JPEGView/Independent JPEG Group/wrppm.c

/*
 * wrppm.c
 *
 * Copyright (C) 1991-1994, 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 routines to write output images in PPM/PGM format.
 * The PBMPLUS library is NOT required to compile this software
 * (but it is highly useful as a set of PPM image manipulation programs).
 *
 * These routines may need modification for non-Unix environments or
 * specialized applications.  As they stand, they assume output to
 * an ordinary stdio stream.
 */

#include "cdjpeg.h"		/* Common decls for cjpeg/djpeg applications */

#ifdef PPM_SUPPORTED


/*
 * Haven't yet got around to making this work with text-format output,
 * hence cannot handle pixels wider than 8 bits.
 */

#if BITS_IN_JSAMPLE != 8
  Sorry, this code only copes with 8-bit JSAMPLEs. /* deliberate syntax err */
#endif

/*
 * In fact, it's worse than that: we want JSAMPLE to be a char, so that we
 * can just fwrite() the decompressed data to a raw-format PPM or PGM file.
 *
 * The output buffer needs to be writable by fwrite().  On PCs, we must
 * allocate the buffer in near data space, because we are assuming small-data
 * memory model, wherein fwrite() can't reach far memory.  If you need to
 * process very wide images on a PC, you might have to compile in large-memory
 * model, or else replace fwrite() with a putc() loop --- which will be much
 * slower.
 */


/* Private version of data destination object */

typedef struct {
  struct djpeg_dest_struct pub;	/* public fields */

  JSAMPLE *iobuffer;		/* non-FAR pointer to I/O buffer */
  JSAMPROW pixrow;		/* FAR pointer to same */
  JDIMENSION buffer_width;	/* width of one row */
} ppm_dest_struct;

typedef ppm_dest_struct * ppm_dest_ptr;


/*
 * Write some pixel data.
 * In this module rows_supplied will always be 1.
 */

METHODDEF void
put_pixel_rows (j_decompress_ptr cinfo, djpeg_dest_ptr dinfo,
		JDIMENSION rows_supplied)
{
  ppm_dest_ptr dest = (ppm_dest_ptr) dinfo;

  (void) JFWRITE(dest->pub.output_file, dest->iobuffer, dest->buffer_width);
}


/*
 * Write some pixel data when color quantization is in effect.
 * We have to demap the color index values to straight data.
 */

METHODDEF void
put_demapped_rgb (j_decompress_ptr cinfo, djpeg_dest_ptr dinfo,
		  JDIMENSION rows_supplied)
{
  ppm_dest_ptr dest = (ppm_dest_ptr) dinfo;
  register char * bufferptr;
  register int pixval;
  register JSAMPROW ptr;
  register JSAMPROW color_map0 = cinfo->colormap[0];
  register JSAMPROW color_map1 = cinfo->colormap[1];
  register JSAMPROW color_map2 = cinfo->colormap[2];
  register JDIMENSION col;

  ptr = dest->pub.buffer[0];
  bufferptr = (char *) dest->iobuffer;
  for (col = cinfo->output_width; col > 0; col--) {
    pixval = GETJSAMPLE(*ptr++);
    *bufferptr++ = (char) GETJSAMPLE(color_map0[pixval]);
    *bufferptr++ = (char) GETJSAMPLE(color_map1[pixval]);
    *bufferptr++ = (char) GETJSAMPLE(color_map2[pixval]);
  }
  (void) JFWRITE(dest->pub.output_file, dest->iobuffer, dest->buffer_width);
}


METHODDEF void
put_demapped_gray (j_decompress_ptr cinfo, djpeg_dest_ptr dinfo,
		   JDIMENSION rows_supplied)
{
  ppm_dest_ptr dest = (ppm_dest_ptr) dinfo;
  register char * bufferptr;
  register JSAMPROW ptr;
  register JSAMPROW color_map = cinfo->colormap[0];
  register JDIMENSION col;

  ptr = dest->pub.buffer[0];
  bufferptr = (char *) dest->iobuffer;
  for (col = cinfo->output_width; col > 0; col--) {
    *bufferptr++ = (char) GETJSAMPLE(color_map[GETJSAMPLE(*ptr++)]);
  }
  (void) JFWRITE(dest->pub.output_file, dest->iobuffer, dest->buffer_width);
}


/*
 * Startup: write the file header.
 */

METHODDEF void
start_output (j_decompress_ptr cinfo, djpeg_dest_ptr dinfo)
{
  ppm_dest_ptr dest = (ppm_dest_ptr) dinfo;

  /* Emit file header */
  switch (cinfo->out_color_space) {
  case JCS_GRAYSCALE:
    /* emit header for raw PGM format */
    fprintf(dest->pub.output_file, "P5\n%ld %ld\n%d\n",
	    (long) cinfo->output_width, (long) cinfo->output_height, 255);
    break;
  case JCS_RGB: