text: // Copyright (c) 2012 The Chromium Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file.
  
  #ifndef CHROME_BROWSER_EXTENSIONS_IMAGE_LOADER_H_
  #define CHROME_BROWSER_EXTENSIONS_IMAGE_LOADER_H_
  
  #include <map>
  #include <set>
  
  #include "base/callback_forward.h"
  #include "base/gtest_prod_util.h"
  #include "base/memory/weak_ptr.h"
  #include "chrome/browser/profiles/profile_keyed_service.h"
  #include "chrome/common/extensions/extension_resource.h"
  #include "third_party/skia/include/core/SkBitmap.h"
  #include "ui/base/layout.h"
  #include "ui/gfx/size.h"
  
  class Profile;
  
  namespace gfx {
  class Image;
  }
  
  namespace extensions {
  
  class Extension;
  
  // This class is responsible for asynchronously loading extension images and
  // calling a callback when an image is loaded.
  // The views need to load their icons asynchronously might be deleted before
  // the images have loaded. If you pass your callback using a weak_ptr, this
  // will make sure the callback won't be called after the view is deleted.
  class ImageLoader : public ProfileKeyedService {
   public:
    // Information about a singe image representation to load from an extension
    // resource.
    struct ImageRepresentation {
      // Enum values to indicate whether to resize loaded bitmap when it is larger
      // than |desired_size| or always resize it.
      enum ResizeCondition {
        RESIZE_WHEN_LARGER,
        ALWAYS_RESIZE,
      };
  
      ImageRepresentation(const ExtensionResource& resource,
                          ResizeCondition resize_condition,
                          const gfx::Size& desired_size,
                          ui::ScaleFactor scale_factor);
      ~ImageRepresentation();
  
      // Extension resource to load.
      ExtensionResource resource;
  
      ResizeCondition resize_condition;
  
      // When |resize_method| is ALWAYS_RESIZE or when the loaded image is larger
      // than |desired_size| it will be resized to these dimensions.
      gfx::Size desired_size;
  
      // |scale_factor| is used to construct the loaded gfx::ImageSkia.
      ui::ScaleFactor scale_factor;
    };
  
    struct LoadResult;
  
    // Returns the instance for the given profile, or NULL if none. This is
    // a convenience wrapper around ImageLoaderFactory::GetForProfile.
    static ImageLoader* Get(Profile* profile);
  
    ImageLoader();
    virtual ~ImageLoader();
  
    // Checks whether image is a component extension resource. Returns false
    // if a given |resource| does not have a corresponding image in bundled
    // resources. Otherwise fills |resource_id|. This doesn't check if the
    // extension the resource is in is actually a component extension.
    static bool IsComponentExtensionResource(
        const FilePath& extension_path,
        const FilePath& resource_path,
        int* resource_id);
  
    // Specify image resource to load. If the loaded image is larger than
    // |max_size| it will be resized to those dimensions. IMPORTANT NOTE: this
    // function may call back your callback synchronously (ie before it returns)
    // if the image was found in the cache.
    // Note this method loads a raw bitmap from the resource. All sizes given are
    // assumed to be in pixels.
    void LoadImageAsync(const extensions::Extension* extension,
                        const ExtensionResource& resource,
                        const gfx::Size& max_size,
                        const base::Callback<void(const gfx::Image&)>& callback);
  
    // Same as LoadImage() above except it loads multiple images from the same
    // extension. This is used to load multiple resolutions of the same image
    // type.
    void LoadImagesAsync(const extensions::Extension* extension,
                         const std::vector<ImageRepresentation>& info_list,
                         const base::Callback<void(const gfx::Image&)>& callback);
  
   private:
    base::WeakPtrFactory<ImageLoader> weak_ptr_factory_;
  
    static void LoadImagesOnBlockingPool(
        const std::vector<ImageRepresentation>& info_list,
        const std::vector<SkBitmap>& bitmaps,
        std::vector<LoadResult>* load_result);
  
    void ReplyBack(
        const std::vector<LoadResult>* load_result,
        const base::Callback<void(const gfx::Image&)>& callback);
  };
  
  }  // namespace extensions
  
  #endif  // CHROME_BROWSER_EXTENSIONS_IMAGE_LOADER_H_
  