拖动鼠标时如何在绘图中获取鼠标坐标？
package parabolademo;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
import java.awt.geom.Point2D;
import java.awt.geom.Rectangle2D;
import org.jfree.chart.ChartFactory;
import org.jfree.chart.ChartMouseEvent;
import org.jfree.chart.ChartMouseListener;
import org.jfree.chart.ChartPanel;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.entity.ChartEntity;
import org.jfree.chart.entity.XYItemEntity;
import org.jfree.chart.plot.PlotOrientation;
import org.jfree.chart.plot.XYPlot;
import org.jfree.data.function.Function2D;
import org.jfree.data.function.PolynomialFunction2D;
import org.jfree.data.general.DatasetUtilities;
import org.jfree.data.xy.XYDataset;
import org.jfree.ui.ApplicationFrame;
import org.jfree.ui.RefineryUtilities;
public class ParabolaDemo extends ApplicationFrame {
/*
* @param title the frame title.
*/
int flag = 0;
double delta = 0;
double px = 0.0, py = 0.0, chartpx = 0.0, chartpy = 0.0,
chartX = 0.0, chartY = 0.0;
int windowheight = 270;
ChartPanel chartPanel;
public ParabolaDemo(final String title) {
super(title);
double[] a = {0.0, 0.0, 1.0};
Function2D p = new PolynomialFunction2D(a);
double lrange = -20.0;
double rrange = 20.0;
XYDataset dataset = DatasetUtilities.sampleFunction2D(p, lrange, rrange, 1000, "y = f(x)");
double max = 0.0;
if (a[2] < 0) {
max = p.getValue(-a[1] / 2*a[2]);
}
else {
if (p.getValue(lrange) > p.getValue(rrange))
max = p.getValue(lrange);
else
max = p.getValue(rrange);
}
System.out.println("max = " + max);
delta = max / 16.4;
final JFreeChart chart = ChartFactory.createXYLineChart(
"Parabola",
"X",
"Y",
dataset,
PlotOrientation.VERTICAL,
true,
true,
false
);
chartPanel = new ChartPanel(chart);
chartPanel.addMouseMotionListener(new MotionListener());
chartPanel.addChartMouseListener(new ChartMouseListener() {
@Override
public void chartMouseClicked(ChartMouseEvent cme) {
}
@Override
public void chartMouseMoved(ChartMouseEvent cme) {
ChartEntity ce = cme.getEntity();
if (ce instanceof XYItemEntity) {
flag = 1;
XYItemEntity e = (XYItemEntity) ce;
XYDataset d = ((XYItemEntity) ce).getDataset();
int i = ((XYItemEntity) ce).getItem();
chartpx = d.getXValue(0, i);
chartpy = d.getYValue(0, i);
//System.out.println("X:" + chartpx + ", Y:" + chartpy);
}
else
flag = 0;
Point2D po = chartPanel.translateScreenToJava2D(cme.getTrigger().getPoint());
Rectangle2D plotArea = chartPanel.getScreenDataArea();
XYPlot plot = (XYPlot) chart.getPlot(); // your plot
chartX = plot.getDomainAxis().java2DToValue(po.getX(), plotArea, plot.getDomainAxisEdge());
chartY = plot.getRangeAxis().java2DToValue(po.getY(), plotArea, plot.getRangeAxisEdge());
//System.out.println("X:" + chartX + ", Y:" + chartY);
}
});
chartPanel.setPreferredSize(new java.awt.Dimension(500, windowheight));
chartPanel.setDomainZoomable(false);
chartPanel.setRangeZoomable(false);
setContentPane(chartPanel);
}
public static void main(final String[] args) {
final ParabolaDemo demo = new ParabolaDemo("Parabola Plot Demo");
demo.pack();
RefineryUtilities.centerFrameOnScreen(demo);
demo.setVisible(true);
}
public class MotionListener implements MouseMotionListener {
@Override
public void mouseDragged(MouseEvent me) {
double dx = 0.0, dy = 0.0;
dx = me.getX();
dy = windowheight - me.getY();
if (flag == 1)
System.out.println("Dragged! x = " + dx + ", y = " + dy);
}
@Override
public void mouseMoved(MouseEvent me) {
}
}
}
当用
拖动鼠标时，我只能得到鼠标坐标dx = me.getX();
dy = windowheight - me.getY();
但是坐标是鼠标坐标，而不是情节坐标。如何在MouseDragged中获得 plot 坐标？