www.pudn.com > src.rar > SwimmingFishCanvas.java

/* 
* Copyright (c) 1996, 1997 Bill Venners. All Rights Reserved. 
* 
* This Java source file is part of the Interactive Illustrations Web 
* Site, which is delivered in the applets directory of the CD-ROM 
* that accompanies the book "Inside the Java Virtual Machine" by Bill 
* Venners, published by McGraw-Hill, 1997,ISBN: 0-07-913248-0. This 
* source file is provided for evaluation purposes only, but you can 
* redistribute it under certain conditions, described in the full 
* copyright notice below. 
* 
* Full Copyright Notice: 
* 
* All the web pages and Java applets delivered in the applets 
* directory of the CD-ROM, consisting of ".html," ".gif," ".class," 
* and ".java" files, are copyrighted (c) 1996, 1997 by Bill 
* Venners, and all rights are reserved.  This material may be copied 
* and placed on any commercial or non-commercial web server on any 
* network (including the internet) provided that the following 
* guidelines are followed: 
* 
* a. All the web pages and Java Applets (".html," ".gif," ".class," 
* and ".java" files), including the source code, that are delivered 
* in the applets directory of the CD-ROM that 
* accompanies the book must be published together on the same web 
* site. 
* 
* b. All the web pages and Java Applets (".html," ".gif," ".class," 
* and ".java" files) must be published "as is" and may not be altered 
* in any way. 
* 
* c. All use and access to this web site must be free, and no fees 
* can be charged to view these materials, unless express written 
* permission is obtained from Bill Venners. 
* 
* d. The web pages and Java Applets may not be distributed on any 
* media, other than a web server on a network, and may not accompany 
* any book or publication. 
* 
* BILL VENNERS MAKES NO REPRESENTATIONS OR WARRANTIES ABOUT THE 
* SUITABILITY OF THE SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING 
* BUT NOT LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY, 
* FITNESS FOR PARTICULAR PURPOSE, OR NON-INFRINGEMENT.  BILL VENNERS 
* SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY A LICENSEE AS A 
* RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS 
* DERIVATIVES. 
*/ 
import java.awt.*; 
 
/** 
* This class upon which the red, blue, and yellow fish are 
* painted swimming. This class contains the code that 
* does the animation. 
* 
* @author  Bill Venners 
*/ 
public class SwimmingFishCanvas extends Canvas implements Runnable { 
 
    private Thread runner; 
 
    private Image offscreenImage; 
    private Graphics og; 
 
    private final int swimmingFishGroupWidth = 150; 
    private int xSwimmingFishGroupPos = 0 - swimmingFishGroupWidth; 
    private int ySwimmingFishGroupPos = 20; 
    private BigRedFishIcon bigSwimmingRedFish = new BigRedFishIcon(true); 
    private MediumBlueFishIcon mediumSwimmingBlueFish = new MediumBlueFishIcon(true); 
    private LittleYellowFishIcon littleSwimmingYellowFish = new LittleYellowFishIcon(true); 
 
    SwimmingFishCanvas() { 
 
        setBackground(Color.blue); 
    } 
 
    public void start() { 
        if (runner == null) { 
            runner = new Thread(this); 
            runner.start(); 
        } 
    } 
 
    public void stop() { 
        if (runner != null) { 
            runner.stop(); 
            runner = null; 
        } 
    } 
 
    public void run() { 
        while (true) { 
 
            repaint(); 
            try { 
                Thread.sleep(20); 
            } 
            catch (InterruptedException e) { 
            } 
        } 
    } 
 
    public Dimension minimumSize() { 
        return new Dimension(500, 240); 
    } 
 
    public Dimension preferredSize() { 
        return new Dimension(500, 240); 
    } 
 
    public void update(Graphics g) { 
 
        g.clipRect(xSwimmingFishGroupPos, ySwimmingFishGroupPos, swimmingFishGroupWidth + 1, bigSwimmingRedFish.getFishHeight()); 
        paint(g); 
    } 
 
    public void paint(Graphics g) { 
 
        // First calculate the positions of the goodies on the canvas based on the width 
        // and height of the canvas. 
        Dimension dim = size(); 
 
        if (offscreenImage == null) { 
 
            offscreenImage = createImage(dim.width, dim.height); 
            og = offscreenImage.getGraphics(); 
        } 
 
        // Divide height into three equal portions. The top portion will hold the object pool. 
        // The middle portion will hold the handle pool. The bottom portion will hold 
        // something that depends on the current mode. 
 
        int yHandlePoolPortion = dim.height / 3; 
        int yModeDependentPortion = 2 * yHandlePoolPortion; 
 
        xSwimmingFishGroupPos += 1; 
 
       if (xSwimmingFishGroupPos > size().width) { 
 
            // Leave 5 pixels on top or bottom of Y range that fish may swim in. 
            int yRange = dim.height - bigSwimmingRedFish.getFishHeight() - 10; 
            ySwimmingFishGroupPos = (int) (((double) yRange) * Math.random()); 
            ySwimmingFishGroupPos += 5; 
 
            xSwimmingFishGroupPos = 0 - swimmingFishGroupWidth; 
        } 
 
        bigSwimmingRedFish.moveFish(xSwimmingFishGroupPos, ySwimmingFishGroupPos); 
        mediumSwimmingBlueFish.moveFish(xSwimmingFishGroupPos + 67, ySwimmingFishGroupPos + 4); 
        littleSwimmingYellowFish.moveFish(xSwimmingFishGroupPos + 120, ySwimmingFishGroupPos + 8); 
 
        // Because update doesn't clear the screen in the case of swimming fish to 
        // reduce flicker, must clear the rectangle here. May as well color the entire 
        // mode dependent portion blue so it looks like water. 
        og.setColor(Color.blue); 
        og.fillRect(0, 0, dim.width, dim.height); 
 
        bigSwimmingRedFish.paint(og); 
        mediumSwimmingBlueFish.paint(og); 
        littleSwimmingYellowFish.paint(og); 
 
        g.drawImage(offscreenImage, 0, 0, this); 
    } 
}