jbuffdst.c

linux下的一款播放器

/* ***** BEGIN LICENSE BLOCK *****
 * Source last modified: $Id: jbuffdst.c,v 1.1.26.1 2004/07/09 01:53:22 hubbe Exp $
 * 
 * Portions Copyright (c) 1995-2004 RealNetworks, Inc. All Rights Reserved.
 * 
 * The contents of this file, and the files included with this file,
 * are subject to the current version of the RealNetworks Public
 * Source License (the "RPSL") available at
 * http://www.helixcommunity.org/content/rpsl unless you have licensed
 * the file under the current version of the RealNetworks Community
 * Source License (the "RCSL") available at
 * http://www.helixcommunity.org/content/rcsl, in which case the RCSL
 * will apply. You may also obtain the license terms directly from
 * RealNetworks.  You may not use this file except in compliance with
 * the RPSL or, if you have a valid RCSL with RealNetworks applicable
 * to this file, the RCSL.  Please see the applicable RPSL or RCSL for
 * the rights, obligations and limitations governing use of the
 * contents of the file.
 * 
 * Alternatively, the contents of this file may be used under the
 * terms of the GNU General Public License Version 2 or later (the
 * "GPL") in which case the provisions of the GPL are applicable
 * instead of those above. If you wish to allow use of your version of
 * this file only under the terms of the GPL, and not to allow others
 * to use your version of this file under the terms of either the RPSL
 * or RCSL, indicate your decision by deleting the provisions above
 * and replace them with the notice and other provisions required by
 * the GPL. If you do not delete the provisions above, a recipient may
 * use your version of this file under the terms of any one of the
 * RPSL, the RCSL or the GPL.
 * 
 * This file is part of the Helix DNA Technology. RealNetworks is the
 * developer of the Original Code and owns the copyrights in the
 * portions it created.
 * 
 * This file, and the files included with this file, is distributed
 * and made available on an 'AS IS' basis, WITHOUT WARRANTY OF ANY
 * KIND, EITHER EXPRESS OR IMPLIED, AND REALNETWORKS HEREBY DISCLAIMS
 * ALL SUCH WARRANTIES, INCLUDING WITHOUT LIMITATION, ANY WARRANTIES
 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, QUIET
 * ENJOYMENT OR NON-INFRINGEMENT.
 * 
 * Technology Compatibility Kit Test Suite(s) Location:
 *    http://www.helixcommunity.org/content/tck
 * 
 * Contributor(s):
 * 
 * ***** END LICENSE BLOCK ***** */

/*
 * jbuffdst.c
 *
 * This allows applications to compress to a buffer using the IJG library
 */
#include "jinclude.h"
#include "jpeglib.h"
#include "jerror.h"


/* Expanded data destination object for stdio output */
typedef struct
{
    struct jpeg_destination_mgr pub;             /* public fields */
    unsigned char *             m_pEntireBuffer; /* start of buffer */
    unsigned long               m_ulTotalBytes;  /* number total bytes in buffer */
}
buffer_dst_mgr;

typedef buffer_dst_mgr * buffer_dst_ptr;

/*
 * Initialize destination --- called by jpeg_start_compress
 * before any data is actually written.
 */

METHODDEF(void)
init_destination (j_compress_ptr cinfo)
{
    buffer_dst_ptr dest = (buffer_dst_ptr) cinfo->dest;

    dest->pub.next_output_byte = dest->m_pEntireBuffer;
    dest->pub.free_in_buffer   = dest->m_ulTotalBytes;
}


/*
 * Empty the output buffer --- called whenever buffer fills up.
 *
 * In typical applications, this should write the entire output buffer
 * (ignoring the current state of next_output_byte & free_in_buffer),
 * reset the pointer & count to the start of the buffer, and return TRUE
 * indicating that the buffer has been dumped.
 *
 * In applications that need to be able to suspend compression due to output
 * overrun, a FALSE return indicates that the buffer cannot be emptied now.
 * In this situation, the compressor will return to its caller (possibly with
 * an indication that it has not accepted all the supplied scanlines).  The
 * application should resume compression after it has made more room in the
 * output buffer.  Note that there are substantial restrictions on the use of
 * suspension --- see the documentation.
 *
 * When suspending, the compressor will back up to a convenient restart point
 * (typically the start of the current MCU). next_output_byte & free_in_buffer
 * indicate where the restart point will be if the current call returns FALSE.
 * Data beyond this point will be regenerated after resumption, so do not
 * write it out when emptying the buffer externally.
 */

METHODDEF(boolean)
empty_output_buffer (j_compress_ptr cinfo)
{
    // This should never be called for us, unless the caller did
    // not give us enough buffer.
    ERREXIT(cinfo, JERR_FILE_WRITE);

    return FALSE;
}


/*
 * Terminate destination --- called by jpeg_finish_compress
 * after all data has been written.  Usually needs to flush buffer.
 *
 * NB: *not* called by jpeg_abort or jpeg_destroy; surrounding
 * application must deal with any cleanup that should happen even
 * for error exit.
 */

METHODDEF(void)
term_destination (j_compress_ptr cinfo)
{
    // No work to do here
}


/*
 * Prepare for output to a stdio stream.
 * The caller must have already opened the stream, and is responsible
 * for closing it after finishing compression.
 */

GLOBAL(void)
jpeg_buffer_dst(j_compress_ptr cinfo, unsigned char *pBuf, unsigned long ulBufLen)
{
    buffer_dst_ptr dest;

    /* The destination object is made permanent so that multiple JPEG images
     * can be written to the same file without re-executing jpeg_stdio_dest.
     * This makes it dangerous to use this manager and a different destination
     * manager serially with the same JPEG object, because their private object
     * sizes may be different.  Caveat programmer.
     */
    if (cinfo->dest == NULL)
    {
        /* first time for this JPEG object? */
        cinfo->dest = (struct jpeg_destination_mgr *) (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo,
                                                                                  JPOOL_PERMANENT,
                                                                                  SIZEOF(buffer_dst_mgr));
    }

    dest                          = (buffer_dst_ptr) cinfo->dest;
    dest->pub.init_destination    = init_destination;
    dest->pub.empty_output_buffer = empty_output_buffer;
    dest->pub.term_destination    = term_destination;
    dest->m_pEntireBuffer         = pBuf;
    dest->m_ulTotalBytes          = ulBufLen;
}

GLOBAL(int)
jpeg_buffer_dst_bytes(j_compress_ptr cinfo)
{
    buffer_dst_ptr dest  = (buffer_dst_ptr) cinfo->dest;
    int            bytes = dest->m_ulTotalBytes - dest->pub.free_in_buffer;
    return bytes;
}