Re: Suggest installing more fonts?

[Eli Zaretskii <eliz@gnu.org>]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Date: Fri, 16 Oct 2020 12:54:13 +0200
> 
> I think, over the years, the most common question users have that has an
> easy-to-fix solution is: "Why is Emacs displaying boxes for some of
> these characters I'm seeing?"  The solution is "install some more
> fonts", of course.
> 
> But could Emacs be more helpful here?  That is, could we somehow,
> unobtrusively, tell the users this when Emacs is trying to display a
> character that it has no fonts for?

That box with the hex code is our way of telling the users that.  What
else can be better, given that there could be more than one such
character?

> For added helpfulness, would it be possible for Emacs to be even more
> specific?  Like, say "sudo apt install fonts-noto-color-emoji
> fonts-symbola", or whatever, depending on the system.

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?

> 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.

> (Perhaps distribution packagers could also push more fonts as part of
> the Emacs installation, but that'd probably be more controversial.)

Yes, it's the responsibility of the distro to make sure the necessary
fonts are installed when Emacs is installed.  If MS-Windows can have
all the fonts to cover the supported scripts, so can GNU/Linux
distros.  They should make sure each Emacs user has fonts to cover all
the scripts known to Emacs.

I think the best we can do here is (a) add more fonts to the default
fontset (it isn't trivial, as quite a few good fonts aren't free); and
(b) have a command to report which of the fonts mentioned in the
default fontset aren't available.