view params
+        presented_platform_views.at(view_id),  // platform view
+        pending_surface_transformation_,       // surface transformation
+        pending_device_pixel_ratio_            // device pixel ratio
+        ));
 
     if (!pending_canvas_spies_.at(view_id)->DidDrawIntoCanvas()) {
       // Nothing was drawn into the overlay canvas, we don't need to composite
@@ -312,8 +327,11 @@ bool EmbedderExternalViewEmbedder::SubmitFrame(GrContext* context) {
     // Indicate a layer for the backing store containing contents rendered by
     // Flutter.
     presented_layers.push_back(MakeBackingStoreLayer(
-        pending_frame_size_, render_target->GetBackingStore(),
-        pending_surface_transformation_));
+        pending_frame_size_,               // frame size
+        render_target->GetBackingStore(),  // backing store
+        pending_surface_transformation_,   // surface transformation
+        pending_device_pixel_ratio_        // device pixel ratio
+        ));
   }
 
   {

shell/platform/embedder/embedder_external_view_embedder.h

@@ -73,7 +73,9 @@ class EmbedderExternalViewEmbedder final : public ExternalViewEmbedder {
   void CancelFrame() override;
 
   // |ExternalViewEmbedder|
-  void BeginFrame(SkISize frame_size, GrContext* context) override;
+  void BeginFrame(SkISize frame_size,
+                  GrContext* context,
+                  double device_pixel_ratio) override;
 
   // |ExternalViewEmbedder|
   void PrerollCompositeEmbeddedView(
@@ -127,6 +129,7 @@ class EmbedderExternalViewEmbedder final : public ExternalViewEmbedder {
                                       RegistryKey::Equal>;
 
   SkISize pending_frame_size_ = SkISize::Make(0, 0);
+  double pending_device_pixel_ratio_ = 1.0;
   SkMatrix pending_surface_transformation_;
   std::map<ViewIdentifier, std::unique_ptr<SkPictureRecorder>>
       pending_recorders_;

shell/platform/embedder/fixtures/main.dart

@@ -430,3 +430,16 @@ void verify_b141980393() {
   };
   window.scheduleFrame();
 }
+
+@pragma('vm:entry-point')
+void can_display_platform_view_with_pixel_ratio() {
+  window.onBeginFrame = (Duration duration) {
+    SceneBuilder builder = SceneBuilder();
+    builder.pushOffset(0.0, 20.0);
+    builder.addPlatformView(42, width: 400.0, height: 280.0);
+    builder.addPicture(Offset(0.0, 0.0), CreateSimplePicture());
+    builder.pop();
+    window.render(builder.build());
+  };
+  window.scheduleFrame();
+}

shell/platform/embedder/tests/embedder_unittests.cc

@@ -652,6 +652,7 @@ TEST_F(EmbedderTest, CompositorMustBeAbleToRenderToOpenGLFramebuffer) {
   event.struct_size = sizeof(event);
   event.width = 800;
   event.height = 600;
+  event.pixel_ratio = 1.0;
   ASSERT_EQ(FlutterEngineSendWindowMetricsEvent(engine.get(), &event),
             kSuccess);
   ASSERT_TRUE(engine.is_valid());
@@ -743,6 +744,7 @@ TEST_F(EmbedderTest, CompositorMustBeAbleToRenderToOpenGLTexture) {
   event.struct_size = sizeof(event);
   event.width = 800;
   event.height = 600;
+  event.pixel_ratio = 1.0;
   ASSERT_EQ(FlutterEngineSendWindowMetricsEvent(engine.get(), &event),
             kSuccess);
   ASSERT_TRUE(engine.is_valid());
@@ -834,6 +836,7 @@ TEST_F(EmbedderTest, CompositorMustBeAbleToRenderToSoftwareBuffer) {
   event.struct_size = sizeof(event);
   event.width = 800;
   event.height = 600;
+  event.pixel_ratio = 1.0;
   ASSERT_EQ(FlutterEngineSendWindowMetricsEvent(engine.get(), &event),
             kSuccess);
   ASSERT_TRUE(engine.is_valid());
@@ -1125,6 +1128,7 @@ TEST_F(EmbedderTest, CompositorMustBeAbleToRenderKnownScene) {
   event.struct_size = sizeof(event);
   event.width = 800;
   event.height = 600;
+  event.pixel_ratio = 1.0;
   ASSERT_EQ(FlutterEngineSendWindowMetricsEvent(engine.get(), &event),
             kSuccess);
   ASSERT_TRUE(engine.is_valid());
@@ -1302,6 +1306,7 @@ TEST_F(EmbedderTest,
   event.struct_size = sizeof(event);
   event.width = 800;
   event.height = 600;
+  event.pixel_ratio = 1.0;
   ASSERT_EQ(FlutterEngineSendWindowMetricsEvent(engine.get(), &event),
             kSuccess);
   ASSERT_TRUE(engine.is_valid());
@@ -1422,6 +1427,7 @@ TEST_F(EmbedderTest, CustomCompositorMustWorkWithCustomTaskRunner) {
     event.struct_size = sizeof(event);
     event.width = 800;
     event.height = 600;
+    event.pixel_ratio = 1.0;
 
