[HarfBuzz] handling of variation selectors

Behdad Esfahbod behdad at behdad.org
Tue Jul 2 16:51:49 PDT 2013

On 13-07-02 09:58 AM, Jonathan Kew wrote:
> This will work fine for fonts that actually expect to handle VS codes in this
> way. The trouble is that in many cases, the VS codepoint will -not- be mapped
> to a suitable glyph code by the cmap; it will simply map to the .notdef glyph,
> which will then appear as a box or similar unwanted artifact in the output.
> (It would also -block- GSUB/GPOS rules from applying as expected to the base
> and any following glyphs.)
> So in the case where the font does not actually map the VS codepoint to a
> glyph, we should simply delete it from the buffer.

My expectation was that even such .notdef will be marked default-ignorable and
hence 1) not block GSUB/GPOS, and 2) be removed after shaping is done.  So,
why is that not working?


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