fadeanim.java

please read it,you can

/*
 * @(#)FadeAnim.java	1.6  98/12/03
 *
 * Copyright 1998 by Sun Microsystems, Inc.,
 * 901 San Antonio Road, Palo Alto, California, 94303, U.S.A.
 * All rights reserved.
 *
 * This software is the confidential and proprietary information
 * of Sun Microsystems, Inc. ("Confidential Information").  You
 * shall not disclose such Confidential Information and shall use
 * it only in accordance with the terms of the license agreement
 * you entered into with Sun.
 */


import java.awt.*;
import java.awt.geom.*;
import java.awt.image.*;
import java.awt.event.*;
import java.util.Vector;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.border.*;
import java.net.URL;


/**
 * The FadeAnim class demonstrates animation of fading and compositing 
 * shapes, text and images.
 */
public class FadeAnim extends JApplet {

    Demo demo;

    public void init() {
        getContentPane().add(demo = new Demo());
        getContentPane().add("East", new DemoControls(demo));
    }

    public void start() {
        demo.start();
    }
  
    public void stop() {
        demo.stop();
    }



    /**
     * The Demo class performs the animation and painting.
     */
    static class Demo extends JPanel implements Runnable {

        private static TexturePaint texture;

        static {
            int w = 10; int h = 10;
            BufferedImage bi = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
            Graphics2D gi = bi.createGraphics();
            Color oc = Color.blue; Color ic = Color.green;
            gi.setPaint(new GradientPaint(0,0,oc,w*.35f,h*.35f,ic));
            gi.fillRect(0, 0, w/2, h/2);
            gi.setPaint(new GradientPaint(w,0,oc,w*.65f,h*.35f,ic));
            gi.fillRect(w/2, 0, w/2, h/2);
            gi.setPaint(new GradientPaint(0,h,oc,w*.35f,h*.65f,ic));
            gi.fillRect(0, h/2, w/2, h/2);
            gi.setPaint(new GradientPaint(w,h,oc,w*.65f,h*.65f,ic));
            gi.fillRect(w/2, h/2, w/2, h/2);
            texture = new TexturePaint(bi,new Rectangle(0,0,w,h));
        }
        private static BasicStroke bs = new BasicStroke(6); 

        // an array of Font objects
        private static Font fonts[] = {
                    new Font("Times New Roman", Font.PLAIN, 64),
                    new Font("serif", Font.BOLD + Font.ITALIC, 24),
                    new Font("Courier", Font.BOLD, 36),
                    new Font("Arial", Font.BOLD + Font.ITALIC, 48),
                    new Font("Helvetica", Font.PLAIN, 52)};

        // an array of String objects 
        private static String strings[] = {
                    "Alpha", "Composite", "Src", "SrcOver", 
                    "SrcIn", "SrcOut", "Clear", "DstOver", "DstIn" };

        // an array of images
        private static String imgs[] = { 
                    "jumptojavastrip.gif", "duke.gif", "star7.gif" };

        // an array of colors
        private static Paint paints[] = { 
                    Color.red, Color.blue, Color.green, Color.magenta, 
                    Color.orange, Color.pink, Color.cyan, texture,
                    Color.yellow, Color.lightGray, Color.white};
        private Vector vector = new Vector(13);
        public int numShapes, numStrings, numImages;
        private Thread thread;
        private BufferedImage bimg;
    
    
        public Demo() {
            setBackground(Color.black);

            // initializes to display 2 strings, 3 images and 8 shapes
            setStrings(2);
            setImages(3);
            setShapes(8);
        }
    
    
        public Image getImage(String name) {
            URL url = FadeAnim.class.getResource(name);
            Image img = getToolkit().getImage(url);
            try {
                MediaTracker tracker = new MediaTracker(this);
                tracker.addImage(img, 0);
                tracker.waitForID(0);
            } catch (Exception e) {}
            return img;
        }

