Refactor ImageBuffer to make OffscreenCanvas match HTMLCanvasElement

third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp

Index: third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp
diff --git a/third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp b/third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp
index 686f2ada187a97216ac8c8b2d231486b72b5a9d9..9ffa5ffdcf4af39327929ad294d5a5e9326a4f53 100644
--- a/third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp
+++ b/third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp
@@ -295,7 +295,7 @@ CanvasRenderingContext* HTMLCanvasElement::GetCanvasRenderingContext(
 
 bool HTMLCanvasElement::ShouldBeDirectComposited() const {
   return (context_ && context_->IsComposited()) ||
-         (HasImageBuffer() && Buffer()->IsExpensiveToPaint()) ||
+         (HasImageBuffer() && GetImageBuffer()->IsExpensiveToPaint()) ||
          (!!surface_layer_bridge_);
 }
 
@@ -324,7 +324,7 @@ void HTMLCanvasElement::DidDraw(const FloatRect& rect) {
     dirty_rect_.Unite(rect);
   }
   if (Is2d() && HasImageBuffer())
-    Buffer()->DidDraw(rect);
+    GetImageBuffer()->DidDraw(rect);
 }
 
 void HTMLCanvasElement::DidDraw() {
@@ -432,7 +432,7 @@ void HTMLCanvasElement::DoDeferredPaintInvalidation() {
   if (RuntimeEnabledFeatures::
           enableCanvas2dDynamicRenderingModeSwitchingEnabled() &&
       !RuntimeEnabledFeatures::canvas2dFixedRenderingModeEnabled()) {
-    if (Is2d() && HasImageBuffer() && Buffer()->IsAccelerated() &&
+    if (Is2d() && HasImageBuffer() && GetImageBuffer()->IsAccelerated() &&
         num_frames_since_last_rendering_mode_switch_ >=
             ExpensiveCanvasHeuristicParameters::kMinFramesBeforeSwitch &&
         !pending_rendering_mode_switch_) {
@@ -454,8 +454,8 @@ void HTMLCanvasElement::DoDeferredPaintInvalidation() {
     }
   }
 
-  if (pending_rendering_mode_switch_ && Buffer() &&
-      !Buffer()->IsAccelerated()) {
+  if (pending_rendering_mode_switch_ && GetImageBuffer() &&
+      !GetImageBuffer()->IsAccelerated()) {
     pending_rendering_mode_switch_ = false;
   }
 
@@ -488,7 +488,7 @@ void HTMLCanvasElement::Reset() {
   // If the size of an existing buffer matches, we can just clear it instead of
   // reallocating.  This optimization is only done for 2D canvases for now.
   if (had_image_buffer && old_size == new_size && Is2d() &&
-      !Buffer()->IsRecording()) {
+      !GetImageBuffer()->IsRecording()) {
     if (!image_buffer_is_clear_) {
       image_buffer_is_clear_ = true;
       context_->clearRect(0, 0, width(), height());
@@ -601,7 +601,8 @@ void HTMLCanvasElement::Paint(GraphicsContext& context, const LayoutRect& r) {
           !context_ || context_->CreationAttributes().alpha()
               ? SkBlendMode::kSrcOver
               : SkBlendMode::kSrc;
-      Buffer()->Draw(context, PixelSnappedIntRect(r), 0, composite_operator);
+      GetImageBuffer()->Draw(context, PixelSnappedIntRect(r), 0,
+                             composite_operator);
     }
   } else {
     // When alpha is false, we should draw to opaque black.
@@ -642,7 +643,7 @@ const AtomicString HTMLCanvasElement::ImageSourceURL() const {
 
 void HTMLCanvasElement::PrepareSurfaceForPaintingIfNeeded() const {
   DCHECK(Is2d());  // This function is called by the 2d context
-  if (Buffer())
+  if (GetImageBuffer())
     image_buffer_->PrepareSurfaceForPaintingIfNeeded();
 }
 
@@ -660,7 +661,7 @@ ImageData* HTMLCanvasElement::ToImageData(SourceDrawingBuffer source_buffer,
     image_data = ImageData::Create(size_);
     if (image_data && HasImageBuffer()) {
       sk_sp<SkImage> snapshot =
-          Buffer()->NewSkImageSnapshot(kPreferNoAcceleration, reason);
+          GetImageBuffer()->NewSkImageSnapshot(kPreferNoAcceleration, reason);
       if (snapshot) {
         SkImageInfo image_info = SkImageInfo::Make(
             width(), height(), kRGBA_8888_SkColorType, kUnpremul_SkAlphaType);
@@ -679,7 +680,8 @@ ImageData* HTMLCanvasElement::ToImageData(SourceDrawingBuffer source_buffer,
   DCHECK(Is2d() || PlaceholderFrame());
   sk_sp<SkImage> snapshot;
   if (HasImageBuffer()) {
-    snapshot = Buffer()->NewSkImageSnapshot(kPreferNoAcceleration, reason);
+    snapshot =
+        GetImageBuffer()->NewSkImageSnapshot(kPreferNoAcceleration, reason);
   } else if (PlaceholderFrame()) {
     DCHECK(PlaceholderFrame()->OriginClean());
     snapshot = PlaceholderFrame()->ImageForCurrentFrame();
@@ -1095,11 +1097,11 @@ void HTMLCanvasElement::UpdateExternallyAllocatedMemory() const {
 }
 
