bball.java

书籍"Java_面向事件编程"的附带光盘代码

import objectdraw.*;
import java.awt.Color;

// A class that implements a nice looking basketball

public class BBall {
    // the color to draw the ball
    private static final Color BALL_ORANGE = new Color(250, 85, 10);
    
    // size and starting angles for cut arc in degrees
    private static final int CUTSIZE = 100;
    private static final int RIGHTCUTSTART = 90 + (180 - CUTSIZE) / 2;
    private static final int LEFTCUTSTART = 270 + (180 - CUTSIZE) / 2;
    
    // the orange part of the ball
    private FilledOval body;
    // the border of the ball
    private FramedOval border;
    // the two curves on the sides of the ball
    private FramedArc leftCut, rightCut;
    // the vertical and horizontal lines through the ball
    private Line vert, horiz;
    
    // initial coordinates of basket ball
    private double initX, initY;
    
    // move the ball by specified offsets
    public void move(double dx, double dy) 
    {
        // move each part of the ball by the offsets provided
        body.move(dx, dy);
        border.move(dx, dy);
        vert.move( dx, dy);
        horiz.move(dx, dy);
        leftCut.move(dx, dy);
        rightCut.move(dx, dy);
    }       
    
    
    // Create a new basketball
    public BBall(double left, double top, 
                 double size, DrawingCanvas aCanvas) 
    {
        // draw the circles that make it look like a ball
        body = new FilledOval(left, top, size, size, aCanvas);
        body.setColor(BALL_ORANGE);             
        border = new FramedOval(left, top, size, size, aCanvas);
        
        // draw the lines and arcs that make it look like a basketball
        rightCut = new FramedArc( left + size * 2 / 3, top,
                                  size, size,
                                  RIGHTCUTSTART, CUTSIZE,  aCanvas);
        leftCut =  new FramedArc( left - size * 2 / 3, top,
                                  size, size,
                                  LEFTCUTSTART, CUTSIZE,   aCanvas);
        vert =  new Line( left + size / 2, top,
                          left + size / 2, top + size,   aCanvas);
        horiz = new Line( left, top + size / 2,
                          left + size, top + size / 2,   aCanvas);
        
        // remember the ball's starting position
        initX = left;
        initY= top;
    }
    
    
    // check to see if the ball contains a specified location
    public boolean contains(Location point) 
    {
        return body.contains(point);
    }
    
    // move the ball to a specified position
    public void moveTo(double x, double y) 
    {
        // determine how far away (x,y) is
        double dx, dy;
        dx = x - body.getX();
        dy = y - body.getY();
        
        // move each part of the ball by the offsets provided
        body.move(dx, dy);
        border.move(dx, dy);
        vert.move( dx, dy);
        horiz.move(dx, dy);
        leftCut.move(dx, dy);
        rightCut.move(dx, dy);
    }
    
    // return the ball to its starting position
    public void reset() 
    {
        this.moveTo(initX, initY);
    }
    
    // return the x coordinate of ball's corner
    public double getX(){
        return body.getX();
    }
    
    // return the y coordinate of ball's corner
    public double getY(){
        return body.getY();
    }
    
}