components/favicon_base/select_favicon_frames.h

   1 // Copyright 2014 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 COMPONENTS_FAVICON_BASE_SELECT_FAVICON_FRAMES_H_
   6 #define COMPONENTS_FAVICON_BASE_SELECT_FAVICON_FRAMES_H_
   7
   8 #include <vector>
   9
  10 #include "base/basictypes.h"
  11
  12 class SkBitmap;
  13
  14 namespace gfx {
  15 class ImageSkia;
  16 class Size;
  17 }
  18
  19 // Score which is smaller than the minimum score returned by
  20 // SelectFaviconFrames() or SelectFaviconFrameIndices().
  21 extern const float kSelectFaviconFramesInvalidScore;
  22
  23 // Takes a list of all bitmaps found in a .ico file, and creates an
  24 // ImageSkia that's |desired_size_in_dip| x |desired_size_in_dip| big.
  25 // Bitmaps are selected by using |SelectFaviconFrameIndices| and the
  26 // platform's supported favicon scales (favicon_base::GetFaviconScales()).
  27 // If |desired_size_in_dip| is 0, the largest bitmap is returned unmodified.
  28 // |original_sizes| are the original sizes of the bitmaps. (For instance,
  29 // WebContents::DownloadImage() does resampling if it is passed a max size.)
  30 // If score is non-NULL, it receives a score between 0 (bad) and 1 (good)
  31 // that describes how well |bitmaps| were able to produce an image at
  32 // |desired_size_in_dip| for |favicon_scales|.
  33 // The score is arbitrary, but it's best for exact size matches,
  34 // and gets worse the more resampling needs to happen.
  35 // If the resampling algorithm is modified, the resampling done in
  36 // FaviconUtil::SelectFaviconFramesFromPNGs() should probably be modified too as
  37 // it inspired by this method.
  38 // If an unsupported scale (not in the favicon_base::GetFaviconScales())
  39 // is requested, the ImageSkia will automatically scales using lancoz3.
  40 gfx::ImageSkia CreateFaviconImageSkia(
  41     const std::vector<SkBitmap>& bitmaps,
  42     const std::vector<gfx::Size>& original_sizes,
  43     int desired_size_in_dip,
  44     float* score);
  45
  46 // Takes a list of the pixel sizes of a favicon's favicon bitmaps and returns
  47 // the indices of the best sizes to use to create an ImageSkia with
  48 // ImageSkiaReps with edge sizes |desired_sizes|. If '0' is one of
  49 // |desired_sizes|, the index of the largest size is returned. If |score| is
  50 // non-NULL, |score| is set to a value between 0 (bad) and 1 (good) that
  51 // describes how well the bitmap data with the sizes at |best_indices| will
  52 // produce the ImageSkia. The score is arbitrary, but it's best for exact
  53 // matches, and gets worse the more resampling needs to happen.
  54 // TODO(pkotwicz): Change API so that |desired_sizes| being empty indicates
  55 // that the index of the largest size is requested.
  56 // TODO(pkotwicz): Remove callers of this method for which |frame_pixel_sizes|
  57 // are the sizes of the favicon bitmaps after they were resized.
  58 void SelectFaviconFrameIndices(const std::vector<gfx::Size>& frame_pixel_sizes,
  59                                const std::vector<int>& desired_sizes,
  60                                std::vector<size_t>* best_indices,
  61                                float* score);
  62
  63 #endif  // COMPONENTS_FAVICON_BASE_SELECT_FAVICON_FRAMES_H_