image_loader.h revision 6d86b77056ed63eb6871182f42a9fd5f07550f90 
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
19namespace content {
20class BrowserContext;
21}
22
23namespace gfx {
24class Image;
25class ImageFamily;
26}
27
28namespace extensions {
29
30class Extension;
31
32typedef base::Callback<void(const gfx::Image&)> ImageLoaderImageCallback;
33typedef 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.
41class 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