image_decoder.h revision 7d4cd473f85ac64c3747c96c277f9e506a0d2246 
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_IMAGE_DECODER_H_
6#define CHROME_BROWSER_IMAGE_DECODER_H_
7
8#include <string>
9#include <vector>
10
11#include "base/compiler_specific.h"
12#include "base/memory/ref_counted.h"
13#include "base/threading/sequenced_worker_pool.h"
14#include "content/public/browser/utility_process_host_client.h"
15
16class SkBitmap;
17
18// Decodes an image in a sandboxed process.
19class ImageDecoder : public content::UtilityProcessHostClient {
20 public:
21  class Delegate {
22   public:
23    // Called when image is decoded.
24    // |decoder| is used to identify the image in case of decoding several
25    // images simultaneously.
26    virtual void OnImageDecoded(const ImageDecoder* decoder,
27                                const SkBitmap& decoded_image) = 0;
28
29    // Called when decoding image failed. Delegate can do some cleanup in
30    // this handler.
31    virtual void OnDecodeImageFailed(const ImageDecoder* decoder) {}
32
33   protected:
34    virtual ~Delegate() {}
35  };
36
37  enum ImageCodec {
38    DEFAULT_CODEC = 0,  // Uses WebKit image decoding (via WebImage).
39    ROBUST_JPEG_CODEC,  // Restrict decoding to robust jpeg codec.
40  };
41
42  ImageDecoder(Delegate* delegate,
43               const std::string& image_data,
44               ImageCodec image_codec);
45
46  // Starts asynchronous image decoding. Once finished, the callback will be
47  // posted back to |task_runner|.
48  void Start(scoped_refptr<base::SequencedTaskRunner> task_runner);
49
50  const std::vector<unsigned char>& get_image_data() const {
51    return image_data_;
52  }
53
54  void set_delegate(Delegate* delegate) { delegate_ = delegate; }
55
56 private:
57  // It's a reference counted object, so destructor is private.
58  virtual ~ImageDecoder();
59
60  // Overidden from UtilityProcessHostClient:
61  virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE;
62
63  // IPC message handlers.
64  void OnDecodeImageSucceeded(const SkBitmap& decoded_image);
65  void OnDecodeImageFailed();
66
67  // Launches sandboxed process that will decode the image.
68  void DecodeImageInSandbox(const std::vector<unsigned char>& image_data);
69
70  Delegate* delegate_;
71  std::vector<unsigned char> image_data_;
72  const ImageCodec image_codec_;
73  scoped_refptr<base::SequencedTaskRunner> task_runner_;
74
75  DISALLOW_COPY_AND_ASSIGN(ImageDecoder);
76};
77
78#endif  // CHROME_BROWSER_IMAGE_DECODER_H_
79