Use inner HWND for accelerated rendering on windows

chrome/gpu/gpu_command_buffer_stub.cc

Index: chrome/gpu/gpu_command_buffer_stub.cc
===================================================================
--- chrome/gpu/gpu_command_buffer_stub.cc	(revision 65702)
+++ chrome/gpu/gpu_command_buffer_stub.cc	(working copy)
@@ -14,6 +14,8 @@
 
 using gpu::Buffer;
 
+#define kCompositorWindowOwner L"kCompositorWindowOwner"
+
 GpuCommandBufferStub::GpuCommandBufferStub(
     GpuChannel* channel,
     gfx::PluginWindowHandle handle,
@@ -38,10 +40,115 @@
       render_view_id_(render_view_id) {
 }
 
+#if defined(OS_WIN)
+static LRESULT CALLBACK CompositorWindowProc(
+    HWND hWnd,

[jam, 2010/11/12 18:08:00]

nit: hwnd

[nduca, 2010/11/12 19:45:32]

Done.

+    UINT message,
+    WPARAM wparam,
+    LPARAM lparam) {
+  switch (message) {
+  case WM_ERASEBKGND:

[jam, 2010/11/12 18:08:00]

nit: the case should be indented in

[nduca, 2010/11/12 19:45:32]

Done.

+    return 0;
+  case WM_DESTROY:
+    return 0;
+  case WM_PAINT:
+    {

[jam, 2010/11/12 18:08:00]

nit: i think you have extra indentation here

[nduca, 2010/11/12 19:45:32]

Done.

+      PAINTSTRUCT paint;
+      BeginPaint(hWnd, &paint);
+      HANDLE h = GetProp(hWnd, kCompositorWindowOwner);
+      GpuCommandBufferStub* stub = reinterpret_cast<GpuCommandBufferStub*>(h);
+      stub->OnCompositorWindowPainted();
+      EndPaint(hWnd, &paint);
+    }
+    break;
+  default:
+    return DefWindowProc(hWnd, message, wparam, lparam);
+  }
+  return 0;
+}
+
+void GpuCommandBufferStub::CreateCompositorWindow() {
+  DCHECK(handle_ != gfx::kNullPluginWindow);
+
+  // Ask the browser to create the the host window.
+  ChildThread* gpu_thread = ChildThread::current();
+  gfx::PluginWindowHandle host_window_id;
+  gpu_thread->Send(new GpuHostMsg_CreateCompositorHostWindow(
+      renderer_id_,
+      render_view_id_,
+      &host_window_id));
+  HWND host_window = static_cast<HWND>(host_window_id);
+
+  // Create the compositor window itself.
+  DCHECK(host_window);
+  static ATOM window_class = 0;
+  if (!window_class) {
+    WNDCLASSEX wcex;
+    wcex.cbSize         = sizeof(wcex);
+    wcex.style          = 0;
+    wcex.lpfnWndProc    = CompositorWindowProc;
+    wcex.cbClsExtra     = 0;
+    wcex.cbWndExtra     = 0;
+    wcex.hInstance      = GetModuleHandle(NULL);
+    wcex.hIcon          = 0;
+    wcex.hCursor        = 0;
+    wcex.hbrBackground  = NULL;
+    wcex.lpszMenuName   = 0;
+    wcex.lpszClassName  = L"CompositorWindowClass";
+    wcex.hIconSm        = 0;
+    window_class = RegisterClassEx(&wcex);
+    DCHECK(window_class);
+  }
+
+  HWND compositor_window = CreateWindowEx(
+    WS_EX_LEFT | WS_EX_LTRREADING | WS_EX_RIGHTSCROLLBAR,

[jam, 2010/11/12 18:08:00]

nit: need 4 spaces for indentation

[nduca, 2010/11/12 19:45:32]

Done.

+    MAKEINTATOM(window_class),
+    0,
+    WS_CHILD | WS_CLIPCHILDREN | WS_CLIPSIBLINGS | WS_DISABLED,
+    0/*x*/, 0/*y*/,

[jam, 2010/11/12 18:08:00]

nit: i don't see this pattern of commenting input parameters much in the code. 
it seems that anybody can figure this out quickly by mousing over the function
name or looking at msdn, so this appears to fall under "don't comment something
that someone can figure out from reading the code"

[nduca, 2010/11/12 19:45:32]

I tend to agree.

+    0/*nWidth*/, 0/*nHeight*/,
+    host_window,
+    0,
+    GetModuleHandle(NULL),
+    0);
+  DCHECK(compositor_window);
+  SetProp(compositor_window, kCompositorWindowOwner,
+      reinterpret_cast<HANDLE>(this));
+
+  RECT parent_rect;
+  GetClientRect(host_window, &parent_rect);
+
+  UINT flags = SWP_NOSENDCHANGING | SWP_NOCOPYBITS | SWP_NOZORDER |
+      SWP_NOACTIVATE | SWP_DEFERERASE | SWP_SHOWWINDOW;
+  SetWindowPos(compositor_window,
+      NULL,
+      0/*x*/, 0/*y*/,
+      parent_rect.right - parent_rect.left,
+      parent_rect.bottom - parent_rect.top,
+      flags);
+  compositor_window_ = static_cast<gfx::PluginWindowHandle>(compositor_window);
+}
+
+void GpuCommandBufferStub::OnCompositorWindowPainted()
+{

[jam, 2010/11/12 18:08:00]

nit: brace bracket on previous line

[nduca, 2010/11/12 19:45:32]

Done.

+  ChildThread* gpu_thread = ChildThread::current();
+  gpu_thread->Send(new GpuHostMsg_ScheduleComposite(
+      renderer_id_, render_view_id_));
+}
+#endif // defined(OS_WIN)
+
+
 GpuCommandBufferStub::~GpuCommandBufferStub() {
   if (processor_.get()) {
     processor_->Destroy();
   }
+#if defined(OS_WIN)
+  if (compositor_window_) {
+    RemoveProp(compositor_window_, kCompositorWindowOwner);
+    DestroyWindow(static_cast<HWND>(compositor_window_));
+    compositor_window_ = NULL;
+  }
+#endif
 }
 
 void GpuCommandBufferStub::OnMessageReceived(const IPC::Message& message) {
@@ -79,6 +186,14 @@
 
   command_buffer_.reset(new gpu::CommandBufferService);
 
+  // Create the child window, if needed
+#if defined(OS_WIN)
+  CreateCompositorWindow();
+  gfx::PluginWindowHandle output_window_handle = compositor_window_;
+#else
+  gfx::PluginWindowHandle output_window_handle = handle_;
+#endif
+
   // Initialize the CommandBufferService and GPUProcessor.
   if (command_buffer_->Initialize(size)) {
     Buffer buffer = command_buffer_->GetRingBuffer();
@@ -87,7 +202,7 @@
           parent_ ? parent_->processor_.get() : NULL;
       processor_.reset(new gpu::GPUProcessor(command_buffer_.get(), NULL));
       if (processor_->Initialize(
-          handle_,
+          output_window_handle,
           initial_size_,
           allowed_extensions_.c_str(),
           requested_attribs_,