gecko/image/encoders/jpeg/nsJPEGEncoder.h

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "imgIEncoder.h"

#include "mozilla/ReentrantMonitor.h"

#include "nsCOMPtr.h"

// needed for JPEG library
#include <stdio.h>

extern "C" {
#include "jpeglib.h"
}

#define NS_JPEGENCODER_CID \
{ /* ac2bb8fe-eeeb-4572-b40f-be03932b56e0 */         \
     0xac2bb8fe,                                     \
     0xeeeb,                                         \
     0x4572,                                         \
    {0xb4, 0x0f, 0xbe, 0x03, 0x93, 0x2b, 0x56, 0xe0} \
}

// Provides JPEG encoding functionality. Use InitFromData() to do the
// encoding. See that function definition for encoding options.

class nsJPEGEncoder : public imgIEncoder
{
  typedef mozilla::ReentrantMonitor ReentrantMonitor;
public:
  NS_DECL_ISUPPORTS
  NS_DECL_IMGIENCODER
  NS_DECL_NSIINPUTSTREAM
  NS_DECL_NSIASYNCINPUTSTREAM

  nsJPEGEncoder();

private:
  ~nsJPEGEncoder();

protected:

  void ConvertHostARGBRow(const PRUint8* aSrc, PRUint8* aDest,
                          PRUint32 aPixelWidth);
  void ConvertRGBARow(const PRUint8* aSrc, PRUint8* aDest, PRUint32 aPixelWidth);

  static void initDestination(jpeg_compress_struct* cinfo);
  static boolean emptyOutputBuffer(jpeg_compress_struct* cinfo);
  static void termDestination(jpeg_compress_struct* cinfo);

  static void errorExit(jpeg_common_struct* cinfo);

  void NotifyListener();

  bool mFinished;

  // image buffer
  PRUint8* mImageBuffer;
  PRUint32 mImageBufferSize;
  PRUint32 mImageBufferUsed;

  PRUint32 mImageBufferReadPoint;

  nsCOMPtr<nsIInputStreamCallback> mCallback;
  nsCOMPtr<nsIEventTarget> mCallbackTarget;
  PRUint32 mNotifyThreshold;

  /*
    nsJPEGEncoder is designed to allow one thread to pump data into it while another
    reads from it.  We lock to ensure that the buffer remains append-only while
    we read from it (that it is not realloced) and to ensure that only one thread
    dispatches a callback for each call to AsyncWait.
   */
  ReentrantMonitor mReentrantMonitor;
};