Re: Copying the View of a JPanel

X wrote:


I tried to write a program to emulate yours but I couldn't do it. I
would be really curious to see your code if you have an SSCCE.

In any case I took a different tact, I copy the data from the first
component with a Robot and then draw it on the second. This works
pretty good but if you put something over the first panel such as
another window, that's what shows up in the second panel. Also I just
refresh the second panel every 100ms. You could capture events on the
first window and trigger a repaint then as well.

This was an interesting question but I am curious as to what the purpose
of it is. Are you trying to make some sort of whiteboard connected
across the net?

Anyway, here is my implementation.

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

public class test extends JPanel implements Runnable {
     JComponent c;
     Robot robot;

     public test(JComponent c) {
         this.c = c;
         try {
             robot = new Robot();
         } catch (AWTException awte) {
             awte.printStackTrace();
         }
     }

     public void run() {
         while (true) {
             try {
                 Thread.sleep(100);
             } catch (InterruptedException ie) { }
             repaint();
         }
     }

     public void paint(Graphics g) {
         Point p = c.getLocationOnScreen();
         Rectangle r = new Rectangle(p,c.getSize());
         BufferedImage bi = robot.createScreenCapture(r);
         g.drawImage(bi,0,0,null);
     }

     public static void main(String[] args) {
         SwingUtilities.invokeLater(new Runnable() {
             public void run() {
                 final JFrame f = new JFrame();
                 f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                 f.setLayout(new FlowLayout());

                 final JPanel p = new JPanel();
                 p.setPreferredSize(new Dimension(400,300));
                 p.setBackground(new Color(0,0,255,40));
                 JButton b = new JButton("Add Component");
                 b.addActionListener(new ActionListener() {
                     public void actionPerformed(ActionEvent ae) {
                         JLabel l = new JLabel("A JLabel");
                         p.add(l);
                         p.invalidate();
                         f.validate();
                         f.repaint();
                     }
                 });
                 p.add(b);
                 f.add(p);

                 test t = new test(p);
                 t.setPreferredSize(new Dimension(400,300));
                 f.add(t);

                 f.pack();
                 f.setVisible(true);

                 new Thread(t).start();
             }
         });
     }
}

--

Knute Johnson
email s/nospam/knute2008/

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