problem with created PDFs and non-named instances of Variation Fonts

[Werner LEMBERG]

[This is a copy of a question asked in the GNOME discourse forum:
https://discourse.gnome.org/t/example-for-pdf-output-created-by-pangocairo-using-variation-fonts/22020
– I'm not sure where to ask specific questions regarding pangocairo.
Sorry for the duplication.]


Folks,


Is there an example that demonstrates how to use pangocairo to produce
a PDF that contains Variation Font instances?

The background for my question is LilyPond, which comes with a cairo
backend (by using the `-dbackend=cairo` command-line option), and
which correctly creates PDFs with named instances of VFs.  However, it
fails to create PDFs with non-named instances, which are silently
replaced with a subsetted non-VF font.

For my tests I used the current git versions of both pango and cairo
(and the current git of LilyPond).

You can find more details here:
https://gitlab.com/lilypond/lilypond/-/issues/6613


    Werner