int read_ppmheader(FILE *handle,int *width,int *height,int *maxcolor,int *depth) {
int bytes;
char buf[2];
/* trap bad arguments */
if (!handle || !width || !height || !maxcolor || !depth)
exit(-1);
*width = *height = *maxcolor = *depth = 0;
/* PPM Header Key, 5 or 6 for now (others are possible) */
bytes = fread(buf,1,2,handle);
if ( (bytes < 2) || (buf[0] != 'P') || ((buf[1] != '6' ) && (buf[1] != '5')))
return -1;
if (buf[1]=='6')
*depth=3;
else
return -1;
*width=ppm_getint(handle);
*height=ppm_getint(handle);
*maxcolor=ppm_getint(handle);
if(*width < 0 || *height < 0 || *maxcolor != 255)
return -1;
return 0;
}
/* Read PPM file */
unsigned char* ppm_read(FILE* file,int& cols,int& rows){
unsigned char* pixels,*pix;
unsigned int r,g,b;
int format,maxval;
int row,col;
/* Get format */
format=ppm_readmagicnumber(file);
/* Get size */
cols=ppm_getint(file);
rows=ppm_getint(file);
maxval=ppm_getint(file);
if(maxval<=0 || maxval>1023){
fprintf(stderr,"Illegal maxval value: %d.\n",maxval);
exit(1);
}
/* Create memory */
pixels=(unsigned char*)malloc(3*rows*cols);
if(!pixels){
fprintf(stderr,"Image too big\n");
exit(1);
}
/* Load pixels */
pix=pixels;
switch(format){
case PPM_FORMAT:
for(row=0; row<rows; row++){
for(col=0; col<cols; col++){
r = (255*ppm_getint(file))/maxval;
g = (255*ppm_getint(file))/maxval;
b = (255*ppm_getint(file))/maxval;
*pix++ = r;
*pix++ = g;
*pix++ = b;
}
}
break;
case RPPM_FORMAT:
for(row=0; row<rows; row++){
for(col=0; col<cols; col++){
r = ppm_getrawbyte(file);
g = ppm_getrawbyte(file);
b = ppm_getrawbyte(file);
*pix++ = r;
*pix++ = g;
*pix++ = b;
}
}
break;
default:
fprintf(stderr,"Unknown format.\n");
exit(1);
break;
}
return pixels;
}