Move the mutators stack handling to preroll (flutter#9651)

* refactoring to move the mutator stack handling to preroll

* more review fixes

flow/embedded_views.h

@@ -185,14 +185,14 @@ class ExternalViewEmbedder {
 
   virtual void BeginFrame(SkISize frame_size) = 0;
 
-  virtual void PrerollCompositeEmbeddedView(int view_id) = 0;
+  virtual void PrerollCompositeEmbeddedView(
+      int view_id,
+      std::unique_ptr<EmbeddedViewParams> params) = 0;
 
   virtual std::vector<SkCanvas*> GetCurrentCanvases() = 0;
 
   // Must be called on the UI thread.
-  virtual SkCanvas* CompositeEmbeddedView(
-      int view_id,
-      std::unique_ptr<flutter::EmbeddedViewParams> params) = 0;
+  virtual SkCanvas* CompositeEmbeddedView(int view_id) = 0;
 
   virtual bool SubmitFrame(GrContext* context);
 

flow/layers/clip_path_layer.cc

@@ -23,12 +23,14 @@ void ClipPathLayer::Preroll(PrerollContext* context, const SkMatrix& matrix) {
   SkRect previous_cull_rect = context->cull_rect;
   SkRect clip_path_bounds = clip_path_.getBounds();
   if (context->cull_rect.intersect(clip_path_bounds)) {
+    context->mutators_stack.pushClipPath(clip_path_);
     SkRect child_paint_bounds = SkRect::MakeEmpty();
     PrerollChildren(context, matrix, &child_paint_bounds);
 
     if (child_paint_bounds.intersect(clip_path_bounds)) {
       set_paint_bounds(child_paint_bounds);
     }
+    context->mutators_stack.pop();
   }
   context->cull_rect = previous_cull_rect;
 }
@@ -60,7 +62,6 @@ void ClipPathLayer::Paint(PaintContext& context) const {
   SkAutoCanvasRestore save(context.internal_nodes_canvas, true);
   context.internal_nodes_canvas->clipPath(clip_path_,
                                           clip_behavior_ != Clip::hardEdge);
-  context.mutators_stack.pushClipPath(clip_path_);
 
   if (clip_behavior_ == Clip::antiAliasWithSaveLayer) {
     context.internal_nodes_canvas->saveLayer(paint_bounds(), nullptr);
@@ -69,7 +70,6 @@ void ClipPathLayer::Paint(PaintContext& context) const {
   if (clip_behavior_ == Clip::antiAliasWithSaveLayer) {
     context.internal_nodes_canvas->restore();
   }
-  context.mutators_stack.pop();
 }
 
 }  // namespace flutter

flow/layers/clip_rect_layer.cc

@@ -16,12 +16,14 @@ ClipRectLayer::~ClipRectLayer() = default;
 void ClipRectLayer::Preroll(PrerollContext* context, const SkMatrix& matrix) {
   SkRect previous_cull_rect = context->cull_rect;
   if (context->cull_rect.intersect(clip_rect_)) {
+    context->mutators_stack.pushClipRect(clip_rect_);
     SkRect child_paint_bounds = SkRect::MakeEmpty();
     PrerollChildren(context, matrix, &child_paint_bounds);
 
     if (child_paint_bounds.intersect(clip_rect_)) {
       set_paint_bounds(child_paint_bounds);
     }
+    context->mutators_stack.pop();
   }
   context->cull_rect = previous_cull_rect;
 }
@@ -50,7 +52,6 @@ void ClipRectLayer::Paint(PaintContext& context) const {
   SkAutoCanvasRestore save(context.internal_nodes_canvas, true);
   context.internal_nodes_canvas->clipRect(clip_rect_,
                                           clip_behavior_ != Clip::hardEdge);
-  context.mutators_stack.pushClipRect(clip_rect_);
 
   if (clip_behavior_ == Clip::antiAliasWithSaveLayer) {
     context.internal_nodes_canvas->saveLayer(clip_rect_, nullptr);
@@ -59,7 +60,6 @@ void ClipRectLayer::Paint(PaintContext& context) const {
   if (clip_behavior_ == Clip::antiAliasWithSaveLayer) {
     context.internal_nodes_canvas->restore();
   }
-  context.mutators_stack.pop();
 }
 
