Prevent JFreeChart DialPlot wrapping around with large values?

Question

My data value can vary between 0-100. I would like to display a JFreeChart DialPlot showing the range 0-30, where values larger than 30 are displayed by having the needle fixed at 30 but the true value displayed on the dial.

The image below shows what my example code currently produces:

Current Output

Here I am displaying the value 50. The dial has wrapped around to point at 14. I would prefer it to be set to the maximum (30), much like with a fuel dial:

Desired Output

Is this possible with JFreeChart? SSCCE code below.

public class DemoChartProblem {

  private final DefaultValueDataset dataset = new DefaultValueDataset(50);
  private final JFrame frame = new JFrame();

  public static void main(String[] args) throws Exception {
    new DemoChartProblem();
  }

  public DemoChartProblem() {
    frame.setPreferredSize(new Dimension(300, 300));
    frame.add(buildDialPlot(0, 30, 5));
    frame.pack();
    frame.setLocationRelativeTo(null);
    frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);

    SwingUtilities.invokeLater(new Runnable() {
      @Override
      public void run() {
        frame.setVisible(true);
      }
    });
  }

  private ChartPanel buildDialPlot(int minimumValue, int maximumValue,
      int majorTickGap) {

    DialPlot plot = new DialPlot(dataset);
    plot.setDialFrame(new StandardDialFrame());
    plot.addLayer(new DialValueIndicator(0));
    plot.addLayer(new DialPointer.Pointer());

    StandardDialScale scale = new StandardDialScale(minimumValue, maximumValue,
        -120, -300, majorTickGap, majorTickGap - 1);
    scale.setTickRadius(0.88);
    scale.setTickLabelOffset(0.20);
    plot.addScale(0, scale);

    return new ChartPanel(new JFreeChart(plot));
  }
}

Answer 1

I would be interested to hear if there are better methods.

The disparity between the DialValueIndicator and the maximumValue may be confusing. As an alternative, signify distinct ranges using StandardDialRange:

int redLine = 3 * maximumValue / 5;
plot.addLayer(new StandardDialRange(minimumValue, redLine, Color.blue));
plot.addLayer(new StandardDialRange(redLine, maximumValue, Color.red));

Setting the frame's preferred size is problematic. Instead, override the getPreferredSize() method of ChartPanel:

return new ChartPanel(new JFreeChart(plot)) {
    @Override
    public Dimension getPreferredSize() {
        return new Dimension(300, 300);
    }
};