/*

IMGLIB: An example image loading library for use with SDL

Copyright (C) 1999 Sam Lantinga

This library is free software; you can redistribute it and/or

modify it under the terms of the GNU Library General Public

License as published by the Free Software Foundation; either

version 2 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

Library General Public License for more details.

You should have received a copy of the GNU Library General Public

License along with this library; if not, write to the Free

Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA

Sam Lantinga

5635-34 Springhouse Dr.

Pleasanton, CA 94588 (USA)

slouken@devolution.com

*/

/* This is a PPM image file loading framework */

#include <stdio.h>

#include <ctype.h>

#include <string.h>

#include "SDL_image.h"

#ifdef LOAD_PPM

/* See if an image is contained in a data source */

int IMG_isPPM(SDL_RWops *src)

{

int is_PPM;

char magic[2];

is_PPM = 0;

if ( SDL_RWread(src, magic, 2, 1) ) {

if ( (strncmp(magic, "P6", 2) == 0) ||

(strncmp(magic, "P3", 2) == 0) ) {

is_PPM = 1;

}

/* P3 is the ASCII PPM format, which is not yet supported */

if ( strncmp(magic, "P3", 2) == 0 ) {

is_PPM = 0;

}

}

return(is_PPM);

}

/* Load a PPM type image from an SDL datasource */

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(0);

}

} 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(0);

}

} while ( isdigit(ch) );

return(number);

}

SDL_Surface *IMG_LoadPPM_RW(SDL_RWops *src)

{

SDL_Surface *surface;

int width, height;

int maxval, x, y;

Uint32 *row;

Uint8 rgb[3];

int read_error;

/* Initialize the data we will clean up when we're done */

surface = NULL;

read_error = 0;

/* Check to make sure we have something to do */

if ( ! src ) {

goto done;

}

/* Read the magic header */

SDL_RWread(src, rgb, 2, 1);

/* Read the width and height */

width = ReadNumber(src);

height = ReadNumber(src);

if ( ! width || ! height ) {

IMG_SetError("Unable to read image width and height");

goto done;

}

/* Read the maximum color component value, and skip to image data */

maxval = ReadNumber(src);

do {

if ( ! SDL_RWread(src, rgb, 1, 1) ) {

IMG_SetError("Unable to read max color component");

goto done;

}

} while ( isspace(rgb[0]) );

SDL_RWseek(src, -1, SEEK_CUR);

/* Create the surface of the appropriate type */

surface = SDL_AllocSurface(SDL_SWSURFACE, width, height, 32,

0x00FF0000,0x0000FF00,0x000000FF,0);

if ( surface == NULL ) {

IMG_SetError("Out of memory");

goto done;

}

/* Read the image into the surface */

for ( y=0; y<surface->h; ++y ) {

row = (Uint32 *)((Uint8 *)surface->pixels + y*surface->pitch);

for ( x=0; x<surface->w; ++x ) {

if ( ! SDL_RWread(src, rgb, 3, 1) ) {

read_error = 1;

goto done;

}

*row++ = ((((Uint32)rgb[0])<<16)|

(((Uint32)rgb[1])<< 8)|

(((Uint32)rgb[2]) ));

}

}

done:

if ( read_error ) {

SDL_FreeSurface(surface);

IMG_SetError("Error reading PPM data");

surface = NULL;

}

return(surface);

}

#else

/* See if an image is contained in a data source */

int IMG_isPPM(SDL_RWops *src)

{

return(0);

}

/* Load a PPM type image from an SDL datasource */

SDL_Surface *IMG_LoadPPM_RW(SDL_RWops *src)

{

return(NULL);

}

#endif /* LOAD_PPM */