Allow DrawingBuffer to present to a bitmap.

Source/core/platform/graphics/gpu/DrawingBuffer.cpp

 /*
  * Copyright (c) 2010, Google 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 21 matching lines @@
 
 #include "core/platform/graphics/gpu/DrawingBuffer.h"
 
 #include <algorithm>
 #include "core/platform/chromium/TraceEvent.h"
 #include "core/platform/graphics/Extensions3D.h"
 #include "core/platform/graphics/GraphicsContext3D.h"
 #include "core/platform/graphics/GraphicsLayer.h"
 #include "public/platform/Platform.h"
 #include "public/platform/WebCompositorSupport.h"
+#include "public/platform/WebExternalBitmap.h"
 #include "public/platform/WebExternalTextureLayer.h"
 #include "public/platform/WebGraphicsContext3D.h"
 
 using namespace std;
 
 namespace WebCore {
 
 // Global resource ceiling (expressed in terms of pixels) for DrawingBuffer creation and resize.
 // When this limit is set, DrawingBuffer::create() and DrawingBuffer::reset() calls that would
 // exceed the global cap will instead clear the buffer.
@@ skipping 117 matching lines @@
     return textureId;
 }
 
 WebKit::WebGraphicsContext3D* DrawingBuffer::context()
 {
     if (!m_context)
         return 0;
     return m_context->webContext();
 }
 
-bool DrawingBuffer::prepareMailbox(WebKit::WebExternalTextureMailbox* outMailbox)
+bool DrawingBuffer::prepareMailbox(WebKit::WebExternalTextureMailbox* outMailbox, WebKit::WebExternalBitmap* bitmap)
 {
     if (!m_context || !m_contentsChanged || !m_lastColorBuffer)
         return false;
 
     m_context->makeContextCurrent();
 
     // Resolve the multisampled buffer into the texture referenced by m_lastColorBuffer mailbox.
     if (multisample())
         commit();
 
+    if (bitmap) {
+        bitmap->setSize(size());
+
+        unsigned char* pixels = bitmap->pixels();
+        bool needPremultiply = m_attributes.alpha && !m_attributes.premultipliedAlpha;
+        GraphicsContext3D::AlphaOp op = needPremultiply ? GraphicsContext3D::AlphaDoPremultiply : GraphicsContext3D::AlphaDoNothing;
+        if (pixels)
+            m_context->readBackFramebuffer(pixels, size().width(), size().height(), GraphicsContext3D::ReadbackSkia, op);
+    }
+
     // We must restore the texture binding since creating new textures,
     // consuming and producing mailboxes changes it.
     ScopedTextureUnit0BindingRestorer restorer(m_context.get(), m_activeTextureUnit, m_texture2DBinding);
 
     // First try to recycle an old buffer.
     RefPtr<MailboxInfo> nextFrontColorBuffer = getRecycledMailbox();
 
     // No buffer available to recycle, create a new one.
     if (!nextFrontColorBuffer) {
         unsigned newColorBuffer = createColorTexture(m_size);
@@ skipping 614 matching lines @@
 
 void DrawingBuffer::bind()
 {
     if (!m_context)
         return;
 
     m_context->bindFramebuffer(GraphicsContext3D::FRAMEBUFFER, m_multisampleFBO ? m_multisampleFBO : m_fbo);
 }
 
 } // namespace WebCore