webgl: optimize webgl.texSubImage2D(video) path.

third_party/WebKit/Source/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 104 matching lines @@
 
     void putByteArray(Multiply, const unsigned char* source, const IntSize& sourceSize, const IntRect& sourceRect, const IntPoint& destPoint);
 
     AffineTransform baseTransform() const { return AffineTransform(); }
     WebLayer* platformLayer() const;
 
     // FIXME: current implementations of this method have the restriction that they only work
     // with textures that are RGB or RGBA format, UNSIGNED_BYTE type and level 0, as specified in
     // Extensions3D::canUseCopyTextureCHROMIUM().
     // Destroys the TEXTURE_2D binding for the active texture unit of the passed context
-    bool copyToPlatformTexture(WebGraphicsContext3D*, Platform3DObject, GLenum, GLenum, GLint, bool, bool);
+    bool copyToPlatformTexture(WebGraphicsContext3D*, GLenum, Platform3DObject, GLenum, GLenum, GLint, bool, bool);
+    bool copySubToPlatformTexture(WebGraphicsContext3D*, GLenum, Platform3DObject, GLint, GLint xoffset,
+        GLint yoffset, GLsizei width, GLsizei height, bool, bool);
 
     bool copyRenderingResultsFromDrawingBuffer(DrawingBuffer*, SourceDrawingBuffer);
 
     void flush(); // process deferred draw commands immediately
     void flushGpu(); // Like flush(), but flushes all the way down to the Gpu context if the surface is accelerated
 
     void notifySurfaceInvalid();
 
     PassRefPtr<SkImage> newSkImageSnapshot(AccelerationHint) const;
     PassRefPtr<Image> newImageSnapshot(AccelerationHint = PreferNoAcceleration) const;
 
     DisplayItemClient displayItemClient() const { return toDisplayItemClient(this); }
     String debugName() const { return "ImageBuffer"; }
 
     void draw(GraphicsContext*, const FloatRect&, const FloatRect*, SkXfermode::Mode);
 
 private:
     ImageBuffer(PassOwnPtr<ImageBufferSurface>);
 
     enum SnapshotState {
         InitialSnapshotState,
         DidAcquireSnapshot,
         DrawnToAfterSnapshot,
     };
     mutable SnapshotState m_snapshotState;
+
+    bool copyToPlatformTextureInternal(bool isFullCopy, WebGraphicsContext3D*, GLenum, Platform3DObject, GLenum, GLenum,
+        GLint, GLint xoffset, GLint yoffset, GLsizei width, GLsizei height, bool, bool);
+
     OwnPtr<ImageBufferSurface> m_surface;
     ImageBufferClient* m_client;
 };
 
 struct ImageDataBuffer {
     ImageDataBuffer(const IntSize& size, const unsigned char* data) : m_data(data), m_size(size) { }
     String PLATFORM_EXPORT toDataURL(const String& mimeType, const double& quality) const;
     bool PLATFORM_EXPORT encodeImage(const String& mimeType, const double& quality, Vector<char>* output) const;
     const unsigned char* pixels() const { return m_data; }
     int height() const { return m_size.height(); }
     int width() const { return m_size.width(); }
 
     const unsigned char* m_data;
     const IntSize m_size;
 };
 
 } // namespace blink
 
 #endif // ImageBuffer_h