1/*  Part of XPCE --- The SWI-Prolog GUI toolkit
    2
    3    Author:        Jan Wielemaker and Anjo Anjewierden
    4    E-mail:        wielemak@science.uva.nl
    5    WWW:           http://www.swi-prolog.org/packages/xpce/
    6    Copyright (c)  2006-2011, University of Amsterdam
    7    All rights reserved.
    8
    9    Redistribution and use in source and binary forms, with or without
   10    modification, are permitted provided that the following conditions
   11    are met:
   12
   13    1. Redistributions of source code must retain the above copyright
   14       notice, this list of conditions and the following disclaimer.
   15
   16    2. Redistributions in binary form must reproduce the above copyright
   17       notice, this list of conditions and the following disclaimer in
   18       the documentation and/or other materials provided with the
   19       distribution.
   20
   21    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   22    "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   23    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
   24    FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
   25    COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
   26    INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
   27    BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   28    LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
   29    CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   30    LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
   31    ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   32    POSSIBILITY OF SUCH DAMAGE.
   33*/
   34
   35:- module(pce_arm, []).   36:- use_module(pce).   37:- use_module(pce_template).   38:- use_module(library(debug)).   39
   40/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
   41Library  pce_arm.pl  provides  a  mechanism    for  feedback  on  active
   42graphicals while to mouse is moving  over   them.  It guaranteed that at
   43most one graphical is `armed' at any time.
   44
   45Graphical objects that wishes to play a role in this must
   46
   47        * Ensure to ->event activates @arm_recogniser
   48        * define the method ->arm: Bool, where @on is send to arm
   49          the object and @off to unarm it.  Objects that accepted
   50          @on are guaranteed to receive ->arm: @off.
   51
   52The currently armed object can be requested using
   53
   54        ?- get(@display, armed, Graphical).
   55
   56The arm library was initially developed for  Triple20. It has been moved
   57to  the  XPCE  core  library  in   version    5.6.9   for   use  in  the
   58cross-referencing GUI (See pce_xref.pl).
   59- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
   60
   61:- pce_begin_class(arm, template,
   62                   "(Un)arm objects in a window").
   63
   64:- pce_group(event).
   65
   66define_event(Name, Parent) :-
   67    (   get(@event_tree, node, Name, Node)
   68    ->  (   get(Node?parent, value, Parent)
   69        ->  true
   70        ;   print_message(error, format('Redefined event ~w', [Name]))
   71        )
   72    ;   new(_, event_node(Name, Parent))
   73    ).
   74
   75:- pce_global(@arm_recogniser,
   76              new(handler(arm,
   77                          message(@event?display, try_arm,
   78                                  @event?receiver)))).
   79:- initialization
   80   define_event(arm, user).   81
   82event(W, Ev:event) :->
   83    (   send(Ev, is_a, loc_move),
   84        get(W, arm, _Target)
   85    ->  true
   86    ;   send(Ev, is_a, area_exit)
   87    ->  send(@display, arm_object, @nil)
   88    ;   true
   89    ),
   90    send_super(W, event, Ev).
   91
   92:- pce_group(arm).
   93
   94arm(W, For:[name|code], Target:graphical) :<-
   95    (   get(@event, position, W, point(X, Y)),
   96        get(W, slot, scroll_offset, point(OX, OY)),
   97        AX is X + OX, AY is Y+OY,
   98        new(Ev, event(arm, W, AX, AY)),
   99        (   For == @default
  100        ->  true
  101        ;   send(Ev, attribute, arm_for, For)
  102        ),
  103        debug(arm, 'Posting arm to ~p at ~d,~d', [W, AX, AY]),
  104        send(Ev, post, W)
  105    ->  get(@display, hypered, arm, Target)
  106    ;   send(@display, arm_object, @nil),
  107        fail
  108    ).
  109
  110:- pce_end_class(arm).
  111
  112
  113:- pce_extend_class(display).
  114
  115try_arm(W, Gr:graphical) :->
  116    (   get(@event, attribute, arm_for, For)
  117    ->  (   atom(For)
  118        ->  send(Gr, has_send_method, For)
  119        ;   send(For, forward_receiver, Gr)
  120        )
  121    ;   true
  122    ),
  123    send(W, arm_object, Gr).
  124
  125arm_object(W, Gr:graphical*) :->
  126    (   get(W, hypered, arm, Old)
  127    ->  (   Old == Gr
  128        ->  true                    % no change
  129        ;   send(W, delete_hypers, arm),
  130            send(Old, arm, @off),
  131            (   Gr \== @nil
  132            ->  send(Gr, arm, @on),
  133                new(_, hyper(W, Gr, arm, arm_window))
  134            ;   true
  135            )
  136        )
  137    ;   (   Gr \== @nil
  138        ->  send(Gr, arm, @on),
  139            new(_, hyper(W, Gr, arm, arm_window))
  140        ;   true
  141        )
  142    ).
  143
  144armed(W, Gr:graphical) :<-
  145    "Find currently armed graphical"::
  146    get(W, hypered, arm, Gr).
  147
  148:- pce_end_class(display)