cc/resources/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/resources/picture_layer_tiling_set.h"

#include <limits>
#include <set>
#include <vector>

namespace cc {

namespace {

class LargestToSmallestScaleFunctor {
 public:
  bool operator() (PictureLayerTiling* left, PictureLayerTiling* right) {
    return left->contents_scale() > right->contents_scale();
  }
};

inline float LargerRatio(float float1, float float2) {
  DCHECK_GT(float1, 0.f);
  DCHECK_GT(float2, 0.f);
  return float1 > float2 ? float1 / float2 : float2 / float1;
}

}  // namespace

// static
scoped_ptr<PictureLayerTilingSet> PictureLayerTilingSet::Create(
    PictureLayerTilingClient* client) {
  return make_scoped_ptr(new PictureLayerTilingSet(client));
}

PictureLayerTilingSet::PictureLayerTilingSet(PictureLayerTilingClient* client)
    : client_(client) {
}

PictureLayerTilingSet::~PictureLayerTilingSet() {
}

void PictureLayerTilingSet::SetClient(PictureLayerTilingClient* client) {
  client_ = client;
  for (size_t i = 0; i < tilings_.size(); ++i)
    tilings_[i]->SetClient(client_);
}

void PictureLayerTilingSet::RemoveTilesInRegion(const Region& region) {
  for (size_t i = 0; i < tilings_.size(); ++i)
    tilings_[i]->RemoveTilesInRegion(region);
}

void PictureLayerTilingSet::CleanUpTilings(
    float min_acceptable_high_res_scale,
    float max_acceptable_high_res_scale,
    const std::vector<PictureLayerTiling*>& needed_tilings,
    bool should_have_low_res,
    PictureLayerTilingSet* twin_set,
    PictureLayerTilingSet* recycled_twin_set) {
  float twin_low_res_scale = 0.f;
  if (twin_set) {
    PictureLayerTiling* tiling =
        twin_set->FindTilingWithResolution(LOW_RESOLUTION);
    if (tiling)
      twin_low_res_scale = tiling->contents_scale();
  }

  std::vector<PictureLayerTiling*> to_remove;
  for (auto* tiling : tilings_) {
    // Keep all tilings within the min/max scales.
    if (tiling->contents_scale() >= min_acceptable_high_res_scale &&
        tiling->contents_scale() <= max_acceptable_high_res_scale) {
      continue;
    }

    // Keep low resolution tilings, if the tiling set should have them.
    if (should_have_low_res &&
        (tiling->resolution() == LOW_RESOLUTION ||
         tiling->contents_scale() == twin_low_res_scale)) {
      continue;
    }

    // Don't remove tilings that are required.
    if (std::find(needed_tilings.begin(), needed_tilings.end(), tiling) !=
        needed_tilings.end()) {
      continue;
    }

    to_remove.push_back(tiling);
  }

  for (auto* tiling : to_remove) {
    PictureLayerTiling* twin_tiling =
        twin_set ? twin_set->FindTilingWithScale(tiling->contents_scale())
                 : nullptr;
    // Only remove tilings from the twin layer if they have
    // NON_IDEAL_RESOLUTION.
    if (twin_tiling && twin_tiling->resolution() == NON_IDEAL_RESOLUTION)
      twin_set->Remove(twin_tiling);

    PictureLayerTiling* recycled_twin_tiling =
        recycled_twin_set
            ? recycled_twin_set->FindTilingWithScale(tiling->contents_scale())
            : nullptr;
    // Remove the tiling from the recycle tree. Note that we ignore resolution,
    // since we don't need to maintain high/low res on the recycle set.
    if (recycled_twin_tiling)
      recycled_twin_set->Remove(recycled_twin_tiling);

    DCHECK_NE(HIGH_RESOLUTION, tiling->resolution());
    Remove(tiling);
  }
}

void PictureLayerTilingSet::MarkAllTilingsNonIdeal() {
  for (auto* tiling : tilings_)
    tiling->set_resolution(NON_IDEAL_RESOLUTION);
}

bool PictureLayerTilingSet::SyncTilings(const PictureLayerTilingSet& other,
                                        const gfx::Size& new_layer_bounds,
                                        const Region& layer_invalidation,
                                        float minimum_contents_scale,
                                        RasterSource* raster_source) {
  if (new_layer_bounds.IsEmpty()) {
    RemoveAllTilings();
    return false;
  }

  tilings_.reserve(other.tilings_.size());

