Pushing BackdropFilter Mutator

backdrop_filter_diff

@@ -0,0 +1,95 @@
+diff --git a/flow/embedded_views.h b/flow/embedded_views.h
+index 7a5a34f330..76b002befd 100644
+--- a/flow/embedded_views.h
++++ b/flow/embedded_views.h
+@@ -345,6 +345,8 @@ class ExternalViewEmbedder {
+   // 'EndFrame', otherwise returns false.
+   bool GetUsedThisFrame() const { return used_this_frame_; }
+
++  void PushMutator() {}
++
+  private:
+   bool used_this_frame_ = false;
+
+diff --git a/flow/layers/backdrop_filter_layer.cc b/flow/layers/backdrop_filter_layer.cc
+index 8e8ef2628a..b059e427c3 100644
+--- a/flow/layers/backdrop_filter_layer.cc
++++ b/flow/layers/backdrop_filter_layer.cc
+@@ -43,6 +43,10 @@ void BackdropFilterLayer::Preroll(PrerollContext* context,
+   Layer::AutoPrerollSaveLayerState save =
+       Layer::AutoPrerollSaveLayerState::Create(context, true, bool(filter_));
+   SkRect child_paint_bounds = SkRect::MakeEmpty();
++  auto visited_platform_views = context->view_embedder->GetVisitedPlatformViews();
++  for (id in visited_platform_views) {
++    context->view_embedder->ApplyMutator(id, alpha);
++  }
+   PrerollChildren(context, matrix, &child_paint_bounds);
+   child_paint_bounds.join(context->cull_rect);
+   set_paint_bounds(child_paint_bounds);
+diff --git a/flow/layers/platform_view_layer.cc b/flow/layers/platform_view_layer.cc
+index 285db390cc..63b7827cf9 100644
+--- a/flow/layers/platform_view_layer.cc
++++ b/flow/layers/platform_view_layer.cc
+@@ -28,6 +28,7 @@ void PlatformViewLayer::Preroll(PrerollContext* context,
+                                            context->mutators_stack);
+   context->view_embedder->PrerollCompositeEmbeddedView(view_id_,
+                                                        std::move(params));
++  context->view_embedder->PushVisitedPlatformView(view_id_);
+ }
+
+ void PlatformViewLayer::Paint(PaintContext& context) const {
+diff --git a/shell/platform/darwin/ios/framework/Source/FlutterPlatformViews.mm b/shell/platform/darwin/ios/framework/Source/FlutterPlatformViews.mm
+index e5325aee85..a6992cca3f 100644
+--- a/shell/platform/darwin/ios/framework/Source/FlutterPlatformViews.mm
++++ b/shell/platform/darwin/ios/framework/Source/FlutterPlatformViews.mm
+@@ -319,6 +319,11 @@ void FlutterPlatformViewsController::EndFrame(
+   }
+ }
+
++void FlutterPlatformViewsController::PushMutator(flutter::Mutator mutator, int64_t platform_view_id) {
++  EmbeddedViewParams params = current_composition_params_[platform_view_id];
++  params.mutatorsStack().PushOpacity(20);
++}
++
+ void FlutterPlatformViewsController::PrerollCompositeEmbeddedView(
+     int view_id,
+     std::unique_ptr<EmbeddedViewParams> params) {
+diff --git a/shell/platform/darwin/ios/framework/Source/FlutterPlatformViews_Internal.h b/shell/platform/darwin/ios/framework/Source/FlutterPlatformViews_Internal.h
+index fde21d23e2..522b847ef4 100644
+--- a/shell/platform/darwin/ios/framework/Source/FlutterPlatformViews_Internal.h
++++ b/shell/platform/darwin/ios/framework/Source/FlutterPlatformViews_Internal.h
+@@ -184,6 +184,8 @@ class FlutterPlatformViewsController {
+   // responder. Returns -1 if no such platform view is found.
+   long FindFirstResponderPlatformViewId();
+
++  void PushMutator(flutter::Mutator mutator, int64_t platform_view_id);
++
+  private:
+   static const size_t kMaxLayerAllocations = 2;
+
+diff --git a/shell/platform/darwin/ios/ios_external_view_embedder.h b/shell/platform/darwin/ios/ios_external_view_embedder.h
+index 6c023d1b79..da160dd023 100644
+--- a/shell/platform/darwin/ios/ios_external_view_embedder.h
++++ b/shell/platform/darwin/ios/ios_external_view_embedder.h
+@@ -64,6 +64,8 @@ class IOSExternalViewEmbedder : public ExternalViewEmbedder {
+   // |ExternalViewEmbedder|
+   bool SupportsDynamicThreadMerging() override;
+
++  void PushMutator() override;
++
+   FML_DISALLOW_COPY_AND_ASSIGN(IOSExternalViewEmbedder);
+ };
+
+diff --git a/shell/platform/darwin/ios/ios_external_view_embedder.mm b/shell/platform/darwin/ios/ios_external_view_embedder.mm
+index 1323fa4c2f..edd4a3adcd 100644
+--- a/shell/platform/darwin/ios/ios_external_view_embedder.mm
++++ b/shell/platform/darwin/ios/ios_external_view_embedder.mm
+@@ -92,4 +92,8 @@ bool IOSExternalViewEmbedder::SupportsDynamicThreadMerging() {
+   return true;
+ }
+
++void PushMutator(int alpha, int view_id) {
++  platform_views_controller_->PushMutator(alpha, view_id);
++}
++
+ }  // namespace flutter

