chrome/browser/chromeos/login/user_image_loader.h

   1 // Copyright (c) 2013 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_CHROMEOS_LOGIN_USER_IMAGE_LOADER_H_
   6 #define CHROME_BROWSER_CHROMEOS_LOGIN_USER_IMAGE_LOADER_H_
   7
   8 #include <map>
   9 #include <string>
  10
  11 #include "base/callback.h"
  12 #include "base/compiler_specific.h"
  13 #include "base/memory/ref_counted.h"
  14 #include "chrome/browser/image_decoder.h"
  15
  16 class SkBitmap;
  17
  18 namespace base {
  19 class SequencedTaskRunner;
  20 }
  21
  22 namespace chromeos {
  23
  24 class UserImage;
  25
  26 // Helper that reads, decodes and optionally resizes an image on a background
  27 // thread. Returns the image in the form of an SkBitmap.
  28 class UserImageLoader : public base::RefCountedThreadSafe<UserImageLoader>,
  29                         public ImageDecoder::Delegate {
  30  public:
  31   // Callback used to return the result of an image load operation.
  32   typedef base::Callback<void(const UserImage& user_image)> LoadedCallback;
  33
  34   // All file I/O, decoding and resizing are done via |background_task_runner|.
  35   UserImageLoader(
  36       ImageDecoder::ImageCodec image_codec,
  37       scoped_refptr<base::SequencedTaskRunner> background_task_runner);
  38
  39   // Load an image in the background and call |loaded_cb| with the result. If
  40   // |size| is positive, the image is cropped to a square and shrunk so that it
  41   // does not exceed |size|x|size|. The first variant of this method reads the
  42   // image from |filepath| on disk, the second processes |data| read into memory
  43   // already.
  44   void Start(const std::string& filepath,
  45              int size,
  46              const LoadedCallback& loaded_cb);
  47   void Start(scoped_ptr<std::string> data,
  48              int size,
  49              const LoadedCallback& loaded_cb);
  50
  51  private:
  52   friend class base::RefCountedThreadSafe<UserImageLoader>;
  53
  54   // Contains attributes we need to know about each image we decode.
  55   struct ImageInfo {
  56     ImageInfo(int size, const LoadedCallback& loaded_cb);
  57     ~ImageInfo();
  58
  59     const int size;
  60     const LoadedCallback loaded_cb;
  61   };
  62
  63   typedef std::map<const ImageDecoder*, ImageInfo> ImageInfoMap;
  64
  65   virtual ~UserImageLoader();
  66
  67   // Reads the image from |filepath| and starts the decoding process. This
  68   // method may only be invoked via the |background_task_runner_|.
  69   void ReadAndDecodeImage(const std::string& filepath,
  70                           const ImageInfo& image_info);
  71
  72   // Decodes the image |data|. This method may only be invoked via the
  73   // |background_task_runner_|.
  74   void DecodeImage(const scoped_ptr<std::string> data,
  75                    const ImageInfo& image_info);
  76
  77   // ImageDecoder::Delegate implementation. These callbacks will only be invoked
  78   // via the |background_task_runner_|.
  79   virtual void OnImageDecoded(const ImageDecoder* decoder,
  80                               const SkBitmap& decoded_image) OVERRIDE;
  81   virtual void OnDecodeImageFailed(const ImageDecoder* decoder) OVERRIDE;
  82
  83   // The foreground task runner on which |this| is instantiated, Start() is
  84   // called and LoadedCallbacks are invoked.
  85   scoped_refptr<base::SequencedTaskRunner> foreground_task_runner_;
  86
  87   // The background task runner on which file I/O, image decoding and resizing
  88   // are done.
  89   scoped_refptr<base::SequencedTaskRunner> background_task_runner_;
  90
  91   // Specify how the file should be decoded in the utility process.
  92   const ImageDecoder::ImageCodec image_codec_;
  93
  94   // Holds information about the images currently being decoded. Accessed via
  95   // |background_task_runner_| only.
  96   ImageInfoMap image_info_map_;
  97
  98   DISALLOW_COPY_AND_ASSIGN(UserImageLoader);
  99 };
 100
 101 }  // namespace chromeos
 102
 103 #endif  // CHROME_BROWSER_CHROMEOS_LOGIN_USER_IMAGE_LOADER_H_