cc/resources/pixel_ref_map.h

   1 // Copyright 2015 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef CC_RESOURCES_PIXEL_REF_MAP_H_
   6 #define CC_RESOURCES_PIXEL_REF_MAP_H_
   7
   8 #include <utility>
   9 #include <vector>
  10
  11 #include "base/containers/hash_tables.h"
  12 #include "base/lazy_instance.h"
  13 #include "base/memory/ref_counted.h"
  14 #include "cc/base/cc_export.h"
  15 #include "third_party/skia/include/core/SkPicture.h"
  16 #include "ui/gfx/geometry/rect.h"
  17 #include "ui/gfx/geometry/size.h"
  18
  19 class SkPixelRef;
  20
  21 namespace cc {
  22
  23 class Picture;
  24
  25 typedef std::pair<int, int> PixelRefMapKey;
  26 typedef std::vector<SkPixelRef*> PixelRefs;
  27 typedef base::hash_map<PixelRefMapKey, PixelRefs> PixelRefHashmap;
  28
  29 // This class is used and owned by cc Picture class. It is used to gather pixel
  30 // refs which would happen after record. It takes in |cell_size| to decide how
  31 // big each grid cell should be.
  32 class CC_EXPORT PixelRefMap {
  33  public:
  34   explicit PixelRefMap(const gfx::Size& cell_size);
  35   ~PixelRefMap();
  36   void GatherPixelRefsFromPicture(SkPicture* picture);
  37
  38   bool empty() const { return data_hash_map_.empty(); }
  39
  40   // This iterator imprecisely returns the set of pixel refs that are needed to
  41   // raster this layer rect from this picture.  Internally, pixel refs are
  42   // clumped into tile grid buckets, so there may be false positives.
  43   class CC_EXPORT Iterator {
  44    public:
  45     // Default iterator constructor that is used as place holder for invalid
  46     // Iterator.
  47     Iterator();
  48     Iterator(const gfx::Rect& layer_rect, const Picture* picture);
  49     ~Iterator();
  50
  51     SkPixelRef* operator->() const {
  52       DCHECK_LT(current_index_, current_pixel_refs_->size());
  53       return (*current_pixel_refs_)[current_index_];
  54     }
  55
  56     SkPixelRef* operator*() const {
  57       DCHECK_LT(current_index_, current_pixel_refs_->size());
  58       return (*current_pixel_refs_)[current_index_];
  59     }
  60
  61     Iterator& operator++();
  62     operator bool() const {
  63       return current_index_ < current_pixel_refs_->size();
  64     }
  65
  66    private:
  67     static base::LazyInstance<PixelRefs> empty_pixel_refs_;
  68     const PixelRefMap* target_pixel_ref_map_;
  69     const PixelRefs* current_pixel_refs_;
  70     unsigned current_index_;
  71
  72     gfx::Rect layer_rect_;
  73
  74     gfx::Point min_point_;
  75     gfx::Point max_point_;
  76     int current_x_;
  77     int current_y_;
  78   };
  79
  80  private:
  81   gfx::Point min_pixel_cell_;
  82   gfx::Point max_pixel_cell_;
  83   gfx::Size cell_size_;
  84
  85   PixelRefHashmap data_hash_map_;
  86 };
  87
  88 }  // namespace cc
  89
  90 #endif  // CC_RESOURCES_PIXEL_REF_MAP_H_