/*

 *  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 convertion 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 */