รบกวนหน่อยครับ JAVA ผมหาวิธีใส่ แบคกาวไม่ ผมลองเอาโค้คใส่ตั้งหลายตัว ผลแสดง แต่ แบคกาวไม่ขึ้น

import java.awt.event.*;
import java.awt.*;
import javax.swing.*;

public class Zoom extends JFrame {
   mapPanel map    = new mapPanel("usa.gif");
  
public Zoom()
{

  addWindowListener(new WindowAdapter() 
   {   public void windowClosing(WindowEvent ev) 
     {dispose();
        System.exit(0);}});
  setBounds(10,10,700,400);
  getContentPane().setLayout(null);
  getContentPane().add(map);   
  setVisible(true);

}
public class mapPanel extends JPanel
{
  Image map;
  double mw,mh;
  double zw,zh;
  double mx,my;
  double zf=1,tx=0,ty=0;

public mapPanel(String name)
{
  setBounds(50,50,200,150);
  setBackground(Color.white);
  map = getToolkit().createImage(name);
  MediaTracker tracker = new MediaTracker(this); 
  tracker.addImage(map,0); 
  try   {tracker.waitForID(0);} 
  catch (InterruptedException e){}
  mw  = map.getWidth(null);
  mh  = map.getHeight(null);
  zw  = 200;
  zh  = 150;
  mx  = mw/2;
  my  = mh/2;

  addMouseListener(new MouseAdapter()
  {
     public void mousePressed(MouseEvent m)
     {
        zf = zf + 0.025;
        double sw = zw / mw;
        double sh = zh / mh;
        double sx = m.getX() / sw;
        double sy = m.getY() / sh;
        tx = mw/2 - (sx-tx);
        ty = mh/2 - (sy-ty);
        repaint();
     }
  });
}
public void paintComponent(Graphics g)
{
  super.paintComponent(g);
  Graphics2D g2 = (Graphics2D)g;
  g2.scale(zf*zw/mw,zf*zh/mh);
  g2.translate(tx/zf,ty/zf);
  g2.drawImage(map,0,0,null);
  g2.dispose();
}   
}      
public static void main(String[]args)
{
  new Zoom ();
}