Java Full Screen window on Linux OSs using native X11 calling

X11FullscreenHelper.java

package org.linux.X11;

import com.sun.jna.Native;
import com.sun.jna.NativeLong;
import com.sun.jna.platform.unix.X11;

import java.awt.*;

/**
 * Author: Vladimir Kravets
 * E-Mail: [email protected]
 * Date: 4/10/13
 * Time: 12:19 AM
 * based on code from VLCJ
 * http://code.google.com/p/vlcj/source/browse/trunk/vlcj/src/main/java/uk/co/caprica/vlcj/runtime/x/LibXUtil.java
 */

public class X11FullscreenHelper {

  private static boolean isFullScreenMode = false;

  /**
   * Ask the window manager to make a window full-screen.
   * <p>
   * This method sends a low-level event to an X window to request that the
   * window be made 'real' full-screen - i.e. the window will be sized to fill
   * the entire screen bounds, and will appear <em>above</em> any window
   * manager screen furniture such as panels and menus.
   * <p>
   * This method should only be called on platforms where X is supported.
   * <p>
   * The implementation makes use of the JNA X11 platform binding.
   *
   * @param w window to make full-screen
   * @param fullScreen <code>true</code> to make the window full-screen; <code>false</code> to restore the window to it's original size and position
   * @return <code>true</code> if the message was successfully sent to the window; <code>false</code> otherwise
   */
  public static boolean setFullScreenWindow(Window w, boolean fullScreen) {
    // Use the JNA platform X11 binding
    X11 x = X11.INSTANCE;
    X11.Display display = null;
    try {
      // Open the display
      display = x.XOpenDisplay(null);
      // Send the message

      int result = sendClientMessage(
        display,
        Native.getWindowID(w),
        "_NET_WM_STATE",
        new NativeLong[]{
          new NativeLong(fullScreen ? _NET_WM_STATE_ADD : _NET_WM_STATE_REMOVE),
          x.XInternAtom(display, "_NET_WM_STATE_FULLSCREEN", false),
          x.XInternAtom(display, "_NET_WM_STATE_ABOVE", false),
          new NativeLong(0L),
          new NativeLong(0L)
        }
      );
      isFullScreenMode = (result != 0) && fullScreen;
      return (result != 0);
    }
    finally {
      if(display != null) {
        // Close the display
        x.XCloseDisplay(display);
      }
    }
  }

  /**
   * Helper method to send a client message to an X window.
   *
   * @param display display
   * @param wid native window identifier
   * @param msg type of message to send
   * @param data0 message data
   * @param data1 message data
   * @return <code>1</code> if the message was successfully sent to the window; <code>0</code> otherwise
   */
  private static int sendClientMessage(X11.Display display, long wid, String msg, NativeLong[] data) {
    // Use the JNA platform X11 binding
    assert (data.length == 5);
    X11 x = X11.INSTANCE;
    // Create and populate a client-event structure
    X11.XEvent event = new X11.XEvent();
    event.type = X11.ClientMessage;
    // Select the proper union structure for the event type and populate it
    event.setType(X11.XClientMessageEvent.class);
    event.xclient.type = X11.ClientMessage;
    event.xclient.serial = new NativeLong(0L);
    event.xclient.send_event = 1;
    event.xclient.message_type = x.XInternAtom(display, msg, false);
    event.xclient.window = new X11.Window(wid);
    event.xclient.format = 32;
    // Select the proper union structure for the event data and populate it
    event.xclient.data.setType(NativeLong[].class);
    System.arraycopy(data, 0, event.xclient.data.l, 0, 5);

    // Send the event
    NativeLong mask = new NativeLong(X11.SubstructureRedirectMask | X11.SubstructureNotifyMask);
    int result = x.XSendEvent(display, x.XDefaultRootWindow(display), 0, mask, event);
    // Flush, since we're not processing an X event loop
    x.XFlush(display);
    // Finally, return the result of sending the event
    return result;
  }

  public static boolean isInFullscreen() {
    // TODO: to get window attribute and check if _NET_WM_STATE_FULLSCREEN set on window
    return isFullScreenMode;
  }

  // X window message definitions
  private static final int _NET_WM_STATE_REMOVE = 0;
  private static final int _NET_WM_STATE_ADD    = 1;

}

hey! Thanks for the workaround! I had trouble getting it to work with jruby, so I did a (primitive) ruby port. It's a bit ugly, but it works ;)

https://gist.github.com/flo-l/f383a541d5d93fc7e9b0