Delay resize of the front buffer until the swap for offscreen buffers.

gpu/command_buffer/service/gles2_cmd_decoder.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 "gpu/command_buffer/service/gles2_cmd_decoder.h"
 
 #include <stdio.h>
 
 #include <algorithm>
 #include <list>
@@ skipping 2516 matching lines @@
     glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
     glClearStencil(0);
     glStencilMaskSeparate(GL_FRONT, -1);
     glStencilMaskSeparate(GL_BACK, -1);
     glClearDepth(0);
     glDepthMask(GL_TRUE);
     glDisable(GL_SCISSOR_TEST);
     glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);
     RestoreClearState();
   }
-
-  // Workaround for NVIDIA driver bug on OS X; crbug.com/89557,
-  // crbug.com/94103. TODO(kbr): figure out reproduction so Apple will
-  // fix this.
-  if (needs_mac_nvidia_driver_workaround_) {
-    offscreen_saved_frame_buffer_->Create();
-    glFinish();
-  }
-
-  // Allocate the offscreen saved color texture.
-  DCHECK(offscreen_saved_color_format_);
-  offscreen_saved_color_texture_->AllocateStorage(
-      offscreen_size_, offscreen_saved_color_format_);
-
-  offscreen_saved_frame_buffer_->AttachRenderTexture(
-      offscreen_saved_color_texture_.get());
-  if (offscreen_saved_frame_buffer_->CheckStatus() !=
-      GL_FRAMEBUFFER_COMPLETE) {
-    LOG(ERROR) << "GLES2DecoderImpl::ResizeOffscreenFrameBuffer failed "
-               << "because offscreen saved FBO was incomplete.";
-    return false;
-  }
-
-  // Destroy the offscreen resolved framebuffers.
-  if (offscreen_resolved_frame_buffer_.get())
-    offscreen_resolved_frame_buffer_->Destroy();
-  if (offscreen_resolved_color_texture_.get())
-    offscreen_resolved_color_texture_->Destroy();
-  offscreen_resolved_color_texture_.reset();
-  offscreen_resolved_frame_buffer_.reset();
-
-  // Clear the offscreen color texture.
-  {
-    ScopedFrameBufferBinder binder(this, offscreen_saved_frame_buffer_->id());
-    glClearColor(0, 0, 0, 0);
-    glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
-    glDisable(GL_SCISSOR_TEST);
-    glClear(GL_COLOR_BUFFER_BIT);
-    RestoreClearState();
-  }
-
-  UpdateParentTextureInfo();
-
   return true;
 }
 
 error::Error GLES2DecoderImpl::HandleResizeCHROMIUM(
     uint32 immediate_data_size, const gles2::ResizeCHROMIUM& c) {
   GLuint width = static_cast<GLuint>(c.width);
   GLuint height = static_cast<GLuint>(c.height);
   TRACE_EVENT2("gpu", "glResizeChromium", "width", width, "height", height);
 #if defined(OS_POSIX) && !defined(OS_MACOSX) && !defined(TOUCH_UI)
   // Make sure that we are done drawing to the back buffer before resizing.
@@ skipping 3985 matching lines @@
 error::Error GLES2DecoderImpl::HandleSwapBuffers(
     uint32 immediate_data_size, const gles2::SwapBuffers& c) {
   bool is_offscreen = !!offscreen_target_frame_buffer_.get();
   int this_frame_number = frame_number_++;
   TRACE_EVENT2("gpu", "GLES2DecoderImpl::HandleSwapBuffers",
                "offscreen", is_offscreen,
                "frame", this_frame_number);
   // If offscreen then don't actually SwapBuffers to the display. Just copy
   // the rendered frame to another frame buffer.
   if (is_offscreen) {
+    if (offscreen_size_ != offscreen_saved_color_texture_->size()) {
+      // Workaround for NVIDIA driver bug on OS X; crbug.com/89557,
+      // crbug.com/94163. TODO(kbr): figure out reproduction so Apple will
+      // fix this.
+      if (needs_mac_nvidia_driver_workaround_) {
+        offscreen_saved_frame_buffer_->Create();
+        glFinish();
+      }
+
+      // Allocate the offscreen saved color texture.
+      DCHECK(offscreen_saved_color_format_);
+      offscreen_saved_color_texture_->AllocateStorage(
+          offscreen_size_, offscreen_saved_color_format_);
+
+      offscreen_saved_frame_buffer_->AttachRenderTexture(
+          offscreen_saved_color_texture_.get());
+      if (offscreen_saved_frame_buffer_->CheckStatus() !=
+          GL_FRAMEBUFFER_COMPLETE) {
+        LOG(ERROR) << "GLES2DecoderImpl::ResizeOffscreenFrameBuffer failed "
+                   << "because offscreen saved FBO was incomplete.";
+        return error::kLostContext;
+      }
+
+      // Destroy the offscreen resolved framebuffers.
+      if (offscreen_resolved_frame_buffer_.get())
+        offscreen_resolved_frame_buffer_->Destroy();
+      if (offscreen_resolved_color_texture_.get())
+        offscreen_resolved_color_texture_->Destroy();
+      offscreen_resolved_color_texture_.reset();
+      offscreen_resolved_frame_buffer_.reset();
+
+      // Clear the offscreen color texture.
+      // TODO(piman): Is this still necessary?

[Ken Russell (switch to Gerrit), 2011/08/30 22:47:13]

I'm quite sure it is -- if the offscreen color texture has increased in width or
height then the copy from the frame buffer will not cover it all, so we must
prevent garbage from showing up in the other regions.

+      {
+        ScopedFrameBufferBinder binder(this,
+                                       offscreen_saved_frame_buffer_->id());
+        glClearColor(0, 0, 0, 0);
+        glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
+        glDisable(GL_SCISSOR_TEST);
+        glClear(GL_COLOR_BUFFER_BIT);
+        RestoreClearState();
+      }
+
+      UpdateParentTextureInfo();
+    }
+
     ScopedGLErrorSuppressor suppressor(this);
 
     if (IsOffscreenBufferMultisampled()) {
       // For multisampled buffers, bind the resolved frame buffer so that
       // callbacks can call ReadPixels or CopyTexImage2D.
       ScopedResolvedFrameBufferBinder binder(this, true, false);
 #if defined(OS_MACOSX)
       if (swap_buffers_callback_.get()) {
         swap_buffers_callback_->Run();
       }
@@ skipping 247 matching lines @@
   return false;
 }
 
 // Include the auto-generated part of this file. We split this because it means
 // we can easily edit the non-auto generated parts right here in this file
 // instead of having to edit some template or the code generator.
 #include "gpu/command_buffer/service/gles2_cmd_decoder_autogen.h"
 
 }  // namespace gles2
 }  // namespace gpu