src/chrome/browser/history/select_favicon_frames.cc

   1 // Copyright (c) 2012 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 "chrome/browser/history/select_favicon_frames.h"
   6
   7 #include <set>
   8
   9 #include "skia/ext/image_operations.h"
  10 #include "third_party/skia/include/core/SkCanvas.h"
  11 #include "ui/gfx/image/image.h"
  12 #include "ui/gfx/image/image_skia.h"
  13 #include "ui/gfx/size.h"
  14
  15 namespace {
  16
  17 size_t BiggestCandidate(const std::vector<gfx::Size>& candidate_sizes) {
  18   size_t max_index = 0;
  19   int max_area = candidate_sizes[0].GetArea();
  20   for (size_t i = 1; i < candidate_sizes.size(); ++i) {
  21     int area = candidate_sizes[i].GetArea();
  22     if (area > max_area) {
  23       max_area = area;
  24       max_index = i;
  25     }
  26   }
  27   return max_index;
  28 }
  29
  30 SkBitmap SampleNearestNeighbor(const SkBitmap& contents, int desired_size) {
  31   SkBitmap bitmap;
  32   bitmap.setConfig(
  33       SkBitmap::kARGB_8888_Config, desired_size, desired_size);
  34   bitmap.allocPixels();
  35   if (!contents.isOpaque())
  36     bitmap.eraseARGB(0, 0, 0, 0);
  37
  38   {
  39     SkCanvas canvas(bitmap);
  40     SkRect dest(SkRect::MakeWH(desired_size, desired_size));
  41     canvas.drawBitmapRect(contents, NULL, dest);
  42   }
  43
  44   return bitmap;
  45 }
  46
  47 enum ResizeMethod {
  48 NONE,
  49 SAMPLE_NEAREST_NEIGHBOUR,
  50 LANCZOS
  51 };
  52
  53 size_t GetCandidateIndexWithBestScore(
  54     const std::vector<gfx::Size>& candidate_sizes_in_pixel,
  55     ui::ScaleFactor scale_factor,
  56     int desired_size_in_dip,
  57     float* score,
  58     ResizeMethod* resize_method) {
  59   DCHECK_NE(desired_size_in_dip, 0);
  60
  61   float scale = ui::GetImageScale(scale_factor);
  62   int desired_size_in_pixel =
  63       static_cast<int>(desired_size_in_dip * scale + 0.5f);
  64
  65   // Try to find an exact match.
  66   for (size_t i = 0; i < candidate_sizes_in_pixel.size(); ++i) {
  67     if (candidate_sizes_in_pixel[i].width() == desired_size_in_pixel &&
  68         candidate_sizes_in_pixel[i].height() == desired_size_in_pixel) {
  69       *score = 1;
  70       *resize_method = NONE;
  71       return i;
  72     }
  73   }
  74
  75   // Huge favicon bitmaps often have a completely different visual style from
  76   // smaller favicon bitmaps. Avoid these favicon bitmaps when a favicon of
  77   // gfx::kFaviconSize DIP is requested.
  78   const int kHugeEdgeSizeInPixel = desired_size_in_pixel * 8;
  79
  80   // Order of preference:
  81   // 1) Bitmaps with width and height smaller than |kHugeEdgeSizeInPixel|.
  82   // 2) Bitmaps which need to be scaled down instead of up.
  83   // 3) Bitmaps which do not need to be scaled as much.
  84   int candidate_index = -1;
  85   float candidate_score = 0;
  86   for (size_t i = 0; i < candidate_sizes_in_pixel.size(); ++i) {
  87     float average_edge_in_pixel = (candidate_sizes_in_pixel[i].width() +
  88         candidate_sizes_in_pixel[i].height()) / 2.0f;
  89
  90     float score = 0;
  91     if (candidate_sizes_in_pixel[i].width() >= kHugeEdgeSizeInPixel ||
  92         candidate_sizes_in_pixel[i].height() >= kHugeEdgeSizeInPixel) {
  93       score = std::min(1.0f, desired_size_in_pixel / average_edge_in_pixel) *
  94           0.01f;
  95     } else if (candidate_sizes_in_pixel[i].width() >= desired_size_in_pixel &&
  96                candidate_sizes_in_pixel[i].height() >= desired_size_in_pixel) {
  97       score = desired_size_in_pixel / average_edge_in_pixel * 0.01f + 0.15f;
  98     } else {
  99       score = std::min(1.0f, average_edge_in_pixel / desired_size_in_pixel) *
 100           0.01f + 0.1f;
 101     }
 102
 103     if (candidate_index == -1 || score > candidate_score) {
 104       candidate_index = i;
 105       candidate_score = score;
 106     }
 107   }
 108   *score = candidate_score;
 109
 110   // Integer multiples are built using nearest neighbor sampling. Otherwise,
 111   // Lanczos scaling is used.
 112   const gfx::Size& candidate_size_in_pixel =
 113       candidate_sizes_in_pixel[candidate_index];
 114   if (candidate_size_in_pixel.IsEmpty()) {
 115     *resize_method = NONE;
 116   } else if (desired_size_in_pixel % candidate_size_in_pixel.width() == 0 &&
 117              desired_size_in_pixel % candidate_size_in_pixel.height() == 0) {
 118     *resize_method = SAMPLE_NEAREST_NEIGHBOUR;
 119   } else {
 120     *resize_method = LANCZOS;
 121   }
 122   return candidate_index;
 123 }
 124
 125 // Represents the index of the best candidate for a |scale_factor| from the
 126 // |candidate_sizes| passed into GetCandidateIndicesWithBestScores().
