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);
}
}