Quelle jcapimin.c Sprache: C

/*
* reserved comment block
* DO NOT REMOVE OR ALTER!
*/
/*
* jcapimin.c
*
* Copyright (C) 1994-1998, 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 code for the compression half
* of the JPEG library.  These are the "minimum" API routines that may be
* needed in either the normal full-compression case or the transcoding-only
* case.
*
* Most of the routines intended to be called directly by an application
* are in this file or in jcapistd.c.  But also see jcparam.c for
* parameter-setup helper routines, jcomapi.c for routines shared by
* compression and decompression, and jctrans.c for the transcoding case.
*/

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

/*
* Initialization of a JPEG compression object.
* The error manager must already be set up (in case memory manager fails).
*/

GLOBAL(void)
jpeg_CreateCompress (j_compress_ptr cinfo, int version, size_t structsize)
{
  int i;

  /* Guard against version mismatches between library and caller. */
  cinfo->mem = NULL;            /* so jpeg_destroy knows mem mgr not called */
  if (version != JPEG_LIB_VERSION)
    ERREXIT2(cinfo, JERR_BAD_LIB_VERSION, JPEG_LIB_VERSION, version);
  if (structsize != SIZEOF(struct jpeg_compress_struct))
    ERREXIT2(cinfo, JERR_BAD_STRUCT_SIZE,
             (int) SIZEOF(struct jpeg_compress_struct), (int) structsize);

  /* For debugging purposes, we zero the whole master structure.
   * But the application has already set the err pointer, and may have set
   * client_data, so we have to save and restore those fields.
   * Note: if application hasn't set client_data, tools like Purify may
   * complain here.
   */
  {
    struct jpeg_error_mgr * err = cinfo->err;
    void * client_data = cinfo->client_data; /* ignore Purify complaint here */
    MEMZERO(cinfo, SIZEOF(struct jpeg_compress_struct));
    cinfo->err = err;
    cinfo->client_data = client_data;
  }
  cinfo->is_decompressor = FALSE;

  /* Initialize a memory manager instance for this object */
  jinit_memory_mgr((j_common_ptr) cinfo);

  /* Zero out pointers to permanent structures. */
  cinfo->progress = NULL;
  cinfo->dest = NULL;

  cinfo->comp_info = NULL;

  for (i = 0; i < NUM_QUANT_TBLS; i++)
    cinfo->quant_tbl_ptrs[i] = NULL;

  for (i = 0; i < NUM_HUFF_TBLS; i++) {
    cinfo->dc_huff_tbl_ptrs[i] = NULL;
    cinfo->ac_huff_tbl_ptrs[i] = NULL;
  }

  cinfo->script_space = NULL;

  cinfo->input_gamma = 1.0;     /* in case application forgets */

  /* OK, I'm ready */
  cinfo->global_state = CSTATE_START;
}

/*
* Destruction of a JPEG compression object
*/

GLOBAL(void)
jpeg_destroy_compress (j_compress_ptr cinfo)
{
  jpeg_destroy((j_common_ptr) cinfo); /* use common routine */
}

/*
* Abort processing of a JPEG compression operation,
* but don't destroy the object itself.
*/

GLOBAL(void)
jpeg_abort_compress (j_compress_ptr cinfo)
{
  jpeg_abort((j_common_ptr) cinfo); /* use common routine */
}

/*
* Forcibly suppress or un-suppress all quantization and Huffman tables.
* Marks all currently defined tables as already written (if suppress)
* or not written (if !suppress).  This will control whether they get emitted
* by a subsequent jpeg_start_compress call.
*
* This routine is exported for use by applications that want to produce
* abbreviated JPEG datastreams.  It logically belongs in jcparam.c, but
* since it is called by jpeg_start_compress, we put it here --- otherwise
* jcparam.o would be linked whether the application used it or not.
*/

GLOBAL(void)
jpeg_suppress_tables (j_compress_ptr cinfo, boolean suppress)
{
  int i;
  JQUANT_TBL * qtbl;
  JHUFF_TBL * htbl;

  for (i = 0; i < NUM_QUANT_TBLS; i++) {
    if ((qtbl = cinfo->quant_tbl_ptrs[i]) != NULL)
      qtbl->sent_table = suppress;
  }

  for (i = 0; i < NUM_HUFF_TBLS; i++) {
    if ((htbl = cinfo->dc_huff_tbl_ptrs[i]) != NULL)
      htbl->sent_table = suppress;
    if ((htbl = cinfo->ac_huff_tbl_ptrs[i]) != NULL)
      htbl->sent_table = suppress;
  }
}

/*
* Finish JPEG compression.
*
* If a multipass operating mode was selected, this may do a great deal of
* work including most of the actual output.
*/

