Re: Suggest installing more fonts?

[Eli Zaretskii <eliz@gnu.org>]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Cc: emacs-devel@gnu.org
> Date: Fri, 16 Oct 2020 15:24:00 +0200
> 
> > For that, you'd need a database of fonts per OS and per release (and I
> > think on GNU systems this will have to depend on the distro as well?),
> > and you'd need to maintain that database.  Who around here knows
> > enough about fonts on different systems to maintain such a database?
> 
> To have perfect coverage, we'd need to do a lot of work.  But we don't
> have to have that, so we don't need to do that much work.
> 
> Having a list of nice fonts with good coverage for, say, the five most
> significant operating systems, should be a list of less than thirty
> font packages.

I doubt it's as few as 30, assuming we want to cover every living
script and some popular dead ones.  But the only way to be sure how
many is to do the work and come up with the list of such fonts.  then
we will see.

> >> Fonts change over the years, so this would be an added maintenance
> >> burden...  but they don't change a lot: New general-use fonts with good
> >> coverage aren't created very often.
> >
> > IME, the fonts do change quite a lot between releases.
> 
> The fonts change, but the number of fonts we care about doesn't.

Since the fonts change, we will need to change the list.

> Popping up a warning buffer (at the first time tofu is displayed per
> session) may be OK

That's not doable, because you cannot pop up anything in the middle of
redisplay.  We could perhaps use the delayed-warnings mechanism, but
is that sufficient?

> Displaying a message in the echo area (again, only the first time we
> tofu in a session) saying something like "Unable to display character;
> type `C-h TO-BE-DETERMINED' for more information" might also be an
> option.

Not from redisplay, we cannot do that.

> Or...  adding help echo text props to tofu?

To each one of them?