chrome/browser/extensions/image_loader.h

   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_