APEX

import java.awt.*;
import java.awt.geom.*;
import java.awt.image.*;
import java.io.*;
import java.net.*;
import javax.imageio.*;
import javax.swing.*;
import javax.swing.border.*;

public class CentredBackgroundBorder implements Border {
    private final BufferedImage image;

    public CentredBackgroundBorder(BufferedImage image) {
        this.image = image;
    }

    public void paintBorder(Component c, Graphics g, int x, int y, int width, int height) {
        x += (width-image.getWidth())/2;
        y += (height-image.getHeight())/2;
        ((Graphics2D) g).drawRenderedImage(image, AffineTransform.getTranslateInstance(x,y));
    }

    public Insets getBorderInsets(Component c) {
        return new Insets(0,0,0,0);
    }

    public boolean isBorderOpaque() {
        return true;
    }

    //demo
    public static void main(String[] args) throws IOException {
        JFrame.setDefaultLookAndFeelDecorated(true);
        JTextArea area = new JTextArea();
        area.setForeground(Color.GREEN);
        area.setOpaque(false);
        area.read(new FileReader("CentredBackgroundBorder.java"), null);
        String url = "http://today.java.net/jag/bio/JagHeadshot.jpg";
        JScrollPane sp = new JScrollPane(area);
        sp.getViewport().setOpaque(false);
        sp.setViewportBorder(new CentredBackgroundBorder(ImageIO.read(new URL(url))));

        JFrame f = new JFrame("BackgroundBorderExample");
        f.getContentPane().add(sp);
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.setSize(600,400);
        f.setLocationRelativeTo(null);
        f.setVisible(true);
    }
}