According to the author's description in https://github.com/takushun-wu/WenYuanFonts/issues/16, https://github.com/takushun-wu/WenYuanFonts/issues/17, the GPOS issue also appears to be related to ConTeXt's support for variable fonts.
Here is the English translation of the author's description from the issue: GPOS: Specifically, this is an issue with the readposition() function in ConTeXt's font-dsp.lmt when parsing GPOS. It is triggered whenever the GPOS table contains a Type 9 positioning subtable extension format and a ValueFormat of yAdvance + YAdvDevice (0x88). Currently, the vkrn table in the WenYuan font (used for vertical kerning—specifically, for kerning Western text rotated 90° in vertical writing) contains a GPOS table of this format, which triggers the issue. This has also been reproduced in other fonts that contain this table (e.g., MXiangHeHeiSCProVar.ttf). subroutine: This is an issue with ConTeXt's own CFF2 parser, font-cff.lmt, when handling glyph outline data that has been subroutinized (i.e., reusable repeated outlines). The font's outline data itself is not problematic. As a temporary workaround, you can use a TTF variable font to avoid the issue, or use the tx tool from the AFDKO suite to remove subroutines from the font (the downside is that the font file size will increase). ___________________________________________________________________________________ If your question is of interest to others as well, please add an entry to the Wiki! maillist : [email protected] / https://mailman.ntg.nl/mailman3/lists/ntg-context.ntg.nl webpage : https://www.pragma-ade.nl / https://context.aanhet.net (mirror) archive : https://github.com/contextgarden/context wiki : https://wiki.contextgarden.net ___________________________________________________________________________________
