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      1 /*
      2  * Copyright (C) 2004, 2006, 2009, 2010 Apple Inc. All rights reserved.
      3  * Copyright (C) 2007 Alp Toker <alp (at) atoker.com>
      4  * Copyright (C) 2010 Torch Mobile (Beijing) Co. Ltd. All rights reserved.
      5  *
      6  * Redistribution and use in source and binary forms, with or without
      7  * modification, are permitted provided that the following conditions
      8  * are met:
      9  * 1. Redistributions of source code must retain the above copyright
     10  *    notice, this list of conditions and the following disclaimer.
     11  * 2. Redistributions in binary form must reproduce the above copyright
     12  *    notice, this list of conditions and the following disclaimer in the
     13  *    documentation and/or other materials provided with the distribution.
     14  *
     15  * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
     16  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     17  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     18  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
     19  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
     20  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
     21  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
     22  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
     23  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     24  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     25  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     26  */
     27 
     28 #ifndef HTMLCanvasElement_h
     29 #define HTMLCanvasElement_h
     30 
     31 #include "core/html/HTMLElement.h"
     32 #include "platform/geometry/FloatRect.h"
     33 #include "platform/geometry/IntSize.h"
     34 #include "wtf/Forward.h"
     35 
     36 #define DefaultInterpolationQuality InterpolationMedium
     37 
     38 namespace WebCore {
     39 
     40 class CanvasContextAttributes;
     41 class CanvasRenderingContext;
     42 class GraphicsContext;
     43 class GraphicsContextStateSaver;
     44 class HTMLCanvasElement;
     45 class Image;
     46 class ImageData;
     47 class ImageBuffer;
     48 class ImageBufferSurface;
     49 class IntSize;
     50 
     51 class CanvasObserver {
     52 public:
     53     virtual ~CanvasObserver() { }
     54 
     55     virtual void canvasChanged(HTMLCanvasElement*, const FloatRect& changedRect) = 0;
     56     virtual void canvasResized(HTMLCanvasElement*) = 0;
     57     virtual void canvasDestroyed(HTMLCanvasElement*) = 0;
     58 };
     59 
     60 class HTMLCanvasElement FINAL : public HTMLElement {
     61 public:
     62     static PassRefPtr<HTMLCanvasElement> create(Document&);
     63     virtual ~HTMLCanvasElement();
     64 
     65     void addObserver(CanvasObserver*);
     66     void removeObserver(CanvasObserver*);
     67 
     68     // Attributes and functions exposed to script
     69     int width() const { return size().width(); }
     70     int height() const { return size().height(); }
     71 
     72     const IntSize& size() const { return m_size; }
     73 
     74     void setWidth(int);
     75     void setHeight(int);
     76     void setAccelerationDisabled(bool accelerationDisabled) { m_accelerationDisabled = accelerationDisabled; }
     77     bool accelerationDisabled() const { return m_accelerationDisabled; }
     78 
     79     void setSize(const IntSize& newSize)
     80     {
     81         if (newSize == size())
     82             return;
     83         m_ignoreReset = true;
     84         setWidth(newSize.width());
     85         setHeight(newSize.height());
     86         m_ignoreReset = false;
     87         reset();
     88     }
     89 
     90     CanvasRenderingContext* getContext(const String&, CanvasContextAttributes* attributes = 0);
     91 
     92     static String toEncodingMimeType(const String& mimeType);
     93     String toDataURL(const String& mimeType, const double* quality, ExceptionState&);
     94     String toDataURL(const String& mimeType, ExceptionState& exceptionState) { return toDataURL(mimeType, 0, exceptionState); }
     95 
     96     // Used for rendering
     97     void didDraw(const FloatRect&);
     98     void notifyObserversCanvasChanged(const FloatRect&);
     99 
    100     void paint(GraphicsContext*, const LayoutRect&, bool useLowQualityScale = false);
    101 
    102     GraphicsContext* drawingContext() const;
    103     GraphicsContext* existingDrawingContext() const;
    104 
    105     CanvasRenderingContext* renderingContext() const { return m_context.get(); }
    106 
    107     void ensureUnacceleratedImageBuffer();
    108     ImageBuffer* buffer() const;
    109     Image* copiedImage() const;
    110     void clearCopiedImage();
    111     PassRefPtr<ImageData> getImageData();
    112     void makePresentationCopy();
    113     void clearPresentationCopy();
    114 
    115     SecurityOrigin* securityOrigin() const;
    116     void setOriginTainted() { m_originClean = false; }
    117     bool originClean() const { return m_originClean; }
    118 
    119     AffineTransform baseTransform() const;
    120 
    121     bool is3D() const;
    122 
    123     bool hasImageBuffer() const { return m_imageBuffer.get(); }
    124 
    125     bool shouldAccelerate(const IntSize&) const;
    126 
    127     InsertionNotificationRequest insertedInto(ContainerNode*) OVERRIDE;
    128 
    129 private:
    130     explicit HTMLCanvasElement(Document&);
    131 
    132     virtual void parseAttribute(const QualifiedName&, const AtomicString&) OVERRIDE;
    133     virtual RenderObject* createRenderer(RenderStyle*);
    134     virtual bool areAuthorShadowsAllowed() const OVERRIDE { return false; }
    135 
    136     void reset();
    137 
    138     PassOwnPtr<ImageBufferSurface> createImageBufferSurface(const IntSize& deviceSize, int* msaaSampleCount);
    139     void createImageBuffer();
    140     void clearImageBuffer();
    141 
    142     void setSurfaceSize(const IntSize&);
    143 
    144     bool paintsIntoCanvasBuffer() const;
    145 
    146     void setExternallyAllocatedMemory(intptr_t);
    147 
    148     HashSet<CanvasObserver*> m_observers;
    149 
    150     IntSize m_size;
    151 
    152     OwnPtr<CanvasRenderingContext> m_context;
    153 
    154     bool m_rendererIsCanvas;
    155 
    156     bool m_ignoreReset;
    157     bool m_accelerationDisabled;
    158     FloatRect m_dirtyRect;
    159 
    160     intptr_t m_externallyAllocatedMemory;
    161 
    162     bool m_originClean;
    163 
    164     // It prevents HTMLCanvasElement::buffer() from continuously re-attempting to allocate an imageBuffer
    165     // after the first attempt failed.
    166     mutable bool m_didFailToCreateImageBuffer;
    167     mutable bool m_didClearImageBuffer;
    168     OwnPtr<ImageBuffer> m_imageBuffer;
    169     mutable OwnPtr<GraphicsContextStateSaver> m_contextStateSaver;
    170 
    171     mutable RefPtr<Image> m_presentedImage;
    172     mutable RefPtr<Image> m_copiedImage; // FIXME: This is temporary for platforms that have to copy the image buffer to render (and for CSSCanvasValue).
    173 };
    174 
    175 DEFINE_NODE_TYPE_CASTS(HTMLCanvasElement, hasTagName(HTMLNames::canvasTag));
    176 
    177 } //namespace
    178 
    179 #endif
    180