Colony

/*

 * Code taken from http://www.codeguru.com/forum/archive/index.php/t-378333.html

 * by 'clown'

 */

#include <stdio.h>

#include "jpeglib.h"

#include "memdst.h"

/*

This a custom destination manager for jpeglib that

enables the use of memory to memory compression.

See IJG documentation for details.

*/

typedef struct {

  struct jpeg_destination_mgr pub; /* base class */

  JOCTET* buffer; /* buffer start address */

  int bufsize; /* size of buffer */

  size_t datasize; /* final size of compressed data */

  int* outsize; /* user pointer to datasize */

  int errcount; /* counts up write errors due to

  buffer overruns */

} memory_destination_mgr;

typedef memory_destination_mgr* mem_dest_ptr;

/* ------------------------------------------------------------- */

/* MEMORY DESTINATION INTERFACE METHODS */

/* ------------------------------------------------------------- */

/* This function is called by the library before any data gets written */

METHODDEF(void)

init_destination (j_compress_ptr cinfo)

{

  mem_dest_ptr dest = (mem_dest_ptr)cinfo->dest;

  dest->pub.next_output_byte = dest->buffer; /* set destination buffer */

  dest->pub.free_in_buffer = dest->bufsize; /* input buffer size */

  dest->datasize = 0; /* reset output size */

  dest->errcount = 0; /* reset error count */

}

/* This function is called by the library if the buffer fills up

I just reset destination pointer and buffer size here.

Note that this behavior, while preventing seg faults

will lead to invalid output streams as data is over-

written.

*/

METHODDEF(boolean)

empty_output_buffer (j_compress_ptr cinfo)

{

  mem_dest_ptr dest = (mem_dest_ptr)cinfo->dest;

  dest->pub.next_output_byte = dest->buffer;

  dest->pub.free_in_buffer = dest->bufsize;

  ++dest->errcount; /* need to increase error count */

  return TRUE;

}

/* Usually the library wants to flush output here.

I will calculate output buffer size here.

Note that results become incorrect, once

empty_output_buffer was called.

This situation is notified by errcount.

*/

METHODDEF(void)

term_destination (j_compress_ptr cinfo)

{

  mem_dest_ptr dest = (mem_dest_ptr)cinfo->dest;

  dest->datasize = dest->bufsize - dest->pub.free_in_buffer;

  if (dest->outsize)

  {

    if (dest->errcount)

      *dest->outsize = -1;

    else

      *dest->outsize = (int)dest->datasize;

  }

}

/* Override the default destination manager initialization

provided by jpeglib. Since we want to use memory-to-memory

compression, we need to use our own destination manager.

*/

GLOBAL(void)

jpeg_memory_dest (j_compress_ptr cinfo, JOCTET* buffer, int bufsize, int* outsize)

{

  mem_dest_ptr dest;

  /* first call for this instance - need to setup */

  if (cinfo->dest == 0) {

    cinfo->dest = (struct jpeg_destination_mgr *)

    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,

    sizeof (memory_destination_mgr));

  }

  dest = (mem_dest_ptr) cinfo->dest;

  dest->bufsize = bufsize;

  dest->buffer = buffer;

  dest->outsize = outsize;

  /* set method callbacks */

  dest->pub.init_destination = init_destination;

  dest->pub.empty_output_buffer = empty_output_buffer;

  dest->pub.term_destination = term_destination;

}