dynarule2.java

Java 范例实战 光盘使用说明 ========================== 本光盘的文件结构如下所示： =====================================

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

public class dynarule2 extends Applet implements Runnable {
    float radius, centralPoint, arcAngle, dist, speed;
    int xSize, ySize, numberOfPics;
    Image img, bufferImage;
    Color bgColor = null;
    MediaTracker tracker = null;
    Graphics bufferGraphics = null;
    Thread thread = null;
    float Pi2 = 6.283185F;

    public dynarule2()
    {
    }

    public void init()
    {
        tracker = new MediaTracker(this);
        xSize = getSize().width;
        ySize = getSize().height;
        String s = getParameter("img");
        img = getImage(getDocumentBase(), s);
        tracker.addImage(img, 0);
        s = getParameter("num");
        numberOfPics = s != null ?
                     Integer.valueOf(s).intValue() : 1;
        s = getParameter("dist");
        dist = s != null ? Float.valueOf(s).floatValue() : 1.0F;
        s = getParameter("speed");
        speed = s != null ? Float.valueOf(s).floatValue() : Pi2 / 400F;
        s = getParameter("bgcolor");
        bgColor = s != null ? 
                new Color(Integer.valueOf(s, 16).intValue()) :
                getBackground();
        bufferImage = createImage(getSize().width, getSize().height);
        bufferGraphics = bufferImage.getGraphics();
    }

    public void start()
    {

        try
        {
            showStatus("dynarule2: Loading image...");
            tracker.waitForID(0);
            showStatus("");
        }
        catch(InterruptedException _ex)
        {
            showStatus("dynarule2: Image loading interrupted");
            return;
        }

        radius = (xSize - img.getWidth(this)) / 2;
        centralPoint = radius;
        arcAngle = 0.0F;

        if(thread == null)
        {
            thread = new Thread(this);
            thread.start();
        }

    }

    public void stop()
    {

        if(thread != null)
        {
            thread.stop();
            thread = null;
        }

    }

    public void run()
    {

        do
        {
            arcAngle += speed;

            if(arcAngle > Pi2)
                arcAngle -= Pi2;

            repaint();

            try
            {
                Thread.sleep(15L);
            }
            catch(InterruptedException _ex) { }

        }
        while(true);

    }

    public void paint(Graphics g)
    {
        bufferGraphics.setColor(bgColor);
        bufferGraphics.fillRect(0, 0, xSize, ySize);
        float angle = arcAngle;

        for(int i = 0; i < numberOfPics; i++)
        {
            int j = (int)(Math.sin(angle) * (double)radius
                    + (double)centralPoint);
            bufferGraphics.drawImage(img, j, 0, this);
            angle += dist;
        }

        g.drawImage(bufferImage, 0, 0, this);
    }

    public final synchronized void update(Graphics g)
    {
        paint(g);
    }
}