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%% wx 1.8 —————————————————————————————————————— 
%%
%% Licensed under the Apache License, 
%% Version 2.0 (the "License"); you may 
%% not use this file except in compliance 
%% with the License. You may obtain a copy 
%% of the License at:
%%
%%     http://www.apache.org/licenses/LICENSE-2.0
%%
%% Unless required by 
%% applicable law or agreed to in writing, software
%% distributed under the License is distributed 
%% on an "AS IS" BASIS, WITHOUT WARRANTIES 
%% OR CONDITIONS OF ANY KIND, either 
%% express or implied. See the 
%% License for the specific 
%% language governing 
%% permissions and
%% limitations 
%% under the 
%% License.
%%%%%%%
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%%
%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%
%% This module is actually handwritten see ../api_gen/wx_extra/wxEvtHandler.erl
%%
%% @doc The Event handler.
%%
%% To get events from wxwidgets objects you subscribe to them by
%% calling connect/[2-3].  Events are sent as messages, if no callback
%% was supplied  These messages will be {@link wx(). #wx{}} where
%% EventRecord is a record that depends on the {@link
%% wxEventType(). event type}.  The records are defined in:
%% wx/include/wx.hrl.
%%
%% If a callback was supplied to connect, the callback will be invoked
%% (in another process) to handle the event. The callback should be of
%% arity 2.  
%%              fun (  EventRecord::wx() , EventObject::wxObject()  ).
%%
%% Beware that the callback will be in executed in new process each time.
%%
%% http://www.wxwidgets.org/manuals/stable/wx_wxevthandler.html
%% —The orginal documentation
%%%%%   
%%
%%   OVERVIEW
%%   ––––––––
%%   A class that can handle events from the windowing system. 
%%   wxWindow (and therefore all window classes) are derived from this class.
%%
%%   When events are received, wxEvtHandler 
%%   invokes the method listed in the event 
%%   table using itself as the object. 
%%
%%   When using multiple inheritance it is 
%%   imperative that the wxEvtHandler(-derived) class 
%%   be the first class inherited such that the "this" 
%%   pointer for the overall object will be identical to the 
%%   "this" pointer for the wxEvtHandler portion.
%%   
%%   RC Note: The whole callback was very confusing for, well quite some time, until 
%%            I realized that each connect call using the callback/anonymous-function
%%            method simply adds a entry onto a stack. This stack is traversed top-down
%%            when the computer is looking for a matching event, hence the 'last subscibed
%%            entry first' bit. The Event:skip() strategies discussed pertain to reading
%%            of this stack. 
%%
%%   See Also:
%%   —————————
%%   
%%   
%%   
-module(wxEvtHandler).
-include("wxe.hrl").
-include("../include/wx.hrl").

%% API
-export([  
                               connect / 2 ,

                             connect / 3 ,

                        disconnect / 1 ,

                      disconnect / 2 ,

                    disconnect / 3
                                                ]).




%% internal exports
-export([ connect_impl/2, disconnect_impl/2 ]).

-export_type([wxEvtHandler/0, wx/0, event/0]).

-type wxEvtHandler() :: wx:wx_object().



           %·%% CONNECT / 2 %%·%

%%
%%
%% @doc Equivalent to {@link connect/3. connect(This, EventType, [])}
            -spec connect(     This :: wxEvtHandler(),
                          EventType ::  wxEventType()   ) ->  ok.

connect(This, EventType)                                  ->  connect(This, EventType, []).





           %·%% CONNECT / 3 %%·%

%%
%%
%% @doc This function subscribes the to events of EventType,
%% in the range id, lastId. The events will be received as messages 
%% if no callback is supplied.
%%
%%
%% Options: 
%%
%%    {id, integer()},       The identifier (or first of the identifier range) to be 
%%                           associated with this event handler. 
%%                           Default ?wxID_ANY
%%
%%    {lastId, integer()},   The second part of the identifier range. 
%%                           If used 'id' must be set as the starting identifier range.
%%                           Default ?wxID_ANY
%%
%%    {skip,  boolean()},    If skip is true further event_handlers will be called.
%%                           This is not used if the 'callback' option is used. 
%%                           Default false.
%%
%%    {callback, function()} Use a callback fun(EventRecord::wx(), EventObject::wxObject()) 
%%                           to process the event. 
%%                              ! Default not specfied !  
%%                              i.e. a message will be delivered to the process calling this function.
%%                              which is confusing as $#!^, as, it basically means nothing.
%%
%%    {userData, term()}     An erlang term that will be sent with the event. Default: [].


             -spec connect(This      :: wxEvtHandler(),
                           EventType ::  wxEventType(),
                          [Option])                    ->  ok
              when
              Option :: { id,        integer() } 
                      | { lastId,    integer() } 
                      | { skip,      boolean() } 
                      |   callback                % business as usual, no 
                      | { callback, function() } 
                      | { userData,     term() }.

connect( This = #wx_ref{type=ThisT} ,
         EventType ,
         Options   )          ->

    EvH = parse_opts(Options, #evh{et=EventType}),
              ?CLASS(ThisT,wxEvtHandler),
            case
                wxe_util:connect_cb(This, EvH)
                of
                   ok                   ->                ok;
                  {badarg, event_type}  ->  erlang:error({badarg,EventType})
            end.


parse_opts([{callback,Fun}|R], Opts)
            when
            is_function(Fun)   ->
                                         parse_opts(R, Opts#evh{ cb=Fun    });

