Re: Suggest installing more fonts?

[Gregory Heytings]

> > About the use cases you are talking about, I haven't seen cases where 
> > "Emacs displays tofu where other applications display characters from 
> > installed fonts".  My experience is that Emacs behaves better than many 
> > other applications in this respect (except for the particular case of 
> > Emojis).
>
> I invite you to read the various font- and fontset-related bug reports 
> we have, and also relevant posts on Reddit and elsewhere out there.

Alas, I could not find anything with your indications.

> > The meaning of my proposal was only to include it _in_ Emacs, in short, 
> > to use, when it exists, the Unifont glyph in produce_glyphless_glyph() 
> > instead of creating a tofu with a hexcode.
>
> As I wrote, this is not easily done, as font installation is a 
> system-wide action, as the font needs to be known by the system-wide 
> utilities and libraries we use for font searching.

Apparently it's not clear, so I'll say one last time that the feature I 
propose does _not_ require to install Unifont system-wide.  It is to 
include Unifont in Emacs (say in etc/unifont), and to offer it as an 
additional option for glyphless-char-display, along with hex-code, 
empty-box, thin-space, and zero-width.  The bitmap data would be used to 
draw the glyph in produce_glyphless_glyph() .

FYI, that feature is not "already in Emacs", as you said: when Unifont is 
installed, it takes precedence over some (but not all, I'm not sure why) 
of the better-looking available fonts.  One example: DejaVu Sans has 
hebrew characters, but with Unifont installed hebrew characters are 
displayed with Unifont.

By the way, while doing various experiments around that question, I found 
a bug in ftcrfont.c.  If a buffer is displayed with a certain font, and 
that font is removed, Emacs segfaults when it redisplays that buffer. 
The bug is in ftcrfont_open, on line 237:

ft_face = cairo_ft_scaled_font_lock_face (scaled_font);

This line should be followed by a:

if (!ft_face)
  {
    unblock_input ();
    /* further cleanup? */
    return Qnil;
  }