view release on metacpan or  search on metacpan

src/Source/LibJPEG/jdapistd.c  view on Meta::CPAN

/*
 * jdapistd.c
 *
 * Copyright (C) 1994-1996, Thomas G. Lane.
 * Modified 2002-2013 by Guido Vollbeding.
 * 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 decompression half
 * of the JPEG library.  These are the "standard" API routines that are
 * used in the normal full-decompression case.  They are not used by a
 * transcoding-only application.  Note that if an application links in
 * jpeg_start_decompress, it will end up linking in the entire decompressor.
 * We thus must separate this file from jdapimin.c to avoid linking the
 * whole decompression library into a transcoder.
 */

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


/* Forward declarations */
LOCAL(boolean) output_pass_setup JPP((j_decompress_ptr cinfo));


/*
 * Decompression initialization.
 * jpeg_read_header must be completed before calling this.
 *
 * If a multipass operating mode was selected, this will do all but the
 * last pass, and thus may take a great deal of time.
 *
 * Returns FALSE if suspended.  The return value need be inspected only if
 * a suspending data source is used.
 */

GLOBAL(boolean)
jpeg_start_decompress (j_decompress_ptr cinfo)
{
  if (cinfo->global_state == DSTATE_READY) {
    /* First call: initialize master control, select active modules */
    jinit_master_decompress(cinfo);
    if (cinfo->buffered_image) {
      /* No more work here; expecting jpeg_start_output next */
      cinfo->global_state = DSTATE_BUFIMAGE;
      return TRUE;
    }
    cinfo->global_state = DSTATE_PRELOAD;
  }
  if (cinfo->global_state == DSTATE_PRELOAD) {
    /* If file has multiple scans, absorb them all into the coef buffer */
    if (cinfo->inputctl->has_multiple_scans) {
#ifdef D_MULTISCAN_FILES_SUPPORTED
      for (;;) {
	int retcode;
	/* Call progress monitor hook if present */
	if (cinfo->progress != NULL)
	  (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
	/* Absorb some more input */
	retcode = (*cinfo->inputctl->consume_input) (cinfo);
	if (retcode == JPEG_SUSPENDED)
	  return FALSE;
	if (retcode == JPEG_REACHED_EOI)
	  break;
	/* Advance progress counter if appropriate */
	if (cinfo->progress != NULL &&
	    (retcode == JPEG_ROW_COMPLETED || retcode == JPEG_REACHED_SOS)) {
	  if (++cinfo->progress->pass_counter >= cinfo->progress->pass_limit) {
	    /* jdmaster underestimated number of scans; ratchet up one scan */
	    cinfo->progress->pass_limit += (long) cinfo->total_iMCU_rows;
	  }
	}
      }
#else
      ERREXIT(cinfo, JERR_NOT_COMPILED);
#endif /* D_MULTISCAN_FILES_SUPPORTED */
    }
    cinfo->output_scan_number = cinfo->input_scan_number;
  } else if (cinfo->global_state != DSTATE_PRESCAN)
    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
  /* Perform any dummy output passes, and set up for the final pass */
  return output_pass_setup(cinfo);
}


/*
 * Set up for an output pass, and perform any dummy pass(es) needed.
 * Common subroutine for jpeg_start_decompress and jpeg_start_output.
 * Entry: global_state = DSTATE_PRESCAN only if previously suspended.
 * Exit: If done, returns TRUE and sets global_state for proper output mode.
 *       If suspended, returns FALSE and sets global_state = DSTATE_PRESCAN.
 */

LOCAL(boolean)
output_pass_setup (j_decompress_ptr cinfo)
{
  if (cinfo->global_state != DSTATE_PRESCAN) {
    /* First call: do pass setup */
    (*cinfo->master->prepare_for_output_pass) (cinfo);
    cinfo->output_scanline = 0;
    cinfo->global_state = DSTATE_PRESCAN;