Allow DrawingBuffer to present to a bitmap.

Source/core/platform/graphics/GraphicsContext3D.h

 /*
  * Copyright (C) 2009 Apple Inc. 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.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 771 matching lines @@
 
     // Helper function which extracts the user-supplied texture
     // data, applying the flipY and premultiplyAlpha parameters.
     // If the data is not tightly packed according to the passed
     // unpackAlignment, the output data will be tightly packed.
     // Returns true if successful, false if any error occurred.
     static bool extractTextureData(unsigned width, unsigned height, GC3Denum format, GC3Denum type, unsigned unpackAlignment, bool flipY, bool premultiplyAlpha, const void* pixels, Vector<uint8_t>& data);
 
     // End GraphicsContext3DImagePacking.cpp functions
 
+    // This is the order of bytes to use when doing a readback.
+    enum ReadbackOrder {
+        ReadbackRGBA,
+        ReadbackSkia
+    };
+
+    // Helper function which does a readback from the currently-bound
+    // framebuffer into a buffer of a certain size with 4-byte pixels.
+    void readBackFramebuffer(unsigned char* pixels, int width, int height, ReadbackOrder, AlphaOp);
+
 private:
     friend class Extensions3D;
 
     GraphicsContext3D(PassOwnPtr<WebKit::WebGraphicsContext3D>, bool preserveDrawingBuffer);
     GraphicsContext3D(PassOwnPtr<WebKit::WebGraphicsContext3DProvider>, bool preserveDrawingBuffer);
 
     // Helper for packImageData/extractImageData/extractTextureData which implement packing of pixel
     // data into the specified OpenGL destination format and type.
     // A sourceUnpackAlignment of zero indicates that the source
     // data is tightly packed. Non-zero values may take a slow path.
     // Destination data will have no gaps between rows.
     // Implemented in GraphicsContext3DImagePacking.cpp
     static bool packPixels(const uint8_t* sourceData, DataFormat sourceDataFormat, unsigned width, unsigned height, unsigned sourceUnpackAlignment, unsigned destinationFormat, unsigned destinationType, AlphaOp, void* destinationData, bool flipY);
 
     void paintFramebufferToCanvas(int framebuffer, int width, int height, bool premultiplyAlpha, ImageBuffer*);
+    // Helper function to flip a bitmap vertically.
+    void flipVertically(uint8_t* data, int width, int height);
 
     // Extensions3D support.
     bool supportsExtension(const String& name);
     bool ensureExtensionEnabled(const String& name);
     bool isExtensionEnabled(const String& name);
 
     void initializeExtensions();
 
     bool preserveDrawingBuffer() const { return m_preserveDrawingBuffer; }
 
     OwnPtr<WebKit::WebGraphicsContext3DProvider> m_provider;
     WebKit::WebGraphicsContext3D* m_impl;
     OwnPtr<WebKit::WebGraphicsContext3D> m_ownedWebContext;
     OwnPtr<Extensions3D> m_extensions;
     OwnPtr<GraphicsContext3DContextLostCallbackAdapter> m_contextLostCallbackAdapter;
     OwnPtr<GraphicsContext3DErrorMessageCallbackAdapter> m_errorMessageCallbackAdapter;
     OwnPtr<GrMemoryAllocationChangedCallbackAdapter> m_grContextMemoryAllocationCallbackAdapter;
     bool m_initializedAvailableExtensions;
     HashSet<String> m_enabledExtensions;
     HashSet<String> m_requestableExtensions;
     bool m_layerComposited;
     bool m_preserveDrawingBuffer;
+    int m_packAlignment;
 
     enum ResourceSafety {
         ResourceSafetyUnknown,
         ResourceSafe,
         ResourceUnsafe
     };
     ResourceSafety m_resourceSafety;
 
     // If the width and height of the Canvas's backing store don't
     // match those that we were given in the most recent call to
     // reshape(), then we need an intermediate bitmap to read back the
     // frame buffer into. This seems to happen when CSS styles are
     // used to resize the Canvas.
     SkBitmap m_resizingBitmap;
 
     GrContext* m_grContext;
     SkAutoTUnref<GrContext> m_ownedGrContext;
+
+    // Used to flip a bitmap vertically.
+    Vector<uint8_t> m_scanline;
 };
 
 } // namespace WebCore
 
 #endif // GraphicsContext3D_h