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// Copyright 2014 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.
#ifndef CC_TILES_TILING_SET_EVICTION_QUEUE_H_
#define CC_TILES_TILING_SET_EVICTION_QUEUE_H_
#include <stddef.h>
#include <vector>
#include "cc/cc_export.h"
#include "cc/tiles/picture_layer_tiling_set.h"
#include "cc/tiles/prioritized_tile.h"
namespace cc {
// This eviction queue returned tiles from all tilings in a tiling set in
// the order in which the tiles should be evicted. It can be thought of as the
// following:
// for all phases:
// for all ordered tilings:
// yield the next tile for the given phase from the given tiling
//
// Phases are the following (in order in which they are processed):
// EVENTUALLY_RECT - Tiles in the eventually region of the tiling.
// SOON_BORDER_RECT - Tiles in the prepainting skirt of the tiling.
// SKEWPORT_RECT - Tiles in the skewport of the tiling.
// PENDING_VISIBLE_RECT - Tiles that will be visible upon activation, not
// required for activation.
// PENDING_VISIBLE_RECT_REQUIRED_FOR_ACTIVATION - Tiles that will be visible
// upon activation, required for activation.
// VISIBLE_RECT_OCCLUDED - Occluded, not required for activation, visible tiles.
// VISIBLE_RECT_UNOCCLUDED - Unoccluded, not required for activation, visible
// tiles.
// VISIBLE_RECT_REQUIRED_FOR_ACTIVATION_OCCLUDED - Occluded, but required for
// activation, visible tiles. This can happen when an active tree tile is
// occluded, but is not occluded on the pending tree (and is required for
// activation).
// VISIBLE_RECT_REQUIRED_FOR_ACTIVATION_UNOCCLUDED - Unoccluded, required for
// activation, tiles.
//
// The tilings are ordered as follows. Suppose we have tilings with the scales
// below:
// 2.0 1.5 1.0(HR) 0.8 0.5 0.25(LR) 0.2 0.1
// With HR referring to high res tiling and LR referring to low res tiling,
// then tilings are processed in this order:
// 2.0 1.5 0.1 0.2 0.5 0.8 0.25(LR) 1.0(HR).
//
// To put it differently:
// 1. Process the highest scale tiling down to, but not including, high res
// tiling.
// 2. Process the lowest scale tiling up to, but not including, the low res
// tiling. In cases without a low res tiling, this is an empty set.
// 3. Process low res tiling up to high res tiling, including neither high
// nor low res tilings. In cases without a low res tiling, this set
// includes all tilings with a lower scale than the high res tiling.
// 4. Process the low res tiling.
// 5. Process the high res tiling.
//
// Additional notes:
// Since eventually the tiles are considered to have the priority which is the
// higher of the two trees, we might visit a tile that should actually be
// returned by its twin. In those situations, the tiles are not returned. That
// is, since the twin has higher priority, it should return it when it gets to
// it. This ensures that we don't block raster because we've returned a tile
// with low priority on one tree, but high combined priority.
class CC_EXPORT TilingSetEvictionQueue {
public:
explicit TilingSetEvictionQueue(PictureLayerTilingSet* tiling_set);
~TilingSetEvictionQueue();
const PrioritizedTile& Top() const;
void Pop();
bool IsEmpty() const;
private:
enum Phase {
EVENTUALLY_RECT,
SOON_BORDER_RECT,
SKEWPORT_RECT,
PENDING_VISIBLE_RECT,
PENDING_VISIBLE_RECT_REQUIRED_FOR_ACTIVATION,
VISIBLE_RECT_OCCLUDED,
VISIBLE_RECT_UNOCCLUDED,
VISIBLE_RECT_REQUIRED_FOR_ACTIVATION_OCCLUDED,
VISIBLE_RECT_REQUIRED_FOR_ACTIVATION_UNOCCLUDED
};
void GenerateTilingOrder(PictureLayerTilingSet* tiling_set);
// Helper base class for individual region iterators.
class EvictionRectIterator {
public:
EvictionRectIterator();
EvictionRectIterator(
std::vector<PictureLayerTiling*>* tilings,
WhichTree tree,
PictureLayerTiling::PriorityRectType priority_rect_type);
bool done() const { return !prioritized_tile_.tile(); }
const PrioritizedTile& operator*() const { return prioritized_tile_; }
protected:
~EvictionRectIterator() = default;
template <typename TilingIteratorType>
bool AdvanceToNextTile(TilingIteratorType* iterator);
template <typename TilingIteratorType>
bool GetFirstTileAndCheckIfValid(TilingIteratorType* iterator);
PrioritizedTile prioritized_tile_;
std::vector<PictureLayerTiling*>* tilings_;
WhichTree tree_;
PictureLayerTiling::PriorityRectType priority_rect_type_;
size_t tiling_index_;
};
class PendingVisibleTilingIterator : public EvictionRectIterator {
public:
PendingVisibleTilingIterator() = default;
PendingVisibleTilingIterator(std::vector<PictureLayerTiling*>* tilings,
WhichTree tree,
bool return_required_for_activation_tiles);
PendingVisibleTilingIterator& operator++();
private:
bool TileMatchesRequiredFlags(const PrioritizedTile& tile) const;
TilingData::DifferenceIterator iterator_;
bool return_required_for_activation_tiles_;
};
class VisibleTilingIterator : public EvictionRectIterator {
public:
VisibleTilingIterator() = default;
VisibleTilingIterator(std::vector<PictureLayerTiling*>* tilings,
WhichTree tree,
bool return_occluded_tiles,
bool return_required_for_activation_tiles);
VisibleTilingIterator& operator++();
private:
bool TileMatchesRequiredFlags(const PrioritizedTile& tile) const;
TilingData::Iterator iterator_;
bool return_occluded_tiles_;
bool return_required_for_activation_tiles_;
};
class SkewportTilingIterator : public EvictionRectIterator {
public:
SkewportTilingIterator() = default;
SkewportTilingIterator(std::vector<PictureLayerTiling*>* tilings,
WhichTree tree);
SkewportTilingIterator& operator++();
private:
TilingData::ReverseSpiralDifferenceIterator iterator_;
};
class SoonBorderTilingIterator : public EvictionRectIterator {
public:
SoonBorderTilingIterator() = default;
SoonBorderTilingIterator(std::vector<PictureLayerTiling*>* tilings,
WhichTree tree);
SoonBorderTilingIterator& operator++();
private:
TilingData::ReverseSpiralDifferenceIterator iterator_;
};
class EventuallyTilingIterator : public EvictionRectIterator {
public:
EventuallyTilingIterator() = default;
EventuallyTilingIterator(std::vector<PictureLayerTiling*>* tilings,
WhichTree tree);
EventuallyTilingIterator& operator++();
private:
TilingData::ReverseSpiralDifferenceIterator iterator_;
};
void AdvancePhase();
WhichTree tree_;
Phase phase_;
PrioritizedTile current_tile_;
std::vector<PictureLayerTiling*> tilings_;
EventuallyTilingIterator eventually_iterator_;
SoonBorderTilingIterator soon_iterator_;
SkewportTilingIterator skewport_iterator_;
PendingVisibleTilingIterator pending_visible_iterator_;
VisibleTilingIterator visible_iterator_;
};
} // namespace cc
#endif // CC_TILES_TILING_SET_EVICTION_QUEUE_H_