Rendering a single point in a JFreeChart based on the current Value of a Slider

问题

I'm not yet as much into Java as I'd like to be, so I find my current task to be quite a bit challenging:

A chart showing data gathered in another class.
A slider whose end value is determined by the last entry of in the dataset used in the chart.
The playbutton currently doesn't do anything except letting the slider tick in steps of 5 until it is paused again.

My problem right now is: I am supposed to highlight one item at a time in the chart based on which value the slider currently shows.

And to be honest... I'm not yet used to renderers yet.

If I understood it correctly I would need to use

 renderer.drawItem(java.awt.Graphics2D g2,
          XYItemRendererState state,
          java.awt.geom.Rectangle2D dataArea,
          PlotRenderingInfo info,
          XYPlot plot,
          ValueAxis domainAxis,
          ValueAxis rangeAxis,
          XYDataset dataset,
          int series,
          int item,
          CrosshairState crosshairState,
          int pass)

but I am totally inexperienced with as well the method as its arguments and got no idea how to initialize them.

I mean... I got a plot, a dataset, and 2 series from the chart, I also suggest "item" would be the index of the item to highlight in the series, which I could convert from the slider-value.

Unfortunately plaguing google about it turned out to be rather frustrating since all I got was the very code I posted above on about 50 different pages (I gave up after).

I would like to know ... first of all if I am even about to use the correct method and, as ashamed as I am to ask like this... how to use it.

Well... looking forward to some answers and... thanks in advance.

回答1:

Well, I now solved my problem in a different way than I intended to but it works out just fine for me.

Instead of highlighting a point in the curves I just simply add a Domainmarker that would adjust based on the value the slider currently shows.

class1 TestSlider

private HashSet<SliderListener> sliderListenerSet = new HashSet<SliderListener>();

public void addSliderListener(SliderListener Listener){
    sliderListenerSet.add(Listener);
}

slider.addChangeListener(this);

public void stateChanged(ChangeEvent e) {
    // TODO Auto-generated method stub
    JSlider source = (JSlider)e.getSource();
    if (!source.getValueIsAdjusting()) {
            fireSliderChanged();
    }
} 

public void fireSliderChanged(){
    for (SliderListener currentListener : sliderListenerSet)
        currentListener.sliderValueChanged();
}

class2 SliderListener

public interface SliderListener extends EventListener{

public void SliderValueChanged();
}

class3 Chart

Marker marker = new ValueMarker(0);
plot.addDomainMarker(marker); //so that it would be there at the beginning
TestSlider ts = new TestSlider();

ts.addSliderListener(new SliderListener(){

        @Override
        public void sliderValueChanged() {

            plot.removeDomainMarker(marker); //I only want one of them at a time - the one with the value the slider is currently showing so remove the old one...
            marker = new ValueMarker(ts.slider.getValue());
            plot.addDomainMarker(marker); // ... and add the one with the new value
        }

    });

}

I tried to keep it as short and universal as I could and I hope I didnt cut out anything important. Well, I'm still new to this site, so... in case I did a mistake somewhere feel free to tell me.

来源：https://stackoverflow.com/questions/25711318/rendering-a-single-point-in-a-jfreechart-based-on-the-current-value-of-a-slider

标签

charts

jfreechart

itemrenderer

jslider

changelistener