javamacossplash-screenalways-on-top

Java SplashScreen always on top for Mac


I am using macOS 10.14.2 and JDK 1.8.0_192.

For my application, I have a splash screen using Java's java.awt.SplashScreen.

When I run my application on Windows, the splash screen will hide under an overlapping window if said window is clicked on.

However, on macOS, the splash screen hides for a split second before it forces itself on top again.

This can be seen with Java's SplashScreen example code:

The VM argument required is "-splash:pathToImage" where pathToImage is a path in your system to the following image: https://i.sstatic.net/Kdgl3.gif (download required)

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package splash;

import java.awt.AlphaComposite;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Frame;
import java.awt.Graphics2D;
import java.awt.Menu;
import java.awt.MenuBar;
import java.awt.MenuItem;
import java.awt.RenderingHints;
import java.awt.SplashScreen;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.awt.event.WindowListener;

public class SplashDemo extends Frame implements ActionListener {
    private static final long serialVersionUID = 1L;

    private static void renderSplashFrame(Graphics2D g, int frame) {
        final String[] comps = {"foo", "bar", "baz"};
        g.setComposite(AlphaComposite.Clear);
        g.fillRect(120, 140, 200, 40);
        g.setPaintMode();
        g.setColor(Color.BLACK);
        g.drawString("Loading " + comps[(frame / 5) % 3] + "...", 120, 150);
    }

    private SplashDemo() {
        super("SplashScreen demo");
        setSize(300, 200);
        setLayout(new BorderLayout());
        Menu m1 = new Menu("File");
        MenuItem mi1 = new MenuItem("Exit");
        m1.add(mi1);
        mi1.addActionListener(this);
        this.addWindowListener(closeWindow);

        MenuBar mb = new MenuBar();
        setMenuBar(mb);
        mb.add(m1);
        final SplashScreen splash = SplashScreen.getSplashScreen();
        if(splash == null) {
            System.out.println("SplashScreen.getSplashScreen() returned null");
            return;
        }
        Graphics2D g = splash.createGraphics();
        if(g == null) {
            System.out.println("g is null");
            return;
        }
        g.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
        for(int i = 0; i < 100; i++) {
            renderSplashFrame(g, i);
            splash.update();
            try {
                Thread.sleep(90);
            }
            catch(InterruptedException ignored) {}
        }
        splash.close();
        setVisible(true);
        toFront();
    }

    @Override
    public void actionPerformed(ActionEvent ae) {
        System.exit(0);
    }

    private static WindowListener closeWindow = new WindowAdapter() {
        @Override
        public void windowClosing(WindowEvent e) {
            e.getWindow().dispose();
        }
    };

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

If it makes it easier, here's a link to a compiled jar with the above code: https://github.com/Jorl17/jar2app/files/1456251/SplashDemo.jar.zip.

It already has the image internally and was compiled with the following line in the manifest "SplashScreen-Image: splash.gif", so the VM argument isn't required.


Solution

  • This has been confirmed to be a bug in Java after this question was created: https://bugs.openjdk.java.net/browse/JDK-8216158