  // Remove any tilings that aren't in |other| or don't meet the minimum.
  for (size_t i = 0; i < tilings_.size(); ++i) {
    float scale = tilings_[i]->contents_scale();
    if (scale >= minimum_contents_scale && !!other.FindTilingWithScale(scale))
      continue;
    // Swap with the last element and remove it.
    tilings_.swap(tilings_.begin() + i, tilings_.end() - 1);
    tilings_.pop_back();
    --i;
  }

  bool have_high_res_tiling = false;

  // Add any missing tilings from |other| that meet the minimum.
  for (size_t i = 0; i < other.tilings_.size(); ++i) {
    float contents_scale = other.tilings_[i]->contents_scale();
    if (contents_scale < minimum_contents_scale)
      continue;
    if (PictureLayerTiling* this_tiling = FindTilingWithScale(contents_scale)) {
      this_tiling->set_resolution(other.tilings_[i]->resolution());

      this_tiling->UpdateTilesToCurrentRasterSource(
          raster_source, layer_invalidation, new_layer_bounds);
      this_tiling->CreateMissingTilesInLiveTilesRect();
      if (this_tiling->resolution() == HIGH_RESOLUTION)
        have_high_res_tiling = true;

      DCHECK(this_tiling->tile_size() ==
             client_->CalculateTileSize(this_tiling->tiling_size()))
          << "tile_size: " << this_tiling->tile_size().ToString()
          << " tiling_size: " << this_tiling->tiling_size().ToString()
          << " CalculateTileSize: "
          << client_->CalculateTileSize(this_tiling->tiling_size()).ToString();
      continue;
    }
    scoped_ptr<PictureLayerTiling> new_tiling = PictureLayerTiling::Create(
        contents_scale,
        new_layer_bounds,
        client_);
    new_tiling->set_resolution(other.tilings_[i]->resolution());
    if (new_tiling->resolution() == HIGH_RESOLUTION)
      have_high_res_tiling = true;
    tilings_.push_back(new_tiling.Pass());
  }
  tilings_.sort(LargestToSmallestScaleFunctor());

  return have_high_res_tiling;
}

PictureLayerTiling* PictureLayerTilingSet::AddTiling(
    float contents_scale,
    const gfx::Size& layer_bounds) {
  for (size_t i = 0; i < tilings_.size(); ++i)
    DCHECK_NE(tilings_[i]->contents_scale(), contents_scale);

  tilings_.push_back(
      PictureLayerTiling::Create(contents_scale, layer_bounds, client_));
  PictureLayerTiling* appended = tilings_.back();

  tilings_.sort(LargestToSmallestScaleFunctor());
  return appended;
}

int PictureLayerTilingSet::NumHighResTilings() const {
  int num_high_res = 0;
  for (size_t i = 0; i < tilings_.size(); ++i) {
    if (tilings_[i]->resolution() == HIGH_RESOLUTION)
      num_high_res++;
  }
  return num_high_res;
}

PictureLayerTiling* PictureLayerTilingSet::FindTilingWithScale(
    float scale) const {
  for (size_t i = 0; i < tilings_.size(); ++i) {
    if (tilings_[i]->contents_scale() == scale)
      return tilings_[i];
  }
  return NULL;
}

PictureLayerTiling* PictureLayerTilingSet::FindTilingWithResolution(
    TileResolution resolution) const {
  auto iter = std::find_if(tilings_.begin(), tilings_.end(),
                           [resolution](const PictureLayerTiling* tiling) {
    return tiling->resolution() == resolution;
  });
  if (iter == tilings_.end())
    return NULL;
  return *iter;
}

void PictureLayerTilingSet::RemoveAllTilings() {
  tilings_.clear();
}

void PictureLayerTilingSet::Remove(PictureLayerTiling* tiling) {
  ScopedPtrVector<PictureLayerTiling>::iterator iter =
    std::find(tilings_.begin(), tilings_.end(), tiling);
  if (iter == tilings_.end())
    return;
  tilings_.erase(iter);
}

void PictureLayerTilingSet::RemoveAllTiles() {
  for (size_t i = 0; i < tilings_.size(); ++i)
    tilings_[i]->Reset();
}

float PictureLayerTilingSet::GetSnappedContentsScale(
    float start_scale,
    float snap_to_existing_tiling_ratio) const {
  // If a tiling exists within the max snapping ratio, snap to its scale.
  float snapped_contents_scale = start_scale;
  float snapped_ratio = snap_to_existing_tiling_ratio;
  for (const auto* tiling : tilings_) {
    float tiling_contents_scale = tiling->contents_scale();
    float ratio = LargerRatio(tiling_contents_scale, start_scale);
    if (ratio < snapped_ratio) {
      snapped_contents_scale = tiling_contents_scale;
      snapped_ratio = ratio;
    }
  }
  return snapped_contents_scale;
}

