Comment 24 for bug 1883369

(In reply to Lee Salzman [:lsalzman] from comment #14)
> (In reply to Augustin Trancart [:autra] from comment #13)
> > > I found the ugly rendering is also persistent (not just on hover) on some websites
> >
> > Yes, one of those websites is the demo version of codimd (https://demo.codimd.org, in the preview pane). It is not *always* bad though, but it eventually gets there, and then it stays ugly.
> >
> > > local font rendering settings (freetype prefs etc) may be part of the formula, as well as whatever the sites are doing in their css/js.
> >
> > I can test some other local settings if you want.
>
> Do you use hintfull in your fontconfig hintstyle settings? It might be that when it is rendering with subpixel AA it uses the LCD-hinting algorithm, whereas when it goes to grayscale it has to use the normal hinting algorithm. If so, if you try using some other hintstyle like hintslight explicitly in your fontconfig settings, does it fix it?

Ok so thanks to your message, I have be able to dig into this a bit. By default I use hintslight (10-hinting-slight.conf is linked into my /etc/fonts/conf.d), but the font that bugs is Roboto, that has its own config file in /etc/fonts/conf.d, and it uses hintfull. So I've edited this file directly, and every other value stops the jittering for me (it does not stop some weird spacing though, for instance sometimes the "i" is to close one of its sibling).

So I'm wondering: what is the correct fix here? Is this a config bug and I should raise the issue to the fontconfig package mainteneur? A font issue? Or a firefox one?