Support browser side thumbnailing for GPU composited pages on Windows.

content/browser/renderer_host/render_widget_host_view_win.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/renderer_host/render_widget_host_view_win.h"
 
 #include <algorithm>
 #include <peninputpanel_i.c>
 
 #include "base/bind.h"
@@ skipping 890 matching lines @@
 BackingStore* RenderWidgetHostViewWin::AllocBackingStore(
     const gfx::Size& size) {
   return new BackingStoreWin(render_widget_host_, size);
 }
 
 void RenderWidgetHostViewWin::SetBackground(const SkBitmap& background) {
   content::RenderWidgetHostViewBase::SetBackground(background);
   render_widget_host_->SetBackground(background);
 }
 
+bool RenderWidgetHostViewWin::CopyFromCompositingSurface(
+      const gfx::Size& size,
+      skia::PlatformCanvas* output) {
+  if (!accelerated_surface_.get())
+    return false;
+
+  if (size.IsEmpty())
+    return false;
+
+  std::vector<unsigned char> pixels(4 * size.GetArea());
+  if(!accelerated_surface_->CopyTo(size, &pixels))
+    return false;
+
+  SkBitmap bitmap;
+  bitmap.setConfig(SkBitmap::kARGB_8888_Config, size.width(), size.height());
+  bitmap.setPixels(&pixels[0]);
+
+  if (!output->initialize(size.width(), size.height(), true))
+    return false;
+  output->writePixels(bitmap, 0, 0);

[vangelis, 2012/03/08 17:34:35]

Is it possible to call accelerated_surface_->CopyTo() directly onto the output
canvas' pixels to avoid this copy? 

[mazda, 2012/03/10 07:51:37]

I changed AccceleratedSurface::CopyTo to take void* as an argument following
apatrick's comment, so now it's possible to pass the raw pointer of SkBitmap in
this PlatformCanvas. I modified the code that way.

+  return true;
+}
+
 void RenderWidgetHostViewWin::UnhandledWheelEvent(
     const WebKit::WebMouseWheelEvent& event) {
 }
 
 void RenderWidgetHostViewWin::ProcessTouchAck(
     WebKit::WebInputEvent::Type type, bool processed) {
   if (type == WebKit::WebInputEvent::TouchStart)
     UpdateDesiredTouchMode(processed);
 }
 
@@ skipping 1736 matching lines @@
 void RenderWidgetHostViewWin::ResetPointerDownContext() {
   // If the default focus on the page is on an edit field and we did not
   // receive a focus change in the context of a pointer down message, it means
   // that the pointer down message occurred on the edit field and we should
   // display the on screen keyboard
   if (!received_focus_change_after_pointer_down_ && virtual_keyboard_)
     DisplayOnScreenKeyboardIfNeeded();
   received_focus_change_after_pointer_down_ = false;
   pointer_down_context_ = false;
 }