Dynamic Data Example Shows how to use the WebGraph library to display realtime, streaming data. This example shows how to create a custom subclass of DataSource to represent dynamic data, data that changes over time. back to index The source code:

/**
 * @version $Id: DynamicDataExample.java,v 1.2 2000/11/13 18:47:16 Administrator Exp $
 */

import java.applet.*;
import java.awt.*;

import com.smartmoney.webgraph.*;

public class DynamicDataExample
        extends Applet
{

    public void init()
    {
        ParameterParser parser = new ParameterParser(this);
        NumericGraph graph = new NumericGraph();
        DynamicDataSource dataSource = new DynamicDataSource();
        GraphModel model = new GraphModel(dataSource);
        GraphElement line = new LineElement(model);
        line.setColor(Color.green.darker());
        line.setShowCallout(false);
        graph.addGraphElement(line);
        graph.setGraphMinimum(-1.2);
        graph.setGraphMaximum(1.2);
        graph.setDrawXValue(false);
        graph.setDrawXLabels(false);
        GraphParameterParser.parse(graph, parser);
        setLayout(new BorderLayout());
        add(graph, BorderLayout.CENTER);
        dataSource.start();
    }
}

class DynamicDataSource
        extends DataSource
        implements Runnable
{
    static final int ARRAY_SIZE = 300;

    private DataSet currentData;
    private Thread thread;
    private double factor;

    public int size()
    {
        return ARRAY_SIZE;
    }

    synchronized public DataSet getData()
    {
        if (currentData == null) fillData();
        return currentData;
    }

    public int getNormalIndex()
    {
        return 0;
    }

    public int getType()
    {
        return TDOUBLE;
    }

    synchronized private void fillData()
    {
        if (currentData == null)
        {
            currentData = new DataSet();
            currentData.xValues = new GraphableDouble[300];
            for (int i = 0; i < ARRAY_SIZE; i++)
                currentData.xValues[i] = new GraphableDouble(i);
            currentData.yValues = new double[][]{new double[ARRAY_SIZE]};
        }
        for (int i = 0; i < ARRAY_SIZE; i++)
            currentData.yValues[0][i]
                    //= (.8 + (.4 * Math.random())) *
                    = Math.sin(factor) * Math.sin(2 * Math.PI * i / ARRAY_SIZE);
        factor += Math.PI / 17;
        if (factor >= 2 * Math.PI) factor = 0;
    }

    public void start()
    {
        if (thread != null)
            thread.stop();
        thread = new Thread(this);
        thread.start();
    }

    public void run()
    {
        factor = 0;
        while (Thread.currentThread() == thread)
        {
            try
            {
                Thread.sleep(33);
            } catch (InterruptedException e)
            {
            }
            fillData();
            updateListeners();
        }
    }
}

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