A host of micro-optimizations and a refactor of TimeForBoundsToIntersect

cc/picture_layer_tiling.cc

 // Copyright 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.
 
 #include "cc/picture_layer_tiling.h"
 
+#include "base/debug/trace_event.h"
 #include "cc/math_util.h"
 #include "ui/gfx/rect_conversions.h"
 #include "ui/gfx/size_conversions.h"
 
 namespace cc {
 
 scoped_ptr<PictureLayerTiling> PictureLayerTiling::Create(
     float contents_scale,
     gfx::Size tile_size) {
   return make_scoped_ptr(new PictureLayerTiling(contents_scale, tile_size));
@@ skipping 273 matching lines @@
 }
 
 void PictureLayerTiling::UpdateTilePriorities(
     WhichTree tree,
     const gfx::Size& device_viewport,
     float last_layer_contents_scale,
     float current_layer_contents_scale,
     const gfx::Transform& last_screen_transform,
     const gfx::Transform& current_screen_transform,
     double time_delta) {
+  TRACE_EVENT0("cc", "PictureLayerTiling::UpdateTilePriorities");
   gfx::Rect content_rect = ContentRect();
   if (content_rect.IsEmpty())
     return;
 
   gfx::Rect view_rect(gfx::Point(), device_viewport);
   float current_scale = current_layer_contents_scale / contents_scale_;
   float last_scale = last_layer_contents_scale / contents_scale_;
 
   if (last_screen_transform.IsIdentityOrTranslation() &&
       current_screen_transform.IsIdentityOrTranslation())
@@ skipping 14 matching lines @@
       gfx::Rect tile_bound = tiling_data_.TileBounds(key.first, key.second);
       gfx::RectF current_screen_rect = gfx::ScaleRect(
           tile_bound,
           current_scale,
           current_scale) + current_offset;
       gfx::RectF last_screen_rect = gfx::ScaleRect(
           tile_bound,
           last_scale,
           last_scale) + last_offset;
 
+      priority.distance_to_visible_in_pixels =

[enne (OOO), 2013/01/30 06:53:56]

Please don't create unnecessary diff churn by moving things around.

[whunt, 2013/01/30 21:07:33]

This is a performance optimization.

[enne (OOO), 2013/01/30 21:50:12]

Could you explain?

+          TilePriority::manhattanDistance(current_screen_rect, view_rect);
+
       priority.time_to_visible_in_seconds =
           TilePriority::TimeForBoundsToIntersect(
               last_screen_rect, current_screen_rect, time_delta, view_rect);
 
-      priority.distance_to_visible_in_pixels =
-          TilePriority::manhattanDistance(current_screen_rect, view_rect);
       it->second->set_priority(tree, priority);
     }
   }
   else
   {
     for (TileMap::const_iterator it = tiles_.begin();
            it != tiles_.end(); ++it) {
       TileMapKey key = it->first;
       TilePriority priority;
       priority.resolution = resolution_;
 
       gfx::Rect tile_bound = tiling_data_.TileBounds(key.first, key.second);
       gfx::RectF current_layer_content_rect = gfx::ScaleRect(
           tile_bound,
           current_scale,
           current_scale);
       gfx::RectF current_screen_rect = MathUtil::mapClippedRect(
           current_screen_transform, current_layer_content_rect);
       gfx::RectF last_layer_content_rect = gfx::ScaleRect(
           tile_bound,
           last_scale,
           last_scale);
       gfx::RectF last_screen_rect  = MathUtil::mapClippedRect(
           last_screen_transform, last_layer_content_rect);
 
+      priority.distance_to_visible_in_pixels =
+          TilePriority::manhattanDistance(current_screen_rect, view_rect);
+
       priority.time_to_visible_in_seconds =
           TilePriority::TimeForBoundsToIntersect(
               last_screen_rect, current_screen_rect, time_delta, view_rect);
 
-      priority.distance_to_visible_in_pixels =
-          TilePriority::manhattanDistance(current_screen_rect, view_rect);
       it->second->set_priority(tree, priority);
     }
   }
 }
 
 void PictureLayerTiling::DidBecomeActive() {
   for (TileMap::const_iterator it = tiles_.begin(); it != tiles_.end(); ++it) {
     it->second->set_priority(ACTIVE_TREE, it->second->priority(PENDING_TREE));
     it->second->set_priority(PENDING_TREE, TilePriority());
 
     // Tile holds a ref onto a picture pile. If the tile never gets invalidated
     // and recreated, then that picture pile ref could exist indefinitely.  To
     // prevent this, ask the client to update the pile to its own ref.  This
     // will cause PicturePileImpls and their clones to get deleted once the
     // corresponding PictureLayerImpl and any in flight raster jobs go out of
     // scope.
     client_->UpdatePile(it->second);
   }
 }
 
 }  // namespace cc