Re: Sharing Gtk.Adjustment objects among several Gtk.SpinButton widgets

[Pozz Pozz <pozzugno gmail com>]

2016-11-14 16:39 GMT+01:00 Emmanuele Bassi <ebassi gmail com>:

> Hi;
>
> On 14 November 2016 at 15:36, Pozz Pozz <pozzugno gmail com> wrote:
> > Is it possible to have a single Gtk.Adjustment for several Gtk.SpinButton
> > widgets? I couldn't understand if the adjustment is only used by
> SpinButton
> > to know the range (and some additional details, such as the page size),
> or
> > the adjustment is used also for the value storage place.
> >
> > I tried to create two SpinButtons and to set a single adjustment, but it
> > seems to me changing the value of a SpinButton will change the value of
> the
> > other SpinButton too. So it seems it isn't possible to share one
> adjustment
> > among several widgets.
> >
> > Of course, I'm supponsing the case of several parameters that have
> > different values but the same range properties (min, max, page step, ...)
>
> A GtkAdjustment is a "model", whereas the widgets using the adjustment
> are the "views". So, if you use the same GtkAdjustment instance, all
> widgets will share the same underlying state. This is by design.
>
> If you want to create different widgets with the same adjustment
> parameters but not sharing the same state you will have to create
> different GtkAdjustment instances — plausibly using a factory method.

Thank you for your answer. My doubt was derived from the following
statements [1]:

        "The GtkAdjustment object does not update the value itself. Instead
it is left up to the
        owner of the GtkAdjustment to control the value."

At first, I thought the value (actual state) was managed (and stored)
directly by the widget, without
changing the value of associated adjustment.
> From your words, that sentence says the widgets explicitly change the value
of its adjustment, when needed.


[1] https://developer.gnome.org/gtk3/stable/GtkAdjustment.html