bug#42824: 26.3; Feature request: implement 'smooth scroll' in djvu.el package

[dalanicolai <dalanicolai@gmail.com>]

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FYI it is inspired by `pdf-view-next-line-or-next-page` (and complement) of
the pdf-tools package.

On Mon, 26 Oct 2020 at 22:43, Lars Ingebrigtsen <larsi@gnus.org> wrote:

> Roland, could you take a look at this suggestion -- I've not used
> djvu.el myself, so I'm not sure whether this would make sense or not:
>
> dalanicolai@gmail.com writes:
>
> > The djvu.el pacakge is a beautiful package but unfortunately it is not
> > designed for reading djvu documents (The comments in the file say it is
> > meant to be used with DjView). Probably for that reason there is no
> > smooth scroll over pages implemented (at least I am not aware of that
> > functionality), i.e. you can scroll smoothly over a
> > single page but you can only do a full page jump to a next or previous
> > page.
> > This means that when you are at the bottom/top of a page and jump to
> > the
> > next/previous page then you end up at the bottom/top of that page,
> > which is annoying. Anyway, smooth scrolling can be implemented with
> > only
> > a view simple lines. So I would like to propose to add the following
> > lines to djvu.el:
> >
> >     (defun djvu-scroll-up-or-next-page ()
> >       (interactive)
> >       (scroll-up-line 5)
> >       (when (= (window-vscroll) 0)
> >         (djvu-next-page 1)))
> >
> >     (defun djvu-scroll-down-or-previous-page ()
> >       (interactive)
> >       (if (not (= (window-vscroll) 0))
> >           (scroll-down-line 5)
> >         (djvu-prev-page 1)
> >         (scroll-up-command))))
> >
> > By adding these lines emacs can be perfectly used as a djvu reader
> > (although it does not show annotations).
>
> --
> (domestic pets only, the antidote for overdose, milk.)
>    bloggy blog: http://lars.ingebrigtsen.no
>

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