/*

* png2pnm.c --- conversion from PNG-file to PGM/PPM-file

* copyright (C) 1999 by Willem van Schaik <willem@schaik.com>

*

* version 1.0 - 1999.10.15 - First version.

*

* Permission to use, copy, modify, and distribute this software and

* its documentation for any purpose and without fee is hereby granted,

* provided that the above copyright notice appear in all copies and

* that both that copyright notice and this permission notice appear in

* supporting documentation. This software is provided "as is" without

* express or implied warranty.

*/

#include <stdio.h>

#include <stdlib.h>

#ifdef __TURBOC__

#include <mem.h>

#include <fcntl.h>

#endif

#ifndef BOOL

#define BOOL unsigned char

#endif

#ifndef TRUE

#define TRUE (BOOL) 1

#endif

#ifndef FALSE

#define FALSE (BOOL) 0

#endif

#ifdef __TURBOC__

#define STDIN 0

#define STDOUT 1

#define STDERR 2

#endif

/* to make png2pnm verbose so we can find problems (needs to be before png.h) */

#ifndef PNG_DEBUG

#define PNG_DEBUG 0

#endif

#include "png.h"

/* Define png_jmpbuf() in case we are using a pre-1.0.6 version of libpng */

#ifndef png_jmpbuf

# define png_jmpbuf(png_ptr) ((png_ptr)->jmpbuf)

#endif

/* function prototypes */

int main (int argc, char *argv[]);

void usage ();

BOOL png2pnm (FILE *png_file, FILE *pnm_file, FILE *alpha_file, BOOL raw, BOOL alpha);

/*

* main

*/

int main(int argc, char *argv[])

{

FILE *fp_rd = stdin;

FILE *fp_wr = stdout;

FILE *fp_al = NULL;

BOOL raw = TRUE;

BOOL alpha = FALSE;

int argi;

for (argi = 1; argi < argc; argi++)

{

if (argv[argi][0] == '-')

{

switch (argv[argi][1])

{

case 'n':

raw = FALSE;

break;

case 'r':

raw = TRUE;

break;

case 'a':

alpha = TRUE;

argi++;

if ((fp_al = fopen (argv[argi], "wb")) == NULL)

{

fprintf (stderr, "PNM2PNG\n");

fprintf (stderr, "Error: can not create alpha-channel file %s\n", argv[argi]);

exit (1);

}

break;

case 'h':

case '?':

usage();

exit(0);

break;

default:

fprintf (stderr, "PNG2PNM\n");

fprintf (stderr, "Error: unknown option %s\n", argv[argi]);

usage();

exit(1);

break;

} /* end switch */

}

else if (fp_rd == stdin)

{

if ((fp_rd = fopen (argv[argi], "rb")) == NULL)

{

fprintf (stderr, "PNG2PNM\n");

fprintf (stderr, "Error: file %s does not exist\n", argv[argi]);

exit (1);

}

}

else if (fp_wr == stdout)

{

if ((fp_wr = fopen (argv[argi], "wb")) == NULL)

{

fprintf (stderr, "PNG2PNM\n");

fprintf (stderr, "Error: can not create file %s\n", argv[argi]);

exit (1);

}

}

else

{

fprintf (stderr, "PNG2PNM\n");

fprintf (stderr, "Error: too many parameters\n");

usage();

exit(1);

}

} /* end for */

#ifdef __TURBOC__

/* set stdin/stdout if required to binary */

if (fp_rd == stdin)

{

setmode (STDIN, O_BINARY);

}

if ((raw) && (fp_wr == stdout))

{

setmode (STDOUT, O_BINARY);

}

#endif

/* call the conversion program itself */

if (png2pnm (fp_rd, fp_wr, fp_al, raw, alpha) == FALSE)

{

fprintf (stderr, "PNG2PNM\n");

fprintf (stderr, "Error: unsuccessful conversion of PNG-image\n");

exit(1);

}

/* close input file */

fclose (fp_rd);

/* close output file */

fclose (fp_wr);

/* close alpha file */

if (alpha)

fclose (fp_al);

return 0;

}

/*

* usage

*/

void usage()

{

fprintf (stderr, "PNG2PNM\n");

fprintf (stderr, " by Willem van Schaik, 1999\n");

#ifdef __TURBOC__

fprintf (stderr, " for Turbo-C and Borland-C compilers\n");

#else

fprintf (stderr, " for Linux (and Unix) compilers\n");

