chrome/browser/manifest/manifest_icon_downloader.cc

   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 #include "chrome/browser/manifest/manifest_icon_downloader.h"
   6
   7 #include <limits>
   8
   9 #include "chrome/browser/manifest/manifest_icon_selector.h"
  10 #include "content/public/browser/browser_thread.h"
  11 #include "content/public/browser/web_contents.h"
  12 #include "skia/ext/image_operations.h"
  13 #include "ui/gfx/screen.h"
  14
  15 bool ManifestIconDownloader::Download(
  16     content::WebContents* web_contents,
  17     const GURL& icon_url,
  18     int ideal_icon_size_in_dp,
  19     int minimum_icon_size_in_dp,
  20     const ManifestIconDownloader::IconFetchCallback& callback) {
  21   DCHECK(minimum_icon_size_in_dp <= ideal_icon_size_in_dp);
  22   if (!web_contents || !icon_url.is_valid())
  23     return false;
  24
  25   const gfx::Screen* screen =
  26       gfx::Screen::GetScreenFor(web_contents->GetNativeView());
  27
  28   const float device_scale_factor =
  29       screen->GetPrimaryDisplay().device_scale_factor();
  30   const int ideal_icon_size_in_px =
  31       static_cast<int>(round(ideal_icon_size_in_dp * device_scale_factor));
  32   const int minimum_icon_size_in_px =
  33       static_cast<int>(round(minimum_icon_size_in_dp * device_scale_factor));
  34
  35   web_contents->DownloadImage(
  36       icon_url,
  37       false, // is_favicon
  38       0,     // max_bitmap_size - 0 means no maximum size.
  39       false, // bypass_cache
  40       base::Bind(&ManifestIconDownloader::OnIconFetched,
  41                  ideal_icon_size_in_px,
  42                  minimum_icon_size_in_px,
  43                  callback));
  44   return true;
  45 }
  46
  47 void ManifestIconDownloader::OnIconFetched(
  48     int ideal_icon_size_in_px,
  49     int minimum_icon_size_in_px,
  50     const ManifestIconDownloader::IconFetchCallback& callback,
  51     int id,
  52     int http_status_code,
  53     const GURL& url,
  54     const std::vector<SkBitmap>& bitmaps,
  55     const std::vector<gfx::Size>& sizes) {
  56   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
  57
  58   const int closest_index = FindClosestBitmapIndex(
  59       ideal_icon_size_in_px, minimum_icon_size_in_px, bitmaps);
  60
  61   if (closest_index == -1) {
  62     callback.Run(SkBitmap());
  63     return;
  64   }
  65
  66   const SkBitmap& chosen = bitmaps[closest_index];
  67
  68   // Only scale if we need to scale down. For scaling up we will let the system
  69   // handle that when it is required to display it. This saves space in the
  70   // webapp storage system as well.
  71   if (chosen.height() > ideal_icon_size_in_px) {
  72     content::BrowserThread::PostTask(
  73         content::BrowserThread::IO,
  74         FROM_HERE,
  75         base::Bind(&ManifestIconDownloader::ScaleIcon,
  76                    ideal_icon_size_in_px,
  77                    chosen,
  78                    callback));
  79     return;
  80   }
  81
  82   callback.Run(chosen);
  83 }
  84
  85 void ManifestIconDownloader::ScaleIcon(
  86     int ideal_icon_size_in_px,
  87     const SkBitmap& bitmap,
  88     const ManifestIconDownloader::IconFetchCallback& callback) {
  89   DCHECK_CURRENTLY_ON(content::BrowserThread::IO);
  90
  91   const SkBitmap& scaled = skia::ImageOperations::Resize(
  92       bitmap,
  93       skia::ImageOperations::RESIZE_BEST,
  94       ideal_icon_size_in_px,
  95       ideal_icon_size_in_px);
  96
  97   content::BrowserThread::PostTask(
  98       content::BrowserThread::UI,
  99       FROM_HERE,
 100       base::Bind(callback, scaled));
 101 }
 102
 103 int ManifestIconDownloader::FindClosestBitmapIndex(
 104     int ideal_icon_size_in_px,
 105     int minimum_icon_size_in_px,
 106     const std::vector<SkBitmap>& bitmaps) {
 107   int best_index = -1;
 108   int best_delta = std::numeric_limits<int>::min();
 109   const int max_negative_delta =
 110       minimum_icon_size_in_px - ideal_icon_size_in_px;
 111
 112   for (size_t i = 0; i < bitmaps.size(); ++i) {
 113     if (bitmaps[i].height() != bitmaps[i].width())
 114       continue;
 115
 116     int delta = bitmaps[i].width() - ideal_icon_size_in_px;
 117     if (delta == 0)
 118       return i;
 119
 120     if (best_delta > 0 && delta < 0)
 121       continue;
 122
 123     if ((best_delta > 0 && delta < best_delta) ||
 124         (best_delta < 0 && delta > best_delta && delta >= max_negative_delta)) {
 125       best_index = i;
 126       best_delta = delta;
 127     }
 128   }
 129   return best_index;
 130 }