Raster PictureLayerTiling with fractional translation

cc/tiles/picture_layer_tiling_set.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/tiles/picture_layer_tiling_set.h"
 
 #include <stddef.h>
 
 #include <limits>
 #include <set>
@@ skipping 63 matching lines @@
     // If the twin (pending) tiling set is empty, it was not updated for the
     // current frame. So we drop tilings from our set as well, instead of
     // leaving behind unshared tilings that are all non-ideal.
     RemoveAllTilings();
     return;
   }
 
   bool tiling_sort_required = false;
   for (const auto& pending_twin_tiling : pending_twin_set->tilings_) {
     float contents_scale = pending_twin_tiling->contents_scale();
+    gfx::Vector2dF contents_translation =
+        pending_twin_tiling->contents_translation();
     PictureLayerTiling* this_tiling = FindTilingWithScale(contents_scale);

[enne (OOO), 2016/08/22 22:57:39]

What if there are multiple tilings with the same scale but different
translations?

[trchen, 2016/08/29 10:14:48]

Currently the easiest thing to do is to replace. It shouldn't be terribly
difficult to extend the tiling set to accommodate both. I think we can do it in
a separate CL.

     if (!this_tiling) {
-      std::unique_ptr<PictureLayerTiling> new_tiling(new PictureLayerTiling(
-          tree_, contents_scale, raster_source_, client_));
+      std::unique_ptr<PictureLayerTiling> new_tiling(
+          new PictureLayerTiling(tree_, contents_scale, contents_translation,
+                                 raster_source_, client_));
       tilings_.push_back(std::move(new_tiling));
       this_tiling = tilings_.back().get();
       tiling_sort_required = true;
       state_since_last_tile_priority_update_.added_tilings = true;
     }
     this_tiling->TakeTilesAndPropertiesFrom(pending_twin_tiling.get(),
                                             layer_invalidation);
   }
 
   if (tiling_sort_required) {
@@ skipping 157 matching lines @@
   tilings_.erase(to_remove, tilings_.end());
 }
 
 void PictureLayerTilingSet::MarkAllTilingsNonIdeal() {
   for (const auto& tiling : tilings_)
     tiling->set_resolution(NON_IDEAL_RESOLUTION);
 }
 
 PictureLayerTiling* PictureLayerTilingSet::AddTiling(
     float contents_scale,
+    const gfx::Vector2dF& contents_translation,
     scoped_refptr<RasterSource> raster_source) {
   if (!raster_source_)
     raster_source_ = raster_source;
 
   for (size_t i = 0; i < tilings_.size(); ++i) {
     DCHECK_NE(tilings_[i]->contents_scale(), contents_scale);
     DCHECK_EQ(tilings_[i]->raster_source(), raster_source.get());
   }
 
-  tilings_.push_back(base::WrapUnique(
-      new PictureLayerTiling(tree_, contents_scale, raster_source, client_)));
+  tilings_.push_back(base::WrapUnique(new PictureLayerTiling(
+      tree_, contents_scale, contents_translation, raster_source, client_)));
   PictureLayerTiling* appended = tilings_.back().get();
   state_since_last_tile_priority_update_.added_tilings = true;
 
   std::sort(tilings_.begin(), tilings_.end(), LargestToSmallestScaleFunctor());
   return appended;
 }
 
 int PictureLayerTilingSet::NumHighResTilings() const {
   return std::count_if(tilings_.begin(), tilings_.end(),
                        [](const std::unique_ptr<PictureLayerTiling>& tiling) {
@@ skipping 462 matching lines @@
     case LOWER_THAN_LOW_RES:
       range = TilingRange(low_res_range.end, tilings_size);
       break;
   }
 
   DCHECK_LE(range.start, range.end);
   return range;
 }
 
 }  // namespace cc