Painting in the backgroung

Question

all,
I'm having a problem with drawing an image in a JTabbedPane.
Consider a JTabbedPane with two JPanel as tabs.
in first tab I have a text field in the second a JComboBox and a small JPanel
(let's call it the picturePanel)
Items selected in the JComboBox trigger the painting of an image in the
picturePanel.
At init :
JComboBox is disabled and picturePanel does not contain anything.
JTextField is empty
When a user types a value in the text field it enables the JComboBox
in second tab.
The user then goes to second tab and selects a picture which is correctly drawn.
Now lets consider that the user goes back to first tab and modifies the value in the textfield.
I then want to restore the state of the components of second tab as they were at the init.
No problem for the JComboBox, the problem is for the picturePanel.
How do I remove the picture in the Graphics object of the picturePanel ?
I simply tryed to fill a rectangle in place of the picture but as the selected tab is the first one,
the rectangle is displayed on this first tab !!!
I tried to integrate the condition isVisible() to the picturePanel before filling the rectangle
but it did not change anything.
I have an ugly way which is to remove the picturePanel and add a new one but
I'd prefer to implement one of your suggestions.
thx.

Answer 1

import java.awt.*;
import java.awt.event.*;
import java.awt.geom.*;
import java.awt.image.BufferedImage;
import java.io.*;
import java.net.*;
import javax.imageio.ImageIO;
import javax.swing.*;
import javax.swing.event.*;
public class TabTalk
    public static void main(String[] args)
        JTextField textField = new JTextField(16);
        final JPanel fieldPanel = new JPanel();
        fieldPanel.add(textField);
        String[] fileNames = {
            "cougar.jpg", "redfox.jpg", "bclynx.jpg", "greathornedowl.jpg"
        final ImageTabComponent imageComponent = new ImageTabComponent();
        final JComboBox comboBox = new JComboBox(fileNames);
        comboBox.addActionListener(new ActionListener()
            public void actionPerformed(ActionEvent e)
                String fileName = (String)comboBox.getSelectedItem();
                imageComponent.setImage(fileName);
        JPanel imagePanel = new JPanel(new GridBagLayout());
        GridBagConstraints gbc = new GridBagConstraints();
        gbc.insets = new Insets(5,5,5,5);
        gbc.weightx = 1.0;
        gbc.gridwidth = gbc.REMAINDER;
        imagePanel.add(comboBox, gbc);
        gbc.weighty = 1.0;
        gbc.fill = gbc.BOTH;
        imagePanel.add(new JScrollPane(imageComponent), gbc);
        final JTabbedPane tabbedPane = new JTabbedPane();
        tabbedPane.addTab("textfield", fieldPanel);
        tabbedPane.addTab("image", imagePanel);
        tabbedPane.addChangeListener(new ChangeListener()
            public void stateChanged(ChangeEvent e)
                Component c = tabbedPane.getSelectedComponent();
                if(c.equals(fieldPanel))
                    imageComponent.setImage(null);
        JFrame f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.getContentPane().add(tabbedPane);
        f.setSize(400,400);
        f.setLocation(200,200);
        f.setVisible(true);
class ImageTabComponent extends JPanel
    BufferedImage image;
    public ImageTabComponent()
        image = null;
        setBackground(Color.black);
    protected void paintComponent(Graphics g)
        super.paintComponent(g);
        Graphics2D g2 = (Graphics2D)g;
        g2.setRenderingHint(RenderingHints.KEY_INTERPOLATION,
                            RenderingHints.VALUE_INTERPOLATION_BICUBIC);
        int w = getWidth();
        int h = getHeight();
        if(image != null)
            int imageWidth = image.getWidth();
            int imageHeight = image.getHeight();
            int x = (w - imageWidth)/2;
            int y = (h - imageHeight)/2;
            AffineTransform at = AffineTransform.getTranslateInstance(x, y);
            g2.drawRenderedImage(image, at);
    public Dimension getPreferredSize()
        Dimension d = new Dimension(10,10);
        if(image != null)
            d = new Dimension(image.getWidth(), image.getHeight());
        return d;
    public void setImage(String fileName)
        if(fileName != null)
            loadImage(fileName);
        else
            image = null;
        revalidate();
        repaint();
    private void loadImage(String fileName)
        String prefix = "images/";
        try
            URL url = getClass().getResource(prefix + fileName);
            image = ImageIO.read(url);
        catch(MalformedURLException mue)
            System.out.println("url: " + mue.getMessage());
        catch(IOException ioe)
           System.out.println("read: " + ioe.getMessage());
}