void drawline(){
	int x = _x, y = _y,fl=0;
	int dx = _abs(_x2 - x), dy=_abs(_y2 - y);
	int sy , sx;
	if (dx){
		sx = (_x2 - x) / dx;
	} else {
		sx = 0;
	}
	if (dy){
		sy = (_y2 - y) / dy;
	} else {
		sy = 0;
	}
	if (dy > dx){
		int t = dx;
		dx = dy;
		dy = t;
		fl = 1;
	} 
	int e = - dx,de=2*dy;
	for (int i = 0; i < dx; i++){
		SetPixel(x, y);
		e += de;
		if (fl){
			y += sy;
		} else {
			x += sx;
		}
		while (e >= 0){
			if (fl){
				x += sx;
			}
			else {
				y += sy;
			}
			e -= 2 * dx;
		}
	}
}