bug#35079: 26.1; Font rendering - problem with bdf fonts

[handa]

In article <837eb8nddt.fsf@gnu.org>, Eli Zaretskii <eliz@gnu.org> writes:

> > For this, I found that fontconfig gives 'spacing' parameter of that font
> > as FC_CHARCELL.  I think the spacing of that font should be FC_DUAL.
> > Anyway, src/xftfont.c of Emacs does not know about FC_CHARCELL.  So,
> > emacs treats that font as a mono-space font.
> > 
> > I think you can modify the spacing paramter of that font to FC_DUAL by
> > writing some code in ~/.fonts.conf.
> > 
> > Or, please try to apply this patch to src/xftfont.c, and rebuild emacs.

> Should I install this change now?  Can it do any harm?

I can't tell because I don't know the exact meaning of FC_CHARCELL.

> I found this in
> https://github.com/freedesktop/xorg-libXft/blob/master/NEWS:

>   Version 2.1.7

>   Change FC_CHARCELL and FC_MONO interpretation.  FC_MONO no longer clips
>   glyphs to charcell, you must specify FC_CHARCELL for that.

> But I guess you saw this too?  It sounds like FC_CHARCELL is the same
> as monospaced, but with clipping to character cell, whatever that may
> mean.

I noticed that page, but I did not understand what it means.  If
spacing of FC_CHARCELL is the same as FC_MONO, why is it used for
Unifont which is surely not mono-spaced?

---
K. Handa
handa@gnu.org