float PictureLayerTilingSet::GetMaximumContentsScale() const {
  if (tilings_.empty())
    return 0.f;
  // The first tiling has the largest contents scale.
  return tilings_[0]->contents_scale();
}

bool PictureLayerTilingSet::UpdateTilePriorities(
    const gfx::Rect& required_rect_in_layer_space,
    float ideal_contents_scale,
    double current_frame_time_in_seconds,
    const Occlusion& occlusion_in_layer_space,
    bool can_require_tiles_for_activation) {
  bool tiling_needs_update = false;
  // TODO(vmpstr): Check if we have to early out here, or if we can just do it
  // as part of computing tile priority rects for tilings.
  for (auto* tiling : tilings_) {
    if (tiling->NeedsUpdateForFrameAtTimeAndViewport(
            current_frame_time_in_seconds, required_rect_in_layer_space)) {
      tiling_needs_update = true;
      break;
    }
  }
  if (!tiling_needs_update)
    return false;

  for (auto* tiling : tilings_) {
    tiling->set_can_require_tiles_for_activation(
        can_require_tiles_for_activation);
    tiling->ComputeTilePriorityRects(
        required_rect_in_layer_space, ideal_contents_scale,
        current_frame_time_in_seconds, occlusion_in_layer_space);
  }
  return true;
}

void PictureLayerTilingSet::GetAllTilesForTracing(
    std::set<const Tile*>* tiles) const {
  for (auto* tiling : tilings_)
    tiling->GetAllTilesForTracing(tiles);
}

PictureLayerTilingSet::CoverageIterator::CoverageIterator(
    const PictureLayerTilingSet* set,
    float contents_scale,
    const gfx::Rect& content_rect,
    float ideal_contents_scale)
    : set_(set),
      contents_scale_(contents_scale),
      ideal_contents_scale_(ideal_contents_scale),
      current_tiling_(-1) {
  missing_region_.Union(content_rect);

  for (ideal_tiling_ = 0;
       static_cast<size_t>(ideal_tiling_) < set_->tilings_.size();
       ++ideal_tiling_) {
    PictureLayerTiling* tiling = set_->tilings_[ideal_tiling_];
    if (tiling->contents_scale() < ideal_contents_scale_) {
      if (ideal_tiling_ > 0)
        ideal_tiling_--;
      break;
    }
  }

  DCHECK_LE(set_->tilings_.size(),
            static_cast<size_t>(std::numeric_limits<int>::max()));

  int num_tilings = set_->tilings_.size();
  if (ideal_tiling_ == num_tilings && ideal_tiling_ > 0)
    ideal_tiling_--;

  ++(*this);
}

PictureLayerTilingSet::CoverageIterator::~CoverageIterator() {
}

gfx::Rect PictureLayerTilingSet::CoverageIterator::geometry_rect() const {
  if (!tiling_iter_) {
    if (!region_iter_.has_rect())
      return gfx::Rect();
    return region_iter_.rect();
  }
  return tiling_iter_.geometry_rect();
}

gfx::RectF PictureLayerTilingSet::CoverageIterator::texture_rect() const {
  if (!tiling_iter_)
    return gfx::RectF();
  return tiling_iter_.texture_rect();
}

gfx::Size PictureLayerTilingSet::CoverageIterator::texture_size() const {
  if (!tiling_iter_)
    return gfx::Size();
  return tiling_iter_.texture_size();
}

Tile* PictureLayerTilingSet::CoverageIterator::operator->() const {
  if (!tiling_iter_)
    return NULL;
  return *tiling_iter_;
}

Tile* PictureLayerTilingSet::CoverageIterator::operator*() const {
  if (!tiling_iter_)
    return NULL;
  return *tiling_iter_;
}

TileResolution PictureLayerTilingSet::CoverageIterator::resolution() const {
  const PictureLayerTiling* tiling = CurrentTiling();
  DCHECK(tiling);
  return tiling->resolution();
}

PictureLayerTiling* PictureLayerTilingSet::CoverageIterator::CurrentTiling()
    const {
  if (current_tiling_ < 0)
    return NULL;
  if (static_cast<size_t>(current_tiling_) >= set_->tilings_.size())
    return NULL;
  return set_->tilings_[current_tiling_];
}

int PictureLayerTilingSet::CoverageIterator::NextTiling() const {
  // Order returned by this method is:
  // 1. Ideal tiling index
  // 2. Tiling index < Ideal in decreasing order (higher res than ideal)
  // 3. Tiling index > Ideal in increasing order (lower res than ideal)
  // 4. Tiling index > tilings.size() (invalid index)
  if (current_tiling_ < 0)
    return ideal_tiling_;
  else if (current_tiling_ > ideal_tiling_)
    return current_tiling_ + 1;
  else if (current_tiling_)
    return current_tiling_ - 1;
  else
    return ideal_tiling_ + 1;
}