flow/embedded_views.cc

@@ -36,6 +36,11 @@ void MutatorsStack::PushOpacity(const int& alpha) {
   vector_.push_back(element);
 };
 
+void MutatorsStack::PushBackdropFilter(const sk_sp<SkImageFilter>& filter) {
+  std::shared_ptr<Mutator> element = std::make_shared<Mutator>(filter);
+  vector_.push_back(element);
+};
+
 void MutatorsStack::Pop() {
   vector_.pop_back();
 };

flow/embedded_views.h

@@ -21,7 +21,14 @@
 namespace flutter {
 
 // TODO(chinmaygarde): Make these enum names match the style guide.
-enum MutatorType { clip_rect, clip_rrect, clip_path, transform, opacity };
+enum MutatorType {
+  clip_rect,
+  clip_rrect,
+  clip_path,
+  transform,
+  opacity,
+  backdrop_filter
+};
 
 // Stores mutation information like clipping or transform.
 //
@@ -49,6 +56,9 @@ class Mutator {
       case opacity:
         alpha_ = other.alpha_;
         break;
+      case backdrop_filter:
+        filter_ = other.filter_;
+        break;
       default:
         break;
     }
@@ -61,12 +71,15 @@ class Mutator {
   explicit Mutator(const SkMatrix& matrix)
       : type_(transform), matrix_(matrix) {}
   explicit Mutator(const int& alpha) : type_(opacity), alpha_(alpha) {}
+  explicit Mutator(const sk_sp<SkImageFilter>& filter)
+      : type_(backdrop_filter), filter_(filter) {}
 
   const MutatorType& GetType() const { return type_; }
   const SkRect& GetRect() const { return rect_; }
   const SkRRect& GetRRect() const { return rrect_; }
   const SkPath& GetPath() const { return *path_; }
   const SkMatrix& GetMatrix() const { return matrix_; }
+  const sk_sp<SkImageFilter>& GetFilter() const { return filter_; }
   const int& GetAlpha() const { return alpha_; }
   float GetAlphaFloat() const { return (alpha_ / 255.0); }
 
@@ -85,6 +98,8 @@ class Mutator {
         return matrix_ == other.matrix_;
       case opacity:
         return alpha_ == other.alpha_;
+      case backdrop_filter:
+        return filter_ == other.filter_;
     }
 
     return false;
@@ -111,6 +126,7 @@ class Mutator {
     SkMatrix matrix_;
     SkPath* path_;
     int alpha_;
+    sk_sp<SkImageFilter> filter_;
   };
 
 };  // Mutator
@@ -133,6 +149,7 @@ class MutatorsStack {
   void PushClipPath(const SkPath& path);
   void PushTransform(const SkMatrix& matrix);
   void PushOpacity(const int& alpha);
+  void PushBackdropFilter(const sk_sp<SkImageFilter>& filter);
 
   // Removes the `Mutator` on the top of the stack
   // and destroys it.
@@ -224,6 +241,10 @@ class EmbeddedViewParams {
   // Clippings are ignored.
   const SkRect& finalBoundingRect() const { return final_bounding_rect_; }
 
+  void PushFilter(sk_sp<SkImageFilter> filter) {
+    mutators_stack_.PushBackdropFilter(filter);
+  }
+
   bool operator==(const EmbeddedViewParams& other) const {
     return size_points_ == other.size_points_ &&
            mutators_stack_ == other.mutators_stack_ &&
@@ -345,9 +366,22 @@ class ExternalViewEmbedder {
   // 'EndFrame', otherwise returns false.
   bool GetUsedThisFrame() const { return used_this_frame_; }
 
+  std::vector<int64_t> GetVisitedPlatformViews() {
+    return visited_platform_views_;
+  }
+
+  void PushVisitedPlatformView(int64_t view_id) {
+    visited_platform_views_.push_back(view_id);
+  }
+
+  virtual void FilterPlatformViews(int64_t view_id,
+                                   sk_sp<SkImageFilter> filter) {}
+
  private:
   bool used_this_frame_ = false;
 
+  std::vector<int64_t> visited_platform_views_;
+
   FML_DISALLOW_COPY_AND_ASSIGN(ExternalViewEmbedder);
 
