How to custom the shape of a JPanel or JLabel?

Question

I'm displaying an image in a JLabel. I want to show that image in a circular shape i.e. I want the shape of the JLabel to be a Circle which is Rectangle by default. How to setShape of the JPanel or JLabel?? setUndecorated() and setShape() is defined only for Frame?? Is there any possibility to change the shape of other components like JPanel and JLabel??

Answer 1

A component is always rectangular, however, you can use custom painting and transparency to make the component appear non-rectangular

Take a look at Perfoming Custom Painting and 2D Graphics

Updated with example

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridBagLayout;
import java.awt.Insets;
import java.awt.RenderingHints;
import java.awt.geom.Path2D;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class FunkyShapedComponent {

    public static void main(String[] args) {
        new FunkyShapedComponent();
    }

    public FunkyShapedComponent() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                }

                JPanel testPane = new JPanel();
                testPane.setBackground(Color.RED);
                testPane.setLayout(new GridBagLayout());
                testPane.add(new FunkyPane());

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setLayout(new BorderLayout());
                frame.add(testPane);
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class FunkyPane extends JPanel {

        public FunkyPane() {
            setLayout(new GridBagLayout());
            add(new JLabel("This is a simple test"));
            setOpaque(false);
        }

        @Override
        public Insets getInsets() {
            return new Insets(10, 10, 10, 10);
        }

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);

            int width = getWidth() - 1;
            int height = getHeight() - 1;

            int radius = Math.min(width, height) / 10;

            Path2D p = new Path2D.Float();
            p.moveTo(0, radius / 2);
            p.curveTo(0, 0, 0, 0, radius / 2, 0);
            p.curveTo(width / 4, radius, width / 4, radius, (width / 2) - radius, radius / 2);
            p.curveTo(width / 2, 0, width / 2, 0, (width / 2) + radius, radius / 2);
            p.curveTo(width - (width / 4), radius, width - (width / 4), radius, width - (radius / 2), 0);
            p.curveTo(width, 0, width, 0, width, radius / 2);

            p.curveTo(width - radius, height / 4, width - radius, height / 4, width - (radius / 2), (height / 2) - radius);
            p.curveTo(width, height / 2, width, height / 2, width - (radius / 2), (height / 2) + radius);
            p.curveTo(width - radius, height - (height / 4), width - radius, height - (height / 4), width, height - (radius / 2));
            p.curveTo(width, height, width, height, width - (radius / 2), height);

            p.curveTo(width - (width / 4), height - radius, width - (width / 4), height - radius, (width / 2) + radius, height - (radius / 2));
            p.curveTo(width / 2, height, width / 2, height, (width / 2) - radius, height - (radius / 2));
            p.curveTo((width / 4), height - radius, (width / 4), height - radius, (radius / 2), height);
            p.curveTo(0, height, 0, height, 0, height - (radius / 2));

            p.curveTo(radius, height - (height / 4), radius, height - (height / 4), (radius / 2), (height / 2) + radius);
            p.curveTo(0, height / 2, 0, height / 2, (radius / 2), (height / 2) - radius);
            p.curveTo(radius, (height / 4), radius, (height / 4), 0, (radius / 2));

            p.closePath();

            Graphics2D g2d = (Graphics2D) g.create();
            g2d.setRenderingHint(RenderingHints.KEY_ALPHA_INTERPOLATION, RenderingHints.VALUE_ALPHA_INTERPOLATION_QUALITY);
            g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
            g2d.setRenderingHint(RenderingHints.KEY_COLOR_RENDERING, RenderingHints.VALUE_COLOR_RENDER_QUALITY);
            g2d.setRenderingHint(RenderingHints.KEY_DITHERING, RenderingHints.VALUE_DITHER_ENABLE);
            g2d.setRenderingHint(RenderingHints.KEY_FRACTIONALMETRICS, RenderingHints.VALUE_FRACTIONALMETRICS_ON);
            g2d.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
            g2d.setRenderingHint(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);
            g2d.setRenderingHint(RenderingHints.KEY_STROKE_CONTROL, RenderingHints.VALUE_STROKE_PURE);
            g2d.setColor(getBackground());
            g2d.fill(p);
            g2d.dispose();

        }
    }
}