[HarfBuzz] MarkCoverage and BaseCoverage data

[Werner LEMBERG]

Behdad,


is there any way in HarfBuzz to access the glyph indices in
MarkCoverage and BaseCoverage tables?  Or Coverage tables in general?

Problem: For ttfautohint, I need all GSUB glyphs that aren't shifted
in GPOS.[*]  Right now, I simply subtract the GPOS set from the GSUB
set; this works since I never look at `kern', for example.

However, for Indic lookups, this removes far too much glyphs:
Mandatory tables like `abvm' actually contain glyphs in the
`BaseCoverage' table that are not shifted...


    Werner


[*] For example, the `sups' feature might be implemented by using the
    `subs' glyphs shifted upwards.