Create blanket backdrop filter mutator

flow/embedded_views.cc

@@ -36,6 +36,11 @@ void MutatorsStack::PushOpacity(const int& alpha) {
   vector_.push_back(element);
 };
 
+void MutatorsStack::PushBackdropFilter(const DlImageFilter& 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 DlImageFilter& 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 DlImageFilter& 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_;
+    const DlImageFilter* 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 DlImageFilter& filter);
 
   // Removes the `Mutator` on the top of the stack
   // and destroys it.

flow/mutators_stack_unittests.cc

@@ -89,6 +89,15 @@ TEST(MutatorsStack, PushOpacity) {
   ASSERT_TRUE(iter->get()->GetAlpha() == 240);
 }
 
+TEST(MutatorsStack, PushBackdropFilter) {
+  MutatorsStack stack;
+  auto filter = DlBlurImageFilter(5, 5, DlTileMode::kClamp);
+  stack.PushBackdropFilter(filter);
+  auto iter = stack.Bottom();
+  ASSERT_TRUE(iter->get()->GetType() == MutatorType::backdrop_filter);
+  ASSERT_TRUE(iter->get()->GetFilter() == filter);
+}
+
 TEST(MutatorsStack, Pop) {
   MutatorsStack stack;
   SkMatrix matrix;

shell/platform/android/platform_view_android_jni_impl.cc

@@ -1457,6 +1457,7 @@ void PlatformViewAndroidJNIImpl::FlutterViewOnDisplayPlatformView(
       // https://github.com/flutter/flutter/issues/58426
       case clip_path:
       case opacity:
+      case backdrop_filter:
         break;
     }
     ++iter;

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

@@ -422,6 +422,8 @@ - (BOOL)flt_hasFirstResponderInViewHierarchySubtree {
       case opacity:
         embedded_view.alpha = (*iter)->GetAlphaFloat() * embedded_view.alpha;
         break;
+      case backdrop_filter:
+        break;
     }
     ++iter;
   }

shell/platform/embedder/embedder_layers.cc

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