ash/desktop_background/wallpaper_resizer.cc

   1 // Copyright (c) 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 "ash/desktop_background/wallpaper_resizer.h"
   6
   7 #include "ash/desktop_background/wallpaper_resizer_observer.h"
   8 #include "base/bind.h"
   9 #include "base/logging.h"
  10 #include "base/threading/sequenced_worker_pool.h"
  11 #include "base/threading/worker_pool.h"
  12 #include "content/public/browser/browser_thread.h"
  13 #include "third_party/skia/include/core/SkImage.h"
  14 #include "ui/gfx/image/image_skia_rep.h"
  15 #include "ui/gfx/skia_util.h"
  16
  17 using content::BrowserThread;
  18
  19 namespace ash {
  20 namespace {
  21
  22 // For our scaling ratios we need to round positive numbers.
  23 int RoundPositive(double x) {
  24   return static_cast<int>(floor(x + 0.5));
  25 }
  26
  27 // Resizes |orig_bitmap| to |target_size| using |layout| and stores the
  28 // resulting bitmap at |resized_bitmap_out|.
  29 void Resize(SkBitmap orig_bitmap,
  30             const gfx::Size& target_size,
  31             WallpaperLayout layout,
  32             SkBitmap* resized_bitmap_out) {
  33   DCHECK(BrowserThread::GetBlockingPool()->RunsTasksOnCurrentThread());
  34   SkBitmap new_bitmap = orig_bitmap;
  35
  36   const int orig_width = orig_bitmap.width();
  37   const int orig_height = orig_bitmap.height();
  38   const int new_width = target_size.width();
  39   const int new_height = target_size.height();
  40
  41   if (orig_width > new_width || orig_height > new_height) {
  42     gfx::Rect wallpaper_rect(0, 0, orig_width, orig_height);
  43     gfx::Size cropped_size = gfx::Size(std::min(new_width, orig_width),
  44                                        std::min(new_height, orig_height));
  45     switch (layout) {
  46       case WALLPAPER_LAYOUT_CENTER:
  47         wallpaper_rect.ClampToCenteredSize(cropped_size);
  48         orig_bitmap.extractSubset(&new_bitmap,
  49                                   gfx::RectToSkIRect(wallpaper_rect));
  50         break;
  51       case WALLPAPER_LAYOUT_TILE:
  52         wallpaper_rect.set_size(cropped_size);
  53         orig_bitmap.extractSubset(&new_bitmap,
  54                                   gfx::RectToSkIRect(wallpaper_rect));
  55         break;
  56       case WALLPAPER_LAYOUT_STRETCH:
  57         new_bitmap = skia::ImageOperations::Resize(
  58             orig_bitmap, skia::ImageOperations::RESIZE_LANCZOS3,
  59             new_width, new_height);
  60         break;
  61       case WALLPAPER_LAYOUT_CENTER_CROPPED:
  62         if (orig_width > new_width && orig_height > new_height) {
  63           // The dimension with the smallest ratio must be cropped, the other
  64           // one is preserved. Both are set in gfx::Size cropped_size.
  65           double horizontal_ratio = static_cast<double>(new_width) /
  66               static_cast<double>(orig_width);
  67           double vertical_ratio = static_cast<double>(new_height) /
  68               static_cast<double>(orig_height);
  69
  70           if (vertical_ratio > horizontal_ratio) {
  71             cropped_size = gfx::Size(
  72                 RoundPositive(static_cast<double>(new_width) / vertical_ratio),
  73                 orig_height);
  74           } else {
  75             cropped_size = gfx::Size(orig_width, RoundPositive(
  76                 static_cast<double>(new_height) / horizontal_ratio));
  77           }
  78           wallpaper_rect.ClampToCenteredSize(cropped_size);
  79           SkBitmap sub_image;
  80           orig_bitmap.extractSubset(&sub_image,
  81                                     gfx::RectToSkIRect(wallpaper_rect));
  82           new_bitmap = skia::ImageOperations::Resize(
  83               sub_image, skia::ImageOperations::RESIZE_LANCZOS3,
  84               new_width, new_height);
  85         }
  86     }
  87   }
  88
  89   *resized_bitmap_out = new_bitmap;
  90   resized_bitmap_out->setImmutable();
  91 }
  92
  93 }  // namespace
  94
  95 // static
  96 uint32_t WallpaperResizer::GetImageId(const gfx::ImageSkia& image) {
  97   const gfx::ImageSkiaRep& image_rep = image.GetRepresentation(1.0f);
  98   return image_rep.is_null() ? 0 : image_rep.sk_bitmap().getGenerationID();
  99 }
 100
 101 WallpaperResizer::WallpaperResizer(const gfx::ImageSkia& image,
 102                                    const gfx::Size& target_size,
 103                                    WallpaperLayout layout)
 104     : image_(image),
 105       original_image_id_(GetImageId(image_)),
 106       target_size_(target_size),
 107       layout_(layout),
 108       weak_ptr_factory_(this) {
 109   image_.MakeThreadSafe();
 110 }
 111
 112 WallpaperResizer::~WallpaperResizer() {
 113 }
 114
 115 void WallpaperResizer::StartResize() {
 116   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 117   SkBitmap* resized_bitmap = new SkBitmap;
 118   if (!content::BrowserThread::PostBlockingPoolTaskAndReply(
 119           FROM_HERE,
 120           base::Bind(&Resize, *image_.bitmap(), target_size_,
 121                      layout_, resized_bitmap),
 122           base::Bind(&WallpaperResizer::OnResizeFinished,
 123                      weak_ptr_factory_.GetWeakPtr(),
 124                      base::Owned(resized_bitmap)))) {
 125     LOG(WARNING) << "PostSequencedWorkerTask failed. "
 126                  << "Wallpaper may not be resized.";
 127   }
 128 }
 129
 130 void WallpaperResizer::AddObserver(WallpaperResizerObserver* observer) {
 131   observers_.AddObserver(observer);
 132 }
 133
 134 void WallpaperResizer::RemoveObserver(WallpaperResizerObserver* observer) {
 135   observers_.RemoveObserver(observer);
 136 }
 137
 138 void WallpaperResizer::OnResizeFinished(SkBitmap* resized_bitmap) {
 139   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 140   image_ = gfx::ImageSkia::CreateFrom1xBitmap(*resized_bitmap);
 141   FOR_EACH_OBSERVER(WallpaperResizerObserver, observers_,
 142                     OnWallpaperResized());
 143 }
 144
 145 } // namespace ash