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      1 // Copyright (c) 2012 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 CHROME_BROWSER_EXTENSIONS_IMAGE_LOADER_H_
      6 #define CHROME_BROWSER_EXTENSIONS_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/browser_context_keyed_service/browser_context_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 }
     26 
     27 namespace extensions {
     28 
     29 class Extension;
     30 
     31 typedef base::Callback<void(const gfx::Image&)> ImageLoaderCallback;
     32 
     33 // This class is responsible for asynchronously loading extension images and
     34 // calling a callback when an image is loaded.
     35 // The views need to load their icons asynchronously might be deleted before
     36 // the images have loaded. If you pass your callback using a weak_ptr, this
     37 // will make sure the callback won't be called after the view is deleted.
     38 class ImageLoader : public BrowserContextKeyedService {
     39  public:
     40   // Information about a singe image representation to load from an extension
     41   // resource.
     42   struct ImageRepresentation {
     43     // Enum values to indicate whether to resize loaded bitmap when it is larger
     44     // than |desired_size| or always resize it.
     45     enum ResizeCondition {
     46       RESIZE_WHEN_LARGER,
     47       ALWAYS_RESIZE,
     48     };
     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   // Checks whether image is a component extension resource. Returns false
     79   // if a given |resource| does not have a corresponding image in bundled
     80   // resources. Otherwise fills |resource_id|. This doesn't check if the
     81   // extension the resource is in is actually a component extension.
     82   static bool IsComponentExtensionResource(
     83       const base::FilePath& extension_path,
     84       const base::FilePath& resource_path,
     85       int* resource_id);
     86 
     87   // Specify image resource to load. If the loaded image is larger than
     88   // |max_size| it will be resized to those dimensions. IMPORTANT NOTE: this
     89   // function may call back your callback synchronously (ie before it returns)
     90   // if the image was found in the cache.
     91   // Note this method loads a raw bitmap from the resource. All sizes given are
     92   // assumed to be in pixels.
     93   void LoadImageAsync(const extensions::Extension* extension,
     94                       const ExtensionResource& resource,
     95                       const gfx::Size& max_size,
     96                       const ImageLoaderCallback& callback);
     97 
     98   // Same as LoadImage() above except it loads multiple images from the same
     99   // extension. This is used to load multiple resolutions of the same image
    100   // type.
    101   void LoadImagesAsync(const extensions::Extension* extension,
    102                        const std::vector<ImageRepresentation>& info_list,
    103                        const ImageLoaderCallback& callback);
    104 
    105  private:
    106   void ReplyBack(const ImageLoaderCallback& callback,
    107                  const std::vector<LoadResult>& load_result);
    108 
    109   base::WeakPtrFactory<ImageLoader> weak_ptr_factory_;
    110 
    111   DISALLOW_COPY_AND_ASSIGN(ImageLoader);
    112 };
    113 
    114 }  // namespace extensions
    115 
    116 #endif  // CHROME_BROWSER_EXTENSIONS_IMAGE_LOADER_H_
    117