/*****************************************************************************
 * xs_create_xor_gc():  utility routine  
 *
 *         From:
 *                   The X Window System, 
 *            Programming and Applications with Xt
 *                   OPEN LOOK Edition
 *         by
 *              Douglas Young & John Pew
 *              Prentice Hall, 1991
 *
 *              Example described on pages: 
 *
 *
 *  Copyright 1991 by Prentice Hall
 *  All Rights Reserved
 *
 * This code is based on the OPEN LOOK Intrinsics Toolkit (OLIT) and 
 * the X Window System
 *
 * Permission to use, copy, modify, and distribute this software for 
 * any purpose and without fee is hereby granted, provided that the above
 * copyright notice appear in all copies and that both the copyright notice
 * and this permission notice appear in supporting documentation.
 *
 * Prentice Hall and the authors disclaim all warranties with regard to 
 * this software, including all implied warranties of merchantability and 
 * fitness.
 * In no event shall Prentice Hall or the authors be liable for any special,
 * indirect or consequential damages or any damages whatsoever resulting from 
 * loss of use, data or profits, whether in an action of contract, negligence 
 * or other tortious action, arising out of or in connection with the use 
 * or performance of this software.
 *
 * OPEN LOOK is a trademark of UNIX System Laboratories.
 * X Window System is a trademark of the Massachusetts Institute of Technology
 ****************************************************************************/

#include <X11/StringDefs.h>
#include <X11/Intrinsic.h> 

GC
xs_create_xor_gc(w)
  Widget            w;
{
  XGCValues values;
  GC        gc;
  Arg       wargs[10];

  /*
   * Get the background and foreground colors.
   */
  XtSetArg(wargs[0], XtNforeground, &values.foreground);
  XtSetArg(wargs[1], XtNbackground, &values.background);
  XtGetValues(w, wargs, 2);
  /*
   * Set the fg to the XOR of the fg and bg, so if it is
   * XOR'ed with bg, the result will be fg and vice-versa.
   * This effectively achieves inverse video for the line.
   */
  values.foreground = values.foreground ^ values.background;
  /*
   * Set the rubber band gc to use XOR mode and draw 
   * a dashed line.
   */
  values.line_style = LineOnOffDash;
  values.function   = GXxor;
  gc = XtGetGC(w, GCForeground | GCBackground | 
               GCFunction | GCLineStyle, &values);
  return gc;
}