 }  // namespace flutter

flow/layers/clip_rrect_layer.cc

@@ -17,12 +17,14 @@ void ClipRRectLayer::Preroll(PrerollContext* context, const SkMatrix& matrix) {
   SkRect previous_cull_rect = context->cull_rect;
   SkRect clip_rrect_bounds = clip_rrect_.getBounds();
   if (context->cull_rect.intersect(clip_rrect_bounds)) {
+    context->mutators_stack.pushClipRRect(clip_rrect_);
     SkRect child_paint_bounds = SkRect::MakeEmpty();
     PrerollChildren(context, matrix, &child_paint_bounds);
 
     if (child_paint_bounds.intersect(clip_rrect_bounds)) {
       set_paint_bounds(child_paint_bounds);
     }
+    context->mutators_stack.pop();
   }
   context->cull_rect = previous_cull_rect;
 }
@@ -58,7 +60,6 @@ void ClipRRectLayer::Paint(PaintContext& context) const {
   SkAutoCanvasRestore save(context.internal_nodes_canvas, true);
   context.internal_nodes_canvas->clipRRect(clip_rrect_,
                                            clip_behavior_ != Clip::hardEdge);
-  context.mutators_stack.pushClipRRect(clip_rrect_);
 
   if (clip_behavior_ == Clip::antiAliasWithSaveLayer) {
     context.internal_nodes_canvas->saveLayer(paint_bounds(), nullptr);
@@ -67,7 +68,6 @@ void ClipRRectLayer::Paint(PaintContext& context) const {
   if (clip_behavior_ == Clip::antiAliasWithSaveLayer) {
     context.internal_nodes_canvas->restore();
   }
-  context.mutators_stack.pop();
 }
 
 }  // namespace flutter

flow/layers/layer.h

@@ -48,6 +48,7 @@ struct PrerollContext {
   RasterCache* raster_cache;
   GrContext* gr_context;
   ExternalViewEmbedder* view_embedder;
+  MutatorsStack& mutators_stack;
   SkColorSpace* dst_color_space;
   SkRect cull_rect;
 
@@ -83,7 +84,6 @@ class Layer {
     SkCanvas* leaf_nodes_canvas;
     GrContext* gr_context;
     ExternalViewEmbedder* view_embedder;
-    MutatorsStack& mutators_stack;
     const Stopwatch& raster_time;
     const Stopwatch& ui_time;
     TextureRegistry& texture_registry;

flow/layers/layer_tree.cc

@@ -31,10 +31,12 @@ void LayerTree::Preroll(CompositorContext::ScopedFrame& frame,
       frame.canvas() ? frame.canvas()->imageInfo().colorSpace() : nullptr;
   frame.context().raster_cache().SetCheckboardCacheImages(
       checkerboard_raster_cache_images_);
+  MutatorsStack stack;
   PrerollContext context = {
       ignore_raster_cache ? nullptr : &frame.context().raster_cache(),
       frame.gr_context(),
       frame.view_embedder(),
+      stack,
       color_space,
       kGiantRect,
       frame.context().raster_time(),
@@ -83,13 +85,11 @@ void LayerTree::Paint(CompositorContext::ScopedFrame& frame,
     }
   }
 
-  MutatorsStack stack;
   Layer::PaintContext context = {
       (SkCanvas*)&internal_nodes_canvas,
       frame.canvas(),
       frame.gr_context(),
       frame.view_embedder(),
-      stack,
       frame.context().raster_time(),
       frame.context().ui_time(),
       frame.context().texture_registry(),
@@ -121,6 +121,7 @@ sk_sp<SkPicture> LayerTree::Flatten(const SkRect& bounds) {
       nullptr,                  // raster_cache (don't consult the cache)
       nullptr,                  // gr_context  (used for the raster cache)
       nullptr,                  // external view embedder
+      unused_stack,             // mutator stack
       nullptr,                  // SkColorSpace* dst_color_space
       kGiantRect,               // SkRect cull_rect
       unused_stopwatch,         // frame time (dont care)
@@ -138,7 +139,6 @@ sk_sp<SkPicture> LayerTree::Flatten(const SkRect& bounds) {
       canvas,  // canvas
       nullptr,
       nullptr,
-      unused_stack,
       unused_stopwatch,         // frame time (dont care)
       unused_stopwatch,         // engine time (dont care)
       unused_texture_registry,  // texture registry (not supported)

flow/layers/performance_overlay_layer_unittests.cc

@@ -47,13 +47,9 @@ TEST(PerformanceOverlayLayer, Gold) {
   ASSERT_TRUE(surface != nullptr);
 
   flutter::TextureRegistry unused_texture_registry;
-  flutter::MutatorsStack unused_stack;
   flutter::Layer::PaintContext paintContext = {
-      nullptr,        surface->getCanvas(),
-      nullptr,        nullptr,
-      unused_stack,   mock_stopwatch,
-      mock_stopwatch, unused_texture_registry,
-      nullptr,        false};
+      nullptr,        surface->getCanvas(),    nullptr, nullptr, mock_stopwatch,
+      mock_stopwatch, unused_texture_registry, nullptr, false};
 
