Painting on JTabbedPanes

Question

I have code which reads rectangle tags from an svg file and displays them on a canvas in a tabbed pane, when I first click on the tabbed pane the image appears but when I click on another tab then go back to this tab the rectangle is not there. It does not appear to be repainting. How do I set my tabbed pane up so that when a user clicks on a tab the canvas is repainted?

Answer 1

import java.awt.*;
import java.awt.geom.*;
import javax.swing.*;
public class Painting
    JTabbedPane tabbedPane;
    public Painting()
        double[][] coords = {
            { 1.0/4, 1.0/4, 1.0/2, 2.0/3 }, { 1.0/3, 1.0/4, 1.0/3, 3.0/8 }
        Color[] colors = { Color.blue, Color.red };
        tabbedPane = new JTabbedPane();
        tabbedPane.addTab("blue", getPanel(coords[0], colors[0]));
        tabbedPane.addTab("red",  getPanel(coords[1], colors[1]));
    private JPanel getPanel(final double[] d, final Color color)
        JPanel panel = new JPanel()
             * swing always calls this method when your component
             * needs to be rendered so whatever you want to paint
             * will always show up if you put the code in here
            protected void paintComponent(Graphics g)
                super.paintComponent(g);
                Graphics2D g2 = (Graphics2D)g;
                g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                                    RenderingHints.VALUE_ANTIALIAS_ON);
                int w = getWidth();
                int h = getHeight();
                double x      = d[0] * w;
                double y      = d[1] * h;
                double width  = d[2] * w;
                double height = d[3] * h;
                g2.setPaint(color);
                g2.draw(new Rectangle2D.Double(x, y, width, height));
        return panel;
    public static void main(String[] args)
        JFrame f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.getContentPane().add(new Painting().tabbedPane);
        f.setSize(400,400);
        f.setLocation(200,200);
        f.setVisible(true);
}