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

   1 /* -*-c-*-
   2  *
   3  * $Id: xatom.c,v 1.1 1999/08/20 07:28:44 mdw Exp $
   4  *
   5  * Set and fetch X atom properties
   6  *
   7  * (c) 1999 Straylight/Edgeware
   8  */
   9
  10 /*----- Licensing notice --------------------------------------------------*
  11  *
  12  * This file is part of the Edgeware X tools collection.
  13  *
  14  * X tools is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU General Public License as published by
  16  * the Free Software Foundation; either version 2 of the License, or
  17  * (at your option) any later version.
  18  *
  19  * X tools is distributed in the hope that it will be useful,
  20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22  * GNU General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU General Public License
  25  * along with X tools; if not, write to the Free Software Foundation,
  26  * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  27  */
  28
  29 /*----- Revision history --------------------------------------------------*
  30  *
  31  * $Log: xatom.c,v $
  32  * Revision 1.1  1999/08/20 07:28:44  mdw
  33  * New source file for manipulating atom-valued window properties.
  34  *
  35  */
  36
  37 /*----- Header files ------------------------------------------------------*/
  38
  39 #include <stdio.h>
  40 #include <stdlib.h>
  41 #include <string.h>
  42
  43 #include <X11/Xatom.h>
  44 #include <X11/Xlib.h>
  45 #include <X11/Xutil.h>
  46
  47 /*----- Main code ---------------------------------------------------------*/
  48
  49 /* --- @xatom_set@ --- *
  50  *
  51  * Arguments:   @Display *d@ = pointer to display
  52  *              @Window w@ = window to set
  53  *              @Atom p@ = property to set
  54  *              @Atom a@ = atom property value
  55  *
  56  * Returns:     ---
  57  *
  58  * Use:         Sets an atom property on a particular window.
  59  */
  60
  61 void xatom_set(Display *d, Window w, Atom p, Atom a)
  62 {
  63   XChangeProperty(d, w, p, XA_ATOM, 32, PropModeReplace,
  64                   (unsigned char *)&a, 1);
  65 }
  66
  67 /* --- @xatom_get@ --- *
  68  *
  69  * Arguments:   @Display *d@ = pointer to display
  70  *              @Window w@ = window to set
  71  *              @Atom p@ = property to read
  72  *
  73  * Returns:     Atom which is the value of the property.
  74  *
  75  * Use:         Reads an atom property from a particular window.  The value
  76  *              @None@ is returned if there is no atom value.
  77  */
  78
  79 Atom xatom_get(Display *d, Window w, Atom p)
  80 {
  81   Atom type, v;
  82   unsigned long n, left;
  83   int fmt;
  84   unsigned char *buf;
  85
  86   /* --- Fetch the property value --- */
  87
  88   if (XGetWindowProperty(d, w, p,       /* Display, window, property */
  89                          0, 64,         /* Offset, length (both in words) */
  90                          False,         /* Delete after return? */
  91                          XA_ATOM,       /* Data format type */
  92                          &type, &fmt,   /* Actual type and format */
  93                          &n, &left,     /* Amount read, and bytes left */
  94                          &buf)          /* Where to put the buffer */
  95         != Success ||
  96       type != XA_ATOM ||
  97       n < 1 || fmt < 32)
  98     return (None);
  99
 100   /* --- OK, get the atom and return --- *
 101    *
 102    * This assumes that atoms are 32-bit things.  This may not be the case.
 103    * That's a right pain, actually.  It looks as if Xlib is trying to do the
 104    * right thing, so I'll go with that rather than trying to do anything
 105    * clever.  This is actually a bit of a poor interface.
 106    */
 107
 108   v = *(Atom *)buf;
 109   XFree(buf);
 110   return (v);
 111 }
 112
 113 /*----- That's all, folks -------------------------------------------------*/