/*******************************************************************************
	TITLE:	func.c
	AUTHOR:	Ann Li
	DATE: 10/1/00
	COMPILER/SYSTEM: MSVC6.0/NT
	PURPOSE: Using recursion and lined stack to find the connected components in an image
	ARGUMENTS: 
**********************************************************************************/
#include "header.h"
#include "func.h"

/////////////////////////////////////////////////////////////////

// common files for both versions
//	TITLE: readHeader
//   PURPOSE: Read in the information of column, row, and max value of an image.
//   ARGUMENTS:			*fp: points to the input pmg file 
//										*p_header: output parameter. used to store the inforamation scanned from image file
// file stream point as a parameter, more flexible, I think
void readHeader(FILE* fp, header* p_header )
{
	char buf[MAX_LINE];
	int col, row, max;

	// check format sign
	fscanf(fp,"%s",buf);
	if( strcmp(buf,"P2")!=0 ){
		perror("The format is incorrect: it's not the beginning of a PGM file.");
		exit(1);
	}

	// ignore statement
	fscanf(fp,"%s", buf);
	while ( buf[0]=='#' ){
		fgets(buf,MAX_LINE,fp);		// newline character included
		fscanf(fp,"%s",buf);
	}

	// no statement now. column already read
	col = atoi(buf);
	fscanf(fp,"%d",&row);
	fscanf(fp,"%d",&max);

	p_header->col = col;
	p_header->row = row;
	p_header->max_value = max;

}


//	TITLE: readImage
//   PURPOSE: Read in the content of an image
//   ARGUMENTS:			*inputfile: the file name of the image
//										*im: output parameter. used to store the content read in from input file

void readImage( char* inputfile, image* im )
{
	int i, j;
	FILE *fp;

	if ( !(fp=fopen(inputfile, "r")) ){
		perror("The input file cann't be opened");
		exit(1);
	}

	readHeader(fp,&im->header);

	im->p_array = malloc(sizeof(int*)*im->header.row);
	for ( i=0; i<im->header.row; i++ )
		im->p_array[i] = malloc(sizeof(int)*im->header.col);

	for(i = 0; i < im->header.row; i++)
		for(j = 0; j < im->header.col; j++)
			fscanf(fp,"%d",&im->p_array[i][j]);

	fclose(fp);
}

//	TITLE: converPGM
//   PURPOSE: Strech out the input image to use the full range of gray tone
//   ARGUMENTS:			num_components: Number of connected components found 
//										*im: in/output parameter. 

void convertPGM(int num_components, image *im)
{
	int i, j;
	int row, col;
	int offset;

	row = im->header.row;
	col = im->header.col;

	if(num_components == 0)
		return;
	offset = OUTPUT_MAX_VALUE / num_components;

	for(i = 0; i < row; i++)
		for(j = 0; j < col; j++)
			im->p_array[i][j] *= offset;
}