IMG_pnm.c
author Sam Lantinga <slouken@libsdl.org>
Sat, 04 Feb 2006 20:37:17 +0000
changeset 117 e613cf987897
parent 98 9f94c4674cc9
child 118 c5e736a47ad2
permissions -rw-r--r--
Fixed image type functions so they seek back to where they started
slouken@25
     1
/*
slouken@53
     2
    SDL_image:  An example image loading library for use with SDL
slouken@97
     3
    Copyright (C) 1999-2004 Sam Lantinga
slouken@25
     4
slouken@25
     5
    This library is free software; you can redistribute it and/or
slouken@25
     6
    modify it under the terms of the GNU Library General Public
slouken@25
     7
    License as published by the Free Software Foundation; either
slouken@25
     8
    version 2 of the License, or (at your option) any later version.
slouken@25
     9
slouken@25
    10
    This library is distributed in the hope that it will be useful,
slouken@25
    11
    but WITHOUT ANY WARRANTY; without even the implied warranty of
slouken@25
    12
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
slouken@25
    13
    Library General Public License for more details.
slouken@25
    14
slouken@25
    15
    You should have received a copy of the GNU Library General Public
slouken@25
    16
    License along with this library; if not, write to the Free
slouken@25
    17
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
slouken@25
    18
slouken@25
    19
    Sam Lantinga
slouken@53
    20
    slouken@libsdl.org
slouken@25
    21
*/
slouken@25
    22
slouken@53
    23
/* $Id$ */
slouken@53
    24
slouken@25
    25
/*
slouken@25
    26
 * PNM (portable anymap) image loader:
slouken@25
    27
 *
slouken@25
    28
 * Supports: PBM, PGM and PPM, ASCII and binary formats
slouken@25
    29
 * (PBM and PGM are loaded as 8bpp surfaces)
slouken@25
    30
 * Does not support: maximum component value > 255
slouken@25
    31
 */
slouken@25
    32
slouken@25
    33
#include <stdio.h>
slouken@25
    34
#include <stdlib.h>
slouken@25
    35
#include <ctype.h>
slouken@25
    36
#include <string.h>
slouken@25
    37
slouken@25
    38
#include "SDL_image.h"
slouken@25
    39
slouken@25
    40
#ifdef LOAD_PNM
slouken@25
    41
slouken@25
    42
/* See if an image is contained in a data source */
slouken@25
    43
int IMG_isPNM(SDL_RWops *src)
slouken@25
    44
{
slouken@117
    45
	int start;
slouken@117
    46
	int is_PNM;
slouken@25
    47
	char magic[2];
slouken@25
    48
slouken@117
    49
	start = SDL_RWtell(src);
slouken@117
    50
	is_PNM = 0;
slouken@117
    51
	if ( SDL_RWread(src, magic, sizeof(magic), 1) ) {
slouken@117
    52
		/*
slouken@117
    53
		 * PNM magic signatures:
slouken@117
    54
		 * P1	PBM, ascii format
slouken@117
    55
		 * P2	PGM, ascii format
slouken@117
    56
		 * P3	PPM, ascii format
slouken@117
    57
		 * P4	PBM, binary format
slouken@117
    58
		 * P5	PGM, binary format
slouken@117
    59
		 * P6	PPM, binary format
slouken@117
    60
		 */
slouken@117
    61
		if ( magic[0] == 'P' && magic[1] >= '1' && magic[1] <= '6' ) {
slouken@117
    62
			is_PNM = 1;
slouken@117
    63
		}
slouken@117
    64
	}
slouken@117
    65
	SDL_RWseek(src, start, SEEK_SET);
slouken@117
    66
	return(is_PNM);
slouken@25
    67
}
slouken@25
    68
slouken@25
    69
/* read a non-negative integer from the source. return -1 upon error */
slouken@25
    70
static int ReadNumber(SDL_RWops *src)
slouken@25
    71
{
slouken@25
    72
	int number;
slouken@25
    73
	unsigned char ch;
slouken@25
    74
slouken@25
    75
	/* Initialize return value */
