https://bugzilla.redhat.com/show_bug.cgi?id=2179854

--- Comment #26 from Akira TAGOH tagoh@redhat.com --- Created attachment 1954381 --> https://bugzilla.redhat.com/attachment.cgi?id=1954381&action=edit v3

I'm almost consluding that we need to implement full-support of variable fonts if we want to fix this in a legitimate manner. Apparently FreeType considered applications is capable to process variable fonts if one uses some variable fonts related APIs such as FT_Get_MM_Var(). This may be the reason why we saw the fail of loading glyph error from FreeType with my patch. We need to set coordinates with axis. Honestly implementing complete code for variable fonts in f38 timeframe isn't realistic. So I gave up to fix this that way.

FWIW I partly agree with Peng's code, particularly leaving the emboldening conditions to fontconfig. Actually this is the same to what cairo does. However, I wonder if it is really only used for Linux because there are MinGW package for Qt and they could use fontconfig.

I picked it up to my patch and updated a bit to get it work without ifdef. See attached. Also, I built qt5-qtbase (only this time; so you need to try it with X11 only) on copr: https://copr.fedorainfracloud.org/coprs/tagoh/qt5-qtbase/

You can try to test if you like. I did. that works for me.