ui/gfx/image/image_family.cc

   1 // Copyright 2013 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 #include "ui/gfx/image/image_family.h"
   6
   7 #include <cmath>
   8
   9 #include "ui/gfx/geometry/size.h"
  10 #include "ui/gfx/image/image.h"
  11 #include "ui/gfx/image/image_skia.h"
  12
  13 namespace gfx {
  14
  15 ImageFamily::const_iterator::const_iterator() {}
  16
  17 ImageFamily::const_iterator::const_iterator(const const_iterator& other)
  18     : map_iterator_(other.map_iterator_) {}
  19
  20 ImageFamily::const_iterator::const_iterator(
  21     const std::map<MapKey, gfx::Image>::const_iterator& other)
  22     : map_iterator_(other) {}
  23
  24 ImageFamily::const_iterator::~const_iterator() {}
  25
  26 ImageFamily::ImageFamily() {}
  27 ImageFamily::~ImageFamily() {}
  28
  29 void ImageFamily::Add(const gfx::Image& image) {
  30   gfx::Size size = image.Size();
  31   if (size.IsEmpty()) {
  32     map_[MapKey(1.0f, 0)] = image;
  33   } else {
  34     float aspect = static_cast<float>(size.width()) / size.height();
  35     DCHECK_GT(aspect, 0.0f);
  36     map_[MapKey(aspect, size.width())] = image;
  37   }
  38 }
  39
  40 void ImageFamily::Add(const gfx::ImageSkia& image_skia) {
  41   Add(gfx::Image(image_skia));
  42 }
  43
  44 const gfx::Image* ImageFamily::GetBest(int width, int height) const {
  45   if (map_.empty())
  46     return NULL;
  47
  48   // If either |width| or |height| is 0, both are.
  49   float desired_aspect;
  50   if (height == 0 || width == 0) {
  51     desired_aspect = 1.0f;
  52     height = 0;
  53     width = 0;
  54   } else {
  55     desired_aspect = static_cast<float>(width) / height;
  56   }
  57   DCHECK_GT(desired_aspect, 0.0f);
  58
  59   float closest_aspect = GetClosestAspect(desired_aspect);
  60
  61   // If thinner than desired, search for images with width such that the
  62   // corresponding height is greater than or equal to the desired |height|.
  63   int desired_width = closest_aspect <= desired_aspect ?
  64       width : static_cast<int>(ceilf(height * closest_aspect));
  65
  66   // Get the best-sized image with the aspect ratio.
  67   return GetWithExactAspect(closest_aspect, desired_width);
  68 }
  69
  70 float ImageFamily::GetClosestAspect(float desired_aspect) const {
  71   // Find the two aspect ratios on either side of |desired_aspect|.
  72   std::map<MapKey, gfx::Image>::const_iterator greater_or_equal =
  73       map_.lower_bound(MapKey(desired_aspect, 0));
  74   // Early exit optimization if there is an exact match.
  75   if (greater_or_equal != map_.end() &&
  76       greater_or_equal->first.aspect() == desired_aspect) {
  77     return desired_aspect;
  78   }
  79
  80   // No exact match; |greater_or_equal| will point to the first image with
  81   // aspect ratio >= |desired_aspect|, and |less_than| will point to the last
  82   // image with aspect ratio < |desired_aspect|.
  83   if (greater_or_equal != map_.begin()) {
  84     std::map<MapKey, gfx::Image>::const_iterator less_than =
  85         greater_or_equal;
  86     --less_than;
  87     float thinner_aspect = less_than->first.aspect();
  88     DCHECK_GT(thinner_aspect, 0.0f);
  89     DCHECK_LT(thinner_aspect, desired_aspect);
  90     if (greater_or_equal != map_.end()) {
  91       float wider_aspect = greater_or_equal->first.aspect();
  92       DCHECK_GT(wider_aspect, desired_aspect);
  93       if ((wider_aspect / desired_aspect) < (desired_aspect / thinner_aspect))
  94         return wider_aspect;
  95     }
  96     return thinner_aspect;
  97   } else {
  98     // No aspect ratio is less than or equal to |desired_aspect|.
  99     DCHECK(greater_or_equal != map_.end());
 100     float wider_aspect = greater_or_equal->first.aspect();
 101     DCHECK_GT(wider_aspect, desired_aspect);
 102     return wider_aspect;
 103   }
 104 }
 105
 106 const gfx::Image* ImageFamily::GetBest(const gfx::Size& size) const {
 107   return GetBest(size.width(), size.height());
 108 }
 109
 110 const gfx::Image* ImageFamily::GetWithExactAspect(float aspect,
 111                                                   int width) const {
 112   // Find the two images of given aspect ratio on either side of |width|.
 113   std::map<MapKey, gfx::Image>::const_iterator greater_or_equal =
 114       map_.lower_bound(MapKey(aspect, width));
 115   if (greater_or_equal != map_.end() &&
 116       greater_or_equal->first.aspect() == aspect) {
 117     // We have found the smallest image of the same size or greater.
 118     return &greater_or_equal->second;
 119   }
 120
 121   DCHECK(greater_or_equal != map_.begin());
 122   std::map<MapKey, gfx::Image>::const_iterator less_than = greater_or_equal;
 123   --less_than;
 124   // This must be true because there must be at least one image with |aspect|.
 125   DCHECK_EQ(less_than->first.aspect(), aspect);
 126   // We have found the largest image smaller than desired.
 127   return &less_than->second;
 128 }
 129
 130 }  // namespace gfx