GLOBAL(void)
jpeg_finish_compress (j_compress_ptr cinfo)
{
  JDIMENSION iMCU_row;

  if (cinfo->global_state == CSTATE_SCANNING ||
      cinfo->global_state == CSTATE_RAW_OK) {
    /* Terminate first pass */
    if (cinfo->next_scanline < cinfo->image_height)
      ERREXIT(cinfo, JERR_TOO_LITTLE_DATA);
    (*cinfo->master->finish_pass) (cinfo);
  } else if (cinfo->global_state != CSTATE_WRCOEFS)
    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
  /* Perform any remaining passes */
  while (! cinfo->master->is_last_pass) {
    (*cinfo->master->prepare_for_pass) (cinfo);
    for (iMCU_row = 0; iMCU_row < cinfo->total_iMCU_rows; iMCU_row++) {
      if (cinfo->progress != NULL) {
        cinfo->progress->pass_counter = (long) iMCU_row;
        cinfo->progress->pass_limit = (long) cinfo->total_iMCU_rows;
        (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
      }
      /* We bypass the main controller and invoke coef controller directly;
       * all work is being done from the coefficient buffer.
       */
      if (! (*cinfo->coef->compress_data) (cinfo, (JSAMPIMAGE) NULL))
        ERREXIT(cinfo, JERR_CANT_SUSPEND);
    }
    (*cinfo->master->finish_pass) (cinfo);
  }
  /* Write EOI, do final cleanup */
  (*cinfo->marker->write_file_trailer) (cinfo);
  (*cinfo->dest->term_destination) (cinfo);
  /* We can use jpeg_abort to release memory and reset global_state */
  jpeg_abort((j_common_ptr) cinfo);
}

/*
* Write a special marker.
* This is only recommended for writing COM or APPn markers.
* Must be called after jpeg_start_compress() and before
* first call to jpeg_write_scanlines() or jpeg_write_raw_data().
*/

GLOBAL(void)
jpeg_write_marker (j_compress_ptr cinfo, int marker,
                   const JOCTET *dataptr, unsigned int datalen)
{
  JMETHOD(void, write_marker_byte, (j_compress_ptr info, int val));

  if (cinfo->next_scanline != 0 ||
      (cinfo->global_state != CSTATE_SCANNING &&
       cinfo->global_state != CSTATE_RAW_OK &&
       cinfo->global_state != CSTATE_WRCOEFS))
    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);

  (*cinfo->marker->write_marker_header) (cinfo, marker, datalen);
  write_marker_byte = cinfo->marker->write_marker_byte; /* copy for speed */
  while (datalen--) {
    (*write_marker_byte) (cinfo, *dataptr);
    dataptr++;
  }
}

/* Same, but piecemeal. */

GLOBAL(void)
jpeg_write_m_header (j_compress_ptr cinfo, int marker, unsigned int datalen)
{
  if (cinfo->next_scanline != 0 ||
      (cinfo->global_state != CSTATE_SCANNING &&
       cinfo->global_state != CSTATE_RAW_OK &&
       cinfo->global_state != CSTATE_WRCOEFS))
    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);

  (*cinfo->marker->write_marker_header) (cinfo, marker, datalen);
}

GLOBAL(void)
jpeg_write_m_byte (j_compress_ptr cinfo, int val)
{
  (*cinfo->marker->write_marker_byte) (cinfo, val);
}

/*
* Alternate compression function: just write an abbreviated table file.
* Before calling this, all parameters and a data destination must be set up.
*
* To produce a pair of files containing abbreviated tables and abbreviated
* image data, one would proceed as follows:
*
*              initialize JPEG object
*              set JPEG parameters
*              set destination to table file
*              jpeg_write_tables(cinfo);
*              set destination to image file
*              jpeg_start_compress(cinfo, FALSE);
*              write data...
*              jpeg_finish_compress(cinfo);
*
* jpeg_write_tables has the side effect of marking all tables written
* (same as jpeg_suppress_tables(..., TRUE)).  Thus a subsequent start_compress
* will not re-emit the tables unless it is passed write_all_tables=TRUE.
*/

GLOBAL(void)
jpeg_write_tables (j_compress_ptr cinfo)
{
  if (cinfo->global_state != CSTATE_START)
    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);

  /* (Re)initialize error mgr and destination modules */
  (*cinfo->err->reset_error_mgr) ((j_common_ptr) cinfo);
  (*cinfo->dest->init_destination) (cinfo);
  /* Initialize the marker writer ... bit of a crock to do it here. */
  jinit_marker_writer(cinfo);
  /* Write them tables! */
  (*cinfo->marker->write_tables_only) (cinfo);
  /* And clean up. */
  (*cinfo->dest->term_destination) (cinfo);
  /*
   * In library releases up through v6a, we called jpeg_abort() here to free
   * any working memory allocated by the destination manager and marker
   * writer.  Some applications had a problem with that: they allocated space
   * of their own from the library memory manager, and didn't want it to go
   * away during write_tables.  So now we do nothing.  This will cause a
   * memory leak if an app calls write_tables repeatedly without doing a full
   * compression cycle or otherwise resetting the JPEG object.  However, that
   * seems less bad than unexpectedly freeing memory in the normal case.
   * An app that prefers the old behavior can call jpeg_abort for itself after
   * each call to jpeg_write_tables().
   */
}

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