Implement toGpuImage, a synchronous, GPU-resident version of

ci/licenses_golden/licenses_flutter

@@ -872,6 +872,8 @@ FILE: ../../../flutter/lib/ui/painting/codec.cc
 FILE: ../../../flutter/lib/ui/painting/codec.h
 FILE: ../../../flutter/lib/ui/painting/color_filter.cc
 FILE: ../../../flutter/lib/ui/painting/color_filter.h
+FILE: ../../../flutter/lib/ui/painting/display_list_deferred_image_gpu.cc
+FILE: ../../../flutter/lib/ui/painting/display_list_deferred_image_gpu.h
 FILE: ../../../flutter/lib/ui/painting/display_list_image_gpu.cc
 FILE: ../../../flutter/lib/ui/painting/display_list_image_gpu.h
 FILE: ../../../flutter/lib/ui/painting/engine_layer.cc

display_list/display_list_image.cc

@@ -32,4 +32,8 @@ SkIRect DlImage::bounds() const {
   return SkIRect::MakeSize(dimensions());
 }
 
+std::optional<std::string> DlImage::get_error() const {
+  return std::nullopt;
+}
+
 }  // namespace flutter

display_list/display_list_image.h

@@ -6,6 +6,8 @@
 #define FLUTTER_DISPLAY_LIST_DISPLAY_LIST_IMAGE_H_
 
 #include <memory>
+#include <optional>
+#include <string>
 
 #include "flutter/fml/macros.h"
 #include "include/core/SkRefCnt.h"
@@ -27,6 +29,9 @@ namespace flutter {
 ///
 class DlImage : public SkRefCnt {
  public:
+  // Describes which GPU context owns this image.
+  enum class OwningContext { kRaster, kIO };
+
   static sk_sp<DlImage> Make(const SkImage* image);
 
   static sk_sp<DlImage> Make(sk_sp<SkImage> image);
@@ -81,6 +86,16 @@ class DlImage : public SkRefCnt {
   ///
   SkIRect bounds() const;
 
+  //----------------------------------------------------------------------------
+  /// @return     Whether the image method is only safe to use on the raster
+  ///             task runner.
+  virtual OwningContext owning_context() const { return OwningContext::kIO; }
+
+  //----------------------------------------------------------------------------
+  /// @return     An error, if any, that occurred when trying to create the
+  ///             image.
+  virtual std::optional<std::string> get_error() const;
+
  protected:
   DlImage();
 };

lib/ui/BUILD.gn

@@ -30,6 +30,8 @@ source_set("ui") {
     "painting/codec.h",
     "painting/color_filter.cc",
     "painting/color_filter.h",
+    "painting/display_list_deferred_image_gpu.cc",
+    "painting/display_list_deferred_image_gpu.h",
     "painting/display_list_image_gpu.cc",
     "painting/display_list_image_gpu.h",
     "painting/engine_layer.cc",

lib/ui/compositing.dart

@@ -21,6 +21,20 @@ class Scene extends NativeFieldWrapperClass1 {
   @pragma('vm:entry-point')
   Scene._();
 
+  /// Creates a GPU resident image from this scene.
+  ///
+  /// {@macro dart.ui.painting.Picture.toGpuImage}
+  Image toGpuImage(int width, int height) {
+    if (width <= 0 || height <= 0) {
+      throw Exception('Invalid image dimensions.');
+    }
+
+    final _Image image = _Image._();
+    _toGpuImage(width, height, image);
+    return Image._(image, image.width, image.height);
+  }
+  void _toGpuImage(int width, int height, _Image outImage) native 'Scene_toGpuImage';
+
   /// Creates a raster image representation of the current state of the scene.
   /// This is a slow operation that is performed on a background thread.
   ///
@@ -35,7 +49,7 @@ class Scene extends NativeFieldWrapperClass1 {
         if (image == null) {
           callback(null);
         } else {
-          callback(Image._(image));
+          callback(Image._(image, image.width, image.height));
         }
       }),
     );

lib/ui/compositing/scene.cc

@@ -22,6 +22,7 @@ namespace flutter {
 IMPLEMENT_WRAPPERTYPEINFO(ui, Scene);
 
 #define FOR_EACH_BINDING(V) \
+  V(Scene, toGpuImage)      \
   V(Scene, toImage)         \
   V(Scene, dispose)
 
@@ -66,6 +67,23 @@ void Scene::dispose() {
   ClearDartWrapper();
 }
 
+Dart_Handle Scene::toGpuImage(uint32_t width,
+                              uint32_t height,
+                              Dart_Handle raw_image_handle) {
+  TRACE_EVENT0("flutter", "Scene::toImage");
+
+  if (!layer_tree_) {
+    return tonic::ToDart("Scene did not contain a layer tree.");
+  }
+
+  auto picture = layer_tree_->Flatten(SkRect::MakeWH(width, height));
+  if (!picture) {
+    return tonic::ToDart("Could not flatten scene into a layer tree.");
+  }
+
+  Picture::RasterizeToGpuImage(picture, width, height, raw_image_handle);
+}
+
 Dart_Handle Scene::toImage(uint32_t width,
                            uint32_t height,
                            Dart_Handle raw_image_callback) {

lib/ui/compositing/scene.h

@@ -32,6 +32,10 @@ class Scene : public RefCountedDartWrappable<Scene> {
 
   std::unique_ptr<flutter::LayerTree> takeLayerTree();
 
+  Dart_Handle toGpuImage(uint32_t width,
+                         uint32_t height,
+                         Dart_Handle raw_image_handle);
+
   Dart_Handle toImage(uint32_t width,
                       uint32_t height,
                       Dart_Handle image_callback);