Thread: Help required in image filling program.

Hello,
The task is to print out a screen of pixels ' . ' and draw a circle using '*' and then fill it with '*' .
My program does the first two task perfectly but there seems be a problem with the third part (filling) . Instead of filling only inside the figure it fills the whole screen.
This program implements 8-connectivity algorithm , I have tried implementing 4-connectivity also but that too does'nt work. If I try printing a large screen then it simply then program simply exits with and error message.
Please Help me with this . I am a beginner in C , so please be a little more descriptive while explaining solutions.

THANKS

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <math.h>

Code:

struct screen
{
	int w;
	int h;
	char** mat;
};

void fill_2(struct screen* scr,int x,int y)
{
	int x1,xx,y1,yy ;
	scr->mat[x][y] = '*' ;
	for(xx = -1; xx <= 1; xx++)
		for(yy = -1; yy<=1; yy++)
		{
			x1 = x + xx ;
			y1 = y + yy ;
			if((x1 >= 0) && (x1 < scr->w))
				if((y1 >= 0) && (y1 < scr->h))
					if(scr->mat[x1][y1] == '.')
						fill_2(scr,x1,y1);
		}
}

void draw_circle(struct screen* scr,int x,int y, int r)
{
	int deg = 0,i,j;
	float th;
	while(deg <= 360)
	{
		th = (3.14*deg)/180 ;
		i  = x + r*cos(th) + 0.5 ;
		j  = y + r*sin(th) + 0.5 ;
		scr->mat[i][j] = '*' ;
		deg = deg+5;
	}
}

int main(void)
{
	int x,y,r,i,j;
	struct screen scr;
	printf("Enter screen width and height\n");
	scanf("%d %d", &scr.w,&scr.h);
	scr.mat = (char**)malloc(scr.h * sizeof(char*));
	for(i=0; i < scr.h ; i++)
		scr.mat[i] = (char*)malloc((scr.w + 1) * sizeof(char));
	for(i=0 ; i < scr.h; i++)
	{
		for(j=0; j < scr.w; j++)
			scr.mat[i][j] = '.' ;
		scr.mat[i][scr.w] = '\0';
	}
	for(i=0; i < scr.h; i++)
		printf("%s\n",scr.mat[i]);

	printf("Enter circle centre and radius\n");
	scanf("%d %d %d",&x,&y,&r);
	draw_circle(&scr,x,y,r);
                for(i=0; i < scr.h; i++)
		printf("%s\n",scr.mat[i]);

	printf("Enter cordinates\n");
	scanf("%d %d",&x,&y);
	fill_2(&scr,x,y);
                for(i=0; i < scr.h; i++)
		printf("%s\n",scr.mat[i]);
	
	return 0;
}