Implement Asynchronous image encoding for Canvas.toBlob

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

 /*
  * Copyright (C) 2004, 2006, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Alp Toker <alp@atoker.com>
  * Copyright (C) 2010 Torch Mobile (Beijing) Co. Ltd. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
@@ skipping 13 matching lines @@
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef HTMLCanvasElement_h
 #define HTMLCanvasElement_h
 
 #include "bindings/core/v8/ScriptValue.h"
 #include "bindings/core/v8/UnionTypesCore.h"
 #include "core/CoreExport.h"
+#include "core/dom/DOMTypedArray.h"
 #include "core/dom/Document.h"
 #include "core/dom/DocumentVisibilityObserver.h"
 #include "core/fileapi/FileCallback.h"
 #include "core/html/HTMLElement.h"
 #include "core/html/canvas/CanvasImageSource.h"
 #include "platform/geometry/FloatRect.h"
 #include "platform/geometry/IntSize.h"
 #include "platform/graphics/GraphicsTypes.h"
 #include "platform/graphics/GraphicsTypes3D.h"
 #include "platform/graphics/ImageBufferClient.h"
 #include "platform/heap/Handle.h"
+#include "public/platform/WebThread.h"
 
 #define CanvasDefaultInterpolationQuality InterpolationLow
 
 namespace blink {
 
 class AffineTransform;
 class CanvasContextCreationAttributes;
 class CanvasRenderingContext;
 class CanvasRenderingContextFactory;
 class GraphicsContext;
@@ skipping 16 matching lines @@
     DEFINE_INLINE_VIRTUAL_TRACE() { }
 };
 
 class CORE_EXPORT HTMLCanvasElement final : public HTMLElement, public DocumentVisibilityObserver, public CanvasImageSource, public ImageBufferClient {
     DEFINE_WRAPPERTYPEINFO();
     WILL_BE_USING_GARBAGE_COLLECTED_MIXIN(HTMLCanvasElement);
 public:
     DECLARE_NODE_FACTORY(HTMLCanvasElement);
     ~HTMLCanvasElement() override;
 
+    static PassOwnPtr<WebThread> getToBlobThreadInstance();

[Justin Novosad, 2015/09/24 20:51:31]

This is not a proper use of PassOwnPtr. I really think that wrapping the thread
ownership in a singleton would be the way to go here. I looked through blink
code, and I found one really clean example of a singleton that owns a thread,
with explicit initialization and teardown, which is nice because it means we are
not even leaking the singleton. Checkout CompositorWorkerManager. In your case,
you are not in a module, so your global init/uninit would go in WebKit.cpp 

+    static int s_numCanvasInstances; 
+
     void addObserver(CanvasObserver*);
     void removeObserver(CanvasObserver*);
 
     // Attributes and functions exposed to script
     int width() const { return size().width(); }
     int height() const { return size().height(); }
 
     const IntSize& size() const { return m_size; }
 
     void setWidth(int);
@@ skipping 16 matching lines @@
     ScriptValue getContext(ScriptState*, const String&, const CanvasContextCreationAttributes&);
     // Called by Document::getCSSCanvasContext as well as above getContext().
     CanvasRenderingContext* getCanvasRenderingContext(const String&, const CanvasContextCreationAttributes&);
 
     bool isPaintable() const;
 
     static String toEncodingMimeType(const String& mimeType);
     String toDataURL(const String& mimeType, const ScriptValue& qualityArgument, ExceptionState&) const;
     String toDataURL(const String& mimeType, ExceptionState& exceptionState) const { return toDataURL(mimeType, ScriptValue(), exceptionState); }
 
-    void toBlob(FileCallback*, const String& mimeType, const ScriptValue& qualityArgument, ExceptionState&) const;
+    void toBlob(FileCallback*, const String& mimeType, const ScriptValue& qualityArgument, ExceptionState&);
     void toBlob(FileCallback* callback, const String& mimeType, ExceptionState& exceptionState) { return toBlob(callback, mimeType, ScriptValue(), exceptionState); }
 
     // Used for rendering
     void didDraw(const FloatRect&);
     void notifyObserversCanvasChanged(const FloatRect&);
 
     void paint(GraphicsContext*, const LayoutRect&);
 
     SkCanvas* drawingCanvas() const;
     void disableDeferral() const;
@@ skipping 74 matching lines @@
     PassOwnPtr<ImageBufferSurface> createImageBufferSurface(const IntSize& deviceSize, int* msaaSampleCount);
     void createImageBuffer();
     void createImageBufferInternal(PassOwnPtr<ImageBufferSurface> externalSurface);
     bool shouldUseDisplayList(const IntSize& deviceSize);
 
     void setSurfaceSize(const IntSize&);
 
     bool paintsIntoCanvasBuffer() const;
 
     ImageData* toImageData(SourceDrawingBuffer) const;
-    String toDataURLInternal(const String& mimeType, const double* quality, SourceDrawingBuffer) const;
+    String toDataURLInternal(const String& mimeType, const double& quality, SourceDrawingBuffer) const;
+
+    void encodeImageAsync(DOMUint8ClampedArray* imagedata, IntSize imageSize, FileCallback*, const String& mimeType, double quality);
+    void createBlobAndCall(PassOwnPtr<Vector<char>> encodedImage, const String& mimeType, FileCallback*);
 
     WillBeHeapHashSet<RawPtrWillBeWeakMember<CanvasObserver>> m_observers;
 
     IntSize m_size;
 
     OwnPtrWillBeMember<CanvasRenderingContext> m_context;
 
     bool m_ignoreReset;
     bool m_accelerationDisabled;
     FloatRect m_dirtyRect;
 
     mutable intptr_t m_externallyAllocatedMemory;
 
     bool m_originClean;
 
     // It prevents HTMLCanvasElement::buffer() from continuously re-attempting to allocate an imageBuffer
     // after the first attempt failed.
     mutable bool m_didFailToCreateImageBuffer;
     bool m_imageBufferIsClear;
     OwnPtr<ImageBuffer> m_imageBuffer;
 
     mutable RefPtr<Image> m_copiedImage; // FIXME: This is temporary for platforms that have to copy the image buffer to render (and for CSSCanvasValue).
 };
 
 } // namespace blink
 
 #endif // HTMLCanvasElement_h