Revert of cc: Stop locking the raster scale factor at 1 after any change.

cc/layers/picture_layer_impl.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/layers/picture_layer_impl.h"
 
 #include <algorithm>
 #include <cmath>
 #include <limits>
 #include <set>
@@ skipping 51 matching lines @@
       tilings_(CreatePictureLayerTilingSet()),
       ideal_page_scale_(0.f),
       ideal_device_scale_(0.f),
       ideal_source_scale_(0.f),
       ideal_contents_scale_(0.f),
       raster_page_scale_(0.f),
       raster_device_scale_(0.f),
       raster_source_scale_(0.f),
       raster_contents_scale_(0.f),
       low_res_raster_contents_scale_(0.f),
+      raster_source_scale_is_fixed_(false),
       was_screen_space_transform_animating_(false),
       only_used_low_res_last_append_quads_(false),
       is_mask_(is_mask),
       nearest_neighbor_(false) {
   layer_tree_impl()->RegisterPictureLayerImpl(this);
 }
 
 PictureLayerImpl::~PictureLayerImpl() {
   if (twin_layer_)
     twin_layer_->twin_layer_ = nullptr;
@@ skipping 800 matching lines @@
   if (!is_pinching) {
     // When not pinching, match the ideal page scale factor.
     if (raster_page_scale_ != ideal_page_scale_)
       return true;
   }
 
   // Always match the ideal device scale factor.
   if (raster_device_scale_ != ideal_device_scale_)
     return true;
 
-  // When the source scale changes we want to match it, but not when animating.
+  // When the source scale changes we want to match it, but not when animating
+  // or when we've fixed the scale in place.
   if (!draw_properties().screen_space_transform_is_animating &&
+      !raster_source_scale_is_fixed_ &&
       raster_source_scale_ != ideal_source_scale_)
     return true;
 
   if (raster_contents_scale_ > MaximumContentsScale())
     return true;
   if (raster_contents_scale_ < MinimumContentsScale())
     return true;
 
   return false;
 }
@@ skipping 20 matching lines @@
   bool is_pinching = layer_tree_impl()->PinchGestureActive();
   bool is_animating = draw_properties().screen_space_transform_is_animating;
   if (!is_pinching && !is_animating) {
     if (!low_res)
       low_res = AddTiling(low_res_raster_contents_scale_);
     low_res->set_resolution(LOW_RESOLUTION);
   }
 }
 
 void PictureLayerImpl::RecalculateRasterScales() {
-  const float old_raster_contents_scale = raster_contents_scale_;
-  const float old_raster_page_scale = raster_page_scale_;
+  float old_raster_contents_scale = raster_contents_scale_;
+  float old_raster_page_scale = raster_page_scale_;
+  float old_raster_source_scale = raster_source_scale_;
 
   raster_device_scale_ = ideal_device_scale_;
   raster_page_scale_ = ideal_page_scale_;
   raster_source_scale_ = ideal_source_scale_;
   raster_contents_scale_ = ideal_contents_scale_;
 
+  // If we're not animating, or leaving an animation, and the
+  // ideal_source_scale_ changes, then things are unpredictable, and we fix
+  // the raster_source_scale_ in place.
+  if (old_raster_source_scale &&
+      !draw_properties().screen_space_transform_is_animating &&
+      !was_screen_space_transform_animating_ &&
+      old_raster_source_scale != ideal_source_scale_)
+    raster_source_scale_is_fixed_ = true;
+
+  // TODO(danakj): Adjust raster source scale closer to ideal source scale at
+  // a throttled rate. Possibly make use of invalidation_.IsEmpty() on pending
+  // tree. This will allow CSS scale changes to get re-rastered at an
+  // appropriate rate. (crbug.com/413636)
+  if (raster_source_scale_is_fixed_) {
+    raster_contents_scale_ /= raster_source_scale_;
+    raster_source_scale_ = 1.f;
+  }
+
   // During pinch we completely ignore the current ideal scale, and just use
   // a multiple of the previous scale.
   bool is_pinching = layer_tree_impl()->PinchGestureActive();
   if (is_pinching && old_raster_contents_scale) {
     // See ShouldAdjustRasterScale:
     // - When zooming out, preemptively create new tiling at lower resolution.
     // - When zooming in, approximate ideal using multiple of kMaxScaleRatio.
     bool zooming_out = old_raster_page_scale > ideal_page_scale_;
     float desired_contents_scale = old_raster_contents_scale;
     if (zooming_out) {
@@ skipping 148 matching lines @@
   // up larger than |max_texture_size|.
   return nextafterf(max_scale, 0.f);
 }
 
 void PictureLayerImpl::ResetRasterScale() {
   raster_page_scale_ = 0.f;
   raster_device_scale_ = 0.f;
   raster_source_scale_ = 0.f;
   raster_contents_scale_ = 0.f;
   low_res_raster_contents_scale_ = 0.f;
+  raster_source_scale_is_fixed_ = false;
 }
 
 bool PictureLayerImpl::CanHaveTilings() const {
   if (raster_source_->IsSolidColor())
     return false;
   if (!DrawsContent())
     return false;
   if (!raster_source_->HasRecordings())
     return false;
   // If the |raster_source_| has a recording it should have non-empty bounds.
@@ skipping 63 matching lines @@
     std::vector<PrioritizedTile>* prioritized_tiles) const {
   if (!tilings_)
     return;
   tilings_->GetAllPrioritizedTilesForTracing(prioritized_tiles);
 }
 
 void PictureLayerImpl::AsValueInto(
     base::trace_event::TracedValue* state) const {
   LayerImpl::AsValueInto(state);
   state->SetDouble("ideal_contents_scale", ideal_contents_scale_);
-  state->SetDouble("raster_contents_scale", raster_contents_scale_);
   state->SetDouble("geometry_contents_scale", MaximumTilingContentsScale());
   state->BeginArray("tilings");
   tilings_->AsValueInto(state);
   state->EndArray();
 
   MathUtil::AddToTracedValue("tile_priority_rect",
                              viewport_rect_for_tile_priority_in_content_space_,
                              state);
   MathUtil::AddToTracedValue("visible_rect", visible_layer_rect(), state);
 
@@ skipping 36 matching lines @@
 
 bool PictureLayerImpl::IsOnActiveOrPendingTree() const {
   return !layer_tree_impl()->IsRecycleTree();
 }
 
 bool PictureLayerImpl::HasValidTilePriorities() const {
   return IsOnActiveOrPendingTree() && IsDrawnRenderSurfaceLayerListMember();
 }
 
 }  // namespace cc