Reland unobstructed platform views (#17336)

Author: Emmanuel Garcia

flow/embedded_views.cc

@@ -6,10 +6,13 @@
 
 namespace flutter {
 
-bool ExternalViewEmbedder::SubmitFrame(GrContext* context) {
+bool ExternalViewEmbedder::SubmitFrame(GrContext* context,
+                                       SkCanvas* background_canvas) {
   return false;
 };
 
+void ExternalViewEmbedder::FinishFrame(){};
+
 void MutatorsStack::PushClipRect(const SkRect& rect) {
   std::shared_ptr<Mutator> element = std::make_shared<Mutator>(rect);
   vector_.push_back(element);

flow/embedded_views.h

@@ -248,7 +248,10 @@ class ExternalViewEmbedder {
   // Must be called on the UI thread.
   virtual SkCanvas* CompositeEmbeddedView(int view_id) = 0;
 
-  virtual bool SubmitFrame(GrContext* context);
+  virtual bool SubmitFrame(GrContext* context, SkCanvas* background_canvas);
+
+  // This is called after submitting the embedder frame and the surface frame.
+  virtual void FinishFrame();
 
   FML_DISALLOW_COPY_AND_ASSIGN(ExternalViewEmbedder);
 

flow/layers/picture_layer.cc

@@ -59,7 +59,7 @@ void PictureLayer::Paint(PaintContext& context) const {
       return;
     }
   }
-  context.leaf_nodes_canvas->drawPicture(picture());
+  picture()->playback(context.leaf_nodes_canvas);
 }
 
 }  // namespace flutter

flow/layers/picture_layer_unittests.cc

@@ -94,9 +94,6 @@ TEST_F(PictureLayerTest, SimplePicture) {
            1, MockCanvas::SetMatrixData{RasterCache::GetIntegralTransCTM(
                   layer_offset_matrix)}},
 #endif
-       MockCanvas::DrawCall{
-           1, MockCanvas::DrawPictureData{mock_picture->serialize(), SkPaint(),
-                                          SkMatrix()}},
        MockCanvas::DrawCall{1, MockCanvas::RestoreData{0}}});
   EXPECT_EQ(mock_canvas().draw_calls(), expected_draw_calls);
 }

shell/common/rasterizer.cc

@@ -342,9 +342,17 @@ RasterStatus Rasterizer::DrawToSurface(flutter::LayerTree& layer_tree) {
     if (raster_status == RasterStatus::kFailed) {
       return raster_status;
     }
-    frame->Submit();
     if (external_view_embedder != nullptr) {
-      external_view_embedder->SubmitFrame(surface_->GetContext());
+      external_view_embedder->SubmitFrame(surface_->GetContext(),
+                                          root_surface_canvas);
+      // The external view embedder may mutate the root surface canvas while
+      // submitting the frame.
+      // Therefore, submit the final frame after asking the external view
+      // embedder to submit the frame.
+      frame->Submit();
+      external_view_embedder->FinishFrame();
+    } else {
+      frame->Submit();
     }
 
     FireNextFrameCallbackIfPresent();

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

@@ -39,6 +39,7 @@ - (instancetype)init {
   if (self) {
     self.layer.opaque = NO;
     self.userInteractionEnabled = NO;
+    self.autoresizingMask = (UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight);
   }
 
   return self;