cloud.java

书籍"Java_面向事件编程"的附带光盘代码

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

// Modified to produce some snow, sleet, tomatoes, and cows
public class Cloud extends ActiveObject {
    
    // total number of falling objects
    private static final int MAX_OBJECTS = 150;

    // how long to pause between creating objects
    private static final int PAUSETIME = 900;

    // the canvas
    private DrawingCanvas canvas;
    
    // picture of a snowflake
    private Image snowPic;
    
    // for the cow
    private Image upsideDownCow, cow;
    private AudioClip moo;
    
    // size of the screen
    private int screenWidth, screenHeight;
    
    // used to generate random speeds and positions for snowflakes
    private RandomIntGenerator objGen;
    
    public Cloud(
                 Image aSnowPic,
                 Image cow,
                 Image upsideCow,
                 AudioClip moo,
                 int aScreenWidth,
                 int aScreenHeight,
                 DrawingCanvas aCanvas) {
        
        // save the parameters for the "run" method
        canvas = aCanvas;
        snowPic = aSnowPic;
        
        upsideDownCow = upsideCow;
        this.cow = cow;
        this.moo = moo;
        
        screenWidth = aScreenWidth;
        screenHeight = aScreenHeight;
        
        objGen = new RandomIntGenerator(0, screenWidth);
        
        start();
    }
    
    public void run() {
        int objCount = 0;
        
        // continue creating objects until the maximum amount
        // has been created
        while (objCount < MAX_OBJECTS) {
            
            objCount++;

            // create snow, sleet, tomatoes, or cows, randomly
            switch (objGen.nextValue() % 4) {
            case 0 :
                new FallingSnow(canvas, snowPic, 
                                objGen.nextValue(), // x coordinate
                                objGen.nextValue() * 2 / screenWidth + 2, // y speed
                                screenHeight);
                break;
            case 1 :
                new FallingSleet(
                                 canvas,
                                 objGen.nextValue(),
                                 objGen.nextValue() * 4 / screenWidth + 2,
                                 screenHeight);
                break;
            case 2 :
                new FallingTomato(
                                  canvas,
                                  objGen.nextValue(),
                                  objGen.nextValue() * 4 / screenWidth + 2,
                                  screenHeight);
                break;
            case 3 :
                new FallingCow(
                               canvas,
                               cow,
                               upsideDownCow,
                               moo,
                               objGen.nextValue() %(canvas.getWidth() - 100),
                               screenHeight);
                break;
            }
            pause(PAUSETIME);
        }
    }
}