extensions/browser/image_loader.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 EXTENSIONS_BROWSER_IMAGE_LOADER_H_
   6 #define EXTENSIONS_BROWSER_IMAGE_LOADER_H_
   7
   8 #include <set>
   9
  10 #include "base/callback_forward.h"
  11 #include "base/gtest_prod_util.h"
  12 #include "base/memory/weak_ptr.h"
  13 #include "components/keyed_service/core/keyed_service.h"
  14 #include "extensions/common/extension_resource.h"
  15 #include "third_party/skia/include/core/SkBitmap.h"
  16 #include "ui/base/layout.h"
  17 #include "ui/gfx/size.h"
  18
  19 namespace content {
  20 class BrowserContext;
  21 }
  22
  23 namespace gfx {
  24 class Image;
  25 class ImageFamily;
  26 }
  27
  28 namespace extensions {
  29
  30 class Extension;
  31
  32 typedef base::Callback<void(const gfx::Image&)> ImageLoaderImageCallback;
  33 typedef base::Callback<void(const gfx::ImageFamily&)>
  34     ImageLoaderImageFamilyCallback;
  35
  36 // This class is responsible for asynchronously loading extension images and
  37 // calling a callback when an image is loaded.
  38 // The views need to load their icons asynchronously might be deleted before
  39 // the images have loaded. If you pass your callback using a weak_ptr, this
  40 // will make sure the callback won't be called after the view is deleted.
  41 class ImageLoader : public KeyedService {
  42  public:
  43   // Information about a singe image representation to load from an extension
  44   // resource.
  45   struct ImageRepresentation {
  46     // Enum values to indicate whether to resize loaded bitmap when it is larger
  47     // than |desired_size| or always resize it.
  48     enum ResizeCondition { RESIZE_WHEN_LARGER, ALWAYS_RESIZE, NEVER_RESIZE };
  49
  50     ImageRepresentation(const ExtensionResource& resource,
  51                         ResizeCondition resize_condition,
  52                         const gfx::Size& desired_size,
  53                         ui::ScaleFactor scale_factor);
  54     ~ImageRepresentation();
  55
  56     // Extension resource to load.
  57     ExtensionResource resource;
  58
  59     ResizeCondition resize_condition;
  60
  61     // When |resize_method| is ALWAYS_RESIZE or when the loaded image is larger
  62     // than |desired_size| it will be resized to these dimensions.
  63     gfx::Size desired_size;
  64
  65     // |scale_factor| is used to construct the loaded gfx::ImageSkia.
  66     ui::ScaleFactor scale_factor;
  67   };
  68
  69   struct LoadResult;
  70
  71   // Returns the instance for the given |context| or NULL if none. This is
  72   // a convenience wrapper around ImageLoaderFactory::GetForBrowserContext.
  73   static ImageLoader* Get(content::BrowserContext* context);
  74
  75   ImageLoader();
  76   virtual ~ImageLoader();
  77
  78   // Specify image resource to load. If the loaded image is larger than
  79   // |max_size| it will be resized to those dimensions. IMPORTANT NOTE: this
  80   // function may call back your callback synchronously (ie before it returns)
  81   // if the image was found in the cache.
  82   // Note this method loads a raw bitmap from the resource. All sizes given are
  83   // assumed to be in pixels.
  84   void LoadImageAsync(const extensions::Extension* extension,
  85                       const ExtensionResource& resource,
  86                       const gfx::Size& max_size,
  87                       const ImageLoaderImageCallback& callback);
  88
  89   // Same as LoadImageAsync() above except it loads multiple images from the
  90   // same extension. This is used to load multiple resolutions of the same image
  91   // type.
  92   void LoadImagesAsync(const extensions::Extension* extension,
  93                        const std::vector<ImageRepresentation>& info_list,
  94                        const ImageLoaderImageCallback& callback);
  95
  96   // Same as LoadImagesAsync() above except it loads into an image family. This
  97   // is used to load multiple images of different logical sizes as opposed to
  98   // LoadImagesAsync() which loads different scale factors of the same logical
  99   // image size.
 100   //
 101   // If multiple images of the same logical size are loaded, they will be
 102   // combined into a single ImageSkia in the ImageFamily.
 103   void LoadImageFamilyAsync(const extensions::Extension* extension,
 104                             const std::vector<ImageRepresentation>& info_list,
 105                             const ImageLoaderImageFamilyCallback& callback);
 106
 107  private:
 108   void ReplyBack(const ImageLoaderImageCallback& callback,
 109                  const std::vector<LoadResult>& load_result);
 110
 111   void ReplyBackWithImageFamily(const ImageLoaderImageFamilyCallback& callback,
 112                                 const std::vector<LoadResult>& load_result);
 113
 114   base::WeakPtrFactory<ImageLoader> weak_ptr_factory_;
 115
 116   DISALLOW_COPY_AND_ASSIGN(ImageLoader);
 117 };
 118
 119 }  // namespace extensions
 120
 121 #endif  // EXTENSIONS_BROWSER_IMAGE_LOADER_H_