Force JMenuItem size

Question

When I add an icon to a JMenuItem, it's scaled up to the size of the icon. See the difference here:

Can I somehow force it to scale back down to original? If not, is there default icon size for JMenuItem (meaning, what would be the size of the icon when it would perfectly fit in Test1,2,3's icon slot)?

Answer 1

One way to solve this, is to rescale the icon itself :

 ImageIcon i = new ImageIcon((getClass().getResource("new.png")));
 Image image = i.getImage(); // transform it
 Image newimg = image.getScaledInstance(20, 20, java.awt.Image.SCALE_SMOOTH); // scale it the smooth way 
 i = new ImageIcon(newimg);  // transform it back

Then you set this new resized-icon to your JMenuItem :

*In fact you can just force the size of JMenuItem by declaring :

.setPreferredSize(new Dimension(..,..));

but the problem is that the icon won't be scaled, it will look like the following :

Here is the simple demo I wrote :

public class SwingMenuDemo {

private JFrame mainFrame;

public SwingMenuDemo() { prepareGUI(); }

public static void main(String[] args) {
    SwingMenuDemo swingMenuDemo = new SwingMenuDemo();
    swingMenuDemo.showMenuDemo();
}

private void prepareGUI() {
    mainFrame = new JFrame("Java SWING Examples");
    mainFrame.setSize(400, 400);
    mainFrame.setVisible(true);
}

private void showMenuDemo() {
    //create a menu bar
    final JMenuBar menuBar = new JMenuBar();

    //create menus
    JMenu fileMenu = new JMenu("File");

    //create menu items
    JMenuItem test1 = new JMenuItem("test1");
    JMenuItem test2 = new JMenuItem("test2");
    JMenuItem test3 = new JMenuItem("test3");
    JMenuItem test4 = new JMenuItem("test4");

    ImageIcon i = new ImageIcon((getClass().getResource("new.png")));
    Image image = i.getImage(); // transform it
    Image newimg = image.getScaledInstance(20, 20, java.awt.Image.SCALE_SMOOTH); // scale it the smooth way 
    i = new ImageIcon(newimg);  // transform it back

    test4.setIcon(i);

    fileMenu.add(test1);
    fileMenu.add(test2);
    fileMenu.add(test3);
    fileMenu.add(test4);

    menuBar.add(fileMenu);

    //add menubar to the frame
    mainFrame.setJMenuBar(menuBar);
    mainFrame.setVisible(true);
  }
}

The size of original icon :

The scaled icon on JMenuItem :

Answer 2

is there default icon size for JMenuItem

I guess you could take a look at the size of the icons used for JCheckBoxMenuItem and JRadioButtonMenuItem to see what size those icons are.

You can use the UIManager for this:

Icon icon = UIManager.getIcon("RadioButtonMenuItem.checkIcon");
Icon icon = UIManager.getIcon("CheckBoxMenuItem.checkIcon");