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/*
* 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 */
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