/* cs545 F97/98, file add_header.c - add a header to a digital image */
	/* this program is useful if you have a digital image that you want to put into cs545 format */
/* Written by Norman Wittels */
/* 09Apr97	first version */
/* 30Apr97	Updated to handle 24-bit rgb color */

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include <math.h>
#include <limits.h>
#include <time.h>
#include <float.h>

#define FILE_NAME_LENGTH 51 /* length of a file name */
#define MIN(a,b) ((a)<(b) ? (a) : (b)) /* return the minimum value */

typedef struct digital_image
	{
	unsigned int cols; /* digital image size */
	unsigned int rows;
	unsigned int colors; /* 1 for gray scale; 3 for color */
	unsigned char *image; /* the image array */
	struct digital_image *next; /* for linked list */
	} digital_image; /* newly defined type */

/* prototypes */
int write_digital_image(digital_image *im,FILE *f);
void write_user_specified_digital_image_file(digital_image *);


int main()
	{
	FILE *f; /* the file */
	digital_image the_image;
	char file_name[FILE_NAME_LENGTH];
	int cols, rows, colors;
	long int size;
	
	printf("Please enter image width and height (pixels) and number of colors (1 or 3)\n");
	scanf("%d %d %d", &cols, &rows, &colors);
	printf("What is the name of the input raw data file?: ");
	scanf("%s",file_name); /* read file name */
	if ((f = fopen(file_name,"rb"))==NULL) /* could not open file */
		{
		printf("Could not open input file\n");
		return 0;
		} /* end if(fopen()) */

	the_image.cols = cols; the_image.rows = rows; the_image.colors = colors;
	size = (long int) cols * (long int) rows * (long int) colors;
	if ((the_image.image = malloc(size)) == NULL)
		{
		printf("could not allocate memory for digital image\n");
		return 0;
		} /* end if(the_image.image) */
		
	if (fread(the_image.image, 1, size, f) != size)
		{
		printf("Difficulty reading the image. Are you sure the size is correct?\n");
		free(the_image.image);
		return 0;
		} /* end if(fread()) */
	fclose(f);

	write_user_specified_digital_image_file(&the_image);
	printf("goodbye\n");

	} /* end main() */


/*** write a digital image into a file ***/
int write_digital_image(digital_image *im,FILE *f)
	{
	unsigned char header[6];
	unsigned int size = im->rows * im->cols * im->colors; /* image bytes */
	if (im == NULL || f == NULL) return 1; /* error indicator */
	header[0] = MIN((im->cols / 256),255); /* high order bits */ 
	header[1] = im->cols % 256; /* low order bits */
	header[2] = MIN((im->rows / 256),255); /* high order bits */
	header[3] = im->rows % 256; /* low order bits */
	header[4] = MIN((im->colors / 256),255); /* high order bits */
	header[5] = im->colors % 256; /* low order bits */
	if (fwrite(header,1,6,f) != 6) return 1; /* write the header */
	if (fwrite(im->image,1, size,f) != size) return 1; /* write the image data */
	return 0; /* happy return value */
	} /* end write_digital_image() */

/*** query user and write digital image file ***/
void write_user_specified_digital_image_file(digital_image *im)
	{
	FILE *F; /* the file */
	char file_name[FILE_NAME_LENGTH];
	printf("What is the name of the digital image output file?: ");
	scanf("%s",file_name); /* read output file name */
	if ((F = fopen(file_name,"wb"))==NULL) /* open output file */
		{
		printf("Could not open output file\n");
		return;
		} /* end if() */
	if (write_digital_image(im,F)) printf("Could not write output file\n");
	return;
	} /* end write_user_specified_digital_image_file() */


/* Copyright 1997, Norman Wittels */