     ASSERT_EQ(FlutterEngineSendWindowMetricsEvent(engine.get(), &event),
               kSuccess);
@@ -1500,6 +1506,7 @@ TEST_F(EmbedderTest, CompositorMustBeAbleToRenderWithRootLayerOnly) {
   event.struct_size = sizeof(event);
   event.width = 800;
   event.height = 600;
+  event.pixel_ratio = 1.0;
   ASSERT_EQ(FlutterEngineSendWindowMetricsEvent(engine.get(), &event),
             kSuccess);
   ASSERT_TRUE(engine.is_valid());
@@ -1612,6 +1619,7 @@ TEST_F(EmbedderTest, CompositorMustBeAbleToRenderWithPlatformLayerOnBottom) {
   event.struct_size = sizeof(event);
   event.width = 800;
   event.height = 600;
+  event.pixel_ratio = 1.0;
   ASSERT_EQ(FlutterEngineSendWindowMetricsEvent(engine.get(), &event),
             kSuccess);
   ASSERT_TRUE(engine.is_valid());
@@ -1795,6 +1803,7 @@ TEST_F(EmbedderTest,
   // Flutter still thinks it is 800 x 600. Only the root surface is rotated.
   event.width = 800;
   event.height = 600;
+  event.pixel_ratio = 1.0;
   ASSERT_EQ(FlutterEngineSendWindowMetricsEvent(engine.get(), &event),
             kSuccess);
   ASSERT_TRUE(engine.is_valid());
@@ -1829,6 +1838,7 @@ TEST_F(EmbedderTest, CanRenderSceneWithoutCustomCompositor) {
   event.struct_size = sizeof(event);
   event.width = 800;
   event.height = 600;
+  event.pixel_ratio = 1.0;
   ASSERT_EQ(FlutterEngineSendWindowMetricsEvent(engine.get(), &event),
             kSuccess);
 
@@ -1871,6 +1881,7 @@ TEST_F(EmbedderTest, CanRenderSceneWithoutCustomCompositorWithTransformation) {
   // Flutter still thinks it is 800 x 600.
   event.width = 800;
   event.height = 600;
+  event.pixel_ratio = 1.0;
   ASSERT_EQ(FlutterEngineSendWindowMetricsEvent(engine.get(), &event),
             kSuccess);
 
@@ -1905,6 +1916,7 @@ TEST_F(EmbedderTest, CanRenderGradientWithoutCompositor) {
   event.struct_size = sizeof(event);
   event.width = 800;
   event.height = 600;
+  event.pixel_ratio = 1.0;
   ASSERT_EQ(FlutterEngineSendWindowMetricsEvent(engine.get(), &event),
             kSuccess);
 
@@ -1947,6 +1959,7 @@ TEST_F(EmbedderTest, CanRenderGradientWithoutCompositorWithXform) {
   // Flutter still thinks it is 800 x 600.
   event.width = 800;
   event.height = 600;
+  event.pixel_ratio = 1.0;
   ASSERT_EQ(FlutterEngineSendWindowMetricsEvent(engine.get(), &event),
             kSuccess);
 
@@ -1981,6 +1994,7 @@ TEST_F(EmbedderTest, CanRenderGradientWithCompositor) {
   event.struct_size = sizeof(event);
   event.width = 800;
   event.height = 600;
+  event.pixel_ratio = 1.0;
   ASSERT_EQ(FlutterEngineSendWindowMetricsEvent(engine.get(), &event),
             kSuccess);
 
@@ -2024,6 +2038,7 @@ TEST_F(EmbedderTest, CanRenderGradientWithCompositorWithXform) {
   // Flutter still thinks it is 800 x 600.
   event.width = 800;
   event.height = 600;
+  event.pixel_ratio = 1.0;
   ASSERT_EQ(FlutterEngineSendWindowMetricsEvent(engine.get(), &event),
             kSuccess);
 
