NAME

       xpce - Prolog with graphical user interface (GUI)

SYNOPSIS

       xpce prolog-option ...

DESCRIPTION

       XPCE  is  a language independant library for GUI (Graphical User Interfaces).  This manual
       page discusses XPCE/Prolog: the combination of a Prolog environment and XPCE.

       XPCE is an object-oriented engine that can have methods defined in various languages. XPCE
       has about 150 predefined classes that deal mainly with GUI's.  The object engine of XPE is
       made available to Prolog using the following predicates:

   Predicates:
       new(?Ref, +Term)
              Create an XPCE object from Term and bind the object  to  the  reference  Ref.   The
              functor-name  of  Term  describes  the class from which to create an instance.  The
              arguments of Term are used as initialisation arguments for the new object.  If  the
              object was created successfully and Ref is a variable, Ref will be unified with the
              term @<RefNumber>.  If Ref is a term of the form @<Atom>, this term will serve as a
              reference for the new object.

              For  example  ?- new(@p, picture('Hello World').  Creates a graphical window object
              with title "Hello World".

       send(+Ref, +Selector, +Args...)
              Ref is a reference to  an  existing  XPCE  object.   Selector  is  the  name  of  a
              (send-)method  defined  on  (the  class  of)  this  object  and Args are terms that
              describe arguments to be passed to the method.

              send/[2-12] will convert the arguments to XPCE data objects, resolve the  procedure
              (C-function,  Prolog predicate) implementing the method and run the implementation.
              If the execution is successful, send succeeds, otherwise send fails.

              For example ?- send(@p, open, point(400,100)).  opens the picture created above  at
              position 400,100 on the display.

       get(+Ref, +Selector, +Args ..., -Value)
              Ref  is  a  reference  to  an  existing  XPCE  object.   Selector  is the name of a
              (get-)method defined on (the class of) this object and Args are  terms  to  provide
              additional  arguments.  get/[3-13] works similar as send/[2-12] but returns a value
              rather than succeeding/failing (boolean operation).

              For example get(@p, height, H).  Unifies H with the height of the graphical window.

       free(+Ref)
              If Ref is a reference to an XPCE object, invoke send(Ref, free).   to  the  object.
              Otherwise succeed silently.

SEE ALSO

       XPCE's web-home at http://www.swi.psy.uva.nl/projects/xpce/

       Jan  Wielemaker  and Anjo Anjewierden Programming in XPCE/Prolog, University of Amsterdam,
       Dept. of Social Science and Informatics (SWI).

       Jan Wielemaker SWI-Prolog 4.0 Reference Manual.  Available from the SWI-Prolog web-home at
       http://www.swi.psy.uva.nl/projects/SWI-Prolog/

       The  online  manual  system started with ?- manpce.  or ?- user_help on Quintus or SICStus
       Prolog.

       The XPCE WWW home page: http://swi.psy.uva.nl/projects/xpce/home.html

       xpce-client(1), pl(1)

COPYING

       XPCE is distributed under the General Public Licence version 2, also known  as  the  GPL-2
       licence.   The  license  terms  are  in  the  file  COPYING  or  on  the  GNU  website  at
       http://www.gnu.org.

       In a nutshell, you can modify and use XPCE as long as you clearly indicate changes,  don't
       change  copyright  messages  and  distribute  the  complete source of your work with every
       binary copy or make the source in some other form available for free to your users

       Especially if you do not wish to distribute the source  of  your  work  you  may  wish  to
       consider  optaining  a  commercial  license.   Please  visit  the SWI-Prolog home-page for
       details.

COPYRIGHT

       Copyright (c) 1985-2001 University of Amsterdam.

AUTHOR

       Jan Wielemaker and Anjo Anjewierden

                                         February 7, 2001                                 XPCE(1)