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copied!<p>I've had some luck extending <code>JLabel</code> and implementing <code>Icon</code> to get a translucent component working the way I want. You can see the result of various rule combinations in this <a href="http://sites.google.com/site/drjohnbmatthews/composite" rel="nofollow noreferrer">AlphaCompositeDemo</a>. <del>The example below is 100% white atop 50% black.</del></p> <p>Addendum: Note how this example composites opaque text on a clear offscreen background over the translucent frame background.</p> <p>Addendum: Here's a way to make the <a href="http://devdaily.com/blog/post/jfc-swing/transparent-translucent-java-frame-jframe-mac-slider" rel="nofollow noreferrer">whole frame translucent</a>. Unfortunately, it dims the content, too.</p> <p><a href="https://i.stack.imgur.com/rFmOy.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/rFmOy.png" alt="image"></a></p> <pre><code>import java.awt.AlphaComposite; import java.awt.Color; import java.awt.Dimension; import java.awt.EventQueue; import java.awt.Font; import java.awt.FontMetrics; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.RenderingHints; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.awt.image.BufferedImage; import java.text.SimpleDateFormat; import java.util.Date; import javax.swing.JFrame; import javax.swing.JPanel; import javax.swing.Timer; public class Translucent extends JPanel implements ActionListener { private static final int W = 300; private static final int H = 100; private static final Font font = new Font("Serif", Font.PLAIN, 48); private static final SimpleDateFormat df = new SimpleDateFormat("HH:mm:ss"); private final Date now = new Date(); private final Timer timer = new Timer(1000, this); private BufferedImage time; private Graphics2D timeG; public Translucent() { super(true); this.setPreferredSize(new Dimension(W, H)); timer.start(); } @Override protected void paintComponent(Graphics g) { Graphics2D g2d = (Graphics2D) g; g2d.setRenderingHint( RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON); int w = this.getWidth(); int h = this.getHeight(); g2d.setComposite(AlphaComposite.Clear); g2d.fillRect(0, 0, w, h); g2d.setComposite(AlphaComposite.Src); g2d.setPaint(g2d.getBackground()); g2d.fillRect(0, 0, w, h); renderTime(g2d); int w2 = time.getWidth() / 2; int h2 = time.getHeight() / 2; g2d.setComposite(AlphaComposite.SrcOver); g2d.drawImage(time, w / 2 - w2, h / 2 - h2, null); } private void renderTime(Graphics2D g2d) { g2d.setFont(font); String s = df.format(now); FontMetrics fm = g2d.getFontMetrics(); int w = fm.stringWidth(s); int h = fm.getHeight(); if (time == null && timeG == null) { time = new BufferedImage(w, h, BufferedImage.TYPE_INT_ARGB); timeG = time.createGraphics(); timeG.setRenderingHint( RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON); timeG.setFont(font); } timeG.setComposite(AlphaComposite.Clear); timeG.fillRect(0, 0, w, h); timeG.setComposite(AlphaComposite.Src); timeG.setPaint(Color.green); timeG.drawString(s, 0, fm.getAscent()); } private static void create() { JFrame f = new JFrame(); f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); f.setBackground(new Color(0f, 0f, 0f, 0.3f)); f.setUndecorated(true); f.add(new Translucent()); f.pack(); f.setLocationRelativeTo(null); f.setVisible(true); } @Override public void actionPerformed(ActionEvent e) { now.setTime(System.currentTimeMillis()); this.repaint(); } public static void main(String[] args) { EventQueue.invokeLater(new Runnable() { @Override public void run() { create(); } }); } } </code></pre>

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