#endif

fprintf (stderr, "Usage: png2pnm [options] <file>.png [<file>.pnm]\n");

fprintf (stderr, " or: ... | png2pnm [options]\n");

fprintf (stderr, "Options:\n");

fprintf (stderr, " -r[aw] write pnm-file in binary format (P4/P5/P6) (default)\n");

fprintf (stderr, " -n[oraw] write pnm-file in ascii format (P1/P2/P3)\n");

fprintf (stderr, " -a[lpha] <file>.pgm write PNG alpha channel as pgm-file\n");

fprintf (stderr, " -h | -? print this help-information\n");

}

/*

* png2pnm

*/

BOOL png2pnm (FILE *png_file, FILE *pnm_file, FILE *alpha_file, BOOL raw, BOOL alpha)

{

png_struct *png_ptr = NULL;

png_info *info_ptr = NULL;

png_byte buf[8];

png_byte *png_pixels = NULL;

png_byte **row_pointers = NULL;

png_byte *pix_ptr = NULL;

png_uint_32 row_bytes;

png_uint_32 width;

png_uint_32 height;

int bit_depth;

int channels;

int color_type;

int alpha_present;

int row, col;

int ret;

int i;

long dep_16;

/* read and check signature in PNG file */

ret = fread (buf, 1, 8, png_file);

if (ret != 8)

return FALSE;

ret = png_sig_cmp (buf, 0, 8);

if (ret)

return FALSE;

/* create png and info structures */

png_ptr = png_create_read_struct (PNG_LIBPNG_VER_STRING,

NULL, NULL, NULL);

if (!png_ptr)

return FALSE; /* out of memory */

info_ptr = png_create_info_struct (png_ptr);

if (!info_ptr)

{

png_destroy_read_struct (&png_ptr, NULL, NULL);

return FALSE; /* out of memory */

}

if (setjmp (png_jmpbuf(png_ptr)))

{

png_destroy_read_struct (&png_ptr, &info_ptr, NULL);

return FALSE;

}

/* set up the input control for C streams */

png_init_io (png_ptr, png_file);

png_set_sig_bytes (png_ptr, 8); /* we already read the 8 signature bytes */

/* read the file information */

png_read_info (png_ptr, info_ptr);

/* get size and bit-depth of the PNG-image */

png_get_IHDR (png_ptr, info_ptr,

&width, &height, &bit_depth, &color_type,

NULL, NULL, NULL);

/* set-up the transformations */

/* transform paletted images into full-color rgb */

if (color_type == PNG_COLOR_TYPE_PALETTE)

png_set_expand (png_ptr);

/* expand images to bit-depth 8 (only applicable for grayscale images) */

if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8)

png_set_expand (png_ptr);

/* transform transparency maps into full alpha-channel */

if (png_get_valid (png_ptr, info_ptr, PNG_INFO_tRNS))

png_set_expand (png_ptr);

#ifdef NJET

/* downgrade 16-bit images to 8 bit */

if (bit_depth == 16)

png_set_strip_16 (png_ptr);

/* transform grayscale images into full-color */

if (color_type == PNG_COLOR_TYPE_GRAY ||

color_type == PNG_COLOR_TYPE_GRAY_ALPHA)

png_set_gray_to_rgb (png_ptr);

/* only if file has a file gamma, we do a correction */

if (png_get_gAMA (png_ptr, info_ptr, &file_gamma))

png_set_gamma (png_ptr, (double) 2.2, file_gamma);

#endif

/* all transformations have been registered; now update info_ptr data,

* get rowbytes and channels, and allocate image memory */

png_read_update_info (png_ptr, info_ptr);

/* get the new color-type and bit-depth (after expansion/stripping) */

png_get_IHDR (png_ptr, info_ptr, &width, &height, &bit_depth, &color_type,

NULL, NULL, NULL);

/* check for 16-bit files */

if (bit_depth == 16)

{

raw = FALSE;

#ifdef __TURBOC__

pnm_file->flags &= ~((unsigned) _F_BIN);

#endif

}

/* calculate new number of channels and store alpha-presence */

if (color_type == PNG_COLOR_TYPE_GRAY)

channels = 1;

else if (color_type == PNG_COLOR_TYPE_GRAY_ALPHA)

channels = 2;

else if (color_type == PNG_COLOR_TYPE_RGB)

channels = 3;

else if (color_type == PNG_COLOR_TYPE_RGB_ALPHA)

channels = 4;

else

channels = 0; /* should never happen */

alpha_present = (channels - 1) % 2;

