www.pudn.com > imgport.rar > jcomapi.c, change:2008-11-05,size:3216b


/* 
 * 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; 
}