code: protected double computeRippleRadius() {
          double width2 = control.getLayoutBounds().getWidth() * control.getLayoutBounds().getWidth();
          double height2 = control.getLayoutBounds().getHeight() * control.getLayoutBounds().getHeight();
          return Math.min(Math.sqrt(width2 + height2), RIPPLE_MAX_RADIUS) * 1.1 + 5;
      }
docs: compute the ripple radius
  @return the ripple radius size