// Copyright 2015 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_RESOURCES_PIXEL_REF_MAP_H_
#define CC_RESOURCES_PIXEL_REF_MAP_H_

#include <utility>
#include <vector>

#include "base/containers/hash_tables.h"
#include "base/lazy_instance.h"
#include "base/memory/ref_counted.h"
#include "cc/base/cc_export.h"
#include "third_party/skia/include/core/SkPicture.h"
#include "ui/gfx/geometry/rect.h"
#include "ui/gfx/geometry/size.h"

class SkPixelRef;

namespace cc {

class Picture;

typedef std::pair<int, int> PixelRefMapKey;
typedef std::vector<SkPixelRef*> PixelRefs;
typedef base::hash_map<PixelRefMapKey, PixelRefs> PixelRefHashmap;

// This class is used and owned by cc Picture class. It is used to gather pixel
// refs which would happen after record. It takes in |cell_size| to decide how
// big each grid cell should be.
class CC_EXPORT PixelRefMap {
 public:
  explicit PixelRefMap(const gfx::Size& cell_size);
  ~PixelRefMap();
  void GatherPixelRefsFromPicture(SkPicture* picture);

  bool empty() const { return data_hash_map_.empty(); }

  // This iterator imprecisely returns the set of pixel refs that are needed to
  // raster this layer rect from this picture.  Internally, pixel refs are
  // clumped into tile grid buckets, so there may be false positives.
  class CC_EXPORT Iterator {
   public:
    // Default iterator constructor that is used as place holder for invalid
    // Iterator.
    Iterator();
    Iterator(const gfx::Rect& layer_rect, const Picture* picture);
    ~Iterator();

    SkPixelRef* operator->() const {
      DCHECK_LT(current_index_, current_pixel_refs_->size());
      return (*current_pixel_refs_)[current_index_];
    }

    SkPixelRef* operator*() const {
      DCHECK_LT(current_index_, current_pixel_refs_->size());
      return (*current_pixel_refs_)[current_index_];
    }

    Iterator& operator++();
    operator bool() const {
      return current_index_ < current_pixel_refs_->size();
    }

   private:
    static base::LazyInstance<PixelRefs> empty_pixel_refs_;
    const PixelRefMap* target_pixel_ref_map_;
    const PixelRefs* current_pixel_refs_;
    unsigned current_index_;

    gfx::Rect layer_rect_;

    gfx::Point min_point_;
    gfx::Point max_point_;
    int current_x_;
    int current_y_;
  };

 private:
  gfx::Point min_pixel_cell_;
  gfx::Point max_pixel_cell_;
  gfx::Size cell_size_;

  PixelRefHashmap data_hash_map_;
};

}  // namespace cc

#endif  // CC_RESOURCES_PIXEL_REF_MAP_H_