kscreensaver_vroot.h

00001 /*****************************************************************************/
00025 /*****************************************************************************/
00026 /*
00027  * vroot.h -- Virtual Root Window handling header file
00028  *
00029  * This header file redefines the X11 macros RootWindow and DefaultRootWindow,
00030  * making them look for a virtual root window as provided by certain `virtual'
00031  * window managers like swm and tvtwm. If none is found, the ordinary root
00032  * window is returned, thus retaining backward compatibility with standard
00033  * window managers.
00034  * The function implementing the virtual root lookup remembers the result of
00035  * its last invocation to avoid overhead in the case of repeated calls
00036  * on the same display and screen arguments. 
00037  * The lookup code itself is taken from Tom LaStrange's ssetroot program.
00038  *
00039  * Most simple root window changing X programs can be converted to using
00040  * virtual roots by just including
00041  *
00042  * #include <X11/vroot.h>
00043  *
00044  * after all the X11 header files.  It has been tested on such popular
00045  * X clients as xphoon, xfroot, xloadimage, and xaqua.
00046  * It also works with the core clients xprop, xwininfo, xwd, and editres
00047  * (and is necessary to get those clients working under tvtwm).
00048  * It does NOT work with xsetroot; get the xsetroot replacement included in
00049  * the tvtwm distribution instead.
00050  *
00051  * Andreas Stolcke <stolcke@ICSI.Berkeley.EDU>, 9/7/90
00052  * - replaced all NULL's with properly cast 0's, 5/6/91
00053  * - free children list (suggested by Mark Martin <mmm@cetia.fr>), 5/16/91
00054  * - include X11/Xlib.h and support RootWindowOfScreen, too 9/17/91
00055  */
00056 
00057 #ifndef _VROOT_H_
00058 #define _VROOT_H_
00059 
00060 #if !defined(lint) && !defined(SABER)
00061 static const char vroot_rcsid[] = "#Id: vroot.h,v 1.4 1991/09/30 19:23:16 stolcke Exp stolcke #";
00062 #endif
00063 
00064 #include <qwidget.h>
00065 #ifdef Q_WS_X11
00066 #include <X11/X.h>
00067 #include <X11/Xatom.h>
00068 #include <X11/Xlib.h>
00069 
00070 static Window
00071 #if defined(__STDC__) || defined(__cplusplus) /* ANSIfication added by jwz, to avoid superfluous warnings. */
00072 VirtualRootWindowOfScreen(Screen *screen)
00073 #else /* !__STDC__ */
00074 VirtualRootWindowOfScreen(screen) Screen *screen;
00075 #endif /* !__STDC__ */
00076 {
00077     static Screen *save_screen = (Screen *)0;
00078     static Window root = (Window)0;
00079 
00080     if (screen != save_screen) {
00081         Display *dpy = DisplayOfScreen(screen);
00082         Atom __SWM_VROOT = None;
00083         uint i;
00084         Window rootReturn, parentReturn, *children;
00085         unsigned int numChildren;
00086 
00087         root = RootWindowOfScreen(screen);
00088 
00089         /* go look for a virtual root */
00090         __SWM_VROOT = XInternAtom(dpy, "__SWM_VROOT", False);
00091         if (XQueryTree(dpy, root, &rootReturn, &parentReturn,
00092                  &children, &numChildren)) {
00093             for (i = 0; i < numChildren; i++) {
00094                 Atom actual_type;
00095                 int actual_format;
00096                 unsigned long nitems, bytesafter;
00097                 unsigned char *newRoot = 0;
00098 
00099                 if (XGetWindowProperty(dpy, children[i],
00100                     __SWM_VROOT, 0, 1, False, XA_WINDOW,
00101                     &actual_type, &actual_format,
00102                     &nitems, &bytesafter,
00103                     &newRoot) == Success
00104                     && newRoot) 
00105                                 {
00106                     void *tmpRoot = (void *) newRoot;
00107                     root = *(Window*) tmpRoot;
00108                             XFree( (char*) newRoot );
00109                     break;
00110                 }
00111             }
00112             if (children)
00113                 XFree((char *)children);
00114         }
00115 
00116         save_screen = screen;
00117     }
00118 
00119     return root;
00120 }
00121 
00122 #undef RootWindowOfScreen
00123 #define RootWindowOfScreen(s) VirtualRootWindowOfScreen(s)
00124 
00125 #undef RootWindow
00126 #define RootWindow(dpy,screen) VirtualRootWindowOfScreen(ScreenOfDisplay(dpy,screen))
00127 
00128 #undef DefaultRootWindow
00129 #define DefaultRootWindow(dpy) VirtualRootWindowOfScreen(DefaultScreenOfDisplay(dpy))
00130 #endif
00131 
00132 #endif /* _VROOT_H_ */
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