Decoupling backbuffer allocation suggestion from frontbuffer allocation suggestion.

content/common/gpu/image_transport_surface_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.
 
 #if defined(ENABLE_GPU)
 
 #include "content/common/gpu/image_transport_surface.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
@@ skipping 22 matching lines @@
   PbufferImageTransportSurface(GpuChannelManager* manager,
                                GpuCommandBufferStub* stub);
 
   // gfx::GLSurface implementation
   virtual bool Initialize() OVERRIDE;
   virtual void Destroy() OVERRIDE;
   virtual bool IsOffscreen() OVERRIDE;
   virtual bool SwapBuffers() OVERRIDE;
   virtual bool PostSubBuffer(int x, int y, int width, int height) OVERRIDE;
   virtual std::string GetExtensions() OVERRIDE;
-  virtual void SetBufferAllocation(BufferAllocationState state) OVERRIDE;
+  virtual void SetBackbufferAllocation(bool allocated) OVERRIDE;
+  virtual void SetFrontbufferAllocation(bool allocated) OVERRIDE;
 
  protected:
   // ImageTransportSurface implementation
   virtual void OnNewSurfaceACK(uint64 surface_handle,
                                TransportDIB::Handle shm_handle) OVERRIDE;
   virtual void OnBuffersSwappedACK() OVERRIDE;
   virtual void OnPostSubBufferACK() OVERRIDE;
   virtual void OnResizeViewACK() OVERRIDE;
   virtual void OnResize(gfx::Size size) OVERRIDE;
 
  private:
   virtual ~PbufferImageTransportSurface();
   void SendBuffersSwapped();
   void DestroySurface();
+  void AdjustBufferAllocations();
 
   // Tracks the current buffer allocation state.
-  BufferAllocationState buffer_allocation_state_;
+  bool backbuffer_suggested_allocation_;
+  bool frontbuffer_suggested_allocation_;
 
   // Size to resize to when the surface becomes visible.
   gfx::Size visible_size_;
 
   scoped_ptr<ImageTransportHelper> helper_;
 
   DISALLOW_COPY_AND_ASSIGN(PbufferImageTransportSurface);
 };
 
 PbufferImageTransportSurface::PbufferImageTransportSurface(
     GpuChannelManager* manager,
     GpuCommandBufferStub* stub)
     : GLSurfaceAdapter(new gfx::PbufferGLSurfaceEGL(false, gfx::Size(1, 1))),
-      buffer_allocation_state_(BUFFER_ALLOCATION_FRONT_AND_BACK) {
+      backbuffer_suggested_allocation_(true),
+      frontbuffer_suggested_allocation_(true) {
   helper_.reset(new ImageTransportHelper(this,
                                          manager,
                                          stub,
                                          gfx::kNullPluginWindow));
 }
 
 PbufferImageTransportSurface::~PbufferImageTransportSurface() {
   Destroy();
 }
 
@@ skipping 30 matching lines @@
 
   return true;
 }
 
 bool PbufferImageTransportSurface::PostSubBuffer(
     int x, int y, int width, int height) {
   NOTREACHED();
   return false;
 }
 
-void PbufferImageTransportSurface::SetBufferAllocation(
-    BufferAllocationState state) {
-  if (buffer_allocation_state_ == state)
+void PbufferImageTransportSurface::SetBackbufferAllocation(bool allocation) {
+  if (backbuffer_suggested_allocation_ == allocation)
     return;
-  buffer_allocation_state_ = state;
+  backbuffer_suggested_allocation_ = allocation;
+  AdjustBufferAllocations();
+}
 
-  switch (state) {
-    case BUFFER_ALLOCATION_FRONT_AND_BACK:
-      Resize(visible_size_);
-      break;
+void PbufferImageTransportSurface::SetFrontbufferAllocation(bool allocation) {
+  if (frontbuffer_suggested_allocation_ == allocation)
+    return;
+  frontbuffer_suggested_allocation_ = allocation;
+  AdjustBufferAllocations();
+}
 
-    case BUFFER_ALLOCATION_FRONT_ONLY:
-      Resize(gfx::Size(1, 1));
-      break;
-
-    case BUFFER_ALLOCATION_NONE:
-      Resize(gfx::Size(1, 1));
+void PbufferImageTransportSurface::AdjustBufferAllocations() {
+  if (backbuffer_suggested_allocation_) {
+    Resize(visible_size_);

[jonathan.backer, 2012/05/09 18:13:01]

DCHECK that we should have a front buffer?

[mmocny, 2012/05/09 18:59:15]

Again, I don't think so.
Previously we would set BUFFER_ALLOCATION_FRONT_AND_BACK whenever suggest
backbuffer == true, regardless of frontbuffer suggestion.  Now that the two are
decoupled, we shouldn't assume/necessitate front == true when back == true.
On 2012/05/09 18:13:01, jonathan.backer wrote:

+  } else {
+    Resize(gfx::Size(1, 1));
+    if (!frontbuffer_suggested_allocation_)
       helper_->Suspend();
-      break;
-
-    default:
-      NOTREACHED();
   }
   DestroySurface();
 }
 
 void PbufferImageTransportSurface::DestroySurface() {
   GpuHostMsg_AcceleratedSurfaceRelease_Params params;
   helper_->SendAcceleratedSurfaceRelease(params);
 }
 
 std::string PbufferImageTransportSurface::GetExtensions() {
@@ skipping 24 matching lines @@
     uint64 surface_handle,
     TransportDIB::Handle shm_handle) {
   NOTREACHED();
 }
 
 void PbufferImageTransportSurface::OnResizeViewACK() {
   NOTREACHED();
 }
 
 void PbufferImageTransportSurface::OnResize(gfx::Size size) {
-  if (buffer_allocation_state_ == BUFFER_ALLOCATION_FRONT_AND_BACK)
+  if (backbuffer_suggested_allocation_ && frontbuffer_suggested_allocation_)

[jonathan.backer, 2012/05/09 18:13:01]

I think that it may make more sense to DCHECK that we have
frontbuffer_suggested_allocation_ here. I don't that what we want to drop this.

[mmocny, 2012/05/09 18:59:15]

Fair enough.  Shouldn't we DCHECK for both?
Will we ever send resize message when not visible?

On 2012/05/09 18:13:01, jonathan.backer wrote:

[jonathan.backer, 2012/05/10 21:37:48]

AFAIK, we shouldn't resize when not visible. I think that resize is meant for
the backbuffer. So it would be strange to do so. 

     Resize(size);
 
   DestroySurface();
 
   visible_size_ = size;
 }
 
 }  // namespace anonymous
 
 // static
@@ skipping 26 matching lines @@
                                                    handle.transport);
   }
 
   if (surface->Initialize())
     return surface;
   else
     return NULL;
 }
 
 #endif  // ENABLE_GPU