带有MouseOver处理的条形图

Question

我找到了SWTChart library，当我查看条形图时，我试图实现一个包含y值信息的方框，如example所示。

但是，以下代码未显示有关y值的任何信息。

package org.swtchart.examples;

import org.eclipse.swt.SWT;
import org.eclipse.swt.graphics.GC;
import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Event;
import org.eclipse.swt.widgets.Listener;
import org.eclipse.swt.widgets.Shell;
import org.swtchart.Chart;
import org.swtchart.IAxis;
import org.swtchart.IBarSeries;
import org.swtchart.ISeries;
import org.swtchart.ISeries.SeriesType;

/**
* An example for bar chart.
*/
public class BarChartExampleMouseOver {

private static final double[] ySeries = { 0.2, 1.1, 1.9, 2.3, 1.8, 1.5,
    1.8, 2.6, 2.9, 3.2 };

/* Used to remember the location of the highlight point */
private static int highlightX;
private static int highlightY;
protected static boolean highlight;


/**
* The main method.
* 
* @param args
*            the arguments
*/
public static void main(String[] args) {
    Display display = new Display();
    Shell shell = new Shell(display);
    shell.setText("Bar Chart");
    shell.setSize(500, 400);
    shell.setLayout(new FillLayout());

    createChart(shell);

    shell.open();
    while (!shell.isDisposed()) {
    if (!display.readAndDispatch()) {
        display.sleep();
    }
    }
    display.dispose();
}

/**
* create the chart.
* 
* @param parent
*            The parent composite
* @return The created chart
*/
static public Chart createChart(Composite parent) {

    // create a chart
    final Chart chart = new Chart(parent, SWT.NONE);

    // set titles
    chart.getTitle().setText("Bar Chart");
    chart.getAxisSet().getXAxis(0).getTitle().setText("Data Points");
    chart.getAxisSet().getYAxis(0).getTitle().setText("Amplitude");

    // create bar series
    IBarSeries barSeries = (IBarSeries) chart.getSeriesSet().createSeries(
        SeriesType.BAR, "bar series");
    barSeries.setYSeries(ySeries);

    // adjust the axis range
    chart.getAxisSet().adjustRange();

    /* Get the plot area and add the mouse listeners */
    final Composite plotArea = chart.getPlotArea();

    plotArea.addListener(SWT.MouseHover, new Listener() {

    @Override
    public void handleEvent(Event event) {
        IAxis xAxis = chart.getAxisSet().getXAxis(0);
        IAxis yAxis = chart.getAxisSet().getYAxis(0);

        double x = xAxis.getDataCoordinate(event.x);
        double y = yAxis.getDataCoordinate(event.y);

        ISeries[] series = chart.getSeriesSet().getSeries();

        double closestX = 0;
        double closestY = 0;
        double minDist = Double.MAX_VALUE;

        /* over all series */
        for (ISeries serie : series) {
        double[] xS = serie.getXSeries();
        double[] yS = serie.getYSeries();

        /* check all data points */
        for (int i = 0; i < xS.length; i++) {
            /* compute distance to mouse position */
            double newDist = Math.sqrt(Math.pow((x - xS[i]), 2)
                + Math.pow((y - yS[i]), 2));

            /* if closer to mouse, remember */
            if (newDist < minDist) {
            minDist = newDist;
            closestX = xS[i];
            closestY = yS[i];
            }
        }
        }

        /* set tooltip of closest data point */
        plotArea.setToolTipText(closestX + " " + closestY);

        /* remember closest data point */
        highlightX = xAxis.getPixelCoordinate(closestX);
        highlightY = yAxis.getPixelCoordinate(closestY);

        highlight = true;

        /* trigger repaint (paint highlight) */
        plotArea.redraw();
    }
    });

    plotArea.addListener(SWT.MouseMove, new Listener() {

    @Override
    public void handleEvent(Event arg0) {
        highlight = false;

        plotArea.redraw();
    }
    });

    plotArea.addListener(SWT.Paint, new Listener() {

    @Override
    public void handleEvent(Event event) {
        if (highlight) {
        GC gc = event.gc;

        gc.setBackground(Display.getDefault().getSystemColor(
            SWT.COLOR_RED));
        gc.setAlpha(128);

        gc.fillOval(highlightX - 5, highlightY - 5, 10, 10);
        }
    }
    });

    return chart;
}
}

提前谢谢