[cc] Mailbox Output Surface Support

cc/output_surface.cc

 // Copyright (c) 2013 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 "cc/output_surface.h"
 
+#include <set>
+#include <string>
+#include <vector>
+
 #include "base/logging.h"
+#include "base/string_split.h"
+#include "base/string_util.h"
+#include "third_party/WebKit/Source/Platform/chromium/public/WebGraphicsContext3D.h"
+#include "third_party/khronos/GLES2/gl2.h"
+#include "third_party/khronos/GLES2/gl2ext.h"
+#include "ui/gfx/rect.h"
+#include "ui/gfx/size.h"
+
+using std::set;
+using std::string;
+using std::vector;
 
 namespace cc {
 
 OutputSurface::OutputSurface(
     scoped_ptr<WebKit::WebGraphicsContext3D> context3d)
     : client_(NULL),
-      context3d_(context3d.Pass()) {
+      context3d_(context3d.Pass()),
+      has_gl_discard_backbuffer_(false) {
 }
 
 OutputSurface::OutputSurface(
     scoped_ptr<cc::SoftwareOutputDevice> software_device)
     : client_(NULL),
-      software_device_(software_device.Pass()) {
+      software_device_(software_device.Pass()),
+      has_gl_discard_backbuffer_(false) {
 }
 
 OutputSurface::OutputSurface(
     scoped_ptr<WebKit::WebGraphicsContext3D> context3d,
     scoped_ptr<cc::SoftwareOutputDevice> software_device)
     : client_(NULL),
       context3d_(context3d.Pass()),
-      software_device_(software_device.Pass()) {
+      software_device_(software_device.Pass()),
+      has_gl_discard_backbuffer_(false) {
 }
 
 OutputSurface::~OutputSurface() {
 }
 
 bool OutputSurface::BindToClient(
     cc::OutputSurfaceClient* client) {
   DCHECK(client);
   client_ = client;
   if (!context3d_)
     return true;
-  return context3d_->makeContextCurrent();
+  if (!context3d_->makeContextCurrent())
+    return false;
+
+  string extensionsString = UTF16ToASCII(context3d_->getString(GL_EXTENSIONS));
+  vector<string> extensionsList;
+  base::SplitString(extensionsString, ' ', &extensionsList);
+  set<string> extensions(extensionsList.begin(), extensionsList.end());
+
+  has_gl_discard_backbuffer_ =
+      extensions.count("GL_CHROMIUM_discard_backbuffer");
+
+  return true;
 }
 
 void OutputSurface::SendFrameToParentCompositor(CompositorFrame*) {
   NOTIMPLEMENTED();
 }
 
+void OutputSurface::EnsureBackbuffer() {
+  DCHECK(context3d_);
+  if (has_gl_discard_backbuffer_)
+    context3d_->ensureBackbufferCHROMIUM();
+}
+
+void OutputSurface::DiscardBackbuffer() {
+  DCHECK(context3d_);
+  if (has_gl_discard_backbuffer_)
+    context3d_->discardBackbufferCHROMIUM();
+}
+
+void OutputSurface::Reshape(gfx::Size size) {
+  DCHECK(context3d_);
+  context3d_->reshape(size.width(), size.height());
+}
+
+void OutputSurface::BindFramebuffer() {
+  DCHECK(context3d_);
+  context3d_->bindFramebuffer(GL_FRAMEBUFFER, 0);
+}
+
+void OutputSurface::SwapBuffers() {
+  DCHECK(context3d_);
+  // Note that currently this has the same effect as swapBuffers; we should
+  // consider exposing a different entry point on WebGraphicsContext3D.
+  context3d_->prepareTexture();
+}
+
+void OutputSurface::PostSubBuffer(gfx::Rect rect) {
+  DCHECK(context3d_);
+  context3d_->postSubBufferCHROMIUM(
+      rect.x(), rect.y(), rect.width(), rect.height());
+}
+
 }  // namespace cc