@@ -2134,6 +2149,7 @@ TEST_F(EmbedderTest, CanRenderGradientWithCompositorOnNonRootLayer) {
   event.struct_size = sizeof(event);
   event.width = 800;
   event.height = 600;
+  event.pixel_ratio = 1.0;
   ASSERT_EQ(FlutterEngineSendWindowMetricsEvent(engine.get(), &event),
             kSuccess);
 
@@ -2253,6 +2269,7 @@ TEST_F(EmbedderTest, CanRenderGradientWithCompositorOnNonRootLayerWithXform) {
   // Flutter still thinks it is 800 x 600.
   event.width = 800;
   event.height = 600;
+  event.pixel_ratio = 1.0;
   ASSERT_EQ(FlutterEngineSendWindowMetricsEvent(engine.get(), &event),
             kSuccess);
 
@@ -2372,7 +2389,7 @@ TEST_F(EmbedderTest, VerifyB141980393) {
   // achieved via a root surface transformation.
   event.width = flutter_application_rect.width();
   event.height = flutter_application_rect.height();
-
+  event.pixel_ratio = 1.0;
   ASSERT_EQ(FlutterEngineSendWindowMetricsEvent(engine.get(), &event),
             kSuccess);
   ASSERT_TRUE(engine.is_valid());
@@ -2425,6 +2442,7 @@ TEST_F(EmbedderTest, CaDeinitializeAnEngine) {
   event.struct_size = sizeof(event);
   event.width = 800;
   event.height = 600;
+  event.pixel_ratio = 1.0;
   ASSERT_EQ(FlutterEngineSendWindowMetricsEvent(engine.get(), &event),
             kInvalidArguments);
   engine.reset();
@@ -2466,6 +2484,7 @@ TEST_F(EmbedderTest, CanCreateEmbedderWithCustomRenderTaskRunner) {
   event.struct_size = sizeof(event);
   event.width = 800;
   event.height = 600;
+  event.pixel_ratio = 1.0;
   ASSERT_EQ(FlutterEngineSendWindowMetricsEvent(engine.get(), &event),
             kSuccess);
   task_latch.Wait();
@@ -2525,6 +2544,7 @@ TEST_F(EmbedderTest,
     event.struct_size = sizeof(event);
     event.width = 800;
     event.height = 600;
+    event.pixel_ratio = 1.0;
     ASSERT_EQ(FlutterEngineSendWindowMetricsEvent(engine.get(), &event),
               kSuccess);
   });
@@ -2555,5 +2575,181 @@ TEST_F(EmbedderTest,
   }
 }
 
