/**
  * Create a circle for a range ring.
  *
  * @return New circle.
  */
 protected SurfaceCircle createCircle() {
   SurfaceCircle circle = new SurfaceCircle();
   circle.setDelegateOwner(this.getActiveDelegateOwner());
   circle.setAttributes(this.getActiveShapeAttributes());
   return circle;
 }