EngineLayer::dispose

lib/ui/compositing.dart

@@ -61,6 +61,11 @@ abstract class _EngineLayerWrapper implements EngineLayer {
 
   EngineLayer _nativeLayer;
 
+  @override
+  void dispose() {
+    _nativeLayer.dispose();
+  }
+
   // Children of this layer.
   //
   // Null if this layer has no children. This field is populated only in debug

lib/ui/compositing/scene.cc

@@ -62,6 +62,7 @@ Scene::Scene(std::shared_ptr<flutter::Layer> rootLayer,
 Scene::~Scene() {}
 
 void Scene::dispose() {
+  layer_tree_.reset();
   ClearDartWrapper();
 }
 

lib/ui/compositing/scene_builder.cc

@@ -347,9 +347,10 @@ void SceneBuilder::setCheckerboardOffscreenLayers(bool checkerboard) {
 void SceneBuilder::build(Dart_Handle scene_handle) {
   FML_DCHECK(layer_stack_.size() >= 1);
 
-  Scene::create(scene_handle, layer_stack_[0], rasterizer_tracing_threshold_,
-                checkerboard_raster_cache_images_,
-                checkerboard_offscreen_layers_);
+  Scene::create(
+      scene_handle, std::move(layer_stack_[0]), rasterizer_tracing_threshold_,
+      checkerboard_raster_cache_images_, checkerboard_offscreen_layers_);
+  layer_stack_.clear();
   ClearDartWrapper();  // may delete this object.
 }
 

lib/ui/painting.dart

@@ -2233,6 +2233,10 @@ class EngineLayer extends NativeFieldWrapperClass2 {
   /// or extended directly.
   @pragma('vm:entry-point')
   EngineLayer._();
+
+  /// Release the resources used by this object. The object is no longer usable
+  /// after this method is called.
+  void dispose() native 'EngineLayer_dispose';
 }
 
 /// A complex, one-dimensional subset of a plane.

lib/ui/painting/engine_layer.cc

@@ -4,6 +4,7 @@
 
 #include "flutter/lib/ui/painting/engine_layer.h"
 
+#include "flutter/lib/ui/ui_dart_state.h"
 #include "third_party/tonic/converter/dart_converter.h"
 #include "third_party/tonic/dart_args.h"
 #include "third_party/tonic/dart_binding_macros.h"
@@ -13,22 +14,30 @@ using tonic::ToDart;
 
 namespace flutter {
 
+IMPLEMENT_WRAPPERTYPEINFO(ui, EngineLayer);
+
+#define FOR_EACH_BINDING(V) V(EngineLayer, dispose)
+
+DART_BIND_ALL(EngineLayer, FOR_EACH_BINDING)
+
 EngineLayer::EngineLayer(std::shared_ptr<flutter::ContainerLayer> layer)
     : layer_(layer) {}
 
 EngineLayer::~EngineLayer() = default;
 
 size_t EngineLayer::GetAllocationSize() const {
+  // TODO(dnfield): Remove this when scene disposal changes land in the
+  // framework. https://github.com/flutter/flutter/issues/81514
+
   // Provide an approximation of the total memory impact of this object to the
   // Dart GC.  The ContainerLayer may hold references to a tree of other layers,
   // which in turn may contain Skia objects.
   return 3000;
 };
 
-IMPLEMENT_WRAPPERTYPEINFO(ui, EngineLayer);
-
-#define FOR_EACH_BINDING(V)  // nothing to bind
-
-DART_BIND_ALL(EngineLayer, FOR_EACH_BINDING)
+void EngineLayer::dispose() {
+  layer_.reset();
+  ClearDartWrapper();
+}
 
 }  // namespace flutter

lib/ui/painting/engine_layer.h

@@ -32,6 +32,8 @@ class EngineLayer : public RefCountedDartWrappable<EngineLayer> {
 
   static void RegisterNatives(tonic::DartLibraryNatives* natives);
 
+  void dispose();
+
   std::shared_ptr<flutter::ContainerLayer> Layer() const { return layer_; }
 
  private:

lib/ui/painting/image.cc

@@ -44,6 +44,8 @@ Dart_Handle CanvasImage::toByteData(int format, Dart_Handle callback) {
 }
 
 void CanvasImage::dispose() {
+  // TODO(dnfield): Remove the hint freed delegate once Picture disposal is in
+  // the framework https://github.com/flutter/flutter/issues/81514
   auto hint_freed_delegate = UIDartState::Current()->GetHintFreedDelegate();
   if (hint_freed_delegate) {
     hint_freed_delegate->HintFreed(GetAllocationSize());