bug#51704: 29.0.50; set-fontset-font do not work well with :weight 'normal of font-spec

[Lars Ingebrigtsen]

Eli Zaretskii <eliz@gnu.org> writes:

> Can we rethink this incompatible change?  Isn't there a way of
> achieving the same goal without breaking people's font customizations?
> Why was there a need to make 'normal' and 'medium' be different?

Because (some) fonts define both a `normal' and `medium' weight, and
they are different weights.  Previously Emacs couldn't use both.

The basic problem is in the font selection mechanism we choose -- if
we're asking for `normal' (weight 80) and the font doesn't have a weight
in the area of 78-82 (I think it was; it's been a couple of weeks since
I looked at this), it'll just give up and say "I can't find the font"
instead of choosing the closest weight the font does have.  Which would
improve the situation significantly for users.

I briefly tried to find where this selection actually happens in the
font machinery (i.e., whether there's a way to change the range of
acceptable weights), but I didn't find it.  Do you happen to know where
it happens?  If not, I can start trying to debug this again.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no