cc: Fix tiling raster iterator to process all tiles correctly.

cc/resources/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/resources/picture_layer_tiling.h"
 
 #include <algorithm>
 #include <cmath>
 #include <limits>
 
@@ skipping 852 matching lines @@
   if (!current_tile_ || !TileNeedsRaster(current_tile_))
     ++(*this);
 }
 
 PictureLayerTiling::TilingRasterTileIterator::~TilingRasterTileIterator() {}
 
 void PictureLayerTiling::TilingRasterTileIterator::AdvancePhase() {
   DCHECK_LT(type_, TilePriority::EVENTUALLY);
 
   do {
-    type_ = static_cast<TilePriority::PriorityBin>(type_ + 1);
-    if (type_ == TilePriority::EVENTUALLY) {
+    if (type_ == TilePriority::SOON && !skewport_processed_)
+      skewport_processed_ = true;
+    else
+      type_ = static_cast<TilePriority::PriorityBin>(type_ + 1);
+
+    if (type_ == TilePriority::SOON && skewport_processed_) {
+      spiral_iterator_ = TilingData::SpiralDifferenceIterator(
+          &tiling_->tiling_data_,
+          soon_border_rect_in_content_space_,
+          skewport_in_content_space_,
+          visible_rect_in_content_space_);
+    } else if (type_ == TilePriority::EVENTUALLY) {
       spiral_iterator_ = TilingData::SpiralDifferenceIterator(
           &tiling_->tiling_data_,
           eventually_rect_in_content_space_,
           skewport_in_content_space_,
-          visible_rect_in_content_space_);
+          soon_border_rect_in_content_space_);
     }

[reveman, 2014/07/24 12:50:16]

I find this code a bit hard to understand. It might just be that I'm not very
familiar with the phases we go through in this iterator. Could you add a comment
above the loop that lists each phase and then some comments next to the code in
the loop that makes us enter a new phase and why?

[reveman, 2014/07/24 13:12:23]

See my comment on the other patch. Maybe an enum for the phase can clean this up
and remove the need for comments.

[vmpstr, 2014/07/24 16:33:14]

Done.

 
     while (spiral_iterator_) {
       current_tile_ = tiling_->TileAt(spiral_iterator_.index_x(),
                                       spiral_iterator_.index_y());
       if (current_tile_ && TileNeedsRaster(current_tile_))
         break;
       ++spiral_iterator_;
     }
 
     if (!spiral_iterator_ && type_ == TilePriority::EVENTUALLY) {
@@ skipping 14 matching lines @@
         ++visible_iterator_;
         if (!visible_iterator_) {
           AdvancePhase();
           return *this;
         }
         next_index = visible_iterator_.index();
         break;
       case TilePriority::SOON:
         ++spiral_iterator_;
         if (!spiral_iterator_) {
-          if (skewport_processed_) {
-            AdvancePhase();
-            return *this;
-          }
-          skewport_processed_ = true;
-          spiral_iterator_ = TilingData::SpiralDifferenceIterator(
-              &tiling_->tiling_data_,
-              soon_border_rect_in_content_space_,
-              skewport_in_content_space_,
-              visible_rect_in_content_space_);
-          if (!spiral_iterator_) {
-            AdvancePhase();
-            return *this;
-          }
+          AdvancePhase();
+          return *this;
         }
         next_index = spiral_iterator_.index();
         break;
       case TilePriority::EVENTUALLY:
         ++spiral_iterator_;
         if (!spiral_iterator_) {
           current_tile_ = NULL;
           return *this;
         }
         next_index = spiral_iterator_.index();
@@ skipping 42 matching lines @@
   DCHECK(*this);
   do {
     ++tile_iterator_;
   } while (tile_iterator_ != tiling_->eviction_tiles_cache_.end() &&
            (!(*tile_iterator_)->HasResources()));
 
   return *this;
 }
 
 }  // namespace cc