Linux: use X11 window manager events to move window and to show window menu (right-click on window title bar), if custom window decorations are enabled (issue #482)

2026-02-13 15:27:16 -06:00 · 2022-08-20 21:09:49 +02:00
parent 16f3f9e6ff
commit fb4576fc1b
18 changed files with 769 additions and 59 deletions
--- a/flatlaf-natives/flatlaf-natives-linux/src/main/cpp/X11WmUtils.cpp
+++ b/flatlaf-natives/flatlaf-natives-linux/src/main/cpp/X11WmUtils.cpp
@@ -0,0 +1,189 @@
+/*
+ * Copyright 2022 FormDev Software GmbH
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <jawt.h>
+#include <linux/jawt_md.h>
+#include <X11/Xatom.h>
+#include "com_formdev_flatlaf_ui_FlatNativeLinuxLibrary.h"
+
+/**
+ * @author Karl Tauber
+ * @since 2.5
+ */
+
+
+bool sendEvent( JNIEnv *env, jobject window, const char *atom_name,
+	long data0, long data1, long data2, long data3, long data4 );
+bool isWMHintSupported( Display* display, Window rootWindow, Atom atom );
+Window getWindowHandle( JNIEnv* env, JAWT* awt, jobject window, Display** display_return );
+
+
+//---- JNI methods ------------------------------------------------------------
+
+/**
+ * Send _NET_WM_MOVERESIZE to window to initiate moving or resizing.
+ *
+ * https://specifications.freedesktop.org/wm-spec/wm-spec-latest.html#idm45446104441728
+ * https://gitlab.gnome.org/GNOME/gtk/-/blob/main/gdk/x11/gdksurface-x11.c#L3841-3881
+ */
+extern "C"
+JNIEXPORT jboolean JNICALL Java_com_formdev_flatlaf_ui_FlatNativeLinuxLibrary_xMoveOrResizeWindow
+	( JNIEnv *env, jclass cls, jobject window, jint x, jint y, jint direction )
+{
+	return sendEvent( env, window,
+		"_NET_WM_MOVERESIZE",
+		x,
+		y,
+		direction,
+		Button1,		// left mouse button
+		1 );			// source indication
+}
+
+/**
+ * Send _GTK_SHOW_WINDOW_MENU to window to show system window menu.
+ *
+ * https://docs.gtk.org/gdk3/method.Window.show_window_menu.html
+ * https://gitlab.gnome.org/GNOME/gtk/-/blob/main/gdk/x11/gdksurface-x11.c#L4751-4801
+ */
+extern "C"
+JNIEXPORT jboolean JNICALL Java_com_formdev_flatlaf_ui_FlatNativeLinuxLibrary_xShowWindowMenu
+	( JNIEnv *env, jclass cls, jobject window, jint x, jint y )
+{
+	// TODO pass useful value for (input?) devide id ?
+	//
+	// not used in Mutter and Metacity window manager (but maybe in other WMs?): 
+	//     https://github.com/GNOME/mutter/blob/5e5480e620ed5b307902d913f89f5937cc01a28f/src/x11/window-x11.c#L3437
+	//     https://github.com/GNOME/metacity/blob/7c1cc3ca1d8131499b9cf2ef50b295602ffd6112/src/core/window.c#L5699
+	// not used in KWin:
+	//     https://github.com/KDE/kwin/blob/7e1617c2808b7c9b23a8c786327fc88212e10b32/src/netinfo.cpp#L222
+
+	return sendEvent( env, window,
+		"_GTK_SHOW_WINDOW_MENU",
+		0,				//TODO device id
+		x,
+		y,
+		0,
+		0 );
+}
+
+bool sendEvent( JNIEnv *env, jobject window, const char *atom_name,
+	long data0, long data1, long data2, long data3, long data4 )
+{
+	// get the AWT
+	JAWT awt;
+	awt.version = JAWT_VERSION_1_4;
+	if( !JAWT_GetAWT( env, &awt ) )
+		return false;
+
+	// get Xlib window and display from AWT window
+	Display* display;
+	Window w = getWindowHandle( env, &awt, window, &display );
+	if( w == 0 )
+		return false;
+
+	awt.Lock( env );
+
+	Window rootWindow = XDefaultRootWindow( display );
+
+	// check whether window manager supports message
+	Atom atom = XInternAtom( display, atom_name, false );
+	if( !isWMHintSupported( display, rootWindow, atom ) ) {
+		awt.Unlock( env );
+		return false;
+	}
+
+	// ungrab (mouse) pointer and keyboard to allow the window manager to grab them
+	XUngrabPointer( display, CurrentTime );
+	XUngrabKeyboard( display, CurrentTime );
+
+	// build event structure
+	XClientMessageEvent xclient = { 0 };
+	xclient.type = ClientMessage;
+	xclient.window = w;
+	xclient.message_type = atom;
+	xclient.format = 32;
+	xclient.data.l[0] = data0;
+	xclient.data.l[1] = data1;
+	xclient.data.l[2] = data2;
+	xclient.data.l[3] = data3;
+	xclient.data.l[4] = data4;
+
+	// send event
+	XSendEvent( display, rootWindow, False,
+		SubstructureRedirectMask | SubstructureNotifyMask,
+		(XEvent*) &xclient );
+
+	awt.Unlock( env );
+	return true;
+}
+
+
+bool isWMHintSupported( Display* display, Window rootWindow, Atom atom ) {
+	Atom type;
+	int format;
+	unsigned long n_atoms;
+	unsigned long bytes_after;
+	Atom* atoms;
+
+	// get all supported hints
+	XGetWindowProperty( display, rootWindow,
+		XInternAtom( display, "_NET_SUPPORTED", false ),
+		0, 0xffff, False, XA_ATOM,
+		&type, &format, &n_atoms, &bytes_after, (unsigned char**) &atoms );
+
+	if( atoms == NULL )
+		return false;
+
+	if( type != XA_ATOM ) {
+		XFree( atoms );
+		return false;
+	}
+
+	bool supported = false;
+	for( int i = 0; i < n_atoms; i++ ) {
+		if( atoms[i] == atom ) {
+			supported = true;
+			break;
+		}
+	}
+
+	XFree( atoms );
+	return supported;
+}
+
+Window getWindowHandle( JNIEnv* env, JAWT* awt, jobject window, Display** display_return ) {
+	jawt_DrawingSurface* ds = awt->GetDrawingSurface( env, window );
+	if( ds == NULL )
+		return 0;
+
+	jint lock = ds->Lock( ds );
+	if( (lock & JAWT_LOCK_ERROR) != 0 ) {
+		awt->FreeDrawingSurface( ds );
+		return 0;
+	}
+
+	JAWT_DrawingSurfaceInfo* dsi = ds->GetDrawingSurfaceInfo( ds );
+	JAWT_X11DrawingSurfaceInfo* xdsi = (JAWT_X11DrawingSurfaceInfo*) dsi->platformInfo;
+
+	Window handle = xdsi->drawable;
+	*display_return = xdsi->display;
+
+	ds->FreeDrawingSurfaceInfo( dsi );
+	ds->Unlock( ds );
+	awt->FreeDrawingSurface( ds );
+
+	return handle;
+}