cc: Partial draw without partial swap support.

components/display_compositor/buffer_queue.cc

 // Copyright 2014 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 "components/display_compositor/buffer_queue.h"
 
 #include "base/containers/adapters.h"
 #include "base/memory/ptr_util.h"
 #include "build/build_config.h"
 #include "components/display_compositor/gl_helper.h"
@@ skipping 49 matching lines @@
   if (current_surface_) {
     gl_->FramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,
                               texture_target_, current_surface_->texture, 0);
     if (current_surface_->stencil) {
       gl_->FramebufferRenderbuffer(GL_FRAMEBUFFER, GL_STENCIL_ATTACHMENT,
                                    GL_RENDERBUFFER, current_surface_->stencil);
     }
   }
 }
 
+bool BufferQueue::CanPartialDraw(const gfx::Rect& damage) {
+  if (current_surface_)
+    return damage.Contains(current_surface_->damage);
+  if (!available_surfaces_.empty())
+    return damage.Contains(available_surfaces_.back()->damage);
+  return false;
+}
+
 void BufferQueue::CopyBufferDamage(int texture,
                                    int source_texture,
                                    const gfx::Rect& new_damage,
                                    const gfx::Rect& old_damage) {
   gl_helper_->CopySubBufferDamage(texture_target_, texture, source_texture,
                                   SkRegion(gfx::RectToSkIRect(new_damage)),
                                   SkRegion(gfx::RectToSkIRect(old_damage)));
 }
 
 void BufferQueue::UpdateBufferDamage(const gfx::Rect& damage) {
   if (displayed_surface_)
     displayed_surface_->damage.Union(damage);
   for (auto& surface : available_surfaces_)
     surface->damage.Union(damage);
   for (auto& surface : in_flight_surfaces_) {
     if (surface)
       surface->damage.Union(damage);
   }
 }
 
 void BufferQueue::SwapBuffers(const gfx::Rect& damage) {
   if (current_surface_) {
-    if (damage != gfx::Rect(size_)) {
+    if (!damage.Contains(current_surface_->damage)) {
       // Copy damage from the most recently swapped buffer. In the event that
       // the buffer was destroyed and failed to recreate, pick from the most
       // recently available buffer.
       uint32_t texture_id = 0;
       for (auto& surface : base::Reversed(in_flight_surfaces_)) {
         if (surface) {
           texture_id = surface->texture;
           break;
         }
       }
@@ skipping 171 matching lines @@
       texture(texture),
       image(image),
       stencil(stencil),
       damage(rect) {}
 
 BufferQueue::AllocatedSurface::~AllocatedSurface() {
   buffer_queue->FreeSurfaceResources(this);
 }
 
 }  // namespace display_compositor