怎么在JPanel中实现用Jfreechar实现鼠标放上去就显示交点上的数据
时间: 2024-03-09 17:48:27 浏览: 13
要在JPanel中使用JFreeChart实现鼠标放上去就显示交点上的数据,需要使用JFreeChart中的ChartPanel组件来实现。
首先,需要创建一个JFreeChart对象,并将它设置为ChartPanel的chart属性。然后,创建一个ChartMouseListener对象,并将它添加到ChartPanel中。ChartMouseListener的mouseEntered()方法会在鼠标放上去时被调用,可以在这里获取鼠标位置并通过JFreeChart的getXYPlot()方法获取到交点的数据。
以下是示例代码:
```java
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionListener;
import org.jfree.chart.ChartMouseEvent;
import org.jfree.chart.ChartMouseListener;
import org.jfree.chart.ChartPanel;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.plot.XYPlot;
public class MyChartPanel extends ChartPanel implements ChartMouseListener, MouseMotionListener {
private double xValue = Double.NaN;
private double yValue = Double.NaN;
public MyChartPanel(JFreeChart chart) {
super(chart);
addChartMouseListener(this);
addMouseMotionListener(this);
}
@Override
public void chartMouseClicked(ChartMouseEvent event) {
// do nothing
}
@Override
public void chartMouseMoved(ChartMouseEvent event) {
XYPlot plot = getChart().getXYPlot();
double x = plot.getDomainAxis().java2DToValue(event.getTrigger().getX(), getScreenDataArea(), plot.getDomainAxisEdge());
double y = plot.getRangeAxis().java2DToValue(event.getTrigger().getY(), getScreenDataArea(), plot.getRangeAxisEdge());
if (plot.getDomainAxis().getRange().contains(x) && plot.getRangeAxis().getRange().contains(y)) {
xValue = x;
yValue = y;
} else {
xValue = Double.NaN;
yValue = Double.NaN;
}
repaint();
}
public double getXValue() {
return xValue;
}
public double getYValue() {
return yValue;
}
@Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
if (!Double.isNaN(xValue) && !Double.isNaN(yValue)) {
Graphics2D g2 = (Graphics2D) g;
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
g2.setPaint(Color.red);
XYPlot plot = getChart().getXYPlot();
double x = plot.getDomainAxis().valueToJava2D(xValue, getScreenDataArea(), plot.getDomainAxisEdge());
double y = plot.getRangeAxis().valueToJava2D(yValue, getScreenDataArea(), plot.getRangeAxisEdge());
g2.draw(new Line2D.Double(x, getScreenDataArea().getMinY(), x, getScreenDataArea().getMaxY()));
g2.draw(new Line2D.Double(getScreenDataArea().getMinX(), y, getScreenDataArea().getMaxX(), y));
}
}
@Override
public void mouseDragged(MouseEvent e) {
// do nothing
}
@Override
public void mouseMoved(MouseEvent e) {
// do nothing
}
}
```
在使用ChartPanel时,可以使用MyChartPanel代替原来的ChartPanel,并调用getXValue()和getYValue()方法获取交点的数据。注意,为了在交点上显示数据,需要重写MyChartPanel的paintComponent()方法,在交点上绘制一条红色的竖线和一条横线。