    
        // adds images to a Vector
        public void setImages(int num) {
    
            if (num < numImages) {
                Vector v = new Vector(vector.size());
                for (int i = 0; i < vector.size(); i++) {
                    if (((ObjectData) vector.get(i)).object instanceof Image) {
                        v.addElement(vector.get(i));
                    }
                }
                vector.removeAll(v);
                v.setSize(num);
                vector.addAll(v);
            } else {
                Dimension d = getSize();
                for (int i = numImages; i < num; i++) {
                    Object obj = getImage(imgs[i % imgs.length]);
                    if (imgs[i % imgs.length].equals("jumptojavastrip.gif")) {
                        int iw = ((Image) obj).getWidth(null);
                        int ih = ((Image) obj).getHeight(null);
                        BufferedImage bimg = new BufferedImage(iw, ih, BufferedImage.TYPE_INT_RGB);
                        bimg.createGraphics().drawImage((Image) obj, 0, 0, null);
                        obj = bimg;
                    }
                    ObjectData od = new ObjectData(obj, Color.black);
                    od.reset(d.width, d.height);
                    vector.addElement(od);
                }
            }
            numImages = num;
        }

            
        // adds Strings to a Vector
        public void setStrings(int num) {
    
            if (num < numStrings) {
                Vector v = new Vector(vector.size());
                for (int i = 0; i < vector.size(); i++) {
                    if (((ObjectData) vector.get(i)).object instanceof TextData) {
                        v.addElement(vector.get(i));
                    }
                }
                vector.removeAll(v);
                v.setSize(num);
                vector.addAll(v);
            } else {
                Dimension d = getSize();
                for (int i = numStrings; i < num; i++) {
                    int j = i % fonts.length;
                    int k = i % strings.length;
                    Object obj = new TextData(strings[k], fonts[j], this); 
                    ObjectData od = new ObjectData(obj, paints[i%paints.length]);
                    od.reset(d.width, d.height);
                    vector.addElement(od);
                }
            }
            numStrings = num;
        }

            
        // adds shapes to a Vector
        public void setShapes(int num) {
    
            if (num < numShapes) {
                Vector v = new Vector(vector.size());
                for (int i = 0; i < vector.size(); i++) {
                    if (((ObjectData) vector.get(i)).object instanceof Shape) {
                        v.addElement(vector.get(i));
                    }
                }
                vector.removeAll(v);
                v.setSize(num);
                vector.addAll(v);
            } else {
                Dimension d = getSize();
                for (int i = numShapes; i < num; i++) {
                    Object obj = null;
                    switch (i % 7) {
                        case 0 : obj = new GeneralPath(); break;
                        case 1 : obj = new Rectangle2D.Double(); break;
                        case 2 : obj = new Ellipse2D.Double(); break;
                        case 3 : obj = new Arc2D.Double(); break;
                        case 4 : obj = new RoundRectangle2D.Double(); break;
                        case 5 : obj = new CubicCurve2D.Double(); break;
                        case 6 : obj = new QuadCurve2D.Double(); break;
                    }
                    ObjectData od = new ObjectData(obj, paints[i%paints.length]);
                    od.reset(d.width, d.height);
                    vector.addElement(od);
                }
            } 
            numShapes = num;
        }

    
        // calls ObjectData.reset for each item in vector
        public void reset(int w, int h) {
            for (int i = 0; i < vector.size(); i++) {
                ((ObjectData) vector.get(i)).reset(w, h);
            }
        }

    
        // calls ObjectData.step for each item in vector
        public void step(int w, int h) {
            for (int i = 0; i < vector.size(); i++) {
                ((ObjectData) vector.get(i)).step(w, h);
            }
        }
    
    
        public void drawDemo(int w, int h, Graphics2D g2) {
    
            for (int i = 0; i < vector.size(); i++) {
                ObjectData od = (ObjectData) vector.get(i);
                AlphaComposite ac = AlphaComposite.getInstance(
                                       AlphaComposite.SRC_OVER, od.alpha);
                g2.setComposite(ac);
                g2.setPaint(od.paint);
                g2.translate(od.x, od.y);
    
                if (od.object instanceof Image) {
                    g2.drawImage((Image) od.object, 0, 0, this);
                } else if (od.object instanceof TextData) {
                    g2.setFont(((TextData) od.object).font);
                    g2.drawString(((TextData) od.object).string, 0, 0);
                } else if (od.object instanceof QuadCurve2D 
                        || od.object instanceof CubicCurve2D) 
                {
                    g2.setStroke(bs);
                    g2.draw((Shape) od.object);
                } else if (od.object instanceof Shape) {
                    g2.fill((Shape) od.object);
                }
                g2.translate(-od.x, -od.y);
            }
        }
    
    
        public Graphics2D createGraphics2D(int w, int h) {
            Graphics2D g2 = null;
            if (bimg == null || bimg.getWidth() != w || bimg.getHeight() != h) {
                bimg = (BufferedImage) createImage(w, h);