Refactoring source image usage in CanvasRenderingContext2D

Source/core/html/canvas/CanvasImageSource.h

Index: Source/core/html/canvas/CanvasImageSource.h
diff --git a/Source/core/html/canvas/CanvasGradient.h b/Source/core/html/canvas/CanvasImageSource.h
similarity index 54%
copy from Source/core/html/canvas/CanvasGradient.h
copy to Source/core/html/canvas/CanvasImageSource.h
index 599534fb31a150d1c430837011bb9d4a393c0858..7c29e059c5a2c6c4c59efd5d0ef8c3e180c95907 100644
--- a/Source/core/html/canvas/CanvasGradient.h
+++ b/Source/core/html/canvas/CanvasImageSource.h
@@ -24,41 +24,47 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#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;
+
+enum CanvasImageSourceUsage {
+    PatternCanvasImageSourceUsage,
+    DrawCanvasImageSourceUsage
+};
 
-class CanvasGradient : public RefCounted<CanvasGradient>, public ScriptWrappable {
+class CanvasImageSource {
 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));
-    }
+    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;
 
-    Gradient* gradient() const { return m_gradient.get(); }
+    virtual bool isVideoElement() const { return false; }
 
-    void addColorStop(float value, const String& color, ExceptionState&);
+    // 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 { }
 
-private:
-    CanvasGradient(const FloatPoint& p0, const FloatPoint& p1);
-    CanvasGradient(const FloatPoint& p0, float r0, const FloatPoint& p1, float r1);
+    virtual FloatSize sourceSize() const = 0;
+    virtual FloatSize defaultDestinationSize() const { return sourceSize(); }
 
-    RefPtr<Gradient> m_gradient;
+protected:
+    virtual ~CanvasImageSource() { }
 };
 
-} //namespace
+} // namespace WebCore
 
 #endif