superpong.java

书籍"Java_面向事件编程"的附带光盘代码

import objectdraw.*;

// Play a game like Pong but with extra obstacles that
// the ball can bounce off of added to the screen as
// play progresses
public class SuperPong extends WindowController {
    
    // Inset of playing area from edges of canvas
    private static final double MARGIN = 50;
    
    // dimensions of the grid in which bricks are placed
    private static final int COLS= 7;
    private static final int ROWS= 30;
    
    // increments used to choose position of next brick
    private static final double COLINC = 4;
    private static final double ROWINC = -3;
    
    // ratio between size of paddle and bricks
    private static final double PADDLERATIO = 1.5;
    
    // position where next brick will be placed
    private double curRow = 20;
    private double curCol = 1;
    
    // dimensions of a brick
    private double bWidth;
    private double bHeight;
    
    // dimensions of the paddle
    private double paddleWidth;
    private double paddleHeight;
    
    // the boundary of the playing area 
    private FramedRect boundary;
    
    // the paddle
    private FilledRect paddle;
    
    // the collection of bricks placed in the playing area
    private RectCollection theBricks = new RectCollection(ROWS*COLS);
    
    // has at least one ball been launched
    private boolean started = false;
    
    // create the boundary and the paddle
    public void begin() {
        boundary = new FramedRect( MARGIN, MARGIN,
                                   canvas.getWidth() - 2*MARGIN,
                                   canvas.getHeight() - 2*MARGIN,
                                   canvas );
        
        // dimensions of bricks
        bWidth = boundary.getWidth()/COLS;
        bHeight = boundary.getHeight()/ROWS;
        
        // dimensions for the paddle
        paddleWidth = PADDLERATIO*bWidth;
        paddleHeight = 1.5*bHeight;
        
        paddle = 
            new FilledRect( canvas.getWidth()/2 - paddleWidth/2,
                            canvas.getHeight() - (MARGIN + paddleHeight + 2),
                            paddleWidth, paddleHeight, canvas);
    }
    
    // Make a new ball whenever the user clicks
    public void onMouseClick(Location point){
        new SuperPongBall( theBricks, boundary, paddle, canvas);
        started = true;
    }
    
    // make the paddle follow the mouse back and forth
    public void onMouseMove(Location point){
        
        if ( point.getX() < boundary.getX()){
            paddle.moveTo( boundary.getX(), paddle.getY());
        } else if ( point.getX() + paddleWidth > boundary.getX() + boundary.getWidth() ) {
            paddle.moveTo( boundary.getX() + boundary.getWidth() - paddleWidth,
                           paddle.getY());
        } else {
            paddle.moveTo( point.getX(), paddle.getY());
        }
    }
    
    // make the game a bit harder
    public void onMouseEnter(Location point){
        makeItHarder();
    }
    
    // make the game a bit harder
    public void onMouseExit(Location point){
        makeItHarder();
    }
    
    // add new bricks until there is no more room
    private void makeItHarder() {
        if (started) {
            if (curRow > 0 && curRow < ROWS) {
                // add a new brick
                theBricks.add(
                              new FilledRect(
                                             boundary.getX() + 2 + curCol * bWidth,
                                             boundary.getY() + bHeight * curRow,
                                             bWidth - 2,
                                             bHeight - 2,
                                             canvas));
                curCol += COLINC;
                if (curCol >= COLS) {
                    curCol = curCol - COLS;
                    curRow += ROWINC;
                }
            }
        }
    }
    
}