Re: Is Gtk_DrawingArea in gtk-- usable?

[Jon Trowbridge <trow emccta com>]

I'm trying to use the Gtk_DrawingArea class in gtk--...

Tero Pulkkinen <terop@students.cc.tut.fi> writes:
> In gtk-- you can just override the expose_event_impl virtual function - just
> like the gtk's builtin widgets does:
>
> class foo : public Gtk_Drawing_Area {
> public:
>    ...
>   gint expose_event_impl(GdkEventExpose *e) {
>      Gtk_Drawing_Area::expose_event_impl(e); // call base class expose
>      GdkWindow *win=GTK_WIDGET(gtkobject)->window;
>      /* use drawing functions here from the C interface */
>      gdk_draw_arc(win,my_gc,TRUE,my_x,my_y,my_width,my_height,my_start_angle,my_sweep_angle);
>   }
>   ...
> };

I'm having trouble with this approach.  When I do this,
expose_event_impl() gets called only when the window is initially drawn,
and *not* at the time of future exposures.  I tried the same technique
deriving from Gtk_Button, and it worked correctly... expose_event_impl()
was actually called every time the object was exposed.

Is this a bug or feature?  Or am I doing something else wrong?

-Jon Trowbridge
 EMC Capital Management, Inc.