Using Xlib via JNA to move a window

Question

I use JNA to manage application windows on Linux, sending Xlib messages, but cannot move the window.

My initial implementation ran wmctrl in a shell to move windows and successfully move windows. Unfortunately, a noticeable amount of overhead is associated with invoking shell programs with Java, so now I'm trying to make direct API calls using JNA. I am using the X11 example, available on the JNA website, and I can successfully complete several tricks, such as listing window IDs and reading window properties, so I know that JNA + Xlib works, at least in part.

At first, I tried to move windows directly using XMoveWindow(), but the window manager apparently blocked these calls.

I came across a thread that suggested I send a client message using XSendMessage(), so I did it below, but apparently XSendMessage()fails because the window does not move, and I get the return value of 0. I suppose I omitted something obvious, but I cannot understand it. Any suggestions?

Note that for the purposes of this example, the main method has a hard-coded window identifier. This is the identifier of the window of the window I'm trying to move (obtained using wmctrl -lon the console).

import com.sun.jna.NativeLong;
import com.sun.jna.Pointer;
import com.sun.jna.examples.unix.X11;
import com.sun.jna.examples.unix.X11.Atom;
import com.sun.jna.examples.unix.X11.AtomByReference;
import com.sun.jna.examples.unix.X11.Display;
import com.sun.jna.examples.unix.X11.Window;
import com.sun.jna.examples.unix.X11.WindowByReference;
import com.sun.jna.examples.unix.X11.XEvent;
import com.sun.jna.examples.unix.X11.XTextProperty;
import com.sun.jna.examples.unix.X11.XWindowAttributes;
import com.sun.jna.ptr.IntByReference;
import com.sun.jna.ptr.NativeLongByReference;
import com.sun.jna.ptr.PointerByReference;

private static final int FALSE = 0; /** C-style boolean "false" */
private static final int TRUE  = 1; /** C-style boolean "true" */

public static void main(String[] args) {
    setWindowPos(new Window(0x01300007), 100, 100, 600, 400); // update the Window constructor with the appropriate ID given by wmctrl -l
}


public static boolean setWindowPos(Window window, int x, int y, int w, int h) {
    final X11 x11 = X11.INSTANCE;
    Display display = x11.XOpenDisplay(null);

    NativeLong mask = new NativeLong(X11.SubstructureRedirectMask | X11.SubstructureNotifyMask | X11.ResizeRedirectMask);

    XEvent event = new XEvent();

    String msg = "_NET_MOVERESIZE_WINDOW"; //$NON-NLS-1$

    long grflags = 0l; // use the default gravity of the window
    if (x != -1) grflags |= (1 << 8);
    if (y != -1) grflags |= (1 << 9);
    if (w != -1) grflags |= (1 << 10);
    if (h != -1) grflags |= (1 << 11);

    event.xclient.type = X11.ClientMessage;
    event.xclient.serial = new NativeLong(0l);
    event.xclient.send_event = TRUE;
    event.xclient.message_type = x11.XInternAtom(display, msg, false);
    event.xclient.window = window;
    event.xclient.format = 32;
    event.xclient.data.l[0] = new NativeLong(grflags); // gravity flags
    event.xclient.data.l[1] = new NativeLong(x);
    event.xclient.data.l[2] = new NativeLong(y);
    event.xclient.data.l[3] = new NativeLong(w);
    event.xclient.data.l[4] = new NativeLong(h);

    int status = x11.XSendEvent(display, x11.XDefaultRootWindow(display), FALSE, mask, event);
    x11.XFlush(display); // need to XFlush if we're not reading X events

    if (status == 0) { // 0 indicates XSendEvent failed
        logger.error("setWindowPos: XSendEvent failed (" + msg + ")"); //$NON-NLS-1$
        return false;
    }

    return true;
}

Answer 1

These might be a bit of late answers, but anyway ...

, , , ( "" ) XConfigureRequest . , X-, ( ).

- , ( "" ).

gl hf.

Answer 2

XConfigureWindow?

, , Windows, ...

public static interface X11Ext extends Library
    {
        public static X11Ext INSTANCE = (X11Ext)Native.loadLibrary("X11", X11Ext.class);

        public int XConfigureWindow(X11.Display display, X11.Window window, int value_mask, XWindowChanges changes);

        /**
         * Use value_mask flags:
         * CWX
         * CWY
         * CWWidth
         * CWHeight
         * CWBorderWidth
         * CWSibling
         * CWStackMode
         */
        public class XWindowChanges extends Structure
        {
            public int x;
            public int y;
            public int width;
            public int height;
            public int border_width;
            public X11.Window sibling;
            public int stack_mode;
        }
    }