public void line(double x0,double y0,double x1,double y1){
  offscreen.draw(new Line2D.Double(scaleX(x0),scaleY(y0),scaleX(x1),scaleY(y1)));
  draw();
}

public void line ( double x0 , double y0 , double x1 , double y1 ) { offscreen . draw ( new Line2D . Double ( scaleX ( x0 ) , scaleY ( y0 ) , scaleX ( x1 ) , scaleY ( y1 ) ) ) ; draw ( ) ; }
draws a line from ( x0 , y0 ) to ( x1 , y1 ) .
