bball4two.java

书籍"Java_面向事件编程"的附带光盘代码

import objectdraw.*;

// program for two players to play basketball.
public class BBall4Two extends WindowController{
    
    // Location of the display
    private static final int DISPLAY_X = 150;
    private static final int DISPLAY_Y = 200;
    private static final int DISPLAYSIZE = 16; // in points
    
    // Location and dimensions of the hoop
    private static final int HOOPTOP = 50;
    private static final int HOOPLEFT = 160;
    private static final int HOOPWIDTH = 80;
    private static final int HOOPHEIGHT = 35;
    
    // Initial locations and dimensions of the balls
    private static final int BALLX = 110;
    private static final int BALLY = 300;
    private static final int BALLSIZE = 40;
    private static final int BALLSPACING = 160;
    
    // Distance between balls and score displays
    private static final int SCOREDOWNSET = BALLSIZE + 25;
    
    // the Text objects which display the scores
    private Text leftDisplay, rightDisplay;
    
    // the oval that represent the hoop
    private FramedOval hoop;
    
    // the two balls
    private BBall leftBall, rightBall;
    
    // the ball currently being dragged
    private BBall ballInPlay;
    
    // whether any ball is currently in play
    private boolean carryingBall;
    
    // the scores for each player
    private int leftScore = 0,   rightScore = 0;
    
    // the last previous known location of the mouse
    private Location lastMouse;
    
    // initialize the counter and the text message
    public void begin() {
        
        hoop = new FramedOval( HOOPLEFT, HOOPTOP, HOOPWIDTH, HOOPHEIGHT, canvas);
        
        leftBall = new BBall( BALLX, BALLY, BALLSIZE, canvas);
        rightBall = new BBall( BALLX + BALLSPACING, BALLY, BALLSIZE, canvas);
        
        leftDisplay = new Text("HOME 0", BALLX + BALLSIZE/2, 
                               BALLY + SCOREDOWNSET,  canvas);
        rightDisplay = new Text("VISITORS 0", BALLX + + BALLSPACING + BALLSIZE/2,
                                BALLY + SCOREDOWNSET,   canvas);
        
        leftDisplay.setFontSize(DISPLAYSIZE);
        leftDisplay.move( - leftDisplay.getWidth()/2,0);
        rightDisplay.setFontSize(DISPLAYSIZE);
        rightDisplay.move( - rightDisplay.getWidth()/2,0);
    }
    
    // Note where mouse is depressed
    public void onMousePress(Location point) {
        lastMouse = point;
        if ( leftBall.contains( point ) ) 
            {
                ballInPlay = leftBall;
                carryingBall = true;
            } 
        else if ( rightBall.contains( point ) ) 
            {
                ballInPlay = rightBall;
                carryingBall = true;
            }
    }
    
    // Move the ball as the mouse is dragged
    public void onMouseDrag(Location point) {
        if ( carryingBall ) 
            {
                ballInPlay.move( point.getX() - lastMouse.getX(),
                                 point.getY() - lastMouse.getY() );
                lastMouse = point;
            }
    }
    
    // check to see if either player scored
    public void onMouseRelease(Location point) {
        if ( hoop.contains(point) ) 
            {
                if ( ballInPlay == leftBall ) 
                    {
                        leftScore = leftScore + 2;
                        leftDisplay.setText("HOME " + leftScore );
                    } 
                else if ( ballInPlay == rightBall ) 
                    {
                        rightScore = rightScore + 2;
                        rightDisplay.setText("VISITORS " + rightScore);
                    }
            }
        
        if ( carryingBall ) 
            {
                ballInPlay.reset();
                carryingBall = false;
            }
    }
}