Re: Two questions about overlays

[dalanicolai <dalanicolai@gmail.com>]

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>
> You assume that window-start and window-end will reliably tell you the
> beginning and end of the window in the middle of a Lisp program?
> Their doc strings explicitly say that the values are updated by
> redisplay.  window-end is specifically documented to be accurate only
> after redisplay ends.  I believe this is why you need to call sit-for:
> that function triggers redisplay.


Ah okay, I had not seen/noted that (part of the) docstring. Well, this
clears things up (now for both questions).

Thanks again for your help!

On Tue, 21 Feb 2023 at 16:03, Eli Zaretskii <eliz@gnu.org> wrote:

> > From: dalanicolai <dalanicolai@gmail.com>
> > Date: Tue, 21 Feb 2023 14:39:36 +0100
> > Cc: emacs-devel@gnu.org
> >
> > In this example code, I am simply displaying all images at once,
> > because I am assuming that the images in the directory are not too
> > many and that they are small (which is not a very reasonable
> > assumption, but this is just my personal 'test' function).
> >
> > Indeed, the example does not call sit-for, because it should show that
> > the printed number of overlays, is the number of all images in the
> > directory (instead of only the number of images currently on the
> > screen, i.e. within '(overlays-in (window-start) (window-end))' ).
>
> You assume that window-start and window-end will reliably tell you the
> beginning and end of the window in the middle of a Lisp program?
> Their doc strings explicitly say that the values are updated by
> redisplay.  window-end is specifically documented to be accurate only
> after redisplay ends.  I believe this is why you need to call sit-for:
> that function triggers redisplay.
>
> > B.t.w. I am using Emacs 29 (and 30), and the overlay-recenter is still
> there.
> > Maybe it would be handy to remove it then?
>
> We don't want to remove it because that could break some third-party
> packages.  So we made the function do nothing instead.
>

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