/********
*
*  ppm_gl_io.c
*
*  Description:
*    Routines for loading and saving images between GLCanvases and 
*    raw PPM format image files.
*
*  Author: Chase Garfinkle
*  Date of Version: January 16, 1994
*
*********/

#include <stdio.h>
#include <stdlib.h>
#include "ppm_gl_io.h"

int ppmLoadCanvas(char *filename, struct GLCanvas *canvas)
{
    FILE *fp;
    int width, height, size,  i;
	unsigned int *buf;
    char data[1];

    if ((fp = fopen(filename, "r")) == NULL) {
	fprintf(stderr, "%s: error opening file.\n", filename);
	return 0;
    }

    fscanf(fp, "P6\n");
    fscanf(fp, "#%*[^\n]\n");
/*    fscanf(fp, "#%*[^\n]\n");*/
    fscanf(fp, "%d", &width);
    fscanf(fp, "%d", &height);
    fscanf(fp, "%*d\n");

    size = width * height;
    canvas->width = width;
    canvas->height = height;
    canvas->pixels = (unsigned int *) malloc(size * sizeof(int));

    buf = canvas->pixels;
    for (i = 0; i < size; i++, buf++) {
	fread(data, 1, 1, fp);
	*buf = *data;
	fread(data, 1, 1, fp);
	*buf |= (*data << 8);
	fread(data, 1, 1, fp);
	*buf |= (*data << 16);
    }

    return 1;
}


int ppmSaveCanvas(char *filename, struct GLCanvas *canvas)
{
    FILE *fp;
    int width, height, size,  i;
	unsigned int *buf;
    char data[1];

    if ((fp = fopen(filename, "w")) == NULL) {
	fprintf(stderr, "%s: error opening file.\n", filename);
	return 0;
    }
    
    width = canvas->width;
    height = canvas->height;
    size = width*height;
    fprintf(fp, "P6\n");
    fprintf(fp, "# Comment Line\n");
    fprintf(fp, "%d %d\n", width, height);
    fprintf(fp, "255\n");

    buf = canvas->pixels;
    for (i = 0; i < size; i++, buf++) {
	data[0] = (*buf) & 0xff;
	fwrite(data, 1, 1, fp);
	data[0] = ((*buf) >> 8) & 0xff;
	fwrite(data, 1, 1, fp);
	data[0] = ((*buf) >> 16) & 0xff;
	fwrite(data, 1, 1, fp);
    }

    fclose(fp);
    return 1;
}