防止JFreeChart DialPlot包含大值？

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.

我的数据值可以在0到100之间变化。我想显示一个显示范围0-30的JFreeChart DialPlot，其中通过将针固定在30但显示在表盘上的真实值显示大于30的值。

The image below shows what my example code currently produces:

下图显示了我的示例代码当前生成的内容：

Current Output

电流输出

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:

这里我显示的是值50.表盘已经四处转动指向14.我希望它设置为最大值（30），就像燃料表盘一样：

Desired Output

期望的输出

Is this possible with JFreeChart? SSCCE code below.

这可能与JFreeChart一起使用吗？下面的SSCCE代码。

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));
  }
}

2 个解决方案

#1

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

我很想知道是否有更好的方法。

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

DialValueIndicator和maximumValue之间的差异可能令人困惑。或者，使用StandardDialRange表示不同的范围：

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:

设置框架的首选尺寸是有问题的。而是覆盖ChartPanel的getPreferredSize（）方法：

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

#2

I've just figured out a work-around answer, but I would be interested to hear if there are better methods.

我刚刚想出了一个解决方法，但我很想知道是否有更好的方法。

In this solution, I maintain two DefaultValueDataset objects. One contains the real value and one contains a constrained value, no larger than my dial limit. The needle is associated with the constrained set and the dial value is linked to the real value.

在此解决方案中，我维护两个DefaultValueDataset对象。一个包含实际值，一个包含约束值，不大于我的拨号限制。针与受约束的组相关联，并且刻度盘值与实际值相关联。

public class DemoChartProblem {

  private static final int DISPLAY_MAX = 30;
  private final DefaultValueDataset dataset = new DefaultValueDataset();
  private final DefaultValueDataset displayDataset = new DefaultValueDataset();
  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, DISPLAY_MAX, 5));
    frame.pack();
    frame.setLocationRelativeTo(null);
    frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);

    setValue(50);

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

  private void setValue(int value) {
    dataset.setValue(value);
    displayDataset.setValue(Math.min(DISPLAY_MAX, value));
  }

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

    DialPlot plot = new DialPlot();
    plot.setDataset(0, dataset);
    plot.setDataset(1, displayDataset);

    plot.setDialFrame(new StandardDialFrame());

    // value indicator uses the real data set
    plot.addLayer(new DialValueIndicator(0));

    // needle uses constrained data set
    plot.addLayer(new DialPointer.Pointer(1));

    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));
  }
}