/*  Part of XPCE --- The SWI-Prolog GUI toolkit

    Author:        Jan Wielemaker and Anjo Anjewierden
    E-mail:        jan@swi.psy.uva.nl
    WWW:           http://www.swi.psy.uva.nl/projects/xpce/
    Copyright (c)  1985-2002, University of Amsterdam
    All rights reserved.

    Redistribution and use in source and binary forms, with or without
    modification, are permitted provided that the following conditions
    are met:

    1. Redistributions of source code must retain the above copyright
       notice, this list of conditions and the following disclaimer.

    2. Redistributions in binary form must reproduce the above copyright
       notice, this list of conditions and the following disclaimer in
       the documentation and/or other materials provided with the
       distribution.

    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
    "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
    FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
    COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
    INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
    BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
    LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
    CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
    LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
    ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
    POSSIBILITY OF SUCH DAMAGE.
*/

format('Not yet implemented~n').


%   +stretch_region(Corner, Region)
%
%   Corner is a symbolic name of Region.  Regions are defined as being
%   quarter width and height.

stretch_region(north_east, region(w-w/4, 0    , w/4, h/4)).
stretch_region(north_west, region(0    , 0    , w/4, h/4)).
stretch_region(south_west, region(0    , h-h/4, w/4, h/4)).
stretch_region(south_east, region(w-w/4, h-h/4, w/4, h/4)).


%   +stretch_opposite(Corner, OppositeCorner)
%
%   OppositeCorner is the corner opposite of Corner.

stretch_opposite(north_west, south_east).
stretch_opposite(north_east, south_west).
stretch_opposite(south_west, north_east).
stretch_opposite(south_east, north_west).

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
                             MOVING GRAPHICALS

move-Button
    Drags a graphical by moving the entire graphical each drag-event.  This
    is pleasant in simple drawings as the display always shows the correct
    contents, but annoyingly slow if complex graphicals are moved this way
    or the graphical is moved over complex graphicals.  Use with care!
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

do_make_handlers(move-Button, Group) :-
    !,
    mouse_event_type(Button-down, Down),
    mouse_event_type(Button-drag, Drag),
    mouse_event_type(Button-up, Up),

    !,

    new_handler(DragHandler, Drag,
                block(message(@event_receiver, position,
                              ?(@event_position,
                                difference,
                                ?(@event_window, saved_cursor))))),
    send(DragHandler, active, @off),
    new_handler(DownHandler, Down,
                block(message(DragHandler, active, @on),
                      message(@event_window,
                              saved_cursor, @event_relative))),
    new_handler(UpHandler, Up,
                message(DragHandler, active, @off)),

    new(Group, handler_group(DragHandler, UpHandler, DownHandler)).


/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
                        ATTACH/DETACH HANDLERS

attach_handlers(+Object, +HandlerTypes)
detach_handlers(+Object, +HandlerTypes)
    Attaches (detaches) event handlers defined by HandlerTypes to Object.
    The elements in HandlerTypes are defined by the argument to
    make_handlers/1.  For example:

        attach_handlers(@b, [stretch-left, move-middle]).
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

attach_handlers(_, []) :- !.
attach_handlers(Object, [H|T]) :-
    !,
    attach_handlers(Object, H),
    attach_handlers(Object, T).
attach_handlers(Object, Type) :-
    find_handler(Type, Handler),
    send(Object, recogniser, Handler).

detach_handlers(_, []) :- !.
detach_handlers(Object, [H|T]) :-
    !,
    detach_handlers(Object, H),
    detach_handlers(Object, T).
detach_handlers(Object, Type) :-
    find_handler(Type, Handler),
    send(Object, delete_recogniser, Handler).

find_handler(Type, Handler) :-
    es_handlers(Type, Handler),
    !.
find_handler(Type, Handler) :-
    make_handlers(Type),
    es_handlers(Type, Handler).


                /********************************
                *            UTILITIES          *
                ********************************/

assert_handlers(Type, Handlers) :-
    asserta(es_handlers(Type, Handlers)).

%   new_handler(?@Handler, +EventType, +Message)
%   new_handler(?@Handler, +EventType, +Message, +Region)
%
%   Creates a PCE Handler object which handles events of type EventType
%   and sends out Message.  The optional Region determines where the event
%   is valid (default is the entire area of the graphical).

new_handler(Handler, EventType, Message) :-
    new_handler(Handler, EventType, Message, @default).

new_handler(Handler, EventType, Message, Region) :-
    new(Handler, handler(EventType, Message, Region)).