No success in placing background image in JComboBox drop-down!

Question

Hi All! I have an urgent proble, which I was not able to resolve a full day and a half long!!! I want to place a background image in the dropdown (JPopupMenu) of a JComboBox. Not behind the Menu Items (I know how to do that), but behind the popup itself (the items will have a transparent background). I was surprised to find out that I cannot achieve this via UI delegates (seems paint takes place in JComponent), nor with simply subclassing JPopupMenu (because after I draw the image it is overwritten by a background rectangle). I beleive this is not an easy thing to acheive, but I would accept a complicated solution as well.
Can anyone help me?
Thanks, in advance!

Answer 1

Try this for ideas. Change the filename to a valid image file on your machine.import java.awt.Color;
import java.awt.Component;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.event.InputEvent;
import java.awt.event.MouseEvent;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.DefaultListCellRenderer;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JList;
import javax.swing.SwingUtilities;
import javax.swing.plaf.basic.BasicComboPopup;
import javax.swing.plaf.basic.ComboPopup;
import javax.swing.plaf.metal.MetalComboBoxUI;
public class PictureCombo {
   public static void main(String[] args) {
      SwingUtilities.invokeLater(new Runnable() {
         @Override
         public void run() {
            new PictureCombo().makeUI();
   public void makeUI() {
      Object[] data = {"One", "Two", "Three", "Four", "Five"};
      JComboBox comboBox = new JComboBox(data);
      comboBox.setUI(new PictureComboBoxUI());
      comboBox.setRenderer(new PictureListCellRenderer());
      JFrame frame = new JFrame();
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.add(comboBox);
      frame.pack();
      frame.setLocationRelativeTo(null);
      frame.setVisible(true);
class PictureComboBoxUI extends MetalComboBoxUI {
   @Override
   protected ComboPopup createPopup() {
      return new PictureComboPopup(comboBox);
class PictureComboPopup extends BasicComboPopup {
   Image image;
   public PictureComboPopup(JComboBox comboBox) {
      super(comboBox);
      try {
         image = ImageIO.read(new File("E:/Java/test.jpg"));
      } catch (IOException ex) {
         ex.printStackTrace();
   @Override
   protected JList createList() {
      JList retVal = new JList(comboBox.getModel()) {
         @Override
         public void processMouseEvent(MouseEvent e) {
            if (e.isControlDown()) {
               e = new MouseEvent((Component) e.getSource(), e.getID(), e.
                     getWhen(),
                     e.getModifiers() ^ InputEvent.CTRL_MASK,
                     e.getX(), e.getY(),
                     e.getXOnScreen(), e.getYOnScreen(),
                     e.getClickCount(),
                     e.isPopupTrigger(),
                     MouseEvent.NOBUTTON);
            super.processMouseEvent(e);
         @Override
         protected void paintComponent(Graphics g) {
            if (image != null) {
               g.drawImage(image, 0, 0, comboBox);
            super.paintComponent(g);
      retVal.setOpaque(false);
      return retVal;
class PictureListCellRenderer extends DefaultListCellRenderer {
   @Override
   public Component getListCellRendererComponent(JList list, Object value,
         int index, boolean isSelected, boolean cellHasFocus) {
      super.getListCellRendererComponent(list, value, index, isSelected,
            cellHasFocus);
      Color selBgColor = list.getSelectionBackground();
      selBgColor = new Color(selBgColor.getRGB() & 0xA0FFFFFF, true);
      setBackground(selBgColor);
      setOpaque(isSelected);
      return this;
}db