code: private void setBar(final double VALUE) {
          double factor  = VALUE / gauge.getRange();
  
          if (gauge.isGradientBarEnabled() && !gauge.getGradientBarStops().isEmpty()) {
              Color color = gauge.getGradientLookup().getColorAt(factor);
              fluidBody.setFill(color);
              fluidTop.setFill(color.darker());
          } else if (gauge.getSectionsVisible() && !sections.isEmpty()) {
              int listSize = sections.size();
              for (int i = 0 ; i < listSize ; i++) {
                  if (sections.get(i).contains(VALUE)) {
                      Color color = sections.get(i).getColor();
                      fluidBody.setFill(color);
                      fluidTop.setFill(color.darker());
                      break;
                  }
              }
          }
  
          double centerY = height * 0.71111111 - factor * 0.58888889 * height;
          fluidTop.setCenterY(centerY);
  
          fluidUpperRight.setControlY1(centerY + 0.58888889 * height);
          fluidUpperRight.setControlY2(centerY);
          fluidUpperRight.setY(centerY);
  
          fluidUpperCenter.setControlY1(centerY + 0.06666667 * height);
          fluidUpperCenter.setControlY2(centerY + 0.12222222 * height);
          fluidUpperCenter.setY(centerY + 0.12222222 * height);
  
          fluidUpperLeft.setControlY1(centerY + 0.12222222 * height);
          fluidUpperLeft.setControlY2(centerY + 0.06666667 * height);
          fluidUpperLeft.setY(centerY);
  
          valueText.setText(String.format(locale, formatString, factor * 100));
          valueText.relocate((width - valueText.getLayoutBounds().getWidth()) * 0.5, (height - valueText.getLayoutBounds().getHeight()) * 0.5);
      }
docs: ******************** Private Methods ***********************************