Enable GPU acceleration in 2D OffscreenCanvases on main thread

third_party/WebKit/Source/modules/offscreencanvas2d/OffscreenCanvasRenderingContext2D.cpp

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "modules/offscreencanvas2d/OffscreenCanvasRenderingContext2D.h"
 
 #include "bindings/modules/v8/OffscreenCanvasRenderingContext2DOrWebGLRenderingContextOrWebGL2RenderingContext.h"
 #include "core/frame/ImageBitmap.h"
 #include "core/frame/Settings.h"
 #include "core/workers/WorkerGlobalScope.h"
 #include "core/workers/WorkerSettings.h"
 #include "platform/graphics/ImageBuffer.h"
 #include "platform/graphics/StaticBitmapImage.h"
+#include "platform/graphics/UnacceleratedImageBufferSurface.h"
+#include "platform/graphics/gpu/AcceleratedImageBufferSurface.h"
 #include "wtf/Assertions.h"
 
 #define UNIMPLEMENTED ASSERT_NOT_REACHED
 
 namespace blink {
 
 OffscreenCanvasRenderingContext2D::~OffscreenCanvasRenderingContext2D()
 {
 }
 
@@ skipping 49 matching lines @@
 int OffscreenCanvasRenderingContext2D::height() const
 {
     return getOffscreenCanvas()->height();
 }
 
 bool OffscreenCanvasRenderingContext2D::hasImageBuffer() const
 {
     return !!m_imageBuffer;
 }
 
+bool shouldAccelerate(IntSize surfaceSize)

[esprehn, 2016/08/05 21:28:38]

needs static or anonymous namespace

+{
+    if (!isMainThread())
+        return false; // Add support on Workers crbug.com/
+    return RuntimeEnabledFeatures::accelerated2dCanvasEnabled();
+}
+
 ImageBuffer* OffscreenCanvasRenderingContext2D::imageBuffer() const
 {
     if (!m_imageBuffer) {
-        // TODO: crbug.com/593514 Add support for GPU rendering
+        IntSize surfaceSize(width(), height());
+        OpacityMode opacityMode = m_hasAlpha ? NonOpaque : Opaque;
+        std::unique_ptr<ImageBufferSurface> surface;
+        if (shouldAccelerate(surfaceSize)) {
+            surface.reset(new AcceleratedImageBufferSurface(surfaceSize, opacityMode));
+        }
+
+        if (!surface || !surface->isValid()) {
+            surface.reset(new UnacceleratedImageBufferSurface(surfaceSize, opacityMode, InitializeImagePixels));
+        }
+
         OffscreenCanvasRenderingContext2D* nonConstThis = const_cast<OffscreenCanvasRenderingContext2D*>(this);
-        nonConstThis->m_imageBuffer = ImageBuffer::create(IntSize(width(), height()), m_hasAlpha ? NonOpaque : Opaque, InitializeImagePixels);
+        nonConstThis->m_imageBuffer = ImageBuffer::create(std::move(surface));
 
         if (m_needsMatrixClipRestore) {
             restoreMatrixClipStack(m_imageBuffer->canvas());
             nonConstThis->m_needsMatrixClipRestore = false;
         }
     }
 
     return m_imageBuffer.get();
 }
 
 ImageBitmap* OffscreenCanvasRenderingContext2D::transferToImageBitmap(ExceptionState& exceptionState)
 {
     if (!imageBuffer())
         return nullptr;
-    // TODO: crbug.com/593514 Add support for GPU rendering
-    RefPtr<SkImage> skImage = m_imageBuffer->newSkImageSnapshot(PreferNoAcceleration, SnapshotReasonTransferToImageBitmap);
+    RefPtr<SkImage> skImage = m_imageBuffer->newSkImageSnapshot(PreferAcceleration, SnapshotReasonTransferToImageBitmap);
+    DCHECK(isMainThread() || !skImage->isTextureBacked()); // Acceleration not yet supported in Workers
     RefPtr<StaticBitmapImage> image = StaticBitmapImage::create(skImage.release());
     image->setOriginClean(this->originClean());
     m_imageBuffer.reset(); // "Transfer" means no retained buffer
     m_needsMatrixClipRestore = true;
     return ImageBitmap::create(image.release());
 }
 
 void OffscreenCanvasRenderingContext2D::setOffscreenCanvasGetContextResult(OffscreenRenderingContext& result)
 {
     result.setOffscreenCanvasRenderingContext2D(this);
@@ skipping 55 matching lines @@
     }
 #endif
 }
 
 bool OffscreenCanvasRenderingContext2D::isContextLost() const
 {
     return false;
 }
 
 }