    %% Check Fun Arity?
parse_opts([{callback,CB={nospawn, Fun}}|R], Opts)
            when
            is_function(Fun)   ->
                                         parse_opts(R, Opts#evh{ cb=CB     });

parse_opts([callback|R], Opts) ->
                                         parse_opts(R, Opts#evh{ cb=self() });

parse_opts([{userData, UserData}|R],Opts) ->
                                         parse_opts(R, Opts#evh{ userdata=UserData });

parse_opts([{skip, Skip}|R],Opts)
            when
            is_boolean(Skip)   ->
                                         parse_opts(R, Opts#evh{ skip=Skip });

parse_opts([{id, Id}|R],Opts)
            when
            is_integer(Id)     ->
                                         parse_opts(R, Opts#evh{ id=Id     });

parse_opts([{lastId, Id}|R],Opts)
            when 
            is_integer(Id)     ->
                                         parse_opts(R, Opts#evh{ lastId=Id });

parse_opts([_BadArg|R], Opts)  ->
                                         parse_opts(R, Opts);


parse_opts([], Opts = #evh{id     = Id,
                           lastId = Lid,
                           skip   = Skip,
                           cb     = CB   })  -> 
             if 

       Skip =/= undefined
            andalso
         CB =/= 0           ->  erlang:error({badarg, {combined, skip, callback}});

        Lid =/= ?wxID_ANY
            andalso 
         Id =:= ?wxID_ANY   ->  erlang:error({badarg, no_start_identifier_range});

       Skip =:= undefined   ->  Opts#evh{skip=false};  %% Default
                     
                       true ->  Opts
            end.




%%% DISCONNECT LITERATURE %%%
%%  
%%   Disconnects the given function dynamically from the event handler, 
%%   using the specified parameters as search criteria and returning 
%%   true if a matching function has been found and removed. 
%%   This method can only disconnect functions which have 
%%   been added using the wxEvtHandler::Connect method. 
%%   There is no way to disconnect functions connected
%%   using the (static) event tables.




           %·%% DISCONNECT / 1 %%·%

%%
%%
%% @doc Equivalent to {@link disconnect/3. disconnect(This, null, [])}
%% Can also have an optional callback Fun() as an additional last argument.
            -spec disconnect(This :: wxEvtHandler()) -> boolean().

disconnect(This=#wx_ref{type=ThisT,ref=_ThisRef}) ->
                                                   ?CLASS(ThisT,wxEvtHandler),
                                                    disconnect(This, null, []).






           %·%% DISCONNECT %%·%

%%
%%
%% @doc Equivalent to {@link disconnect/3. disconnect(This, EventType, [])}
            -spec disconnect(This      :: wxEvtHandler(),
                             EventType ::  wxEventType()) -> boolean().

disconnect(This=#wx_ref{type=ThisT,ref=_ThisRef},
           EventType)
             when
             is_atom(EventType) ->
                                 ?CLASS(ThisT,wxEvtHandler),
                                 disconnect(This, EventType, []).





           %·%% DISCONNECT %%·%

%%   
%%   
%%   
%% Return Value:
%% See Also:
%%*%%*%%
%% This function unsubscribes the process or callback fun from the event handler.
%% EventType may be the atom 'null' to match any eventtype.
%% Notice that the options skip and userdata is not used to match the eventhandler.
            -spec disconnect(This      :: wxEvtHandler(),
                             EventType ::  wxEventType(),
                            [Option])  ->      boolean()
             when
             Option :: {id,        integer()}  %  The identifier (or first of the identifier range) 
                                               %  associated with the event handler function.
                     | {lastId,    integer()}  %  The second part of the identifier range associated 
                                               %  with the event handler function.
                     | {callback, function()}. %  The event handler function

disconnect(This=#wx_ref{type=ThisT,ref=_ThisRef},
           EventType, 
           Opts) ->
                  ?CLASS(ThisT,wxEvtHandler),
    
           EvH = parse_opts(Opts, #evh{et=EventType}),
             case wxe_util:disconnect_cb(This, EvH)
             of
                 {badarg, event_type} ->
                                            erlang:error({badarg,EventType});
                                 Bool ->
                                            Bool
    end.





%% @hidden
connect_impl(#wx_ref{type = ThisT,
                     ref  = ThisRef},
                                     #evh{ id       = Winid,
                                           lastId   = LastId,
                                           et       = EventType,
                                           skip     = Skip,
                                           userdata = Userdata,
                                           cb       = FunID})
        when
        is_integer(FunID)->

    EventTypeBin = list_to_binary([atom_to_list(EventType)|[0]]),
     ThisTypeBin = list_to_binary([atom_to_list( ThisT   )|[0]]),
              UD = if
                   Userdata =:= [] -> 0;
                              true -> wxe_util:send_bin(term_to_binary(Userdata)),
                                      1
                   end,
                   wxe_util:call(100, <<ThisRef:32/?UI,
                            Winid:32/?UI,LastId:32/?UI,
                            (wxe_util:from_bool(Skip)):32/?UI,
                            UD:32/?UI,
                            FunID:32/?UI,
                            (size(EventTypeBin)):32/?UI,
                            (size(ThisTypeBin)):32/?UI,
                            %% Note no alignment
                            EventTypeBin/binary,ThisTypeBin/binary>>).






%% @hidden
disconnect_impl(#wx_ref{type=_ThisT,
                         ref=ThisRef
                       },
                #evh{id=Winid, 
                 lastId=LastId, 
                     et=EventType,
                handler=#wx_ref{type=wxeEvtListener,ref=EvtList}}) 
                      ->
                        EventTypeBin = list_to_binary([atom_to_list(EventType)|[0]]),
                        wxe_util:call(101, <<EvtList:32/?UI,
                                ThisRef:32/?UI,Winid:32/?UI,LastId:32/?UI,
                                (size(EventTypeBin)):32/?UI,
                                %% Note no alignment
                                EventTypeBin/binary>>).