patheticpong.java

书籍"Java_面向事件编程"的附带光盘代码

import objectdraw.*;

// plays a pathetic version of pong with no ball-paddle interaction
public class PatheticPong extends WindowController{
    
    // position and dimensions of the court
    private static final int
        COURT_LEFT = 50,
        COURT_TOP = 50,
        COURT_HEIGHT = 300,
        COURT_WIDTH = 250;
    
    // dimensions of the paddle
    private static final int
        PADDLE_WIDTH = 50,
        PADDLE_HEIGHT = 20;

    FilledRect paddle;
    FramedRect boundary;        // the boundary of the playing area.
    
    public void begin()
    {
        // make the playing area
        boundary = new FramedRect(COURT_LEFT, COURT_TOP,
                                  COURT_WIDTH, COURT_HEIGHT,
                                  canvas);
        
        // make the paddle
        paddle =
            new FilledRect(COURT_LEFT + (COURT_WIDTH-PADDLE_WIDTH)/2,
                           COURT_TOP + COURT_HEIGHT - PADDLE_HEIGHT -1,
                           PADDLE_WIDTH, PADDLE_HEIGHT,
                           canvas);
    }
    
    public void onMouseClick(Location point)
    {
        // make a new ball when the player clicks
        new FallingBall(canvas);
    }
    
    public void onMouseMove(Location point)
    {
        if ( point.getX() < COURT_LEFT )
            {
                // place paddle at left edge of the court
                paddle.moveTo( COURT_LEFT,
                               COURT_TOP + COURT_HEIGHT - PADDLE_HEIGHT -1);
            }
        else if ( point.getX() > COURT_LEFT + COURT_WIDTH - PADDLE_WIDTH)
            {
                // place paddle at right edge of the court
                paddle.moveTo( COURT_LEFT + COURT_WIDTH - PADDLE_WIDTH,
                               COURT_TOP + COURT_HEIGHT - PADDLE_HEIGHT -1);
            }
        else
            {
                // keep the edge of the paddle lined up with the mouse
                paddle.moveTo( point.getX(),
                               COURT_TOP + COURT_HEIGHT - PADDLE_HEIGHT -1);
            }
    }
    
}