Partial swap implementation for surfaceless

content/browser/compositor/buffer_queue.cc

Index: content/browser/compositor/buffer_queue.cc
diff --git a/content/browser/compositor/buffer_queue.cc b/content/browser/compositor/buffer_queue.cc
index 8809972ed359cdc55d314acbcd77ddca60654b85..6f40b92759114b9fb9ec8c322ea92afbb311df3a 100644
--- a/content/browser/compositor/buffer_queue.cc
+++ b/content/browser/compositor/buffer_queue.cc
@@ -4,9 +4,13 @@
 
 #include "content/browser/compositor/buffer_queue.h"
 
+#include "content/browser/compositor/image_transport_factory.h"
 #include "content/common/gpu/client/context_provider_command_buffer.h"
+#include "content/common/gpu/client/gl_helper.h"
 #include "gpu/GLES2/gl2extchromium.h"
 #include "gpu/command_buffer/client/gles2_interface.h"
+#include "third_party/skia/include/core/SkRect.h"
+#include "third_party/skia/include/core/SkRegion.h"
 
 namespace content {
 
@@ -46,8 +50,57 @@ void BufferQueue::BindFramebuffer() {
   }
 }
 
-void BufferQueue::SwapBuffers() {
-  in_flight_surfaces_.push(current_surface_);
+void BufferQueue::CopyBufferDamage(int texture,
+                                   int source_texture,
+                                   const gfx::Rect& new_damage,
+                                   const gfx::Rect& old_damage) {
+  ImageTransportFactory::GetInstance()->GetGLHelper()->CopySubBufferDamage(
+      texture,
+      source_texture,
+      SkRegion(SkIRect::MakeXYWH(new_damage.x(),
+                                 new_damage.y(),
+                                 new_damage.width(),
+                                 new_damage.height())),
+      SkRegion(SkIRect::MakeXYWH(old_damage.x(),
+                                 old_damage.y(),
+                                 old_damage.width(),
+                                 old_damage.height())));
+}
+
+void BufferQueue::SwapBuffers(const gfx::Rect& damage) {
+  if (damage != gfx::Rect(size_)) {
+    // We must have a frame available to copy from.
+    DCHECK(!in_flight_surfaces_.empty());
+
+    if (!damage.Contains(current_surface_.damage)) {
+      CopyBufferDamage(current_surface_.texture,
+                       in_flight_surfaces_.back().texture,
+                       damage,
+                       current_surface_.damage);
+      // Because we copied everything except |damage| to this texture,
+      // the cumulative damage for this frame is only |damage| now.
+      in_flight_surfaces_.back().damage = damage;
+    }
+
+    // Compute cumulative damage for all frames.
+    for (size_t i = 0; i < available_surfaces_.size(); i++)
+      available_surfaces_[i].damage.Union(damage);
+    for (std::deque<AllocatedSurface>::iterator it =
+             in_flight_surfaces_.begin();
+         it != in_flight_surfaces_.end();
+         ++it)
+      it->damage.Union(damage);
+  } else {
+    for (size_t i = 0; i < available_surfaces_.size(); i++)
+      available_surfaces_[i].damage = damage;
+    for (std::deque<AllocatedSurface>::iterator it =
+             in_flight_surfaces_.begin();
+         it != in_flight_surfaces_.end();
+         ++it)
+      it->damage = damage;
+  }
+  current_surface_.damage = gfx::Rect();
+  in_flight_surfaces_.push_back(current_surface_);
   current_surface_.texture = 0;
   current_surface_.image = 0;
 }
@@ -70,7 +123,7 @@ void BufferQueue::Reshape(const gfx::Size& size, float scale_factor) {
 void BufferQueue::PageFlipComplete() {
   if (in_flight_surfaces_.size() > 1) {
     available_surfaces_.push_back(in_flight_surfaces_.front());
-    in_flight_surfaces_.pop();
+    in_flight_surfaces_.pop_front();
   }
 }
 
@@ -78,7 +131,7 @@ void BufferQueue::FreeAllSurfaces() {
   FreeSurface(&current_surface_);
   while (!in_flight_surfaces_.empty()) {
     FreeSurface(&in_flight_surfaces_.front());
-    in_flight_surfaces_.pop();
+    in_flight_surfaces_.pop_front();
   }
   for (size_t i = 0; i < available_surfaces_.size(); i++)
     FreeSurface(&available_surfaces_[i]);
@@ -100,9 +153,9 @@ void BufferQueue::FreeSurface(AllocatedSurface* surface) {
 
 BufferQueue::AllocatedSurface BufferQueue::GetNextSurface() {
   if (!available_surfaces_.empty()) {
-    AllocatedSurface id = available_surfaces_.back();
+    AllocatedSurface surface = available_surfaces_.back();
     available_surfaces_.pop_back();
-    return id;
+    return surface;
   }
 
   unsigned int texture = 0;
@@ -122,7 +175,7 @@ BufferQueue::AllocatedSurface BufferQueue::GetNextSurface() {
   allocated_count_++;
   gl->BindTexture(GL_TEXTURE_2D, texture);
   gl->BindTexImage2DCHROMIUM(GL_TEXTURE_2D, id);
-  return AllocatedSurface(texture, id);
+  return AllocatedSurface(texture, id, gfx::Rect(size_));
 }
 
 }  // namespace content