/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/***************************************************************************
 *            jpeg_mem_dest.cc
 *
 *  Thu Jul 28 16:40:08 CEST 2005
 *  Copyright  2005 Bent Bisballe
 *  deva@aasimon.org
 ****************************************************************************/

/*
 *  This file is part of MIaV.
 *
 *  MIaV is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  MIaV is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with MIaV; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
 */
#include "jpeg_mem_dest.h"

#define OUTPUT_BUF_SIZE  4096	/* choose an efficiently ?? size */

/* Expanded data destination object for stdio output */
typedef struct {
  struct jpeg_destination_mgr pub; /* public fields */

  JOCTET * outbuff;		/* target buffer */
  size_t * size;
} mem_destination_mgr;

typedef mem_destination_mgr * mem_dest_ptr;

/*
 * Initialize destination --- called by jpeg_start_compress
 * before any data is actually written.
 */
void init_destination (j_compress_ptr cinfo)
{
  mem_dest_ptr dest = (mem_dest_ptr) cinfo->dest;

  *dest->size = 0;
  dest->pub.next_output_byte = dest->outbuff;
  dest->pub.free_in_buffer = OUTPUT_BUF_SIZE;
}

/*
 * 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.
 */
void term_destination (j_compress_ptr cinfo)
{
  mem_dest_ptr dest = (mem_dest_ptr) cinfo->dest;
  size_t datacount = OUTPUT_BUF_SIZE - dest->pub.free_in_buffer;

  /* Write any data remaining in the buffer */
  if (datacount > 0) {
    dest->outbuff+=datacount;
    *dest->size+=datacount;
  }
}

/*
 * 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.
 */
boolean empty_output_buffer (j_compress_ptr cinfo)
{
  mem_dest_ptr dest = (mem_dest_ptr) cinfo->dest;

  dest->outbuff+=OUTPUT_BUF_SIZE;
  *dest->size+=OUTPUT_BUF_SIZE;

  dest->pub.next_output_byte = dest->outbuff;
  dest->pub.free_in_buffer = OUTPUT_BUF_SIZE;

  return TRUE;
}

/*
 * Prepare for output to a memory buffer.
 . The caller must have already allocated the buffer, and is responsible
 * for closing it after finishing compression.
 */
void jpeg_mem_dest (j_compress_ptr cinfo, char * outbuff, size_t * size)
{
  mem_dest_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(mem_destination_mgr));
  }

  dest = (mem_dest_ptr) cinfo->dest;
  dest->pub.init_destination = init_destination;
  dest->pub.empty_output_buffer = empty_output_buffer;
  dest->pub.term_destination = term_destination;
  dest->outbuff = (JOCTET *)outbuff;
  dest->size = (size_t *)size;
}