m2-GTK4/lib/M2GtkShim.def

DEFINITION MODULE FOR "C" M2GtkShim ;

(*
   m2-GTK4 - C shim for GObject subclassing.

   GNU Modula-2 cannot register a GObject subclass or override vfuncs.
   This module exposes two C-implemented helper types whose snapshot
   vfunc hands a Cairo context to a Modula-2 callback, so custom drawing
   is possible without leaving Modula-2 (and reusing the Cairo binding).

   Provided by lib/m2gtkshim.c:

     M2Widget     a GtkWidget subclass.  The draw callback is
                    PROCEDURE (widget: ADDRESS; cr: ADDRESS;
                               width, height: INTEGER; user: ADDRESS);
                  Set its size with GtkWidget.gtk_widget_set_size_request.

     M2Paintable  a GdkPaintable implementation.  The draw callback is
                    PROCEDURE (cr: ADDRESS; width, height: INTEGER;
                               user: ADDRESS);
                  Give it to a GtkPicture or GtkImage.

   user_data is passed through; the optional destroy procedure runs when
   the object is finalized.
*)

FROM SYSTEM IMPORT ADDRESS;

EXPORT UNQUALIFIED
   M2Widget, M2WidgetDrawFunc,
   M2Paintable, M2PaintableDrawFunc,
   m2_gtk_widget_new, m2_paintable_new;


TYPE
   M2Widget = ADDRESS;
   M2WidgetDrawFunc = ADDRESS;
   M2Paintable = ADDRESS;
   M2PaintableDrawFunc = ADDRESS;

(* GtkWidget *m2_gtk_widget_new(M2WidgetDrawFunc draw, gpointer user_data,
                                GDestroyNotify destroy) *)
PROCEDURE m2_gtk_widget_new (draw: M2WidgetDrawFunc; user_data: ADDRESS;
                             destroy: ADDRESS) : M2Widget;

(* GdkPaintable *m2_paintable_new(M2PaintableDrawFunc draw, int width,
                                  int height, gpointer user_data,
                                  GDestroyNotify destroy) *)
PROCEDURE m2_paintable_new (draw: M2PaintableDrawFunc; width, height: INTEGER;
                            user_data: ADDRESS; destroy: ADDRESS) : M2Paintable;

END M2GtkShim.