Re: Getting started with GtkAda & Glade

[Emmanuel Briot <briot@act-europe.fr>]

karlran1234@yahoo.com (Karl Ran) writes:
> I played a little bit with your suggestions but I haven't found a
> solution for
> for my problem ... due to my lack of Ada/Gtk knowledge., I guess
> 
> Ok, now the code looks like this:
> 
> -----------------------------------------------------------------------
>    function On_Hscale1_Motion_Notify_Event
>      (Object : access Gtk_Widget_Record'Class;
>       Params : Gtk.Arguments.Gtk_Args) return Boolean
>    is
>       Arg1  : Gdk_Event := To_Event (Params, 1);
>       Scale : Gtk_Scale := Gtk_Scale (Object);  
>    begin
>      Put_Line ("Current_Value is " & Gdouble'Image (Get_Value
> (Scale)));
>      return False;
>    end On_Hscale1_Motion_Notify_Event;
> ------------------------------------------------------------------------


Sorry,
I now realize I had looked at the development version of gtk+/GtkAda.
Instead, you would do something like:

  Put_Line (Gdouble'Image (Get_Value (Get_Adjustment (Scale))));

It does seem complex, however this is because the set of possible values for a
lot of widgets in gtk+ are separated from the value they contain. Instead, that
value is stored in a structure called a Gtk_Adjustment (that contains the
current value, the minimum and maximum possible values and a few other
fields). The nice thing is that other widgets can ask to receive signals when
the value is changed (Pretty close to the standard Model-View-Controller model,
I believe).

The new version of gtk+/GtkAda has more direct access functions, even though
they do the same thing as above in the background.

Emmanuel