更新 JFreeChart 时保留用户缩放状态

Question

我正在使用JFreeChart 1.0.14 绘制XYSeries。我确实可以访问所有元素（ChartPanel、JFreeChart、XYSeriesCollection、XYSeries）。不时有新数据要绘制，所以我更新我的系列（为简单起见，我们假设只有一个系列）：

SwingUtilities.invokeLater(new Runnable() {
    @Override
    public void run() {
        XYSeries xyData = new XYSeries("Trace");
        for (int i = 0; i < n; i++)
            xyData.add(data[0][i], data[1][i], false);

        collection.removeAllSeries();
        collection.addSeries(xyData);

        chart.getXYPlot().setRangeAxis(createNewAxis());
    }
});

这一切都很好。但我有一个问题。用户可以通过在绘图中拖动来进行缩放。每次都会重置此缩放，更新数据。这是有道理的，因为我创建了新轴。如何保留用户缩放状态？由于用户还可以选择自动量程/量程，我不想对这些 (Axis#setRange/setAutoRange) 进行某种破解。我发现了一些关于ChartPanel#getScaleX() 的信息。但这始终是上述invokeLater 开头的1.0。我也找不到任何ChartPanel.setScaleX。

我做错了什么还是有另一种方法可以在不更改轴的范围/自动范围行为的情况下保留用户缩放状态？

顺便说一句：我必须重新创建坐标区，因为它们还可以在 logscale 和 linscale 之间切换。

Answer 1

我不认为每次添加新点或调用removeAllSeries()时都需要创建新的XYSeries xyData

这个例子展示了如何将动态数据添加到XYSeriesCollection

import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JPanel;

import org.jfree.chart.ChartFactory;
import org.jfree.chart.ChartPanel;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.axis.LogAxis;
import org.jfree.chart.axis.NumberAxis;
import org.jfree.chart.axis.ValueAxis;
import org.jfree.chart.plot.PlotOrientation;
import org.jfree.chart.plot.XYPlot;
import org.jfree.data.time.Millisecond;
import org.jfree.data.xy.XYDataset;
import org.jfree.data.xy.XYSeries;
import org.jfree.data.xy.XYSeriesCollection;
import org.jfree.ui.ApplicationFrame;
import org.jfree.ui.RefineryUtilities;

/**
 * A demonstration application showing a XYseries chart where you can
 * dynamically add (random) data by clicking on a button.
 */
public class DynamicDataDemo1 extends ApplicationFrame {
    /**
     * Constructs a new demonstration application.
     * 
     * @param title
     *            the frame title.
     */
    public DynamicDataDemo1(String title) {
        super(title);
        MyDemoPanel demoPanel = new MyDemoPanel();
        setContentPane(demoPanel);
    }



    static class MyDemoPanel extends DemoPanel implements ActionListener {
        /** The time series data. */

        /** The most recent value added. */
        private double lastValue1 = 200.0;
        private double lastValue2 = 200.0;
        private XYPlot plot;
        private boolean logAxis = false;
        private String lastSeries = "";
        private final XYSeriesCollection dataset;
        private static String SERIES_NAME =  "Random Data ";
        private static int seriesNumber =  0;
        /**
         * Creates a new instance.
         */
        public MyDemoPanel() {
            super(new BorderLayout());
            lastSeries = SERIES_NAME + (seriesNumber++);
            XYSeries series = new XYSeries(lastSeries);
            dataset = new XYSeriesCollection(series);
            ChartPanel chartPanel = new ChartPanel(createChart(dataset));
            chartPanel.setPreferredSize(new java.awt.Dimension(500, 270));
            addChart(chartPanel.getChart());
            JPanel buttonPanel = new JPanel();
            buttonPanel.setBorder(BorderFactory.createEmptyBorder(4, 4, 4, 4));
            JButton button = new JButton("Add New Data Item");
            button.setActionCommand("ADD_DATA");
            button.addActionListener(this);
            buttonPanel.add(button);
            {
                JButton button2 = new JButton("Switch Axis");
                button2.setActionCommand("SWITCH_AXIS");
                button2.addActionListener(this);
                buttonPanel.add(button2);
            }
            {
                JButton button2 = new JButton("Add Series");
                button2.setActionCommand("ADD_SERIES");
                button2.addActionListener(this);
                buttonPanel.add(button2);
            }
            add(chartPanel);
            add(buttonPanel, BorderLayout.SOUTH);
        }

