Re: Question about scrollbars

["Sebastian Geerken" <S Geerken ping de>]

On Thu, Mar 01, 2001 at 09:22:34AM -0800, Paolo Costabel wrote:
> Sebastian Geerken wrote:
> > Hi.
> >
> > I'm using a GtkLayout in a GtkScrolledWindow, and the area size as
> > well as the adjustment values of the GtkLayout are changed quite
> > often by the program itself. However, I need to catch adjustment
> > changes by *the user* (by using the scrollbars), and distinguish them
> > from changes caused by my program.
> >
> > Currently, I connect a callback to the "value_changed" signal of the
> > adjustments, and keep track where changes come from, by
> > increasing/decreasing a counter before/after my program may affect
> > the adjustments. A zero value of this counter should indicate an user
> > caused change. But this turned out to be quite tricky, and I did not
> > get it working in all cases. So I ask if there is a more direct way
> > to notice changes of the scrollbars.
> [...]
>
> I usually use a global flag when I change a value in the code, like
> this:
>
> program_change = TRUE;
> gtk_adjustment_value_changed(adj);
> program_change = FALSE;
>
> and in the signal
>
> if(program_change)
> {
>       /* do something */
> }
> else
> {
>       /* user changed the scrollbar */
> }
> [...]

Yes, this is what I currently do (I think a counter is a bit safer
that a flag), but I ask whether there is a simpler way, because the
blocking gets quite complicated, and, as I wrote, it is still buggy.
(I guess there are thousands of side effects?) So I thought of a way
to make it simpler than to workaround and search for bugs.

Unfortunately, there are no signals from GtkRange to Gtk[VH]Scrollbar
(not GtkAdjustment) for this.

Sebastian