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      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_
    122