 PaintCanvas* HTMLCanvasElement::DrawingCanvas() const {
-  return Buffer() ? image_buffer_->Canvas() : nullptr;
+  return GetImageBuffer() ? image_buffer_->Canvas() : nullptr;
 }
 
 void HTMLCanvasElement::DisableDeferral(DisableDeferralReason reason) const {
-  if (Buffer())
+  if (GetImageBuffer())
     image_buffer_->DisableDeferral(reason);
 }
 
@@ -1110,7 +1112,7 @@ PaintCanvas* HTMLCanvasElement::ExistingDrawingCanvas() const {
   return image_buffer_->Canvas();
 }
 
-ImageBuffer* HTMLCanvasElement::Buffer() const {
+ImageBuffer* HTMLCanvasElement::GetImageBuffer() const {

[Justin Novosad, 2017/05/01 15:18:57]

Nit (existed before this CL): This function does not deserve "const" IMHO,
especially once its semantics are clarified by renaming it "GetOrCreate". I also
think "const" is overused by the methods that call this function.  const_casts
like the one below are hypocritical and should be avoided with only a few rare
exceptions (e.g. caches, stats needed for validations or consistency checks).

[fserb, 2017/05/02 18:49:30]

done

   DCHECK(context_);
   DCHECK(context_->GetContextType() !=
          CanvasRenderingContext::kContextImageBitmap);
@@ -1163,8 +1165,8 @@ PassRefPtr<Image> HTMLCanvasElement::CopiedImage(
   // The concept of SourceDrawingBuffer is valid on only WebGL.
   if (context_->Is3d())
     need_to_update |= context_->PaintRenderingResultsToCanvas(source_buffer);
-  if (need_to_update && Buffer()) {
-    copied_image_ = Buffer()->NewImageSnapshot(hint, snapshot_reason);
+  if (need_to_update && GetImageBuffer()) {
+    copied_image_ = GetImageBuffer()->NewImageSnapshot(hint, snapshot_reason);
     UpdateExternallyAllocatedMemory();
   }
   return copied_image_;
@@ -1222,7 +1224,7 @@ void HTMLCanvasElement::DidMoveToNewDocument(Document& old_document) {
 void HTMLCanvasElement::WillDrawImageTo2DContext(CanvasImageSource* source) {
   if (ExpensiveCanvasHeuristicParameters::kEnableAccelerationToAvoidReadbacks &&
       SharedGpuContext::AllowSoftwareToAcceleratedCanvasUpgrade() &&
-      source->IsAccelerated() && !Buffer()->IsAccelerated() &&
+      source->IsAccelerated() && !GetImageBuffer()->IsAccelerated() &&
       ShouldAccelerate(kIgnoreResourceLimitCriteria)) {
     OpacityMode opacity_mode =
         context_->CreationAttributes().alpha() ? kNonOpaque : kOpaque;
@@ -1230,7 +1232,7 @@ void HTMLCanvasElement::WillDrawImageTo2DContext(CanvasImageSource* source) {
     std::unique_ptr<ImageBufferSurface> surface =
         CreateAcceleratedImageBufferSurface(opacity_mode, &msaa_sample_count);
     if (surface) {
-      Buffer()->SetSurface(std::move(surface));
+      GetImageBuffer()->SetSurface(std::move(surface));
       SetNeedsCompositingUpdate();
     }
   }
@@ -1277,7 +1279,7 @@ PassRefPtr<Image> HTMLCanvasElement::GetSourceImageForCanvas(
     // cached copy of the backing in the canvas's ImageBuffer.
     RenderingContext()->PaintRenderingResultsToCanvas(kBackBuffer);
     if (HasImageBuffer()) {
-      sk_image = Buffer()->NewSkImageSnapshot(hint, reason);
+      sk_image = GetImageBuffer()->NewSkImageSnapshot(hint, reason);
     } else {
       sk_image = CreateTransparentSkImage(Size());
     }
@@ -1286,8 +1288,8 @@ PassRefPtr<Image> HTMLCanvasElement::GetSourceImageForCanvas(
             kDisableAccelerationToAvoidReadbacks &&
         !RuntimeEnabledFeatures::canvas2dFixedRenderingModeEnabled() &&
         hint == kPreferNoAcceleration && HasImageBuffer() &&
-        Buffer()->IsAccelerated()) {
-      Buffer()->DisableAcceleration();
+        GetImageBuffer()->IsAccelerated()) {
+      GetImageBuffer()->DisableAcceleration();
     }
     RefPtr<Image> image = RenderingContext()->GetImage(hint, reason);
     if (image) {