/* check if alpha is expected to be present in file */

if (alpha && !alpha_present)

{

fprintf (stderr, "PNG2PNM\n");

fprintf (stderr, "Error: PNG-file doesn't contain alpha channel\n");

exit (1);

}

/* row_bytes is the width x number of channels x (bit-depth / 8) */

row_bytes = png_get_rowbytes (png_ptr, info_ptr);

if ((png_pixels = (png_byte *) malloc (row_bytes * height * sizeof (png_byte))) == NULL) {

png_destroy_read_struct (&png_ptr, &info_ptr, NULL);

return FALSE;

}

if ((row_pointers = (png_byte **) malloc (height * sizeof (png_bytep))) == NULL)

{

png_destroy_read_struct (&png_ptr, &info_ptr, NULL);

free (png_pixels);

png_pixels = NULL;

return FALSE;

}

/* set the individual row_pointers to point at the correct offsets */

for (i = 0; i < (height); i++)

row_pointers[i] = png_pixels + i * row_bytes;

/* now we can go ahead and just read the whole image */

png_read_image (png_ptr, row_pointers);

/* read rest of file, and get additional chunks in info_ptr - REQUIRED */

png_read_end (png_ptr, info_ptr);

/* clean up after the read, and free any memory allocated - REQUIRED */

png_destroy_read_struct (&png_ptr, &info_ptr, (png_infopp) NULL);

/* write header of PNM file */

if ((color_type == PNG_COLOR_TYPE_GRAY) ||

(color_type == PNG_COLOR_TYPE_GRAY_ALPHA))

{

fprintf (pnm_file, "%s\n", (raw) ? "P5" : "P2");

fprintf (pnm_file, "%d %d\n", (int) width, (int) height);

fprintf (pnm_file, "%ld\n", ((1L << (int) bit_depth) - 1L));

}

else if ((color_type == PNG_COLOR_TYPE_RGB) ||

(color_type == PNG_COLOR_TYPE_RGB_ALPHA))

{

fprintf (pnm_file, "%s\n", (raw) ? "P6" : "P3");

fprintf (pnm_file, "%d %d\n", (int) width, (int) height);

fprintf (pnm_file, "%ld\n", ((1L << (int) bit_depth) - 1L));

}

/* write header of PGM file with alpha channel */

if ((alpha) &&

((color_type == PNG_COLOR_TYPE_GRAY_ALPHA) ||

(color_type == PNG_COLOR_TYPE_RGB_ALPHA)))

{

fprintf (alpha_file, "%s\n", (raw) ? "P5" : "P2");

fprintf (alpha_file, "%d %d\n", (int) width, (int) height);

fprintf (alpha_file, "%ld\n", ((1L << (int) bit_depth) - 1L));

}

/* write data to PNM file */

pix_ptr = png_pixels;

for (row = 0; row < height; row++)

{

for (col = 0; col < width; col++)

{

for (i = 0; i < (channels - alpha_present); i++)

{

if (raw)

fputc ((int) *pix_ptr++ , pnm_file);

else

if (bit_depth == 16){

dep_16 = (long) *pix_ptr++;

fprintf (pnm_file, "%ld ", (dep_16 << 8) + ((long) *pix_ptr++));

}

else

fprintf (pnm_file, "%ld ", (long) *pix_ptr++);

}

if (alpha_present)

{

if (!alpha)

{

pix_ptr++; /* alpha */

if (bit_depth == 16)

pix_ptr++;

}

else /* output alpha-channel as pgm file */

{

if (raw)

fputc ((int) *pix_ptr++ , alpha_file);

else

if (bit_depth == 16){

dep_16 = (long) *pix_ptr++;

fprintf (alpha_file, "%ld ", (dep_16 << 8) + (long) *pix_ptr++);

}

else

fprintf (alpha_file, "%ld ", (long) *pix_ptr++);

}

} /* if alpha_present */

if (!raw)

if (col % 4 == 3)

fprintf (pnm_file, "\n");

} /* end for col */

if (!raw)

if (col % 4 != 0)

fprintf (pnm_file, "\n");

} /* end for row */

if (row_pointers != (unsigned char**) NULL)

free (row_pointers);

if (png_pixels != (unsigned char*) NULL)

free (png_pixels);

return TRUE;

} /* end of source */