/*    SDL_image:  An example image loading library for use with SDL    Copyright (C) 1997-2006 Sam Lantinga    This library is free software; you can redistribute it and/or    modify it under the terms of the GNU Lesser General Public    License as published by the Free Software Foundation; either    version 2.1 of the License, or (at your option) any later version.    This library is distributed in the hope that it will be useful,    but WITHOUT ANY WARRANTY; without even the implied warranty of    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU    Lesser General Public License for more details.    You should have received a copy of the GNU Lesser General Public    License along with this library; if not, write to the Free Software    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA    Sam Lantinga    slouken@libsdl.org*//* * PNM (portable anymap) image loader: * * Supports: PBM, PGM and PPM, ASCII and binary formats * (PBM and PGM are loaded as 8bpp surfaces) * Does not support: maximum component value > 255 */#include <stdio.h>#include <stdlib.h>#include <ctype.h>#include <string.h>#include "SDL_image.h"#ifdef LOAD_PNM/* See if an image is contained in a data source */int IMG_isPNM(SDL_RWops *src){	int start;	int is_PNM;	char magic[2];	if ( !src )		return 0;	start = SDL_RWtell(src);	is_PNM = 0;	if ( SDL_RWread(src, magic, sizeof(magic), 1) ) {		/*		 * PNM magic signatures:		 * P1	PBM, ascii format		 * P2	PGM, ascii format		 * P3	PPM, ascii format		 * P4	PBM, binary format		 * P5	PGM, binary format		 * P6	PPM, binary format		 * P7	PAM, a general wrapper for PNM data		 */		if ( magic[0] == 'P' && magic[1] >= '1' && magic[1] <= '6' ) {			is_PNM = 1;		}	}	SDL_RWseek(src, start, SEEK_SET);	return(is_PNM);}/* read a non-negative integer from the source. return -1 upon error */static int ReadNumber(SDL_RWops *src){	int number;	unsigned char ch;	/* Initialize return value */	number = 0;	/* Skip leading whitespace */	do {		if ( ! SDL_RWread(src, &ch, 1, 1) ) {			return(0);		}		/* Eat comments as whitespace */		if ( ch == '#' ) {  /* Comment is '#' to end of line */			do {				if ( ! SDL_RWread(src, &ch, 1, 1) ) {					return -1;				}			} while ( (ch != '\r') && (ch != '\n') );		}	} while ( isspace(ch) );	/* Add up the number */	do {		number *= 10;		number += ch-'0';		if ( !SDL_RWread(src, &ch, 1, 1) ) {			return -1;		}	} while ( isdigit(ch) );	return(number);}SDL_Surface *IMG_LoadPNM_RW(SDL_RWops *src){	int start;	SDL_Surface *surface = NULL;	int width, height;	int maxval, y, bpl;	Uint8 *row;	Uint8 *buf = NULL;	char *error = NULL;	Uint8 magic[2];	int ascii;	enum { PBM, PGM, PPM, PAM } kind;#define ERROR(s) do { error = (s); goto done; } while(0)	if ( !src ) {		/* The error message has been set in SDL_RWFromFile */		return NULL;	}	start = SDL_RWtell(src);	SDL_RWread(src, magic, 2, 1);	kind = magic[1] - '1';	ascii = 1;	if(kind >= 3) {		ascii = 0;		kind -= 3;	}	width = ReadNumber(src);	height = ReadNumber(src);	if(width <= 0 || height <= 0)		ERROR("Unable to read image width and height");	if(kind != PBM) {		maxval = ReadNumber(src);		if(maxval <= 0 || maxval > 255)			ERROR("unsupported PNM format");	} else		maxval = 255;	/* never scale PBMs */	/* binary PNM allows just a single character of whitespace after	   the last parameter, and we've already consumed it */	if(kind == PPM) {		/* 24-bit surface in R,G,B byte order */		surface = SDL_AllocSurface(SDL_SWSURFACE, width, height, 24,#if SDL_BYTEORDER == SDL_LIL_ENDIAN					   0x000000ff, 0x0000ff00, 0x00ff0000,#else					   0x00ff0000, 0x0000ff00, 0x000000ff,#endif					   0);	} else {		/* load PBM/PGM as 8-bit indexed images */		surface = SDL_AllocSurface(SDL_SWSURFACE, width, height, 8,					   0, 0, 0, 0);	}	if ( surface == NULL )		ERROR("Out of memory");	bpl = width * surface->format->BytesPerPixel;	if(kind == PGM) {		SDL_Color *c = surface->format->palette->colors;		int i;		for(i = 0; i < 256; i++)			c[i].r = c[i].g = c[i].b = i;		surface->format->palette->ncolors = 256;	} else if(kind == PBM) {		/* for some reason PBM has 1=black, 0=white */		SDL_Color *c = surface->format->palette->colors;		c[0].r = c[0].g = c[0].b = 255;		c[1].r = c[1].g = c[1].b = 0;		surface->format->palette->ncolors = 2;		bpl = (width + 7) >> 3;		buf = malloc(bpl);		if(buf == NULL)			ERROR("Out of memory");	}	/* Read the image into the surface */	row = surface->pixels;	for(y = 0; y < height; y++) {		if(ascii) {			int i;			if(kind == PBM) {				for(i = 0; i < width; i++) {					Uint8 ch;					do {						if(!SDL_RWread(src, &ch,							       1, 1))						       ERROR("file truncated");						ch -= '0';					} while(ch > 1);					row[i] = ch;				}			} else {				for(i = 0; i < bpl; i++) {					int c;					c = ReadNumber(src);					if(c < 0)						ERROR("file truncated");					row[i] = c;				}			}		} else {			Uint8 *dst = (kind == PBM) ? buf : row;			if(!SDL_RWread(src, dst, bpl, 1))				ERROR("file truncated");			if(kind == PBM) {				/* expand bitmap to 8bpp */				int i;				for(i = 0; i < width; i++) {					int bit = 7 - (i & 7);					row[i] = (buf[i >> 3] >> bit) & 1;				}			}		}		if(maxval < 255) {			/* scale up to full dynamic range (slow) */			int i;			for(i = 0; i < bpl; i++)				row[i] = row[i] * 255 / maxval;		}		row += surface->pitch;	}done:	free(buf);	if(error) {		SDL_RWseek(src, start, SEEK_SET);		if ( surface ) {			SDL_FreeSurface(surface);			surface = NULL;		}		IMG_SetError(error);	}	return(surface);}#else/* See if an image is contained in a data source */int IMG_isPNM(SDL_RWops *src){	return(0);}/* Load a PNM type image from an SDL datasource */SDL_Surface *IMG_LoadPNM_RW(SDL_RWops *src){	return(NULL);}#endif /* LOAD_PNM */