bball.java

书籍"Java_面向事件编程"的附带光盘代码

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


// A class that draws a nice looking basketball that can be
// moved about the display
public class BBall {
    
    // the color to draw the ball
    private static final Color BALL_ORANGE = new Color(250,85,10);
    
    // size of cut arc in degrees
    private static final int CUTSIZE = 100;
    
    // offset to start of arcs in degrees
    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 black frame around 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 basketball
    double initX, initY;
    
    
    // Create a new basketball
    public BBall(double left, double top,
                 double size,
                 DrawingCanvas aCanvas ) {
        // remember the ball's starting position
        initX = left;
        initY = top;
        
        // 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 through the circle that make it look
        // like a basketball
        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);
        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);
        
    }
    
    // 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);
    }
    
    // move the ball to a specified position
    public void moveTo( double x, double y ) {
        // move the ball by the offsets needed to reach desired location
        this.move ( x - body.getX(), y - body.getY() );
    }
    
    
    // check to see if the ball contains a specified location
    public boolean contains( Location point) {
        return body.contains(point);
    }
    
    // return the ball to its starting position
    public void reset ( ) {
        this.moveTo( initX, initY );
    }
    
    // hide all the parts of a basketball
    public void hide( ) {
        
        body.hide();
        border.hide();
        vert.hide();
        horiz.hide();
        leftCut.hide();
        rightCut.hide();
    }
    
    // show all the parts of a basketball
    public void show( ) {
        
        body.show();
        border.show();
        vert.show();
        horiz.show();
        leftCut.show();
        rightCut.show();
    }
    
}