Refactoring source image usage in CanvasRenderingContext2D

Source/core/html/canvas/CanvasImageSource.h

 /*
  * Copyright (C) 2006, 2007, 2008 Apple Computer, Inc.  All rights reserved.
  * Copyright (C) 2007 Alp Toker <alp@atoker.com>
  *
  * 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
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  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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-#ifndef CanvasGradient_h
-#define CanvasGradient_h
+#ifndef CanvasImageSource_h
+#define CanvasImageSource_h
 
-#include "bindings/v8/ScriptWrappable.h"
-#include "platform/graphics/Gradient.h"
-#include "wtf/Forward.h"
 #include "wtf/PassRefPtr.h"
-#include "wtf/RefCounted.h"
+
+using namespace WTF;
 
 namespace WebCore {
 
 class ExceptionState;
+class HTMLCanvasElement;
+class Image;
 
-class CanvasGradient : public RefCounted<CanvasGradient>, public ScriptWrappable {
-public:
-    static PassRefPtr<CanvasGradient> create(const FloatPoint& p0, const FloatPoint& p1)
-    {
-        return adoptRef(new CanvasGradient(p0, p1));
-    }
-    static PassRefPtr<CanvasGradient> create(const FloatPoint& p0, float r0, const FloatPoint& p1, float r1)
-    {
-        return adoptRef(new CanvasGradient(p0, r0, p1, r1));
-    }
-
-    Gradient* gradient() const { return m_gradient.get(); }
-
-    void addColorStop(float value, const String& color, ExceptionState&);
-
-private:
-    CanvasGradient(const FloatPoint& p0, const FloatPoint& p1);
-    CanvasGradient(const FloatPoint& p0, float r0, const FloatPoint& p1, float r1);
-
-    RefPtr<Gradient> m_gradient;
+enum CanvasImageSourceUsage {
+    PatternCanvasImageSourceUsage,
+    DrawCanvasImageSourceUsage
 };
 
-} //namespace
+class CanvasImageSource {
+public:
+    virtual PassRefPtr<Image> getSourceImageForCanvas(HTMLCanvasElement*, ExceptionState&, CanvasImageSourceUsage, bool* isVolatile = 0) const = 0;
+
+    // IMPORTANT: Result must be independent of whether destinationContext is
+    // already tainted because this function may be used to determine whether
+    // a CanvasPattern is "origin clean", and that pattern may be used on
+    // another canvas, which may not be already tainted.
+    virtual bool wouldTaintOrigin(CanvasRenderingContext* destinationContext) const = 0;
+
+    virtual bool isVideoElement() const { return false; }
+
+    // Adjusts the source and destination rectangles for cases where the actual
+    // source image is a subregion of the image returned by getSourceImageForCanvas.
+    virtual void adjustDrawRects(FloatRect* srcRect, FloatRect* dstRect) const { }
+
+    virtual FloatSize sourceSize() const = 0;
+    virtual FloatSize defaultDestinationSize() const { return sourceSize(); }
+
+protected:
+    virtual ~CanvasImageSource() { }
+};
+
+} // namespace WebCore
 
 #endif