DEFINITION MODULE FOR "C" GObject ;

(*
   m2-GTK4 - GObject: reference counting, properties and signals.
   Mapped onto <glib-object.h>.

   Signals
   -------
   C exposes the g_signal_connect() macro which expands to
   g_signal_connect_data(instance, name, handler, data, NULL, 0).
   Because macros have no symbol, this binding calls the real
   function g_signal_connect_data() directly; the pure-M2 helper
   GtkUtils.Connect wraps the common case.

   A signal handler is a normal C function pointer whose first
   argument is the emitting instance and whose second is the
   user data.  Declare a top-level Modula-2 procedure with the
   right signature and pass it directly or via ADR(...):

      PROCEDURE OnClicked (button: ADDRESS; data: ADDRESS);
      ...
      Connect(button, "clicked", ADR(OnClicked), NIL);

   Because the arity and return type depend on the signal, the
   generic GCallback below is an ADDRESS, as in C.
*)

FROM SYSTEM IMPORT ADDRESS;

EXPORT UNQUALIFIED
   GObject, GType, GCallback, GClosureNotify, GConnectFlags, GSignalHandlerID,
   GConnectDefault, GConnectAfter, GConnectSwapped,
   g_object_get_type, g_object_new, g_type_from_name,
   g_object_ref, g_object_unref,
   g_signal_connect_data, g_signal_handler_disconnect,
   g_signal_emit_by_name,
   g_object_set, g_object_get;


TYPE
   GObject = ADDRESS;
   (* A GType is a gsize-wide run-time type identifier. *)
   GType = LONGCARD;
   (* generic function pointer - pass ADR(proc) *)
   GCallback = ADDRESS;
   GClosureNotify = ADDRESS;
   GConnectFlags = CARDINAL;
   GSignalHandlerID = LONGCARD;

CONST
   GConnectDefault = 0;
   GConnectAfter   = 1;   (* call the handler after the default handler *)
   GConnectSwapped = 2;   (* swap instance and user data *)

(* GType g_object_get_type(void) *)
PROCEDURE g_object_get_type () : GType;

(* GType g_type_from_name(const gchar *name) *)
PROCEDURE g_type_from_name (name: ARRAY OF CHAR) : GType;

(* gpointer g_object_new(GType object_type, const gchar *first_property_name, ...) *)
PROCEDURE g_object_new (object_type: GType;
                        first_property_name: ARRAY OF CHAR; ...) : ADDRESS;

(* gpointer g_object_ref(gpointer object) *)
PROCEDURE g_object_ref (object: GObject) : GObject;

(* void g_object_unref(gpointer object) *)
PROCEDURE g_object_unref (object: GObject);

(* gulong g_signal_connect_data(gpointer instance, const gchar *detailed_signal,
      GCallback c_handler, gpointer data, GClosureNotify destroy_data,
      GConnectFlags connect_flags) *)
PROCEDURE g_signal_connect_data (instance: GObject;
                                 detailed_signal: ARRAY OF CHAR;
                                 c_handler: GCallback;
                                 data: ADDRESS;
                                 destroy_data: GClosureNotify;
                                 connect_flags: GConnectFlags) : [ GSignalHandlerID ];

(* void g_signal_handler_disconnect(gpointer instance, gulong handler_id) *)
PROCEDURE g_signal_handler_disconnect (instance: GObject;
                                       handler_id: GSignalHandlerID);

(* void g_signal_emit_by_name(gpointer instance, const gchar *detailed_signal, ...) *)
PROCEDURE g_signal_emit_by_name (instance: GObject;
                                 detailed_signal: ARRAY OF CHAR; ...);

(* void g_object_set(gpointer object, const gchar *first_property_name, ...) *)
PROCEDURE g_object_set (object: GObject;
                        first_property_name: ARRAY OF CHAR; ...);

(* void g_object_get(gpointer object, const gchar *first_property_name, ...) *)
PROCEDURE g_object_get (object: GObject;
                        first_property_name: ARRAY OF CHAR; ...);

END GObject.