private double touchToTumbDistance(double touchX,double normalizedThumbValue){
  return Math.abs(touchX - normalizedToScreen(normalizedThumbValue));
}

private double touchToTumbDistance ( double touchX , double normalizedThumbValue ) { return Math . abs ( touchX - normalizedToScreen ( normalizedThumbValue ) ) ; }
decides if given x - coordinate in screen space needs to be interpreted as " within " the normalized thumb x - coordinate .
