|Subject:||Re: [ft-devel] Variable fonts: hhea/typo/win metrics interpreted differently for instances compared to static fonts?|
|Date:||Thu, 31 Jan 2019 00:37:08 +0000|
Even more testing.ftview and Qt actually do the same GTK does: they don't add the line gap to the top, so text fields look compressed when the USE_TYPO_METRICS bit is set and typo asc+desc is smaller than hhea asc+desc. I'm not sure this is supposed to happen?! Didn't test MVAR modification.
Firefox and Chromium disregard FT_Face's ascender, descender and height attributes and use either hhea (I think; no USE_TYPO_METRICS) or typo metrics (USE_TYPO_METRICS), modifying typo metrics and the FT_Face attributes through the MVAR table therefore has no effect unless the USE_TYPO_METRICS bit is set.
The document body of a new text file in LibreOffice Writer 184.108.40.206 stays the same regardless of bit so I think LO Writer is doing it right. It doesn't support VFs though so I can't test MVAR modifications.
Behdad, I'm not completely sure of typo deltas in MVAR modifying the currently active metrics. Given that the hhea set is basically a legacy value and is probably taller spaced than the typo metrics, so we might end up doing things the designer didn't intend? What FF/Chromium do strikes me as saner, i.e. writing typo metrics to FT_Face ascender/descender/height when USE_TYPO_METRICS is set :/
Otherwise, I'd say unless anyone has objections, I think we can merge the branch.
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