jcomapi.c 3.04 KB
Newer Older
wester committed
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106
/*
 * jcomapi.c
 *
 * Copyright (C) 1994-1997, Thomas G. Lane.
 * This file is part of the Independent JPEG Group's software.
 * For conditions of distribution and use, see the accompanying README file.
 *
 * This file contains application interface routines that are used for both
 * compression and decompression.
 */

#define JPEG_INTERNALS
#include "jinclude.h"
#include "jpeglib.h"


/*
 * Abort processing of a JPEG compression or decompression operation,
 * but don't destroy the object itself.
 *
 * For this, we merely clean up all the nonpermanent memory pools.
 * Note that temp files (virtual arrays) are not allowed to belong to
 * the permanent pool, so we will be able to close all temp files here.
 * Closing a data source or destination, if necessary, is the application's
 * responsibility.
 */

GLOBAL(void)
jpeg_abort (j_common_ptr cinfo)
{
  int pool;

  /* Do nothing if called on a not-initialized or destroyed JPEG object. */
  if (cinfo->mem == NULL)
    return;

  /* Releasing pools in reverse order might help avoid fragmentation
   * with some (brain-damaged) malloc libraries.
   */
  for (pool = JPOOL_NUMPOOLS-1; pool > JPOOL_PERMANENT; pool--) {
    (*cinfo->mem->free_pool) (cinfo, pool);
  }

  /* Reset overall state for possible reuse of object */
  if (cinfo->is_decompressor) {
    cinfo->global_state = DSTATE_START;
    /* Try to keep application from accessing now-deleted marker list.
     * A bit kludgy to do it here, but this is the most central place.
     */
    ((j_decompress_ptr) cinfo)->marker_list = NULL;
  } else {
    cinfo->global_state = CSTATE_START;
  }
}


/*
 * Destruction of a JPEG object.
 *
 * Everything gets deallocated except the master jpeg_compress_struct itself
 * and the error manager struct.  Both of these are supplied by the application
 * and must be freed, if necessary, by the application.  (Often they are on
 * the stack and so don't need to be freed anyway.)
 * Closing a data source or destination, if necessary, is the application's
 * responsibility.
 */

GLOBAL(void)
jpeg_destroy (j_common_ptr cinfo)
{
  /* We need only tell the memory manager to release everything. */
  /* NB: mem pointer is NULL if memory mgr failed to initialize. */
  if (cinfo->mem != NULL)
    (*cinfo->mem->self_destruct) (cinfo);
  cinfo->mem = NULL;		/* be safe if jpeg_destroy is called twice */
  cinfo->global_state = 0;	/* mark it destroyed */
}


/*
 * Convenience routines for allocating quantization and Huffman tables.
 * (Would jutils.c be a more reasonable place to put these?)
 */

GLOBAL(JQUANT_TBL *)
jpeg_alloc_quant_table (j_common_ptr cinfo)
{
  JQUANT_TBL *tbl;

  tbl = (JQUANT_TBL *)
    (*cinfo->mem->alloc_small) (cinfo, JPOOL_PERMANENT, SIZEOF(JQUANT_TBL));
  tbl->sent_table = FALSE;	/* make sure this is false in any new table */
  return tbl;
}


GLOBAL(JHUFF_TBL *)
jpeg_alloc_huff_table (j_common_ptr cinfo)
{
  JHUFF_TBL *tbl;

  tbl = (JHUFF_TBL *)
    (*cinfo->mem->alloc_small) (cinfo, JPOOL_PERMANENT, SIZEOF(JHUFF_TBL));
  tbl->sent_table = FALSE;	/* make sure this is false in any new table */
  return tbl;
}