mdw@git.distorted.org.uk Git - xtoys/blob - libxatom.c

   1 /* -*-c-*-
   2  *
   3  * Messing with X atom properties
   4  *
   5  * (c) 2007 Straylight/Edgeware
   6  */
   7
   8 /*----- Licensing notice --------------------------------------------------*
   9  *
  10  * This file is part of the Edgeware X tools collection.
  11  *
  12  * X tools is free software; you can redistribute it and/or modify
  13  * it under the terms of the GNU General Public License as published by
  14  * the Free Software Foundation; either version 2 of the License, or
  15  * (at your option) any later version.
  16  *
  17  * X tools is distributed in the hope that it will be useful,
  18  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20  * GNU General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU General Public License
  23  * along with X tools; if not, write to the Free Software Foundation,
  24  * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  25  */
  26
  27 /*----- Header files ------------------------------------------------------*/
  28
  29 #include <stddef.h>
  30
  31 #include <X11/Xlib.h>
  32 #include <X11/Xatom.h>
  33
  34 #include "libxatom.h"
  35
  36 /*----- Main code ---------------------------------------------------------*/
  37
  38 /* --- @xatom_set@ --- *
  39  *
  40  * Arguments:   @Display *d@ = pointer to display
  41  *              @Window w@ = window to set
  42  *              @Atom p@ = property to set
  43  *              @Atom a@ = atom property value
  44  *
  45  * Returns:     ---
  46  *
  47  * Use:         Sets an atom property on a particular window.
  48  */
  49
  50 void xatom_set(Display *d, Window w, Atom p, Atom a)
  51 {
  52   XChangeProperty(d, w, p, XA_ATOM, 32, PropModeReplace,
  53                   (unsigned char *)&a, 1);
  54   XSync(d, False);
  55 }
  56
  57 /* --- @xatom_get@ --- *
  58  *
  59  * Arguments:   @Display *d@ = pointer to display
  60  *              @Window w@ = window to set
  61  *              @Atom p@ = property to read
  62  *
  63  * Returns:     Atom which is the value of the property.
  64  *
  65  * Use:         Reads an atom property from a particular window.  The value
  66  *              @None@ is returned if there is no atom value.
  67  */
  68
  69 Atom xatom_get(Display *d, Window w, Atom p)
  70 {
  71   Atom type, v;
  72   unsigned long n, left;
  73   int fmt;
  74   unsigned char *buf;
  75
  76   /* --- Fetch the property value --- */
  77
  78   if (XGetWindowProperty(d, w, p,       /* Display, window, property */
  79                          0, 64,         /* Offset, length (both in words) */
  80                          False,         /* Delete after return? */
  81                          XA_ATOM,       /* Data format type */
  82                          &type, &fmt,   /* Actual type and format */
  83                          &n, &left,     /* Amount read, and bytes left */
  84                          &buf)          /* Where to put the buffer */
  85         != Success ||
  86       type != XA_ATOM ||
  87       n < 1 || fmt < 32)
  88     return (None);
  89
  90   /* --- OK, get the atom and return --- *
  91    *
  92    * This assumes that atoms are 32-bit things.  This may not be the case.
  93    * That's a right pain, actually.  It looks as if Xlib is trying to do the
  94    * right thing, so I'll go with that rather than trying to do anything
  95    * clever.  This is actually a bit of a poor interface.
  96    */
  97
  98   v = *(Atom *)buf;
  99   XFree(buf);
 100   return (v);
 101 }
 102
 103 /* --- @xatom_delete@ --- *
 104  *
 105  * Arguments:   @Display *d@ = pointer to display
 106  *              @Window w@ = window containing atom
 107  *              @Atom p@ = property to delete
 108  *
 109  * Returns:     ---
 110  *
 111  * Use:         Removes a property from a window.
 112  */
 113
 114 void xatom_delete(Display *d, Window w, Atom p)
 115 {
 116   XDeleteProperty(d, w, p);
 117   XSync(d, False);
 118 }
 119
 120 /* --- @xatom_wait@ --- *
 121  *
 122  * Arguments:   @Display *d@ = pointer to display
 123  *              @Window w@ = window to watch
 124  *              @Atom p@ = property to fetch
 125  *              @const Atom *aa@ = pointer to vector of atoms
 126  *              @size_t n@ = numer of atoms in vector
 127  *
 128  * Returns:     The matching atom.
 129  *
 130  * Use:         Waits for the given property on the window to match one of
 131  *              the @aa[i]@.
 132  */
 133
 134 Atom xatom_wait(Display *d, Window w, Atom p, const Atom *aa, size_t n)
 135 {
 136   Atom a;
 137   size_t i;
 138   XEvent event;
 139
 140   XSelectInput(d, w, PropertyChangeMask);
 141   for (;;) {
 142     a = xatom_get(d, w, p);
 143     if (a != None) {
 144       if (!n) return (a);
 145       for (i = 0; i < n; i++)
 146         if (a == aa[i]) return (a);
 147     }
 148     do XNextEvent(d, &event); while (event.type != PropertyNotify);
 149   }
 150 }
 151
 152 /*----- That's all, folks -------------------------------------------------*/