Re: Is Gtk_DrawingArea in gtk-- usable?
- From: Owen Taylor <owt1 cornell edu>
- To: gtk-list redhat com
- Subject: Re: Is Gtk_DrawingArea in gtk-- usable?
- Date: 02 Feb 1998 14:34:06 -0500
Jon Trowbridge <trow@emccta.com> writes:
> 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?
You need to do the gtk-- equivalent:
gtk_widget_set_events (drawing_area, GDK_EXPOSURE_MASK)
Hope this helps,
Owen
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