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
19namespace content {
20class BrowserContext;
21}
22
23namespace gfx {
24class Image;
25}
26
27namespace extensions {
28
29class Extension;
30
31typedef 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.
38class 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