ShapedWindowDemo.java

import java.awt.*; //Graphics2D, LinearGradientPaint, Point, Window, Window.Type;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.SwingUtilities;
import java.awt.image.BufferedImage;
import java.io.File;
import javax.imageio.ImageIO;
import java.io.IOException;

/**
 * From JavaMagazine May/June 2012
 * @author josh
 */
public class ShapedWindowDemo {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        //switch to the right thread
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                JFrame frame = new JFrame("About box");
                //turn of window decorations
                frame.setUndecorated(true);
                //turn off the background
                frame.setBackground(new Color(255,255,255,0));
                frame.setContentPane(new AboutComponent());
                frame.pack();
                //size the window
                frame.setSize(500, 200);
                frame.setVisible(true);
                //center on screen
                frame.setLocationRelativeTo(null);
            }
        }
        );
    }

    private static class AboutComponent extends JComponent {
        private BufferedImage image;

        public AboutComponent() {
            try {
              image = ImageIO.read(new File("circle.jpg"));
           } catch (IOException ex) {
                // handle exception...
           }
        }
        public void paintComponent(Graphics graphics) {
            Graphics2D g = (Graphics2D) graphics;
            g.drawImage(image, 0, 0, null);
        }
    }
}