PictureLayerTilingSet::CoverageIterator&
PictureLayerTilingSet::CoverageIterator::operator++() {
  bool first_time = current_tiling_ < 0;

  if (!*this && !first_time)
    return *this;

  if (tiling_iter_)
    ++tiling_iter_;

  // Loop until we find a valid place to stop.
  while (true) {
    while (tiling_iter_ &&
           (!*tiling_iter_ || !tiling_iter_->IsReadyToDraw())) {
      missing_region_.Union(tiling_iter_.geometry_rect());
      ++tiling_iter_;
    }
    if (tiling_iter_)
      return *this;

    // If the set of current rects for this tiling is done, go to the next
    // tiling and set up to iterate through all of the remaining holes.
    // This will also happen the first time through the loop.
    if (!region_iter_.has_rect()) {
      current_tiling_ = NextTiling();
      current_region_.Swap(&missing_region_);
      missing_region_.Clear();
      region_iter_ = Region::Iterator(current_region_);

      // All done and all filled.
      if (!region_iter_.has_rect()) {
        current_tiling_ = set_->tilings_.size();
        return *this;
      }

      // No more valid tiles, return this checkerboard rect.
      if (current_tiling_ >= static_cast<int>(set_->tilings_.size()))
        return *this;
    }

    // Pop a rect off.  If there are no more tilings, then these will be
    // treated as geometry with null tiles that the caller can checkerboard.
    gfx::Rect last_rect = region_iter_.rect();
    region_iter_.next();

    // Done, found next checkerboard rect to return.
    if (current_tiling_ >= static_cast<int>(set_->tilings_.size()))
      return *this;

    // Construct a new iterator for the next tiling, but we need to loop
    // again until we get to a valid one.
    tiling_iter_ = PictureLayerTiling::CoverageIterator(
        set_->tilings_[current_tiling_],
        contents_scale_,
        last_rect);
  }

  return *this;
}

PictureLayerTilingSet::CoverageIterator::operator bool() const {
  return current_tiling_ < static_cast<int>(set_->tilings_.size()) ||
      region_iter_.has_rect();
}

void PictureLayerTilingSet::AsValueInto(base::debug::TracedValue* state) const {
  for (size_t i = 0; i < tilings_.size(); ++i) {
    state->BeginDictionary();
    tilings_[i]->AsValueInto(state);
    state->EndDictionary();
  }
}

size_t PictureLayerTilingSet::GPUMemoryUsageInBytes() const {
  size_t amount = 0;
  for (size_t i = 0; i < tilings_.size(); ++i)
    amount += tilings_[i]->GPUMemoryUsageInBytes();
  return amount;
}

PictureLayerTilingSet::TilingRange PictureLayerTilingSet::GetTilingRange(
    TilingRangeType type) const {
  // Doesn't seem to be the case right now but if it ever becomes a performance
  // problem to compute these ranges each time this function is called, we can
  // compute them only when the tiling set has changed instead.
  TilingRange high_res_range(0, 0);
  TilingRange low_res_range(tilings_.size(), tilings_.size());
  for (size_t i = 0; i < tilings_.size(); ++i) {
    const PictureLayerTiling* tiling = tilings_[i];
    if (tiling->resolution() == HIGH_RESOLUTION)
      high_res_range = TilingRange(i, i + 1);
    if (tiling->resolution() == LOW_RESOLUTION)
      low_res_range = TilingRange(i, i + 1);
  }

  TilingRange range(0, 0);
  switch (type) {
    case HIGHER_THAN_HIGH_RES:
      range = TilingRange(0, high_res_range.start);
      break;
    case HIGH_RES:
      range = high_res_range;
      break;
    case BETWEEN_HIGH_AND_LOW_RES:
      // TODO(vmpstr): This code assumes that high res tiling will come before
      // low res tiling, however there are cases where this assumption is
      // violated. As a result, it's better to be safe in these situations,
      // since otherwise we can end up accessing a tiling that doesn't exist.
      // See crbug.com/429397 for high res tiling appearing after low res
      // tiling discussion/fixes.
      if (high_res_range.start <= low_res_range.start)
        range = TilingRange(high_res_range.end, low_res_range.start);
      else
        range = TilingRange(low_res_range.end, high_res_range.start);
      break;
    case LOW_RES:
      range = low_res_range;
      break;
    case LOWER_THAN_LOW_RES:
      range = TilingRange(low_res_range.end, tilings_.size());
      break;
  }

  DCHECK_LE(range.start, range.end);
  return range;
}

}  // namespace cc