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   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  * Jamie Zawinski <jwz@jwz.org>, 14-Aug-2004
  65  * - changes to get gcc to stop whining about "type punning".
  66  *
  67  * Jamie Zawinski <jwz@jwz.org>, 16-Dec-2004
  68  * - fixed that last fix.
  69  */
  70
  71 #ifndef _VROOT_H_
  72 #define _VROOT_H_
  73 #define _XSCREENSAVER_VROOT_H_
  74
  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 #";
  79 #endif
  80
  81 #include <X11/X.h>
  82 #include <X11/Xatom.h>
  83 #include <X11/Xlib.h>
  84
  85 static Window VirtualRootWindowOfScreen(Screen *screen)
  86 {
  87         static Screen *save_screen = 0;
  88         static Window root = (Window)0;
  89
  90         if(screen != save_screen) {
  91                 Display *dpy = DisplayOfScreen(screen);
  92                 Atom __SWM_VROOT = None;
  93                 int i;
  94                 Window rootReturn, parentReturn, *children;
  95                 unsigned int numChildren;
  96
  97                 /* first check for a hex or decimal window ID in the environment */
  98                 const char *xss_id = getenv("XSCREENSAVER_WINDOW");
  99                 if(xss_id && *xss_id) {
 100                         unsigned long id = 0;
 101                         char c;
 102                         if(1 == sscanf (xss_id, " 0x%lx %c", &id, &c) ||
 103                                         1 == sscanf (xss_id, " %lu %c",   &id, &c)) {
 104                                 root = (Window) id;
 105                                 save_screen = screen;
 106                                 return root;
 107                         }
 108                 }
 109
 110                 root = RootWindowOfScreen(screen);
 111
 112                 /* go look for a virtual root */
 113                 __SWM_VROOT = XInternAtom(dpy, "__SWM_VROOT", False);
 114                 if(XQueryTree(dpy, root, &rootReturn, &parentReturn,
 115                                         &children, &numChildren)) {
 116                         for(i=0; i<numChildren; i++) {
 117                                 Atom actual_type;
 118                                 int actual_format;
 119                                 unsigned long nitems, bytesafter;
 120                                 unsigned char *newRoot = 0;
 121
 122                                 if(XGetWindowProperty(dpy, children[i],
 123                                                         __SWM_VROOT, 0, 1, False, XA_WINDOW,
 124                                                         &actual_type, &actual_format,
 125                                                         &nitems, &bytesafter,
 126                                                         &newRoot) == Success
 127                                                 && newRoot) {
 128                                         root = *((Window*) newRoot);
 129                                         break;
 130                                 }
 131                         }
 132                         if(children)
 133                                 XFree((char*)children);
 134                 }
 135
 136                 save_screen = screen;
 137         }
 138
 139         return root;
 140 }
 141
 142 #endif /* _VROOT_H_ */