exo: Avoid creating transparent texture quads.

components/exo/surface.cc

 // Copyright 2015 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/exo/surface.h"
 
 #include <utility>
 
 #include "base/callback_helpers.h"
 #include "base/logging.h"
@@ skipping 766 matching lines @@
   gfx::Rect quad_rect = gfx::Rect(contents_surface_size);
   cc::SharedQuadState* quad_state =
       render_pass->CreateAndAppendSharedQuadState();
   quad_state->quad_layer_bounds = contents_surface_size;
   quad_state->visible_quad_layer_rect = quad_rect;
   quad_state->opacity = state_.alpha;
 
   std::unique_ptr<cc::DelegatedFrameData> delegated_frame(
       new cc::DelegatedFrameData);
   if (current_resource_.id) {
-    cc::TextureDrawQuad* texture_quad =
-        render_pass->CreateAndAppendDrawQuad<cc::TextureDrawQuad>();
-    float vertex_opacity[4] = {1.0, 1.0, 1.0, 1.0};
-    gfx::Rect opaque_rect;
-    if (state_.blend_mode == SkXfermode::kSrc_Mode ||
-        state_.opaque_region.contains(gfx::RectToSkIRect(quad_rect))) {
-      opaque_rect = quad_rect;
-    } else if (state_.opaque_region.isRect()) {
-      opaque_rect = gfx::SkIRectToRect(state_.opaque_region.getBounds());
+    // Texture quad is only needed if buffer is not fully transparent.
+    if (state_.alpha) {
+      cc::TextureDrawQuad* texture_quad =
+          render_pass->CreateAndAppendDrawQuad<cc::TextureDrawQuad>();
+      float vertex_opacity[4] = {1.0, 1.0, 1.0, 1.0};
+      gfx::Rect opaque_rect;
+      if (state_.blend_mode == SkXfermode::kSrc_Mode ||
+          state_.opaque_region.contains(gfx::RectToSkIRect(quad_rect))) {
+        opaque_rect = quad_rect;
+      } else if (state_.opaque_region.isRect()) {
+        opaque_rect = gfx::SkIRectToRect(state_.opaque_region.getBounds());
+      }
+
+      texture_quad->SetNew(quad_state, quad_rect, opaque_rect, quad_rect,
+                           current_resource_.id, true, uv_top_left,
+                           uv_bottom_right, SK_ColorTRANSPARENT, vertex_opacity,
+                           false, false, state_.only_visible_on_secure_output);
+      delegated_frame->resource_list.push_back(current_resource_);
     }
-
-    texture_quad->SetNew(quad_state, quad_rect, opaque_rect, quad_rect,
-                         current_resource_.id, true, uv_top_left,
-                         uv_bottom_right, SK_ColorTRANSPARENT, vertex_opacity,
-                         false, false, state_.only_visible_on_secure_output);
-    delegated_frame->resource_list.push_back(current_resource_);
   } else {
     cc::SolidColorDrawQuad* solid_quad =
         render_pass->CreateAndAppendDrawQuad<cc::SolidColorDrawQuad>();
     solid_quad->SetNew(quad_state, quad_rect, quad_rect, SK_ColorBLACK, false);
   }
 
   delegated_frame->render_pass_list.push_back(std::move(render_pass));
   cc::CompositorFrame frame;
   frame.delegated_frame_data = std::move(delegated_frame);
 
@@ skipping 21 matching lines @@
 
 int64_t Surface::GetPropertyInternal(const void* key,
                                      int64_t default_value) const {
   std::map<const void*, Value>::const_iterator iter = prop_map_.find(key);
   if (iter == prop_map_.end())
     return default_value;
   return iter->second.value;
 }
 
 }  // namespace exo