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/CanvasImageSource.h b/Source/core/html/canvas/CanvasImageSource.h
new file mode 100644
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+++ b/Source/core/html/canvas/CanvasImageSource.h
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+/*
+ * 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
+ * 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 CanvasImageSource_h
+#define CanvasImageSource_h
+
+#include "wtf/PassRefPtr.h"
+
+namespace WebCore {
+
+class Image;
+class SecurityOrigin;
+
+enum SourceImageMode {
+    CopySourceImageIfVolatile,
+    DontCopySourceImage
+};
+
+enum SourceImageStatus {
+    NormalSourceImageStatus,
+    ExternalSourceImageStatus, // Shared with another GPU context
+    UndecodableSourceImageStatus, // Image element with a 'broken' image
+    ZeroSizeCanvasSourceImageStatus, // Source is a canvas with width or heigh of zero
+    IncompleteSourceImageStatus, // Image element with no source media
+    InvalidSourceImageStatus,
+};
+
+class CanvasImageSource {
+public:
+    virtual PassRefPtr<Image> getSourceImageForCanvas(SourceImageMode, SourceImageStatus* = 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(SecurityOrigin* destinationSecurityOrigin) 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