java JFreeChart：通过鼠标单击获取数据源值

JFreeChart : obtain data source value on mouse click

提问by Omry Yadan

I have a JFreeChart instance that displays process memory status, initialized as follows:

我有一个显示进程内存状态的 JFreeChart 实例，初始化如下：

m_data = new TimeSeriesCollection();
TimeSeries vmsize = new TimeSeries("VMSize");
TimeSeries resident = new TimeSeries("Resisdent");
TimeSeries shared = new TimeSeries("Shared memory");
TimeSeries code = new TimeSeries("Code");
TimeSeries data = new TimeSeries("Data");
m_data.addSeries(vmsize);
m_data.addSeries(resident);
m_data.addSeries(shared);
m_data.addSeries(code);
m_data.addSeries(data);
JFreeChart chart = ChartFactory.createTimeSeriesChart("Memory usage", "Time", "Size", m_data, true, true, false);
m_chart = new ChartPanel(chart);

Later I add values to each TimeSeries in the TimeSeriesCollection. I would like to somehow know - when the user clicks on the Chart - either what time associated with that columm, or even better - what is the index of the value.

稍后我将值添加到 TimeSeriesCollection 中的每个 TimeSeries。我想知道 - 当用户点击图表时 - 与该列关联的时间，或者更好 - 值的索引是什么。

I looked at the JFreeChart and ChartMouseListener classes, but I could not figure out how to do that (also the documentation of JFreeChart is annoyingly scarce, I guess they are trying to get people to buy their developer's guide).

我查看了 JFreeChart 和 ChartMouseListener 类，但我不知道如何做到这一点（JFreeChart 的文档也非常稀缺，我猜他们正试图让人们购买他们的开发人员指南）。

回答by user482963

if you click dead on the item, the event.getEntity() function returns XYItem and then from there onwards

如果您在项目上单击死，则 event.getEntity() 函数返回 XYItem，然后从那里开始

XYItemEntity xyitem=(XYItemEntity) event.getEntity(); // get clicked entity
XYDataset dataset = (XYDataset)xyitem.getDataset(); // get data set
System.out.println(xyitem.getItem()+" item of "+xyitem.getSeriesIndex()+"series");
System.out.println(dataset.getXValue(xyitem.getSeriesIndex(), xyitem.getItem()));
System.out.println(dataset.getYValue(xyitem.getSeriesIndex(), xyitem.getItem()));
Comparable comparable=dataset.getSeriesKey(0);
XYPlot xyplot = (XYPlot) event.getChart().getPlot();
System.out.println(xyplot.getRangeCrosshairValue());

however incase you do not click on the item itself but your crosshair is set to auto lock on data, in such case the crosshair will move to nearest item but since the item has not been clicked, you will not be able to get the XYItem and hence you cannot know the series and item index, to solve this problem there is this code below, it should be put in the catch clause while the above mentioned code should be in try clause

但是，如果您没有点击项目本身，但您的十字准线设置为自动锁定数据，在这种情况下，十字准线将移动到最近的项目，但由于尚未点击该项目，您将无法获得 XYItem 和因此你无法知道系列和项目索引，为了解决这个问题，下面有这段代码，它应该放在catch子句中，而上面提到的代码应该在try子句中

first define a function which will take crosshair value at domain and range and also Xydataset, this functions returns an inner class object that groups item index and series index

首先定义一个函数，它将在域和范围以及 Xydataset 处获取十字准线值，该函数返回一个内部类对象，该对象将项目索引和系列索引分组

public static SeriesAndItemIndex getItemIndex(double domainVal,double rangeVal,XYDataset xydataset){
Comparable comparable;
int indexOf;
for(int i=0;i<xydataset.getSeriesCount();i++){

comparable =  xydataset.getSeriesKey(i);
     indexOf=xydataset.indexOf(comparable);
for(int j=0 ; j<xydataset.getItemCount(indexOf);j++){

    double x=xydataset.getXValue(indexOf, j);
    double y=xydataset.getYValue(indexOf, j);

    if(x == domainVal && y==rangeVal){
        return  new SeriesAndItemIndex(j,indexOf);//return item index and series index
                }


            }
        }
        return null;
    }

private static class SeriesAndItemIndex{ ///inner CLASS to group series and item clicked index
        public int itemIndex;
        public int seriesIndex;
        public SeriesAndItemIndex(int i,int s){
            itemIndex=i;
            seriesIndex=s;
        }

        @Override
        public String toString(){
            return "itemIndex="+itemIndex+",seriesIndex="+seriesIndex;
        }
    }

how to use it?

如何使用它？

try{......code block from the top

}catch(Exception e){

Object source=event.getSource();
JFreeChart chartpanel=(JFreeChart)source;
XYPlot xyplot = (XYPlot) chartpanel.getPlot();
XYDataset xydataset= xyplot.getDataset();
double d=xyplot.getDomainCrosshairValue(); //get crosshair X value
double r =xyplot.getRangeCrosshairValue(); //get crosshair y value
SeriesAndItemIndex index=getItemIndex(d,r,xydataset);
if(index != null){
    System.out.println(index.toString());
}
}

回答by fasseg

hmm should work, if you replace the last two lines by something like this:

嗯应该工作，如果你用这样的东西替换最后两行：

ChartPanel panel=new ChartPanel(ChartFactory.createTimeSeriesChart("Memory usage", "Time", "Size", m_data, true, true, false)));
panel.addChartMouseListener(new ChartMouseListener(){
    void chartMouseClicked(ChartMouseEvent e){
        [...do something on click...]
    }
    void chartMouseMoved(ChartMouseEvent e){
        [...do something on move...]
    }
});
return panel;