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,
   M2ListModel, M2ListModelGetNItemsFunc, M2ListModelGetItemFunc,
   M2LayoutManager, M2LayoutMeasureFunc, M2LayoutAllocateFunc,
   M2SnapshotPaintable, M2SnapshotDrawFunc,
   m2_gtk_widget_new, m2_paintable_new,
   m2_snapshot_paintable_new,
   m2_list_model_new, m2_list_model_items_changed,
   m2_layout_manager_new, m2_layout_allocate_child;


TYPE
   M2Widget = ADDRESS;
   M2WidgetDrawFunc = ADDRESS;
   M2Paintable = ADDRESS;
   M2PaintableDrawFunc = ADDRESS;
   M2ListModel = ADDRESS;
   (* PROCEDURE (user: ADDRESS) : CARDINAL *)
   M2ListModelGetNItemsFunc = ADDRESS;
   (* PROCEDURE (position: CARDINAL; user: ADDRESS) : ADDRESS
      Must return a new reference (transfer full). *)
   M2ListModelGetItemFunc = ADDRESS;
   M2LayoutManager = ADDRESS;
   (* PROCEDURE (widget: ADDRESS; orientation: INTEGER; for_size: INTEGER;
                   VAR minimum, natural: INTEGER; user: ADDRESS) *)
   M2LayoutMeasureFunc = ADDRESS;
   (* PROCEDURE (widget: ADDRESS; width, height, baseline: INTEGER;
                   user: ADDRESS) *)
   M2LayoutAllocateFunc = ADDRESS;
   M2SnapshotPaintable = ADDRESS;
   (* PROCEDURE (snapshot: ADDRESS; width, height: INTEGER; user: ADDRESS) *)
   M2SnapshotDrawFunc = 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;

(* GdkPaintable *m2_snapshot_paintable_new(M2SnapshotDrawFunc draw, int width,
                                           int height, gpointer user_data,
                                           GDestroyNotify destroy) *)
PROCEDURE m2_snapshot_paintable_new (draw: M2SnapshotDrawFunc;
                                     width, height: INTEGER;
                                     user_data: ADDRESS;
                                     destroy: ADDRESS) : M2SnapshotPaintable;

(* GListModel *m2_list_model_new(M2ListModelGetNItemsFunc get_n_items,
                                 M2ListModelGetItemFunc get_item,
                                 GType item_type, gpointer user_data,
                                 GDestroyNotify destroy) *)
PROCEDURE m2_list_model_new (get_n_items: M2ListModelGetNItemsFunc;
                             get_item: M2ListModelGetItemFunc;
                             item_type: LONGCARD; user_data: ADDRESS;
                             destroy: ADDRESS) : M2ListModel;

(* void m2_list_model_items_changed(GListModel *model, guint position,
                                     guint removed, guint added) *)
PROCEDURE m2_list_model_items_changed (model: M2ListModel;
                                       position, removed, added: CARDINAL);

(* GtkLayoutManager *m2_layout_manager_new(M2LayoutMeasureFunc measure,
                                            M2LayoutAllocateFunc allocate,
                                            gpointer user_data,
                                            GDestroyNotify destroy) *)
PROCEDURE m2_layout_manager_new (measure: M2LayoutMeasureFunc;
                                 allocate: M2LayoutAllocateFunc;
                                 user_data: ADDRESS;
                                 destroy: ADDRESS) : M2LayoutManager;

(* void m2_layout_allocate_child(GtkWidget *child, int x, int y,
                                  int width, int height) *)
PROCEDURE m2_layout_allocate_child (child: ADDRESS; x, y, width, height: INTEGER);

END M2GtkShim.