+TEST_F(EmbedderTest,
+       CompositorMustBeAbleToRenderKnownScenePixelRatioOnSurface) {
+  auto& context = GetEmbedderContext();
+
+  EmbedderConfigBuilder builder(context);
+  builder.SetOpenGLRendererConfig(SkISize::Make(800, 600));
+  builder.SetCompositor();
+  builder.SetDartEntrypoint("can_display_platform_view_with_pixel_ratio");
+
+  context.GetCompositor().SetRenderTargetType(
+      EmbedderTestCompositor::RenderTargetType::kOpenGLTexture);
+
+  fml::AutoResetWaitableEvent latch;
+  context.GetCompositor().SetNextPresentCallback(
+      [&](const FlutterLayer** layers, size_t layers_count) {
+        ASSERT_EQ(layers_count, 3u);
+
+        // Layer 0 (Root)
+        {
+          FlutterBackingStore backing_store = *layers[0]->backing_store;
+          backing_store.type = kFlutterBackingStoreTypeOpenGL;
+          backing_store.did_update = true;
+          backing_store.open_gl.type = kFlutterOpenGLTargetTypeTexture;
+
+          FlutterLayer layer = {};
+          layer.struct_size = sizeof(layer);
+          layer.type = kFlutterLayerContentTypeBackingStore;
+          layer.backing_store = &backing_store;
+          layer.size = FlutterSizeMake(800.0, 600.0);
+          layer.offset = FlutterPointMake(0.0, 0.0);
+
+          ASSERT_EQ(*layers[0], layer);
+        }
+
+        // Layer 1
+        {
+          FlutterPlatformView 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(800.0, 560.0);
+          layer.offset = FlutterPointMake(0.0, 40.0);
+
+          ASSERT_EQ(*layers[1], layer);
+        }
+
+        // Layer 2
+        {
+          FlutterBackingStore backing_store = *layers[2]->backing_store;
+          backing_store.type = kFlutterBackingStoreTypeOpenGL;
+          backing_store.did_update = true;
+          backing_store.open_gl.type = kFlutterOpenGLTargetTypeTexture;
+
+          FlutterLayer layer = {};
+          layer.struct_size = sizeof(layer);
+          layer.type = kFlutterLayerContentTypeBackingStore;
+          layer.backing_store = &backing_store;
+          layer.size = FlutterSizeMake(800.0, 600.0);
+          layer.offset = FlutterPointMake(0.0, 0.0);
+
+          ASSERT_EQ(*layers[2], layer);
+        }
+
+        latch.Signal();
+      });
+
+  auto engine = builder.LaunchEngine();
+
+  // Send a window metrics events so frames may be scheduled.
+  FlutterWindowMetricsEvent event = {};
+  event.struct_size = sizeof(event);
+  event.width = 400;
+  event.height = 300;
+  event.pixel_ratio = 2.0;
+  ASSERT_EQ(FlutterEngineSendWindowMetricsEvent(engine.get(), &event),
+            kSuccess);
+  ASSERT_TRUE(engine.is_valid());
+
+  latch.Wait();
+}
+
+TEST_F(
+    EmbedderTest,
+    CompositorMustBeAbleToRenderKnownScenePixelRatioOnSurfaceWithRootSurfaceXformation) {
+  auto& context = GetEmbedderContext();
+
+  EmbedderConfigBuilder builder(context);
+  builder.SetOpenGLRendererConfig(SkISize::Make(600, 800));
+  builder.SetCompositor();
+  builder.SetDartEntrypoint("can_display_platform_view_with_pixel_ratio");
+
+  context.GetCompositor().SetRenderTargetType(
+      EmbedderTestCompositor::RenderTargetType::kOpenGLTexture);
+
+  const auto root_surface_transformation =
+      SkMatrix().preTranslate(0, 800).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);
+
+        // Layer 0 (Root)
+        {
+          FlutterBackingStore backing_store = *layers[0]->backing_store;
+          backing_store.type = kFlutterBackingStoreTypeOpenGL;
+          backing_store.did_update = true;
+          backing_store.open_gl.type = kFlutterOpenGLTargetTypeTexture;
+
+          FlutterLayer layer = {};
+          layer.struct_size = sizeof(layer);
+          layer.type = kFlutterLayerContentTypeBackingStore;
+          layer.backing_store = &backing_store;
+          layer.size = FlutterSizeMake(600.0, 800.0);
+          layer.offset = FlutterPointMake(0.0, 0.0);
+
+          ASSERT_EQ(*layers[0], layer);
+        }
+
+        // Layer 1
+        {
+          FlutterPlatformView 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(560.0, 800.0);
+          layer.offset = FlutterPointMake(40.0, 0.0);
+
+          ASSERT_EQ(*layers[1], layer);
+        }
+
+        // Layer 2
+        {
+          FlutterBackingStore backing_store = *layers[2]->backing_store;
+          backing_store.type = kFlutterBackingStoreTypeOpenGL;
+          backing_store.did_update = true;
+          backing_store.open_gl.type = kFlutterOpenGLTargetTypeTexture;
+
+          FlutterLayer layer = {};
+          layer.struct_size = sizeof(layer);
+          layer.type = kFlutterLayerContentTypeBackingStore;
+          layer.backing_store = &backing_store;
+          layer.size = FlutterSizeMake(600.0, 800.0);
+          layer.offset = FlutterPointMake(0.0, 0.0);
+
+          ASSERT_EQ(*layers[2], layer);
+        }
+
+        latch.Signal();
+      });
+
+  auto engine = builder.LaunchEngine();
+
+  // Send a window metrics events so frames may be scheduled.
+  FlutterWindowMetricsEvent event = {};
+  event.struct_size = sizeof(event);
+  event.width = 400;
+  event.height = 300;
+  event.pixel_ratio = 2.0;
+  ASSERT_EQ(FlutterEngineSendWindowMetricsEvent(engine.get(), &event),
+            kSuccess);
+  ASSERT_TRUE(engine.is_valid());
+
+  latch.Wait();
+}
+
 }  // namespace testing
 }  // namespace flutter