SWTChart鼠标事件处理

Question

我发现SWTChart library，只是想知道如何用鼠标选择一个范围，例如， 1到3在x轴上，我会得到属于所选x值的所有y轴值。

a busy cat http://www.swtchart.org/screenshots/img/area.png

package org.swtchart.examples; 

import org.eclipse.swt.SWT; 
import org.eclipse.swt.layout.FillLayout; 
import org.eclipse.swt.widgets.Composite; 
import org.eclipse.swt.widgets.Display; 
import org.eclipse.swt.widgets.Shell; 
import org.swtchart.Chart; 
import org.swtchart.ILineSeries; 
import org.swtchart.ISeries.SeriesType; 

/** 
* An example for area chart. 
*/ 
public class AreaChartExample { 

    private static final double[] ySeries1 = { 0.1, 0.38, 0.71, 0.92, 1.0 }; 

    private static final double[] ySeries2 = { 1.2, 3.53, 3.1, 0.1, 0.5 }; 

    /** 
    * The main method. 
    * 
    * @param args 
    *   the arguments 
    */ 
    public static void main(String[] args) { 
     Display display = new Display(); 
     Shell shell = new Shell(display); 
     shell.setText("Area 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 
     Chart chart = new Chart(parent, SWT.NONE); 

     // set titles 
     chart.getTitle().setText("Area Chart"); 

     // create line series 
     ILineSeries lineSeries1 = (ILineSeries) chart.getSeriesSet() 
       .createSeries(SeriesType.LINE, "line series 1"); 
     lineSeries1.setYSeries(ySeries1); 
     lineSeries1.setLineColor(Display.getDefault().getSystemColor(
       SWT.COLOR_RED)); 
     lineSeries1.enableArea(true); 

     ILineSeries lineSeries2 = (ILineSeries) chart.getSeriesSet() 
       .createSeries(SeriesType.LINE, "line series 2"); 
     lineSeries2.setYSeries(ySeries2); 
     lineSeries2.enableArea(true); 

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

     return chart; 
    } 
} 

怎么可能包括用于在上面的例子中选择的范围内的鼠标事件？

预先感谢您。

Answer 1

下面的代码应该给你一个关于如何做到这一点的想法。基本上，你必须得到chart的chartArea，添加收听者SWT.MouseDown和SWT.MouseUp，并记住两个事件的位置。回答您的评论：是的，您可以使用SWT.Paint侦听器添加“突出显示”功能。

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.ILineSeries; 
import org.swtchart.ISeries.SeriesType; 

    /** 
    * An example for area chart. 
    */ 
    public class AreaChartExample { 

     private static final double[] ySeries1 = { 0.1, 0.38, 0.71, 0.92, 1.0 }; 

     private static final double[] ySeries2 = { 1.2, 3.53, 3.1, 0.1, 0.5 }; 

     /* Used to remember location point of mouse down */ 
     private static double startX; 
     private static double startY; 

     private static int startXPos; 
     private static int startYPos; 

     private static int currentX; 
     private static int currentY; 

     private static boolean drag = false; 

     /** 
     * The main method. 
     * 
     * @param args 
     *   the arguments 
     */ 
     public static void main(String[] args) { 
      Display display = new Display(); 
      Shell shell = new Shell(display); 
      shell.setText("Area 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("Area Chart"); 

      // create line series 
      ILineSeries lineSeries1 = (ILineSeries) chart.getSeriesSet() 
        .createSeries(SeriesType.LINE, "line series 1"); 
      lineSeries1.setYSeries(ySeries1); 
      lineSeries1.setLineColor(Display.getDefault().getSystemColor(
        SWT.COLOR_RED)); 
      lineSeries1.enableArea(true); 

      ILineSeries lineSeries2 = (ILineSeries) chart.getSeriesSet() 
        .createSeries(SeriesType.LINE, "line series 2"); 
      lineSeries2.setYSeries(ySeries2); 
      lineSeries2.enableArea(true); 

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

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

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

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

        startX = xAxis.getDataCoordinate(event.x); 
        startY = yAxis.getDataCoordinate(event.y); 

        startXPos = event.x; 
        startYPos = event.y; 

        drag = true; 
       } 
      }); 

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

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

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

        System.out.println(startX + " " + endX); 
        System.out.println(startY + " " + endY); 

        drag = false; 

        plotArea.redraw(); 
       } 
      }); 

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

       @Override 
       public void handleEvent(Event event) { 
        if(drag) 
        { 
         currentX = event.x; 
         currentY = event.y; 

         plotArea.redraw(); 
        } 
       } 
      }); 

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

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

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

         int minX = Math.min(startXPos, currentX); 
         int minY = Math.min(startYPos, currentY); 

         int maxX = Math.max(startXPos, currentX); 
         int maxY = Math.max(startYPos, currentY); 

         int width = maxX - minX; 
         int height = maxY - minY; 

         gc.fillRectangle(minX, minY, width, height); 
        } 
       } 
      }); 

      return chart; 
     } 
    }