Re: Suggest installing more fonts?

[Gregory Heytings]

> > > I know.  I was just pointing out that there are several problems 
> > > (missing fonts is one of them, but not the only one), so before trying 
> > > to solve "the problem", we should be clear about which one it is and 
> > > try and figure out whether it's indeed the most common.
> >
> > A user has (usually) no idea of these "several problems", and knows 
> > even less how to fix them.  For such users the problem is simply "Emacs 
> > displays gibberish".  That is "the problem" IMO.  Everything else are 
> > technicalities that very few know/understand/have the patience to deal 
> > with.
> >
> > So IMO for these users it would be much better to display characters 
> > with a low-resolution font, together with a warning (and perhaps a 
> > pointer to a short guide) (as a help-echo and/or in the echo area), 
> > instead of a tofu.
>
> Then the problem will become "Emacs uses an ugly font where other apps 
> don't", and we are none the wiser.

_All_ apps have that problem, it is _not_ an Emacs-specific problem.  I 
provided two examples with apps that have a lot more available manpower 
than Emacs (Chromium and VS Code) in which that problem also exists. 
What _all_ apps do in that case is to display a tofu.

> IMO, we should try fixing whatever problems are there (and AFAIU there's 
> more than one) without using ugly fonts.  For example, problems with 
> displaying Emoji are due to some missing infrastructure (see a separate 
> discussion about that), and once we add that, the result will be much 
> better than anything you could get with Unifont.

It's a very complex problem, which is why it exists in all apps.  I don't 
know a single app in which that problem does not exist.

FWIW, here is my solution for Emojis (on Debian, after installing the 
fonts-noto-color-emoji package):

fc-match --format='%{charset}\n' NotoColorEmoji | tr ' ' '\n' | grep '^[^-][^-][^-][^-]' | grep -v '^200d$' | 
sed 's/^/#x/;s/-/ . #x/;s/^\(#[^#]*#[^#]*\)/!(\1)/;s/^\(.*\)$/(set-fontset-font "fontset-default" 
\1 "NotoColorEmoji")/' | tr '!' "'"

This creates 154 calls to "set-fontset-font", and as a result 
https://unicode.org/Public/UNIDATA/emoji/emoji-data.txt is displayed 
nicely by Emacs.  I'm sure you will tell me that you don't like that 
solution ;-)  But I doubt it is possible to do really better, because 
Emojis are scattered across the whole Unicode code space.

> IOW, using Unifont is simply a kind of admission of defeat: we don't 
> really know why Emacs doesn't find a good font, so we take the easy path 
> of providing _some_ font that will always work, albeit show ugly glyphs. 
> I see no need to declare defeat, as we have facilities in Emacs to solve 
> these problems in a better way, once we understand them.  We should 
> therefore try to understand the problems better, and once understood, 
> solve them properly.

The meaning of my proposal was, in fact, the exact opposite of an 
admission of defeat, it was to make Emacs better in that respect than all 
other apps.  Displaying a tofu is an admission of defeat, and it's what 
all other apps do.  They say to the user: "I don't know how to display 
that character, so I just give up without giving you any clue." 
Displaying a bitmap glyph with a warning message is doing something 
better: the users see the characters and get an indication on what they 
could do to see them better.

Another example: I have no fonts to display tamil characters on my 
computer.  Which means every app, including Emacs, displays tamil 
characters as a sequence of tofus.  I attach three pictures of the same 
short tamil text displayed by Emacs, one with its current behavior 
(tamil-no-font.png), one if it used Unifont as a fallback 
(tamil-unifont.png), and one if a proper tamil font (the Debian package 
fonts-lohit-taml) is installed (tamil-good-font.png).  I do agree (of 
course) that tamil-good-font.png is better than tamil-unifont.png, but I 
really can't understand how tamil-no-font.png could be considered better 
than tamil-unifont.png.

tamil-no-font.png
Description: PNG image

tamil-unifont.png
Description: PNG image

tamil-good-font.png
Description: PNG image