This CL implements the first draft of Canvas 2D Context Attributes, aka getContext('2d', { alpha: f…

Source/core/platform/graphics/ImageBuffer.h

 /*
  * Copyright (C) 2006 Nikolas Zimmermann <zimmermann@kde.org>
  * Copyright (C) 2007, 2008, 2009 Apple Inc. All rights reserved.
  * 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.
@@ skipping 55 matching lines @@
     enum BackingStoreCopy {
         CopyBackingStore, // Guarantee subsequent draws don't affect the copy.
         DontCopyBackingStore // Subsequent draws may affect the copy.
     };
 
     enum ScaleBehavior {
         Scaled,
         Unscaled
     };
 
+    enum OpacityMode {
+        NonOpaque,
+        Opaque,
+    };
+
     class ImageBuffer {
         WTF_MAKE_NONCOPYABLE(ImageBuffer); WTF_MAKE_FAST_ALLOCATED;
     public:
         // Will return a null pointer on allocation failure.
-        static PassOwnPtr<ImageBuffer> create(const IntSize& size, float resolutionScale = 1, ColorSpace colorSpace = ColorSpaceDeviceRGB, RenderingMode renderingMode = Unaccelerated)
+        static PassOwnPtr<ImageBuffer> create(const IntSize& size, float resolutionScale = 1, ColorSpace colorSpace = ColorSpaceDeviceRGB, RenderingMode renderingMode = Unaccelerated, OpacityMode opacityMode = NonOpaque)
         {
             bool success = false;
-            OwnPtr<ImageBuffer> buf = adoptPtr(new ImageBuffer(size, resolutionScale, colorSpace, renderingMode, success));
+            OwnPtr<ImageBuffer> buf = adoptPtr(new ImageBuffer(size, resolutionScale, colorSpace, renderingMode, opacityMode, success));
             if (!success)
                 return nullptr;
             return buf.release();
         }
 
         static PassOwnPtr<ImageBuffer> createCompatibleBuffer(const IntSize&, float resolutionScale, ColorSpace, const GraphicsContext*, bool hasAlpha);
 
         ~ImageBuffer();
 
         // The actual resolution of the backing store
@@ skipping 43 matching lines @@
 
     private:
         ImageBufferData m_data;
         IntSize m_size;
         IntSize m_logicalSize;
         float m_resolutionScale;
         OwnPtr<GraphicsContext> m_context;
 
         // This constructor will place its success into the given out-variable
         // so that create() knows when it should return failure.
-        ImageBuffer(const IntSize&, float resolutionScale, ColorSpace, RenderingMode, bool& success);
+        ImageBuffer(const IntSize&, float resolutionScale, ColorSpace, RenderingMode, OpacityMode, bool& success);
         ImageBuffer(const IntSize&, float resolutionScale, ColorSpace, const GraphicsContext*, bool hasAlpha, bool& success);
     };
 
     String ImageDataToDataURL(const ImageData&, const String& mimeType, const double* quality);
 
 } // namespace WebCore
 
 #endif // ImageBuffer_h