Java swing JComponent "size"

Solution 1:

As an alternative, consider the The Button API, which includes the method setRolloverIcon() "to make the button display the specified icon when the cursor passes over it."

Addendum: For example,

import java.net.MalformedURLException;
import java.net.URL;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;

public class ButtonIconTest {

    public static void main(String[] args) {

        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGui();
            }
        });
    }

    private static void createAndShowGui() {
        String base = "http://download.oracle.com/"
            + "javase/tutorial/uiswing/examples/components/"
            + "RadioButtonDemoProject/src/components/images/";
        ImageIcon dog = null;
        ImageIcon pig = null;
        try {
            dog = new ImageIcon(new URL(base + "Dog.gif"));
            pig = new ImageIcon(new URL(base + "Pig.gif"));
        } catch (MalformedURLException ex) {
            ex.printStackTrace(System.err);
            return;
        }
        JFrame frame = new JFrame("Rollover Test");
        JPanel panel = new JPanel();
        panel.add(new JLabel(dog));
        panel.add(new JLabel(pig));

        JButton button = new JButton(dog);
        button.setRolloverIcon(pig);
        panel.add(button);

        frame.add(panel);

        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);
    }
}

Solution 2:

I assume your image contains ONLY 4 'customWidget' objects (in a 2x2 grid).

Your code is working as I would expect. Your MouseListener methods are responding to MouseEvents for 'customWidget' (not the image drawn in 'customWidget'), which is sized to take up 1/4 of the image, so they will respond when it enters the enlarged area. The error is actually in your Test program, because you are allowing the custom button widget to be larger than the image.

If you want a Test program that provides an image similar to yours, you should create a larger grid (say 4x4), and then only place your buttons in every other grid node. Place an empty component into the gaps.