src/chrome/browser/image_decoder.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_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
  16 class SkBitmap;
  17
  18 // Decodes an image in a sandboxed process.
  19 class 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   void set_shrink_to_fit(bool shrink_to_fit) { shrink_to_fit_ = shrink_to_fit; }
  56
  57  private:
  58   // It's a reference counted object, so destructor is private.
  59   ~ImageDecoder() override;
  60
  61   // Overidden from UtilityProcessHostClient:
  62   bool OnMessageReceived(const IPC::Message& message) override;
  63
  64   // IPC message handlers.
  65   void OnDecodeImageSucceeded(const SkBitmap& decoded_image);
  66   void OnDecodeImageFailed();
  67
  68   // Launches sandboxed process that will decode the image.
  69   void DecodeImageInSandbox(const std::vector<unsigned char>& image_data);
  70
  71   Delegate* delegate_;
  72   std::vector<unsigned char> image_data_;
  73   const ImageCodec image_codec_;
  74   scoped_refptr<base::SequencedTaskRunner> task_runner_;
  75   bool shrink_to_fit_; // if needed for IPC msg size limit
  76
  77   DISALLOW_COPY_AND_ASSIGN(ImageDecoder);
  78 };
  79
  80 #endif  // CHROME_BROWSER_IMAGE_DECODER_H_