Implement CompositorCC::ReadPixels

ui/gfx/compositor/compositor.cc

 // Copyright (c) 2011 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 "ui/gfx/compositor/compositor.h"
 
 #include "ui/gfx/compositor/compositor_observer.h"
 #include "ui/gfx/compositor/layer.h"
 
 namespace ui {
@@ skipping 50 matching lines @@
 }
 
 void Compositor::OnRootLayerChanged() {
   ScheduleDraw();
 }
 
 void Compositor::DrawTree() {
   root_layer_->DrawTree();
 }
 
+void Compositor::SwizzleRGBAToBGRAAndFlip(unsigned char* pixels,
+                                          const gfx::Size& image_size) {
+  // Swizzle from RGBA to BGRA
+  size_t bitmap_size = 4 * image_size.width() * image_size.height();
+  for(size_t i = 0; i < bitmap_size; i += 4)
+    std::swap(pixels[i], pixels[i + 2]);
+
+  // Vertical flip to transform from GL co-ords
+  size_t row_size = 4 * image_size.width();
+  scoped_array<unsigned char> tmp_row(new unsigned char[row_size]);
+  for(int row = 0; row < image_size.height() / 2; row++) {
+    memcpy(tmp_row.get(),
+           &pixels[row * row_size],
+           row_size);
+    memcpy(&pixels[row * row_size],
+           &pixels[bitmap_size - (row + 1) * row_size],
+           row_size);
+    memcpy(&pixels[bitmap_size - (row + 1) * row_size],
+           tmp_row.get(),
+           row_size);
+  }
+}
+
 void Compositor::NotifyStart(bool clear) {
   OnNotifyStart(clear);
 }
 
 void Compositor::NotifyEnd() {
   OnNotifyEnd();
   FOR_EACH_OBSERVER(CompositorObserver,
                     observer_list_,
                     OnCompositingEnded(this));
 }
 
 }  // namespace ui