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/* -*- 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;
}
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