Make LayerTree::Flatten use DisplayList

flow/layers/layer_tree.cc

@@ -113,15 +113,10 @@ void LayerTree::Paint(CompositorContext::ScopedFrame& frame,
   }
 }
 
-sk_sp<SkPicture> LayerTree::Flatten(const SkRect& bounds) {
+sk_sp<DisplayList> LayerTree::Flatten(const SkRect& bounds) {
   TRACE_EVENT0("flutter", "LayerTree::Flatten");
 
-  SkPictureRecorder recorder;
-  auto* canvas = recorder.beginRecording(bounds);
-
-  if (!canvas) {
-    return nullptr;
-  }
+  DisplayListCanvasRecorder builder(bounds);
 
   MutatorsStack unused_stack;
   const FixedRefreshRateStopwatch unused_stopwatch;
@@ -147,14 +142,14 @@ sk_sp<SkPicture> LayerTree::Flatten(const SkRect& bounds) {
       // clang-format on
   };
 
-  SkISize canvas_size = canvas->getBaseLayerSize();
+  SkISize canvas_size = builder.getBaseLayerSize();
   SkNWayCanvas internal_nodes_canvas(canvas_size.width(), canvas_size.height());
-  internal_nodes_canvas.addCanvas(canvas);
+  internal_nodes_canvas.addCanvas(&builder);
 
   Layer::PaintContext paint_context = {
       // clang-format off
       .internal_nodes_canvas         = &internal_nodes_canvas,
-      .leaf_nodes_canvas             = canvas,
+      .leaf_nodes_canvas             = &builder,
       .gr_context                    = nullptr,
       .view_embedder                 = nullptr,
       .raster_time                   = unused_stopwatch,
@@ -178,7 +173,7 @@ sk_sp<SkPicture> LayerTree::Flatten(const SkRect& bounds) {
     }
   }
 
-  return recorder.finishRecordingAsPicture();
+  return builder.Build();
 }
 
 }  // namespace flutter

flow/layers/layer_tree.h

@@ -35,7 +35,7 @@ class LayerTree {
   void Paint(CompositorContext::ScopedFrame& frame,
              bool ignore_raster_cache = false) const;
 
-  sk_sp<SkPicture> Flatten(const SkRect& bounds);
+  sk_sp<DisplayList> Flatten(const SkRect& bounds);
 
   Layer* root_layer() const { return root_layer_.get(); }
 

lib/ui/painting/picture.cc

@@ -58,17 +58,17 @@ Dart_Handle Picture::toImage(uint32_t width,
                              uint32_t height,
                              Dart_Handle raw_image_callback) {
   if (display_list_.skia_object()) {
-    return RasterizeToImage(
-        [display_list = display_list_.skia_object()](SkCanvas* canvas) {
-          display_list->RenderTo(canvas);
-        },
-        width, height, raw_image_callback);
+    return RasterizeToImage(display_list_.skia_object(), width, height,
+                            raw_image_callback);
   } else {
     if (!picture_.skia_object()) {
       return tonic::ToDart("Picture is null");
     }
-    return RasterizeToImage(picture_.skia_object(), width, height,
-                            raw_image_callback);
+    return RasterizeToImage(
+        [picture = picture_.skia_object()](SkCanvas* canvas) {
+          canvas->drawPicture(picture);
+        },
+        width, height, raw_image_callback);
   }
 }
 
@@ -88,13 +88,13 @@ size_t Picture::GetAllocationSize() const {
   }
 }
 
-Dart_Handle Picture::RasterizeToImage(sk_sp<SkPicture> picture,
+Dart_Handle Picture::RasterizeToImage(sk_sp<DisplayList> display_list,
                                       uint32_t width,
                                       uint32_t height,
                                       Dart_Handle raw_image_callback) {
   return RasterizeToImage(
-      [picture](SkCanvas* canvas) { canvas->drawPicture(picture); }, width,
-      height, raw_image_callback);
+      [display_list](SkCanvas* canvas) { display_list->RenderTo(canvas); },
+      width, height, raw_image_callback);
 }
 
 Dart_Handle Picture::RasterizeToImage(

lib/ui/painting/picture.h

@@ -46,7 +46,7 @@ class Picture : public RefCountedDartWrappable<Picture> {
 
   static void RegisterNatives(tonic::DartLibraryNatives* natives);
 
-  static Dart_Handle RasterizeToImage(sk_sp<SkPicture> picture,
+  static Dart_Handle RasterizeToImage(sk_sp<DisplayList> display_list,
                                       uint32_t width,
                                       uint32_t height,
                                       Dart_Handle raw_image_callback);

testing/dart/observatory/tracing_test.dart

@@ -65,6 +65,6 @@ void main() {
       }
     }
     expect(saveLayerRecordCount, 3);
-    expect(saveLayerCount, 3);
+    expect(saveLayerCount, 6);
   });
 }