slouken@25
    76
	number = 0;
slouken@25
    77
slouken@25
    78
	/* Skip leading whitespace */
slouken@25
    79
	do {
slouken@25
    80
		if ( ! SDL_RWread(src, &ch, 1, 1) ) {
slouken@25
    81
			return(0);
slouken@25
    82
		}
slouken@25
    83
		/* Eat comments as whitespace */
slouken@25
    84
		if ( ch == '#' ) {  /* Comment is '#' to end of line */
slouken@25
    85
			do {
slouken@25
    86
				if ( ! SDL_RWread(src, &ch, 1, 1) ) {
slouken@25
    87
					return -1;
slouken@25
    88
				}
slouken@25
    89
			} while ( (ch != '\r') && (ch != '\n') );
slouken@25
    90
		}
slouken@25
    91
	} while ( isspace(ch) );
slouken@25
    92
slouken@25
    93
	/* Add up the number */
slouken@25
    94
	do {
slouken@25
    95
		number *= 10;
slouken@25
    96
		number += ch-'0';
slouken@25
    97
slouken@25
    98
		if ( !SDL_RWread(src, &ch, 1, 1) ) {
slouken@25
    99
			return -1;
slouken@25
   100
		}
slouken@25
   101
	} while ( isdigit(ch) );
slouken@25
   102
slouken@25
   103
	return(number);
slouken@25
   104
}
slouken@25
   105
slouken@25
   106
SDL_Surface *IMG_LoadPNM_RW(SDL_RWops *src)
slouken@25
   107
{
slouken@25
   108
	SDL_Surface *surface = NULL;
slouken@25
   109
	int width, height;
slouken@25
   110
	int maxval, y, bpl;
slouken@25
   111
	Uint8 *row;
slouken@25
   112
	Uint8 *buf = NULL;
slouken@25
   113
	char *error = NULL;
slouken@25
   114
	Uint8 magic[2];
slouken@25
   115
	int ascii;
slouken@25
   116
	enum { PBM, PGM, PPM } kind;
slouken@25
   117
slouken@25
   118
#define ERROR(s) do { error = (s); goto done; } while(0)
slouken@25
   119
slouken@98
   120
	if ( !src ) {
slouken@98
   121
		/* The error message has been set in SDL_RWFromFile */
slouken@98
   122
		return NULL;
slouken@98
   123
	}
slouken@98
   124
slouken@25
   125
	SDL_RWread(src, magic, 2, 1);
slouken@25
   126
	kind = magic[1] - '1';
slouken@25
   127
	ascii = 1;
slouken@25
   128
	if(kind >= 3) {
slouken@25
   129
		ascii = 0;
slouken@25
   130
		kind -= 3;
slouken@25
   131
	}
slouken@25
   132
slouken@25
   133
	width = ReadNumber(src);
slouken@25
   134
	height = ReadNumber(src);
slouken@25
   135
	if(width <= 0 || height <= 0)
slouken@25
   136
		ERROR("Unable to read image width and height");
slouken@25
   137
slouken@25
   138
	if(kind != PBM) {
slouken@25
   139
		maxval = ReadNumber(src);
slouken@25
   140
		if(maxval <= 0 || maxval > 255)
slouken@25
   141
			ERROR("unsupported PNM format");
slouken@25
   142
	} else
slouken@25
   143
		maxval = 255;	/* never scale PBMs */
slouken@25
   144
slouken@25
   145
	/* binary PNM allows just a single character of whitespace after
slouken@25
   146
	   the last parameter, and we've already consumed it */
slouken@25
   147
slouken@25
   148
	if(kind == PPM) {
slouken@25
   149
		/* 24-bit surface in R,G,B byte order */
slouken@25
   150
		surface = SDL_AllocSurface(SDL_SWSURFACE, width, height, 24,
slouken@25
   151
#if SDL_BYTEORDER == SDL_LIL_ENDIAN
slouken@25
   152
					   0x000000ff, 0x0000ff00, 0x00ff0000,
slouken@25
   153
#else
slouken@25
   154
					   0x00ff0000, 0x0000ff00, 0x000000ff,
slouken@25
   155
#endif
slouken@25
   156
					   0);
slouken@25
   157
	} else {
slouken@25
   158
		/* load PBM/PGM as 8-bit indexed images */
slouken@25
   159
		surface = SDL_AllocSurface(SDL_SWSURFACE, width, height, 8,
slouken@25
   160
					   0, 0, 0, 0);
slouken@25
   161
	}
slouken@25
   162
	if ( surface == NULL )
slouken@25
   163
		ERROR("Out of memory");
slouken@25
