text: /*
   * 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.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   *
   * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
   * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
   * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
   * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
   * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
   * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
   * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
   * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   * (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/dom/Document.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 GraphicsContext;
  class GraphicsContextStateSaver;
  class HTMLCanvasElement;
  class Image;
  class ImageData;
  class ImageBuffer;
  class ImageBufferSurface;
  class IntSize;
  class RecordingImageBufferFallbackSurfaceFactory;
  
  class CanvasObserver : public WillBeGarbageCollectedMixin {
      DECLARE_EMPTY_VIRTUAL_DESTRUCTOR_WILL_BE_REMOVED(CanvasObserver);
  public:
      virtual void canvasChanged(HTMLCanvasElement*, const FloatRect& changedRect) = 0;
      virtual void canvasResized(HTMLCanvasElement*) = 0;
  #if !ENABLE(OILPAN)
      virtual void canvasDestroyed(HTMLCanvasElement*) = 0;
  #endif
  
      virtual void trace(Visitor*) { }
  };
  
  class HTMLCanvasElement final : public HTMLElement, public DocumentVisibilityObserver, public CanvasImageSource, public ImageBufferClient, public blink::WebThread::TaskObserver {
      DEFINE_WRAPPERTYPEINFO();
      WILL_BE_USING_GARBAGE_COLLECTED_MIXIN(HTMLCanvasElement);
  public:
      DECLARE_NODE_FACTORY(HTMLCanvasElement);
      virtual ~HTMLCanvasElement();
  
      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);
      void setHeight(int);
      void setAccelerationDisabled(bool accelerationDisabled) { m_accelerationDisabled = accelerationDisabled; }
      bool accelerationDisabled() const { return m_accelerationDisabled; }
  
      void setSize(const IntSize& newSize)
      {
          if (newSize == size())
              return;
          m_ignoreReset = true;
          setWidth(newSize.width());
          setHeight(newSize.height());
          m_ignoreReset = false;
          reset();
      }
  
      // Called by HTMLCanvasElement's V8 bindings.
      ScriptValue getContext(ScriptState*, const String&, const CanvasContextCreationAttributes&);
      // Called by Document::getCSSCanvasContext as well as above getContext() variant.
      void getContext(const String&, const CanvasContextCreationAttributes&, CanvasRenderingContext2DOrWebGLRenderingContext&);
      bool isPaintable() const;
  
      static String toEncodingMimeType(const String& mimeType);
      String toDataURL(const String& mimeType, const double* quality, ExceptionState&) const;
      String toDataURL(const String& mimeType, ExceptionState& exceptionState) const { return toDataURL(mimeType, 0, exceptionState); }
  
      // Used for rendering
      void didDraw(const FloatRect&);
      void notifyObserversCanvasChanged(const FloatRect&);
  
      void paint(GraphicsContext*, const LayoutRect&);
  
      GraphicsContext* drawingContext() const;
      GraphicsContext* existingDrawingContext() const;
  
      CanvasRenderingContext* renderingContext() const { return m_context.get(); }
  
      void ensureUnacceleratedImageBuffer();
      ImageBuffer* buffer() const;
      PassRefPtr<Image> copiedImage(SourceDrawingBuffer) const;
      void clearCopiedImage();
  
      SecurityOrigin* securityOrigin() const;
      bool originClean() const { return m_originClean; }
      void setOriginTainted() { m_originClean = false; }
  
      AffineTransform baseTransform() const;
  
      bool is3D() const;
  
      bool hasImageBuffer() const { return m_imageBuffer; }
      bool hasValidImageBuffer() const;
      void discardImageBuffer();
  
      bool shouldAccelerate(const IntSize&) const;
  
      virtual const AtomicString imageSourceURL() const override;
  
      virtual InsertionNotificationRequest insertedInto(ContainerNode*) override;
  
      // DocumentVisibilityObserver implementation
      virtual void didChangeVisibilityState(PageVisibilityState) override;
  
      // CanvasImageSource implementation
      virtual PassRefPtr<Image> getSourceImageForCanvas(SourceImageMode, SourceImageStatus*) const override;
      virtual bool wouldTaintOrigin(SecurityOrigin*) const override;
      virtual FloatSize sourceSize() const override;
  
      // ImageBufferClient implementation
      virtual void notifySurfaceInvalid() override;
      virtual bool isDirty() override { return !m_dirtyRect.isEmpty(); }
      virtual void didFinalizeFrame() override;
      virtual void restoreCanvasMatrixClipStack() override;
  
      // Implementation of WebThread::TaskObserver methods
      virtual void willProcessTask() override;
      virtual void didProcessTask() override;
  
      virtual void trace(Visitor*) override;
  
  protected:
      virtual void didMoveToNewDocument(Document& oldDocument) override;
  
  private:
      explicit HTMLCanvasElement(Document&);
  
      virtual void parseAttribute(const QualifiedName&, const AtomicString&) override;
      virtual RenderObject* createRenderer(RenderStyle*) override;
      virtual void didRecalcStyle(StyleRecalcChange) override;
      virtual bool areAuthorShadowsAllowed() const override { return false; }
  
      void reset();
  
      PassOwnPtr<RecordingImageBufferFallbackSurfaceFactory> createSurfaceFactory(const IntSize& deviceSize, int* msaaSampleCount) const;
      PassOwnPtr<ImageBufferSurface> createImageBufferSurface(const IntSize& deviceSize, int* msaaSampleCount);
      void createImageBuffer();
      void createImageBufferInternal();
      bool shouldUseDisplayList(const IntSize& deviceSize);
  
      void resetDirtyRect();
  
      void setSurfaceSize(const IntSize&);
  
      bool paintsIntoCanvasBuffer() const;
  
      void updateExternallyAllocatedMemory() const;
  
      String toDataURLInternal(const String& mimeType, const double* quality, SourceDrawingBuffer) const;
  
      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 OwnPtr<GraphicsContextStateSaver> m_contextStateSaver;
  
      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
  