Re: Can't get Gdk::Window from Gtk::Window

["Jonathon Jongsma" <jonathon quotidian org>]

On Mon, Mar 24, 2008 at 11:33 PM, Adam Nielsen <a nielsen shikadi net> wrote:
> Hi all,
>
>  I'm just starting out with gtkmm (and GTK in general) and I'm trying to
>  make one of these fancy semi-transparent windows.  I have some example C
>  code, but I'm trying to port it to C++ with gtkmm.
>
>  I'm stuck trying to figure out how to get a Gdk::Window from a
>  Gtk::Window.  The docs at
>  http://www.gtkmm.org/docs/gtkmm-2.4/docs/reference/html/classGtk_1_1Widget.html
>  reflect the C code and say I should do this:
>
>  gtk_widget_realize (window);
>  gdk_window_set_back_pixmap (window->window, <tt>0</tt>, <tt>false</tt>);
>  gtk_widget_show (window);
>
>  I'm guessing the C code (and HTML!) were included in the C++ docs by
>  accident, but the best I can come up with as a C++ translation is this:
>  (which is in a class descended from Gtk::Window)
>
>    this->realize();
>    gdk_window_set_back_pixmap(GTK_WIDGET(this->gobj())->window, 0,
>      false);
>    this->show();
>
>  Which looks horrible, and I don't even know if it works.  I thought
>  maybe I could use Gtk::Window::get_frame() to get a Gdk::Window instead,
>  but that function always returns NULL, apparently because of the
>  underlying windowing system.

You should be able to use Gtk::Widget::get_window().  This will return
NULL before the widget is realized, but after it is realized it should
return a valid Gdk::Window.

>  At any rate, even if I could get a valid Gdk::Window object, the
>  documentation at
>  http://www.gtkmm.org/docs/gtkmm-2.4/docs/reference/html/classGdk_1_1Window.html
>  says I should pass 0 as the first parameter to
>  Gdk::Window::set_back_pixmap(), but this gives me a compile-time error,
>  because the first parameter is not an integer (it's a const
>  Glib::RefPtr<Pixmap>&)

(I don't remember if you ever got a reply or not, but just in case you didnt...)

Yes, this seems like a case where the the C documentation was not
customized correctly for the C++ API.  I think you should be able to
pass a 'NULL' RefPtr<Pixmap> to this parameter and it should work.
e.g.
Glib::RefPtr<Pixmap> none;
w->set_back_pixmap(none ...)

I haven't tested it to make sure though.

here's a bug I filed for the issue:
http://bugzilla.gnome.org/show_bug.cgi?id=525967

-- 
jonner