1 /*
2 * Article 12523 of comp.windows.x:
3 * From: stolcke@ICSI.Berkeley.EDU (Andreas Stolcke)
4 * Subject: Converting programs to virtual root
5 * Date: 8 Sep 90 02:26:14 GMT
6 *
7 * Andreas Stolcke
8 * International Computer Science Institute stolcke@icsi.Berkeley.EDU
9 * 1957 Center St., Suite 600, Berkeley, CA 94704 (415) 642-4274 ext. 126
10 *
11 * vroot.h -- Virtual Root Window handling header file
12 *
13 * This header file redefines the X11 macros RootWindow and DefaultRootWindow,
14 * making them look for a virtual root window as provided by certain `virtual'
15 * window managers like swm and tvtwm. If none is found, the ordinary root
16 * window is returned, thus retaining backward compatibility with standard
17 * window managers.
18 * The function implementing the virtual root lookup remembers the result of
19 * its last invocation to avoid overhead in the case of repeated calls
20 * on the same display and screen arguments.
21 * The lookup code itself is taken from Tom LaStrange's ssetroot program.
22 *
23 * Most simple root window changing X programs can be converted to using
24 * virtual roots by just including
25 *
26 * #include "vroot.h"
27 *
28 * after all the X11 header files. It has been tested on such popular
29 * X clients as xphoon, xfroot, xloadimage, and xaqua.
30 *
31 * Andreas Stolcke <stolcke@ICSI.Berkeley.EDU>, 9/7/90
32 * - replaced all NULL's with properly cast 0's, 5/6/91
33 * - free children list (suggested by Mark Martin <mmm@cetia.fr>), 5/16/91
34 */
35 #define DONTOPTIMISE /* unclutter needs to search from scratch each time */
36
37 #include <X11/X.h>
38 #include <X11/Xatom.h>
39
40 static Window
VirtualRootWindow(dpy,screen)41 VirtualRootWindow(dpy, screen)
42 Display *dpy;
43 {
44 static Display *save_dpy = (Display *)0;
45 static int save_screen = -1;
46 static Window root = (Window)0;
47
48 #ifdef DONTOPTIMISE
49 {
50 #else
51 if (dpy != save_dpy || screen != save_screen) {
52 #endif
53 Atom __SWM_VROOT = None;
54 int i;
55 Window rootReturn, parentReturn, *children;
56 unsigned int numChildren;
57
58 root = RootWindow(dpy, screen);
59
60 /* go look for a virtual root */
61 __SWM_VROOT = XInternAtom(dpy, "__SWM_VROOT", False);
62 if (XQueryTree(dpy, root, &rootReturn, &parentReturn,
63 &children, &numChildren)) {
64 for (i = 0; i < numChildren; i++) {
65 Atom actual_type;
66 int actual_format;
67 unsigned long nitems, bytesafter;
68 Window *newRoot = (Window *)0;
69
70 if (XGetWindowProperty(dpy, children[i],
71 __SWM_VROOT, 0, 1, False, XA_WINDOW,
72 &actual_type, &actual_format,
73 &nitems, &bytesafter,
74 (unsigned char **) &newRoot) == Success
75 && newRoot) {
76 root = *newRoot;
77 break;
78 }
79 }
80 if (children)
81 XFree((char *)children);
82 }
83
84 save_dpy = dpy;
85 save_screen = screen;
86 }
87
88 return root;
89 }
90
91 #undef DefaultRootWindow
92 #define DefaultRootWindow(dpy) RootWindow(dpy, DefaultScreen(dpy))
93
94 #undef RootWindow
95 #define RootWindow(dpy,screen) VirtualRootWindow(dpy,screen)
96