How to remove border corners in JButton?

Question

I have a JButton with FlatLaf GUI.

FlatLaf allow me set client properties to some components, in this case I use 'JButton.buttonType' property

Example:

JButton myButton = new JButton();
myButton.putClientProperty("JButton.buttonType","roundRect");

And this paints a rounded button.

The problem occurs when I send an Icon to the button

myButton.setIcon(new ImageIcon(getClass().getResource("/path/image.png")));

And this paints the image like:

As can be seen, this paints the image using the rectangle of my button. The borderPaint can be seen, and effectively is a perfect circle, but the border corners always show.

How can I remove those corners?

Answer 1

You could create a custom Icon class:

import java.awt.*;
import java.awt.geom.*;
import java.awt.image.*;
import java.net.*;
import javax.swing.*;

public class OvalImageIcon extends ImageIcon
{
    private BufferedImage oval;

    public OvalImageIcon()
    {
        super();
    }

    public OvalImageIcon(String fileName)
    {
        super(fileName);
    }

    public OvalImageIcon(URL url)
    {
        super(url);
    }

    @Override
    public void setImage(Image image)
    {
        super.setImage(image);

        oval = null;
    }

    @Override
    public void paintIcon(Component c, Graphics g, int x, int y)
    {
        if (oval == null)
        {
            oval = new BufferedImage(getIconWidth(), getIconHeight(), BufferedImage.TYPE_INT_ARGB);
            Graphics2D ovalGraphics = oval.createGraphics();
            ovalGraphics.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
            ovalGraphics.drawImage(getImage(), 0, 0, null);

            //  Use AlphaComposite to apply oval mask

            Shape ovalMask = new Ellipse2D.Double(0, 0, getIconWidth(), getIconHeight());
            Area imageArea = new Area( new Rectangle(0, 0, getIconWidth(), getIconHeight()) );
            imageArea.subtract( new Area( ovalMask ) );
            ovalGraphics.setComposite(AlphaComposite.getInstance(AlphaComposite.DST_IN));
            ovalGraphics.setColor( new Color(0, 0, 0, 0) );
            ovalGraphics.fill(imageArea);
            ovalGraphics.dispose();
        }

        g.drawImage(oval, x, y, null);
    }

    public static void main(String[] args)
    {
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGUI();
            }
        });
    }

    public static void createAndShowGUI()
    {
        Icon icon = new OvalImageIcon("mong.jpg");
        JLabel label = new JLabel( icon );

        JFrame f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.add(label);
        f.pack();
        f.setLocationRelativeTo( null );
        f.setVisible(true);
    }
}

Above code should paint an oval of the image based on the width and height of the original image.