 127 struct SelectionResult {
 128   // index in |candidate_sizes| of the best candidate.
 129   size_t index;
 130
 131   // The ScaleFactor for which |index| is the best candidate.
 132   ui::ScaleFactor scale_factor;
 133
 134   // How the bitmap data that the bitmap with |candidate_sizes[index]| should
 135   // be resized for displaying in the UI.
 136   ResizeMethod resize_method;
 137 };
 138
 139 void GetCandidateIndicesWithBestScores(
 140     const std::vector<gfx::Size>& candidate_sizes,
 141     const std::vector<ui::ScaleFactor>& scale_factors,
 142     int desired_size,
 143     float* match_score,
 144     std::vector<SelectionResult>* results) {
 145   if (candidate_sizes.empty()) {
 146     *match_score = 0.0f;
 147     return;
 148   }
 149
 150   if (desired_size == 0) {
 151     // Just return the biggest image available.
 152     SelectionResult result;
 153     result.index = BiggestCandidate(candidate_sizes);
 154     result.scale_factor = ui::SCALE_FACTOR_100P;
 155     result.resize_method = NONE;
 156     results->push_back(result);
 157     if (match_score)
 158       *match_score = 1.0f;
 159     return;
 160   }
 161
 162   float total_score = 0;
 163   for (size_t i = 0; i < scale_factors.size(); ++i) {
 164     float score;
 165     SelectionResult result;
 166     result.scale_factor = scale_factors[i];
 167     result.index = GetCandidateIndexWithBestScore(candidate_sizes,
 168         result.scale_factor, desired_size, &score, &result.resize_method);
 169     results->push_back(result);
 170     total_score += score;
 171   }
 172
 173   if (match_score)
 174     *match_score = total_score / scale_factors.size();
 175 }
 176
 177 // Resize |source_bitmap| using |resize_method|.
 178 SkBitmap GetResizedBitmap(const SkBitmap& source_bitmap,
 179                           int desired_size_in_dip,
 180                           ui::ScaleFactor scale_factor,
 181                           ResizeMethod resize_method) {
 182   float scale = ui::GetImageScale(scale_factor);
 183   int desired_size_in_pixel = static_cast<int>(
 184       desired_size_in_dip * scale + 0.5f);
 185
 186   switch (resize_method) {
 187     case NONE:
 188       return source_bitmap;
 189     case SAMPLE_NEAREST_NEIGHBOUR:
 190       return SampleNearestNeighbor(source_bitmap, desired_size_in_pixel);
 191     case LANCZOS:
 192       return skia::ImageOperations::Resize(
 193           source_bitmap, skia::ImageOperations::RESIZE_LANCZOS3,
 194           desired_size_in_pixel, desired_size_in_pixel);
 195   }
 196   return source_bitmap;
 197 }
 198
 199 }  // namespace
 200
 201 const float kSelectFaviconFramesInvalidScore = -1.0f;
 202
 203 gfx::ImageSkia SelectFaviconFrames(
 204     const std::vector<SkBitmap>& bitmaps,
 205     const std::vector<gfx::Size>& original_sizes,
 206     const std::vector<ui::ScaleFactor>& scale_factors,
 207     int desired_size,
 208     float* match_score) {
 209   std::vector<SelectionResult> results;
 210   GetCandidateIndicesWithBestScores(original_sizes, scale_factors,
 211       desired_size, match_score, &results);
 212
 213   gfx::ImageSkia multi_image;
 214   for (size_t i = 0; i < results.size(); ++i) {
 215     const SelectionResult& result = results[i];
 216     SkBitmap resized_bitmap = GetResizedBitmap(bitmaps[result.index],
 217         desired_size, result.scale_factor, result.resize_method);
 218     multi_image.AddRepresentation(
 219         gfx::ImageSkiaRep(resized_bitmap,
 220                           ui::GetImageScale(result.scale_factor)));
 221   }
 222   return multi_image;
 223 }
 224
 225 void SelectFaviconFrameIndices(
 226     const std::vector<gfx::Size>& frame_pixel_sizes,
 227     const std::vector<ui::ScaleFactor>& scale_factors,
 228     int desired_size,
 229     std::vector<size_t>* best_indices,
 230     float* match_score) {
 231   std::vector<SelectionResult> results;
 232   GetCandidateIndicesWithBestScores(frame_pixel_sizes, scale_factors,
 233       desired_size, match_score, &results);
 234
 235   std::set<size_t> already_added;
 236   for (size_t i = 0; i < results.size(); ++i) {
 237     size_t index = results[i].index;
 238     // GetCandidateIndicesWithBestScores() will return duplicate indices if the
 239     // bitmap data with |frame_pixel_sizes[index]| should be used for multiple
 240     // scale factors. Remove duplicates here such that |best_indices| contains
 241     // no duplicates.
 242     if (already_added.find(index) == already_added.end()) {
 243       already_added.insert(index);
 244       best_indices->push_back(index);
 245     }
 246   }
 247 }