bug#65052: 30.0.50; [PATCH] Scroll-{up, down} does not update tracking info in image-dired

[Eli Zaretskii]

> From: Manuel Giraud <manuel@ledu-giraud.fr>
> Cc: 65052@debbugs.gnu.org
> Date: Fri, 04 Aug 2023 20:25:30 +0200
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> >> Date: Fri, 04 Aug 2023 16:55:45 +0200
> >> From:  Manuel Giraud via "Bug reports for GNU Emacs,
> >>  the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
> >> 
> >> Here is a patch that updates header tracking in image-dired when
> >> scrolling up or down.
> >
> > What is "header tracking"?
> >
> > More generally, could you please explain what problem are you trying
> > to solve here?
> 
> Yes, sorry.  When you are using image-dired, there is a header line with
> some informations (by default name of the file, its size and so on, see
> `image-dired-display-properties-format').  Those informations are
> updated when you move from one thumbnail to another (by mean of
> C-{f,b,n,p}).  But they are not updated with C-v/M-v.  This patch fixes
> this.

OK, but then this part:

> +  ;; "one line" dance to update tracking and header
> +  (image-dired-next-line)
> +  (image-dired-previous-line))

looks like a kludge.  Can't we have a cleaner code for updating the
header data?  If image-dired-previous/next-line can update the data,
why cannot the scroll commands do the same without calling the
line-movement commands?