java的画图的小疑点、

package com.tur.demo;

import javax.swing.*;
import java.awt.*;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.geom.Rectangle2D;

public class Hello extends JPanel {
    private Rectangle2D imageBoundingRect; // 图像的矩形区
    private Point       mousePressedPos;   // 鼠标按下的位置
    private boolean     imageSelected = false; // 图像被选中

    private Image       image;

    public Hello() {
        imageBoundingRect = new Rectangle2D.Double(10, 10, 150, 150);
        mousePressedPos = new Point();
        image = new ImageIcon("/Users/Biao/Desktop/x.png").getImage();

        MyMouseAdapter ma = new MyMouseAdapter();
        addMouseListener(ma);
        addMouseMotionListener(ma);
    }

    @Override
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);

        Graphics2D g2d = (Graphics2D) g;

        // 在此矩形框内绘制图像
        g2d.drawImage(image,
                      (int) imageBoundingRect.getX(),
                      (int) imageBoundingRect.getY(),
                      (int) imageBoundingRect.getWidth(),
                      (int) imageBoundingRect.getHeight(),
                      this);

        if (imageSelected) {
            // 图像被选中时高亮边框
            g2d.setColor(Color.RED);
            g2d.draw(imageBoundingRect);
        }
    }

    private static void createGuiAndShow() {