1 /* -*- Mode: C; tab-width: 2 -*- */
2 /*****************************************************************************/
3 /** Copyright 1991 by Andreas Stolcke **/
4 /** Copyright 1990 by Solbourne Computer Inc. **/
5 /** Longmont, Colorado **/
6 /** **/
7 /** All Rights Reserved **/
8 /** **/
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. **/
17 /** **/
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 /*****************************************************************************/
27 /*
28 * vroot.h -- Virtual Root Window handling header file
29 *
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
34 * window managers.
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.
39 *
40 * Most simple root window changing X programs can be converted to using
41 * virtual roots by just including
42 *
43 * #include <X11/vroot.h>
44 *
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.
51 *
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
56 *
57 * Jamie Zawinski <jwz@jwz.org>, 28-Apr-1997
58 * - use ANSI C
59 *
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.
63 */
64
65 #ifndef _VROOT_H_
66 #define _VROOT_H_
67 #define _XSCREENSAVER_VROOT_H_
68
69 #if !defined(lint) && !defined(SABER)
70 static const char vroot_rcsid[] =
71 "#Id: vroot.h,v 1.5 2003/09/04 01:04:38 jwz Exp #" "\n"
72 "#Id: vroot.h,v 1.4 1991/09/30 19:23:16 stolcke Exp stolcke #";
73 #endif
74
75 #include <X11/X.h>
76 #include <X11/Xatom.h>
77 #include <X11/Xlib.h>
78
79 #include <stdlib.h>
80
81 static Window
82 #ifdef __STDC__ /* ANSIfication added by jwz, to avoid superfluous warnings. */
VirtualRootWindowOfScreen(Screen * screen)83 VirtualRootWindowOfScreen(Screen *screen)
84 #else /* !__STDC__ */
85 VirtualRootWindowOfScreen(screen) Screen *screen;
86 #endif /* !__STDC__ */
87 {
88 static Screen *save_screen = (Screen *)0;
89 static Window root = (Window)0;
90
91 if (screen != save_screen) {
92 Display *dpy = DisplayOfScreen(screen);
93 Atom __SWM_VROOT = None;
94 int i;
95 Window rootReturn, parentReturn, *children;
96 unsigned int numChildren;
97
98 /* first check for a hex or decimal window ID in the environment */
99 const char *xss_id = getenv("XSCREENSAVER_WINDOW");
100 if (xss_id && *xss_id) {
101 unsigned long id = 0;
102 char c;
103 if (1 == sscanf (xss_id, " 0x%lx %c", &id, &c) ||
104 1 == sscanf (xss_id, " %lu %c", &id, &c)) {
105 root = (Window) id;
106 save_screen = screen;
107 return root;
108 }
109 }
110
111 root = RootWindowOfScreen(screen);
112
113 /* go look for a virtual root */
114 __SWM_VROOT = XInternAtom(dpy, "__SWM_VROOT", False);
115 if (XQueryTree(dpy, root, &rootReturn, &parentReturn,
116 &children, &numChildren)) {
117 for (i = 0; i < numChildren; i++) {
118 Atom actual_type;
119 int actual_format;
120 unsigned long nitems, bytesafter;
121 Window *newRoot = (Window *)0;
122
123 if (XGetWindowProperty(dpy, children[i],
124 __SWM_VROOT, 0, 1, False, XA_WINDOW,
125 &actual_type, &actual_format,
126 &nitems, &bytesafter,
127 (unsigned char **) &newRoot) == Success
128 && newRoot) {
129 root = *newRoot;
130 break;
131 }
132 }
133 if (children)
134 XFree((char *)children);
135 }
136
137 save_screen = screen;
138 }
139
140 return root;
141 }
142
143 #undef RootWindowOfScreen
144 #define RootWindowOfScreen(s) VirtualRootWindowOfScreen(s)
145
146 #undef RootWindow
147 #define RootWindow(dpy,screen) VirtualRootWindowOfScreen(ScreenOfDisplay(dpy,screen))
148
149 #undef DefaultRootWindow
150 #define DefaultRootWindow(dpy) VirtualRootWindowOfScreen(DefaultScreenOfDisplay(dpy))
151
152 #endif /* _VROOT_H_ */
153