How to change jdesktoppane default background image?

Question

How to change jdesktoppane background image in MDI (Multiple Documents interface) using java netbeans? Means I added the jdesktoppane to java MDI so now I want to change default background image of that jdesktoppane which I'm using in java MDI. Any easy way?

Check attached snapshot link may be you will better understand my question what I want.

http://i50.tinypic.com/iml1e9.jpg

Answer 1

+1 to MadProgrammers comment.

Simply override JDesktopPane paintComponent(..) and call drawImage(Image img,int x,int y,ImageObserver io) to draw an image.

Dont forget to honor the paint chain and call super.paintComponent(g) as first call in overridden paintComponent(..) method

Here is an example:

import java.awt.*;
import java.awt.event.*;
import java.awt.image.BufferedImage;
import java.net.URL;
import javax.imageio.ImageIO;
import javax.swing.JDesktopPane;
import javax.swing.JFrame;
import javax.swing.JInternalFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.SwingUtilities;

public class JInternalFrameDemo {

    private JDesktopPane jdpDesktop;
    private static int openFrameCount = 0;
    private BufferedImage img;

    public JInternalFrameDemo() {
        JFrame frame = new JFrame("JInternalFrame Usage Demo");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        try {
            img = ImageIO.read(new URL("http://images1.wikia.nocookie.net/__cb20120817224359/villains/images/6/6a/Nine-Tailed_Fox_(Naruto).jpg"));
        } catch (Exception ex) {
            ex.printStackTrace();
        }

        // A specialized layered pane to be used with JInternalFrames
        jdpDesktop = new JDesktopPane() {
            @Override
            protected void paintComponent(Graphics grphcs) {
                super.paintComponent(grphcs);
                grphcs.drawImage(img, 0, 0, null);
            }

            @Override
            public Dimension getPreferredSize() {
                return new Dimension(img.getWidth(), img.getHeight());
            }
        };



        createFrame(); // Create first window

        frame.setContentPane(jdpDesktop);

        frame.setJMenuBar(createMenuBar());

        // Make dragging faster by setting drag mode to Outline
        jdpDesktop.putClientProperty("JDesktopPane.dragMode", "outline");

        frame.pack();
        frame.setVisible(true);
    }

    protected JMenuBar createMenuBar() {
        JMenuBar menuBar = new JMenuBar();
        JMenu menu = new JMenu("Frame");
        menu.setMnemonic(KeyEvent.VK_N);
        JMenuItem menuItem = new JMenuItem("New IFrame");
        menuItem.setMnemonic(KeyEvent.VK_N);
        menuItem.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                createFrame();
            }
        });
        menu.add(menuItem);
        menuBar.add(menu);
        return menuBar;
    }

    protected void createFrame() {
        MyInternalFrame frame = new MyInternalFrame();
        frame.setVisible(true);
        // Every JInternalFrame must be added to content pane using JDesktopPane
        jdpDesktop.add(frame);
        try {
            frame.setSelected(true);
        } catch (java.beans.PropertyVetoException e) {
        }
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                new JInternalFrameDemo();
            }
        });
    }

    class MyInternalFrame extends JInternalFrame {

        static final int xPosition = 30, yPosition = 30;

        public MyInternalFrame() {
            super("IFrame #" + (++openFrameCount), true, // resizable
                    true, // closable
                    true, // maximizable
                    true);// iconifiable
            setSize(300, 300);
            // Set the window's location.
            setLocation(xPosition * openFrameCount, yPosition
                    * openFrameCount);
        }
    }
}

Answer 2

I resolve it in a separate function to create a desktop object.

Code as below

private JDesktopPane intializeDesktop(JDesktopPane mydesktop,String imagePath,int scalx,int scaly) {

        // A specialized layered pane to be used with JInternalFrames
        mydesktop = new JDesktopPane() {
            ImageIcon icon = new ImageIcon(imagePath);
            Image image = icon.getImage();

            Image newimage = image.getScaledInstance(scalx, scaly, Image.SCALE_SMOOTH);

            @Override
            protected void paintComponent(Graphics g) {
                super.paintComponent(g);
                g.drawImage(newimage, 0, 0, this);
            }
        };

        return mydesktop;
    }