New approach to fix this:
69f9fbc420
Previous approach was reverted as it was too broad. See context:
https://github.com/behdad/harfbuzz/issues/347#issuecomment-267838368
With U+05E9,U+05B8,U+05C1,U+05DC and Arial Unicode, we now (correctly) disable
GDEF and GPOS, so we get results very close to Uniscribe, but slightly different
since our fallback position logic is not exactly the same:
Before: [gid1166=3+991|gid1142=0+737|gid5798=0+1434]
After: [gid1166=3+991|gid1142=0@402,-26+0|gid5798=0+1434]
Uniscribe: [gid1166=3+991|gid1142=0@348,0+0|gid5798=0+1434]
New API:
- hb_font_get_nominal_glyph_func_t
- hb_font_get_variation_glyph_func_t
- hb_font_funcs_set_nominal_glyph_func()
- hb_font_funcs_set_variation_glyph_func()
- hb_font_get_nominal_glyph()
- hb_font_get_variation_glyph()
Deprecated API:
- hb_font_get_glyph_func_t
- hb_font_funcs_set_glyph_func()
Clients that implement their own font-funcs are encouraged to replace
their get_glyph() implementation with a get_nominal_glyph() and
get_variation_glyph() pair. The variation version can assume that
variation_selector argument is not zero.
Test stats remain unchanged, except for Malayalam, which we investigate:
BENGALI: 353725 out of 354188 tests passed. 463 failed (0.130722%)
DEVANAGARI: 707307 out of 707394 tests passed. 87 failed (0.0122987%)
GUJARATI: 366349 out of 366457 tests passed. 108 failed (0.0294714%)
GURMUKHI: 60732 out of 60747 tests passed. 15 failed (0.0246926%)
KANNADA: 951190 out of 951913 tests passed. 723 failed (0.0759523%)
KHMER: 299070 out of 299124 tests passed. 54 failed (0.0180527%)
MALAYALAM: 1047584 out of 1048334 tests passed. 750 failed (0.0715421%)
ORIYA: 42320 out of 42329 tests passed. 9 failed (0.021262%)
SINHALA: 271662 out of 271847 tests passed. 185 failed (0.068053%)
TAMIL: 1091753 out of 1091754 tests passed. 1 failed (9.15957e-05%)
TELUGU: 970555 out of 970573 tests passed. 18 failed (0.00185457%)
Myanmar, compared to Windows 10 mmrtext.ttf:
MYANMAR: 1123865 out of 1123883 tests passed. 18 failed (0.00160159%)
Looks like Unsicribe responds to the 'mymr' tag by zeroing marks
GDEF_LATE instead of generic-shaper UNICODE_LATE. Implement that.
Fixes
Bug 81775 - Incorrect Rendering with harfbuzz-ng myanmar unicode
https://bugs.freedesktop.org/show_bug.cgi?id=81775
Micro-test added based on Padauk.
The spec and Uniscribe don't allow these, but UTN#11
specifically says the sequence U+104B,U+1038 is valid.
As such, allow all "P V" sequences. There's about
eight sequences that match that structure, but Roozbeh
thinks it's fine to allow all of them.
Test case: U+104B, U+1038
https://bugs.freedesktop.org/show_bug.cgi?id=71947
The spec and Uniscribe treat it as consonant in the grammar, but
it's not in IndicSyllableCategory.txt, so fix up.
Test sequence: U+1004,U+103A,U+1039,U+104E
https://bugs.freedesktop.org/show_bug.cgi?id=71948
This reverts commit d5bd0590ae.
The reasoning behind that logic was flawed and made under
a misunderstanding of the original problem, and caused
regressions as reported by Jonathan Kew in thread titled
"tibetan marks" in Oct 2013. Apparently I have had fixed
the original problem with this commit:
7e08f1258d
So, revert the faulty commit and everything seems to be in good
shape.
Behdad Esfahbod
Ebrahim Byagowi
David Corbett