   // Specify font file to ensure the same font across different operation
   // systems.

flow/layers/physical_shape_layer_unittests.cc

@@ -28,10 +28,12 @@ TEST(PhysicalShapeLayer, TotalElevation) {
 
   const Stopwatch unused_stopwatch;
   TextureRegistry unused_texture_registry;
+  MutatorsStack unused_stack;
   PrerollContext preroll_context{
       nullptr,                  // raster_cache (don't consult the cache)
       nullptr,                  // gr_context  (used for the raster cache)
       nullptr,                  // external view embedder
+      unused_stack,             // mutator stack
       nullptr,                  // SkColorSpace* dst_color_space
       kGiantRect,               // SkRect cull_rect
       unused_stopwatch,         // frame time (dont care)

flow/layers/platform_view_layer.cc

@@ -23,7 +23,14 @@ void PlatformViewLayer::Preroll(PrerollContext* context,
                       "does not support embedding";
     return;
   }
-  context->view_embedder->PrerollCompositeEmbeddedView(view_id_);
+  std::unique_ptr<EmbeddedViewParams> params =
+      std::make_unique<EmbeddedViewParams>();
+  params->offsetPixels =
+      SkPoint::Make(matrix.getTranslateX(), matrix.getTranslateY());
+  params->sizePoints = size_;
+  params->mutatorsStack = context->mutators_stack;
+  context->view_embedder->PrerollCompositeEmbeddedView(view_id_,
+                                                       std::move(params));
 }
 
 void PlatformViewLayer::Paint(PaintContext& context) const {
@@ -32,16 +39,7 @@ void PlatformViewLayer::Paint(PaintContext& context) const {
                       "does not support embedding";
     return;
   }
-  std::unique_ptr<EmbeddedViewParams> params =
-      std::make_unique<EmbeddedViewParams>();
-  SkMatrix transform = context.leaf_nodes_canvas->getTotalMatrix();
-  params->offsetPixels =
-      SkPoint::Make(transform.getTranslateX(), transform.getTranslateY());
-  params->sizePoints = size_;
-  params->mutatorsStack = context.mutators_stack;
-
-  SkCanvas* canvas =
-      context.view_embedder->CompositeEmbeddedView(view_id_, std::move(params));
+  SkCanvas* canvas = context.view_embedder->CompositeEmbeddedView(view_id_);
   context.leaf_nodes_canvas = canvas;
 }
 }  // namespace flutter

flow/layers/transform_layer.cc

@@ -29,7 +29,7 @@ TransformLayer::~TransformLayer() = default;
 void TransformLayer::Preroll(PrerollContext* context, const SkMatrix& matrix) {
   SkMatrix child_matrix;
   child_matrix.setConcat(matrix, transform_);
-
+  context->mutators_stack.pushTransform(transform_);
   SkRect previous_cull_rect = context->cull_rect;
   SkMatrix inverse_transform_;
   // Perspective projections don't produce rectangles that are useful for
@@ -47,6 +47,7 @@ void TransformLayer::Preroll(PrerollContext* context, const SkMatrix& matrix) {
   set_paint_bounds(child_paint_bounds);
 
   context->cull_rect = previous_cull_rect;
+  context->mutators_stack.pop();
 }
 
 #if defined(OS_FUCHSIA)
@@ -66,10 +67,8 @@ void TransformLayer::Paint(PaintContext& context) const {
 
   SkAutoCanvasRestore save(context.internal_nodes_canvas, true);
   context.internal_nodes_canvas->concat(transform_);
-  context.mutators_stack.pushTransform(transform_);
 
   PaintChildren(context);
-  context.mutators_stack.pop();
 }
 
 }  // namespace flutter

flow/raster_cache.cc

@@ -159,7 +159,6 @@ void RasterCache::Prepare(PrerollContext* context,
     entry.image = Rasterize(context->gr_context, ctm, context->dst_color_space,
                             checkerboard_images_, layer->paint_bounds(),
                             [layer, context](SkCanvas* canvas) {
-                              MutatorsStack stack;
                               SkISize canvas_size = canvas->getBaseLayerSize();
                               SkNWayCanvas internal_nodes_canvas(
                                   canvas_size.width(), canvas_size.height());
@@ -169,7 +168,6 @@ void RasterCache::Prepare(PrerollContext* context,
                                   canvas,
                                   context->gr_context,
                                   nullptr,
-                                  stack,
                                   context->raster_time,
                                   context->ui_time,
                                   context->texture_registry,

flow/scene_update_context.cc

@@ -198,12 +198,10 @@ SceneUpdateContext::ExecutePaintTasks(CompositorContext::ScopedFrame& frame) {
   for (auto& task : paint_tasks_) {
     FML_DCHECK(task.surface);
     SkCanvas* canvas = task.surface->GetSkiaSurface()->getCanvas();
-    flutter::MutatorsStack stack;
     Layer::PaintContext context = {canvas,
                                    canvas,
                                    frame.gr_context(),
                                    nullptr,
-                                   stack,
                                    frame.context().raster_time(),
                                    frame.context().ui_time(),
                                    frame.context().texture_registry(),

