1 /* -*- Mode: C; tab-width: 2 -*- */
2 /*****************************************************************************/
3 /** Copyright 1991 by Andreas Stolcke **/
4 /** Copyright 1990 by Solbourne Computer Inc. **/
5 /** Longmont, Colorado **/
7 /** All Rights Reserved **/
9 /** Permission to use, copy, modify, and distribute this software and **/
10 /** its documentation for any purpose and without fee is hereby **/
11 /** granted, provided that the above copyright notice appear in all **/
12 /** copies and that both that copyright notice and this permis- **/
13 /** sion notice appear in supporting documentation, and that the **/
14 /** name of Solbourne not be used in advertising **/
15 /** in publicity pertaining to distribution of the software without **/
16 /** specific, written prior permission. **/
18 /** ANDREAS STOLCKE AND SOLBOURNE COMPUTER INC. DISCLAIMS ALL WARRANTIES **/
19 /** WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF **/
20 /** MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL ANDREAS STOLCKE **/
21 /** OR SOLBOURNE BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL **/
22 /** DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA **/
23 /** OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER **/
24 /** TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE **/
25 /** OR PERFORMANCE OF THIS SOFTWARE. **/
26 /*****************************************************************************/
28 * vroot.h -- Virtual Root Window handling header file
30 * This header file redefines the X11 macros RootWindow and DefaultRootWindow,
31 * making them look for a virtual root window as provided by certain `virtual'
32 * window managers like swm and tvtwm. If none is found, the ordinary root
33 * window is returned, thus retaining backward compatibility with standard
35 * The function implementing the virtual root lookup remembers the result of
36 * its last invocation to avoid overhead in the case of repeated calls
37 * on the same display and screen arguments.
38 * The lookup code itself is taken from Tom LaStrange's ssetroot program.
40 * Most simple root window changing X programs can be converted to using
41 * virtual roots by just including
43 * #include <X11/vroot.h>
45 * after all the X11 header files. It has been tested on such popular
46 * X clients as xphoon, xfroot, xloadimage, and xaqua.
47 * It also works with the core clients xprop, xwininfo, xwd, and editres
48 * (and is necessary to get those clients working under tvtwm).
49 * It does NOT work with xsetroot; get the xsetroot replacement included in
50 * the tvtwm distribution instead.
52 * Andreas Stolcke <stolcke@ICSI.Berkeley.EDU>, 9/7/90
53 * - replaced all NULL's with properly cast 0's, 5/6/91
54 * - free children list (suggested by Mark Martin <mmm@cetia.fr>), 5/16/91
55 * - include X11/Xlib.h and support RootWindowOfScreen, too 9/17/91
57 * Jamie Zawinski <jwz@jwz.org>, 28-Apr-1997
60 * Jamie Zawinski <jwz@jwz.org>, 3-Sep-2003
61 * - if the environment variable "XSCREENSAVER_WINDOW" is set, use that
62 * as the root window instead of searching for __SWM_VROOT.
64 * Jamie Zawinski <jwz@jwz.org>, 14-Aug-2004
65 * - changes to get gcc to stop whining about "type punning".
67 * Jamie Zawinski <jwz@jwz.org>, 16-Dec-2004
68 * - fixed that last fix.
73 #define _XSCREENSAVER_VROOT_H_
75 #if !defined(lint) && !defined(SABER)
76 static const char vroot_rcsid[] =
77 "#Id: vroot.h,v 1.8 2004/12/16 05:33:54 jwz Exp #" "\n"
78 "#Id: vroot.h,v 1.4 1991/09/30 19:23:16 stolcke Exp stolcke #";
82 #include <X11/Xatom.h>
86 #ifdef __STDC__ /* ANSIfication added by jwz, to avoid superfluous warnings. */
87 VirtualRootWindowOfScreen(Screen *screen)
89 VirtualRootWindowOfScreen(screen) Screen *screen;
90 #endif /* !__STDC__ */
92 static Screen *save_screen = (Screen *)0;
93 static Window root = (Window)0;
95 if (screen != save_screen) {
96 Display *dpy = DisplayOfScreen(screen);
97 Atom __SWM_VROOT = None;
99 Window rootReturn, parentReturn, *children;
100 unsigned int numChildren;
102 /* first check for a hex or decimal window ID in the environment */
103 const char *xss_id = getenv("XSCREENSAVER_WINDOW");
104 if (xss_id && *xss_id) {
105 unsigned long id = 0;
107 if (1 == sscanf (xss_id, " 0x%lx %c", &id, &c) ||
108 1 == sscanf (xss_id, " %lu %c", &id, &c)) {
110 save_screen = screen;
115 root = RootWindowOfScreen(screen);
117 /* go look for a virtual root */
118 __SWM_VROOT = XInternAtom(dpy, "__SWM_VROOT", False);
119 if (XQueryTree(dpy, root, &rootReturn, &parentReturn,
120 &children, &numChildren)) {
121 for (i = 0; i < numChildren; i++) {
124 unsigned long nitems, bytesafter;
125 unsigned char *newRoot = 0;
127 if (XGetWindowProperty(dpy, children[i],
128 __SWM_VROOT, 0, 1, False, XA_WINDOW,
129 &actual_type, &actual_format,
130 &nitems, &bytesafter,
133 root = *((Window *) newRoot);
138 XFree((char *)children);
141 save_screen = screen;
147 #undef RootWindowOfScreen
148 #define RootWindowOfScreen(s) VirtualRootWindowOfScreen(s)
151 #define RootWindow(dpy,screen) VirtualRootWindowOfScreen(ScreenOfDisplay(dpy,screen))
153 #undef DefaultRootWindow
154 #define DefaultRootWindow(dpy) VirtualRootWindowOfScreen(DefaultScreenOfDisplay(dpy))
156 #endif /* _VROOT_H_ */