webgl: optimize webgl.texSubImage2D(video) path.

third_party/WebKit/Source/platform/graphics/ImageBuffer.cpp

 /*
  * Copyright (c) 2008, Google Inc. All rights reserved.
  * Copyright (C) 2009 Dirk Schulze <krit@webkit.org>
  * 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:
  *
  *     * Redistributions of source code must retain the above copyright
@@ skipping 160 matching lines @@
     if (m_snapshotState == DidAcquireSnapshot)
         m_snapshotState = DrawnToAfterSnapshot;
     m_surface->didDraw(rect);
 }
 
 WebLayer* ImageBuffer::platformLayer() const
 {
     return m_surface->layer();
 }
 
-bool ImageBuffer::copyToPlatformTexture(WebGraphicsContext3D* context, Platform3DObject texture, GLenum internalFormat, GLenum destType, GLint level, bool premultiplyAlpha, bool flipY)
+bool ImageBuffer::copyToPlatformTexture(WebGraphicsContext3D* context, GLenum target, Platform3DObject texture,
+    GLenum internalFormat, GLenum destType, GLint level, bool premultiplyAlpha, bool flipY)
 {
-    if (!Extensions3DUtil::canUseCopyTextureCHROMIUM(GL_TEXTURE_2D, internalFormat, destType, level))
+    return copyToPlatformTextureInternal(true, context, target, texture, internalFormat,
+        destType, level, 0, 0, 0, 0, premultiplyAlpha, flipY);
+}
+
+bool ImageBuffer::copySubToPlatformTexture(WebGraphicsContext3D* context, GLenum target, Platform3DObject texture,
+    GLint level, GLint xoffset, GLint yoffset, GLsizei width, GLsizei height, bool premultiplyAlpha, bool flipY)
+{
+    return copyToPlatformTextureInternal(false, context, target, texture, GL_FALSE, GL_FALSE, level,
+        xoffset, yoffset, width, height, premultiplyAlpha, flipY);
+}
+
+bool ImageBuffer::copyToPlatformTextureInternal(bool isFullCopy, WebGraphicsContext3D* context, GLenum target,
+    Platform3DObject texture, GLenum internalFormat, GLenum destType, GLint level, GLint xoffset, GLint yoffset,
+    GLsizei width, GLsizei height, bool premultiplyAlpha, bool flipY)
+{
+    if (!Extensions3DUtil::canUseCopyTextureCHROMIUM(target, internalFormat, destType, level))
         return false;
 
     if (!isSurfaceValid())
         return false;
 
     RefPtr<const SkImage> textureImage = m_surface->newImageSnapshot(PreferAcceleration);
     if (!textureImage)
         return false;
 
     if (!m_surface->isAccelerated())
@@ skipping 18 matching lines @@
     // Contexts may be in a different share group. We must transfer the texture through a mailbox first
     sharedContext->genMailboxCHROMIUM(mailbox->name);
     sharedContext->produceTextureDirectCHROMIUM(textureId, GL_TEXTURE_2D, mailbox->name);
     sharedContext->flush();
 
     mailbox->syncPoint = sharedContext->insertSyncPoint();
 
     context->waitSyncPoint(mailbox->syncPoint);
     Platform3DObject sourceTexture = context->createAndConsumeTextureCHROMIUM(GL_TEXTURE_2D, mailbox->name);
 
+    WGC3Dboolean glFlipY = flipY ? GL_FALSE : GL_TRUE;
+    WGC3Dboolean glPremultiplyAlpha = premultiplyAlpha ? GL_FALSE : GL_TRUE;
+
     // The canvas is stored in a premultiplied format, so unpremultiply if necessary.
     // The canvas is stored in an inverted position, so the flip semantics are reversed.
-    context->copyTextureCHROMIUM(GL_TEXTURE_2D, sourceTexture, texture, internalFormat, destType, flipY ? GL_FALSE : GL_TRUE, GL_FALSE, premultiplyAlpha ? GL_FALSE : GL_TRUE);
+    if (isFullCopy) {
+        context->copyTextureCHROMIUM(target, sourceTexture, texture, internalFormat, destType, glFlipY, GL_FALSE, glPremultiplyAlpha);
+    } else {
+        context->copySubTextureCHROMIUM(target, sourceTexture, texture, xoffset, yoffset, 0, 0, width, height, glFlipY, GL_FALSE, glPremultiplyAlpha);
+    }
 
     context->deleteTexture(sourceTexture);
 
     context->flush();
     sharedContext->waitSyncPoint(context->insertSyncPoint());
 
     // Undo grContext texture binding changes introduced in this function
     provider->grContext()->resetContext(kTextureBinding_GrGLBackendState);
 
     return true;
@@ skipping 141 matching lines @@
     ASSERT(MIMETypeRegistry::isSupportedImageMIMETypeForEncoding(mimeType));
 
     Vector<char> encodedImage;
     if (!encodeImage(mimeType, quality, &encodedImage))
         return "data:,";
 
     return "data:" + mimeType + ";base64," + base64Encode(encodedImage);
 }
 
 } // namespace blink