How to Correctly Repaint a JLabel on a Translucent Window in Java on macOS?

Repaint on translucent component

Question: When attempting to create a translucent window in Java on macOS and adding a JLabel with dynamic text, the component does not repaint correctly.

Solution: To resolve the issue, a custom JLabel can be extended and the Icon interface implemented to achieve the desired translucent effect. Here's an example using AlphaComposite:

import java.awt.AlphaComposite;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import javax.swing.JLabel;

public class TranslucentLabel extends JLabel {

    private Image image;
    private AlphaComposite alphaComposite;

    public TranslucentLabel() {
        super();
        setBackground(new Color(0f,0f,0f,0.3f));
        alphaComposite = AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 0.5f);
    }

    @Override
    public void paintComponent(Graphics g) {
        Graphics2D g2d = (Graphics2D) g;
        g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
        image = createImage(getWidth(), getHeight());
        Graphics2D imageGraphics = (Graphics2D) image.getGraphics();
        imageGraphics.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
        super.paintComponent(imageGraphics);
        g2d.setComposite(alphaComposite);
        g2d.drawImage(image, 0, 0, null);
        g2d.dispose();
    }
}

In this approach, a custom JLabel (TranslucentLabel) is created and the AlphaComposite technique is applied to compose a semi-transparent background over the translucent frame background, ensuring that the component repaints correctly.

The above is the detailed content of How to Correctly Repaint a JLabel on a Translucent Window in Java on macOS?. For more information, please follow other related articles on the PHP Chinese website!