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

@@ -160,11 +160,21 @@
   frame_size_ = frame_size;
 }
 
-void FlutterPlatformViewsController::PrerollCompositeEmbeddedView(int view_id) {
+void FlutterPlatformViewsController::PrerollCompositeEmbeddedView(
+    int view_id,
+    std::unique_ptr<EmbeddedViewParams> params) {
   picture_recorders_[view_id] = std::make_unique<SkPictureRecorder>();
   picture_recorders_[view_id]->beginRecording(SkRect::Make(frame_size_));
   picture_recorders_[view_id]->getRecordingCanvas()->clear(SK_ColorTRANSPARENT);
   composition_order_.push_back(view_id);
+
+  if (current_composition_params_.count(view_id) == 1 &&
+      current_composition_params_[view_id] == *params.get()) {
+    // Do nothing if the params didn't change.
+    return;
+  }
+  current_composition_params_[view_id] = EmbeddedViewParams(*params.get());
+  views_to_recomposite_.insert(view_id);
 }
 
 NSObject<FlutterPlatformView>* FlutterPlatformViewsController::GetPlatformViewByID(int view_id) {
@@ -272,15 +282,14 @@
       head.layer.transform, CATransform3DMakeScale(1 / screenScale, 1 / screenScale, 1));
 }
 
-void FlutterPlatformViewsController::CompositeWithParams(
-    int view_id,
-    std::unique_ptr<flutter::EmbeddedViewParams> params) {
-  CGRect frame = CGRectMake(0, 0, params->sizePoints.width(), params->sizePoints.height());
+void FlutterPlatformViewsController::CompositeWithParams(int view_id,
+                                                         const EmbeddedViewParams& params) {
+  CGRect frame = CGRectMake(0, 0, params.sizePoints.width(), params.sizePoints.height());
   UIView* touchInterceptor = touch_interceptors_[view_id].get();
   touchInterceptor.layer.transform = CATransform3DIdentity;
   touchInterceptor.frame = frame;
 
-  int currentClippingCount = CountClips(params->mutatorsStack);
+  int currentClippingCount = CountClips(params.mutatorsStack);
   int previousClippingCount = clip_count_[view_id];
   if (currentClippingCount != previousClippingCount) {
     clip_count_[view_id] = currentClippingCount;
@@ -291,23 +300,19 @@
         ReconstructClipViewsChain(currentClippingCount, touchInterceptor, oldPlatformViewRoot);
     root_views_[view_id] = fml::scoped_nsobject<UIView>([newPlatformViewRoot retain]);
   }
-  ApplyMutators(params->mutatorsStack, touchInterceptor);
+  ApplyMutators(params.mutatorsStack, touchInterceptor);
 }
 
-SkCanvas* FlutterPlatformViewsController::CompositeEmbeddedView(
-    int view_id,
-    std::unique_ptr<flutter::EmbeddedViewParams> params) {
+SkCanvas* FlutterPlatformViewsController::CompositeEmbeddedView(int view_id) {
   // TODO(amirh): assert that this is running on the platform thread once we support the iOS
   // embedded views thread configuration.
 
-  // Do nothing if the params didn't change.
-  if (current_composition_params_.count(view_id) == 1 &&
-      current_composition_params_[view_id] == *params.get()) {
+  // Do nothing if the view doesn't need to be composited.
+  if (views_to_recomposite_.count(view_id) == 0) {
     return picture_recorders_[view_id]->getRecordingCanvas();
   }
-  current_composition_params_[view_id] = EmbeddedViewParams(*params.get());
-  CompositeWithParams(view_id, std::move(params));
-
+  CompositeWithParams(view_id, current_composition_params_[view_id]);
+  views_to_recomposite_.erase(view_id);
   return picture_recorders_[view_id]->getRecordingCanvas();
 }
 
@@ -323,6 +328,7 @@
   picture_recorders_.clear();
   current_composition_params_.clear();
   clip_count_.clear();
+  views_to_recomposite_.clear();
 }
 
 bool FlutterPlatformViewsController::SubmitFrame(bool gl_rendering,
@@ -414,6 +420,7 @@
     overlays_.erase(viewId);
     current_composition_params_.erase(viewId);
     clip_count_.erase(viewId);
+    views_to_recomposite_.erase(viewId);
   }
   views_to_dispose_.clear();
 }