docs: private double getStartAngle() {
          ScaleDirection scaleDirection = gauge.getScaleDirection();
          Pos            knobPosition   = gauge.getKnobPosition();
          switch(knobPosition) {
              case CENTER_LEFT : return ScaleDirection.CLOCKWISE == scaleDirection ? angleRange * 0.5 + 90 : 90 - angleRange * 0.5;
              case CENTER_RIGHT:
              default          : return ScaleDirection.CLOCKWISE == scaleDirection ? angleRange * 0.5 - 90 : 270 -  angleRange * 0.5;
          }
      }