   164
	bpl = width * surface->format->BytesPerPixel;
slouken@25
   165
	if(kind == PGM) {
slouken@25
   166
		SDL_Color *c = surface->format->palette->colors;
slouken@25
   167
		int i;
slouken@25
   168
		for(i = 0; i < 256; i++)
slouken@25
   169
			c[i].r = c[i].g = c[i].b = i;
slouken@25
   170
		surface->format->palette->ncolors = 256;
slouken@25
   171
	} else if(kind == PBM) {
slouken@25
   172
		/* for some reason PBM has 1=black, 0=white */
slouken@25
   173
		SDL_Color *c = surface->format->palette->colors;
slouken@25
   174
		c[0].r = c[0].g = c[0].b = 255;
slouken@25
   175
		c[1].r = c[1].g = c[1].b = 0;
slouken@25
   176
		surface->format->palette->ncolors = 2;
slouken@25
   177
		bpl = (width + 7) >> 3;
slouken@25
   178
		buf = malloc(bpl);
slouken@25
   179
		if(buf == NULL)
slouken@25
   180
			ERROR("Out of memory");
slouken@25
   181
	}
slouken@25
   182
slouken@25
   183
	/* Read the image into the surface */
slouken@25
   184
	row = surface->pixels;
slouken@25
   185
	for(y = 0; y < height; y++) {
slouken@25
   186
		if(ascii) {
slouken@25
   187
			int i;
slouken@25
   188
			if(kind == PBM) {
slouken@25
   189
				for(i = 0; i < width; i++) {
slouken@25
   190
					Uint8 ch;
slouken@25
   191
					do {
slouken@25
   192
						if(!SDL_RWread(src, &ch,
slouken@25
   193
							       1, 1))
slouken@25
   194
						       ERROR("file truncated");
slouken@25
   195
						ch -= '0';
slouken@25
   196
					} while(ch > 1);
slouken@25
   197
					row[i] = ch;
slouken@25
   198
				}
slouken@25
   199
			} else {
slouken@25
   200
				for(i = 0; i < bpl; i++) {
slouken@25
   201
					int c;
slouken@25
   202
					c = ReadNumber(src);
slouken@25
   203
					if(c < 0)
slouken@25
   204
						ERROR("file truncated");
slouken@25
   205
					row[i] = c;
slouken@25
   206
				}
slouken@25
   207
			}
slouken@25
   208
		} else {
slouken@25
   209
			Uint8 *dst = (kind == PBM) ? buf : row;
slouken@25
   210
			if(!SDL_RWread(src, dst, bpl, 1))
slouken@25
   211
				ERROR("file truncated");
slouken@25
   212
			if(kind == PBM) {
slouken@25
   213
				/* expand bitmap to 8bpp */
slouken@25
   214
				int i;
slouken@25
   215
				for(i = 0; i < width; i++) {
slouken@25
   216
					int bit = 7 - (i & 7);
slouken@25
   217
					row[i] = (buf[i >> 3] >> bit) & 1;
slouken@25
   218
				}
slouken@25
   219
			}
slouken@25
   220
		}
slouken@25
   221
		if(maxval < 255) {
slouken@25
   222
			/* scale up to full dynamic range (slow) */
slouken@25
   223
			int i;
slouken@25
   224
			for(i = 0; i < bpl; i++)
slouken@25
   225
				row[i] = row[i] * 255 / maxval;
slouken@25
   226
		}
slouken@25
   227
		row += surface->pitch;
slouken@25
   228
	}
slouken@25
   229
done:
slouken@25
   230
	free(buf);
slouken@25
   231
	if(error) {
slouken@25
   232
		SDL_FreeSurface(surface);
slouken@25
   233
		IMG_SetError(error);
slouken@25
   234
		surface = NULL;
slouken@25
   235
	}
slouken@25
   236
	return(surface);
slouken@25
   237
}
slouken@25
   238
slouken@25
   239
#else
slouken@25
   240
slouken@25
   241
/* See if an image is contained in a data source */
slouken@25
   242
int IMG_isPNM(SDL_RWops *src)
slouken@25
   243
{
slouken@25
   244
	return(0);
slouken@25
   245
}
slouken@25
   246
slouken@25
   247
/* Load a PNM type image from an SDL datasource */
slouken@25
   248
SDL_Surface *IMG_LoadPNM_RW(SDL_RWops *src)
slouken@25
   249
{
slouken@25
   250
	return(NULL);
slouken@25
   251
}
slouken@25
   252
slouken@25
   253
#endif /* LOAD_PNM */