JViewport in Java Swing Example

 import java.awt.*; 
 import javax.swing.*; 
 import java.awt.event.*; 
 public class JavaExampleScrollPictureInJApplet extends JApplet 
  { 
       public JavaExampleScrollPictureInJApplet() 
        { 
         Container Cntnr = getContentPane(); 
         JViewport ViewPrt = new JViewport(); 
         JPanel Pnl = new JPanel(); 
         Pnl.add(new JLabel(new ImageIcon("Koala.jpg"))); 
         ViewPrt.setView(Pnl); 
         Cntnr.add(ViewPrt,BorderLayout.CENTER); 
         Cntnr.add(new ButtonPanel(ViewPrt),BorderLayout.SOUTH); 
       } 
  } 
        class ButtonPanel extends JPanel implements ActionListener 
          { 
               JViewport ViewPrt; 
               JButton BtnLft = new JButton("Scroll Left"); 
               JButton BtnUp = new JButton("Scroll UP"); 
               JButton BtnDwn = new JButton("Scroll Down"); 
               JButton BtnRght = new JButton("Scroll Right"); 
               public ButtonPanel(JViewport VwPort) 
                { 
                   ViewPrt = VwPort; 
                    add(BtnLft); 
                    add(BtnUp); 
                    add(BtnDwn); 
                    add(BtnRght); 
                   BtnLft.addActionListener(this); 
                   BtnUp.addActionListener(this); 
                   BtnDwn.addActionListener(this); 
                   BtnRght.addActionListener(this); 
                } 
                    public void actionPerformed(ActionEvent e1) 
                   { 
                       Point Pstn = ViewPrt.getViewPosition(); 
                       if(e1.getSource() == BtnLft) Pstn.x += 10;    
                       else if(e1.getSource() == BtnUp) Pstn.y += 10;    
                       else if(e1.getSource() == BtnDwn) Pstn.y -= 10;    
                       else if(e1.getSource() == BtnRght) Pstn.x -= 10;    
                        ViewPrt.setViewPosition(Pstn); 
                    } 
         } 
 /*<APPLET  CODE=JavaExampleScrollPictureInJApplet.class WIDTH=700  HEIGHT=200 ></APPLET>*/