        private JFreeChart createChart(XYDataset dataset) {
            JFreeChart result = ChartFactory.createXYLineChart("Dynamic Data Demo", "Time", "Value", dataset, PlotOrientation.VERTICAL, true, true, false);
            plot = (XYPlot) result.getPlot();
            ValueAxis domainAxis = plot.getDomainAxis();
            domainAxis.setAutoRange(true);
            final ValueAxis rangeAxis = plot.getRangeAxis();
            rangeAxis.setAutoRange(true);
            return result;
        }

        @Override
        public void actionPerformed(ActionEvent e) {
            if (e.getActionCommand().equals("ADD_DATA")) {
                double factor1 = 0.90 + 0.2 * Math.random();
                double factor2 = 0.90 + 0.2 * Math.random();
                this.lastValue1 = this.lastValue1 * factor1;
                this.lastValue2 = this.lastValue2 * factor2;
                Millisecond now = new Millisecond();
                System.out.println("Now = " + now.toString());
                XYSeries series = dataset.getSeries(lastSeries);
                series.add(this.lastValue2, this.lastValue1);
            } else if (e.getActionCommand().equals("SWITCH_AXIS")) {
                if (!logAxis) {
                    LogAxis xAxis = new LogAxis("X");
                    LogAxis yAxis = new LogAxis("Y");               
                    updateZoom(xAxis,yAxis);
                logAxis = true;
                } else {
                    NumberAxis xAxis = new NumberAxis("X");
                    NumberAxis yAxis = new NumberAxis("Y");
                    updateZoom(xAxis,yAxis);
                    logAxis = false;
                }
            } else if (e.getActionCommand().equals("ADD_SERIES")) {
                lastSeries = SERIES_NAME + (seriesNumber++);
                XYSeries series = new XYSeries(lastSeries);
                dataset.addSeries(series);
            }
        }

        private void (ValueAxis xAxis, ValueAxis yAxis) {
            double domainMin = plot.getDomainAxis().getRange().getLowerBound();
            double domainMax = plot.getDomainAxis().getRange().getUpperBound();
            System.out.println(domainMin + "," + domainMax);

            double rangeMin = plot.getRangeAxis().getRange().getLowerBound();
            double rangeMax = plot.getRangeAxis().getRange().getUpperBound();
            System.out.println(rangeMin + "," + rangeMax);                  

            xAxis.setRange(domainMin, domainMax);
            plot.setDomainAxis(xAxis);
            yAxis.setRange(rangeMin, rangeMax);
            plot.setRangeAxis(yAxis);

        }
    }

    public static JPanel createDemoPanel() {
        return new DynamicDataDemo1.MyDemoPanel();
    }

    public static void main(String[] args) {
        DynamicDataDemo1 demo = new DynamicDataDemo1("JFreeChart: Dynamic XYSeries");
        demo.pack();
        RefineryUtilities.centerFrameOnScreen(demo);
        demo.setVisible(true);
    }
}

本示例基于 JFreeChart：DynamicDataDemo1.java。每次单击“添加新数据项”时，都会添加一个新点。在此示例中，当您添加数据点时将保留缩放，但在更改轴时不会保留。

要在将轴从正常比例更改为对数比例时保持缩放，反之亦然，使用两个轴的当前上限和下限，并设置新轴的Range，如updateZoom所示

Answer 2

我不知道如何将“用户缩放状态”从一个轴转移到另一个轴。因此，如果不需要，我确保不要刷新轴（=对数/线性之间的比例没有变化）。如果有变化，用户缩放状态将丢失，这是不幸的。但这不会经常发生，并且是用户控制的，因此用户可能会接受缩放状态重置。