 };  // ExternalViewEmbedder

flow/layers/backdrop_filter_layer.cc

@@ -44,6 +44,12 @@ void BackdropFilterLayer::Preroll(PrerollContext* context,
   Layer::AutoPrerollSaveLayerState save =
       Layer::AutoPrerollSaveLayerState::Create(context, true, bool(filter_));
   SkRect child_paint_bounds = SkRect::MakeEmpty();
+  auto visited_platform_views =
+      context->view_embedder->GetVisitedPlatformViews();
+  for (int64_t id : visited_platform_views) {
+    context->view_embedder->FilterPlatformViews(id, filter_);
+  }
+
   PrerollChildren(context, matrix, &child_paint_bounds);
   child_paint_bounds.join(context->cull_rect);
   set_paint_bounds(child_paint_bounds);

flow/layers/platform_view_layer.cc

@@ -28,6 +28,7 @@ void PlatformViewLayer::Preroll(PrerollContext* context,
                                            context->mutators_stack);
   context->view_embedder->PrerollCompositeEmbeddedView(view_id_,
                                                        std::move(params));
+  context->view_embedder->PushVisitedPlatformView(view_id_);
 }
 
 void PlatformViewLayer::Paint(PaintContext& context) const {

flow/mutators_stack_unittests.cc

@@ -52,6 +52,17 @@ TEST(MutatorsStack, PushClipRect) {
   ASSERT_TRUE(iter->get()->GetRect() == rect);
 }
 
+TEST(MutatorsStack, PushBackdropFilter) {
+  MutatorsStack stack;
+  sk_sp<SkImageFilter> filter;
+  filter->filterBounds(SkIRect::MakeWH(10, 10), SkMatrix::I(),
+                       SkImageFilter::kForward_MapDirection);
+  stack.PushBackdropFilter(filter);
+  auto iter = stack.Bottom();
+  ASSERT_TRUE(iter->get()->GetType() == MutatorType::backdrop_filter);
+  ASSERT_TRUE(iter->get()->GetFilter() == filter);
+}
+
 TEST(MutatorsStack, PushClipRRect) {
   MutatorsStack stack;
   auto rrect = SkRRect::MakeEmpty();

shell/platform/darwin/ios/framework/Source/FlutterPlatformViews.mm

@@ -319,6 +319,13 @@ - (BOOL)flt_hasFirstResponderInViewHierarchySubtree {
   }
 }
 
+void FlutterPlatformViewsController::FilterPlatformViews(int64_t platform_view_id,
+                                                         sk_sp<SkImageFilter> filter) {
+  EmbeddedViewParams params = current_composition_params_[platform_view_id];
+  params.PushFilter(filter);
+  current_composition_params_[platform_view_id] = params;
+}
+
 void FlutterPlatformViewsController::PrerollCompositeEmbeddedView(
     int view_id,
     std::unique_ptr<EmbeddedViewParams> params) {
@@ -422,6 +429,8 @@ - (BOOL)flt_hasFirstResponderInViewHierarchySubtree {
       case opacity:
         embedded_view.alpha = (*iter)->GetAlphaFloat() * embedded_view.alpha;
         break;
+      case backdrop_filter:
+        break;
     }
     ++iter;
   }

shell/platform/darwin/ios/framework/Source/FlutterPlatformViews_Internal.h

@@ -184,6 +184,8 @@ class FlutterPlatformViewsController {
   // responder. Returns -1 if no such platform view is found.
   long FindFirstResponderPlatformViewId();
 
+  void FilterPlatformViews(int64_t platform_view_id, sk_sp<SkImageFilter> filter);
+
  private:
   static const size_t kMaxLayerAllocations = 2;
 

shell/platform/darwin/ios/ios_external_view_embedder.h

@@ -64,6 +64,9 @@ class IOSExternalViewEmbedder : public ExternalViewEmbedder {
   // |ExternalViewEmbedder|
   bool SupportsDynamicThreadMerging() override;
 
+  void FilterPlatformViews(int64_t view_id,
+                           sk_sp<SkImageFilter> filter) override;
+
   FML_DISALLOW_COPY_AND_ASSIGN(IOSExternalViewEmbedder);
 };
 

shell/platform/darwin/ios/ios_external_view_embedder.mm

@@ -92,4 +92,8 @@
   return true;
 }
 
+void IOSExternalViewEmbedder::FilterPlatformViews(int64_t view_id, sk_sp<SkImageFilter> filter) {
+  platform_views_controller_->FilterPlatformViews(view_id, filter);
+}
+
 }  // namespace flutter

shell/platform/embedder/embedder_layers.cc

@@ -147,6 +147,8 @@ void EmbedderLayers::PushPlatformViewLayer(
                     .get());
           }
         } break;
+        case MutatorType::backdrop_filter: {
+        } break;
       }
     }