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.
Follows the order of the Arabic/Syriac specs. Also don't stop
between rlig and calt in non-Arabic scripts.
Micro-tests for Arabic and Mongolian added for the latter.
Originally we fixed those in 79d1007a50.
However, fonts like MongolianWhite don't have GDEF, but have IgnoreMarks
in their LigatureSubstitute init/etc features. We were synthesizing a
GDEF class of mark for Mongolian Variation Selectors and as such the
ligature lookups where not matching. Uniscribe doesn't do that.
I tried with more sophisticated fixes, like, if there is no GDEF and
a lookup-flag mismatch happens, instead of rejecting a match, try
skipping that glyph. That surely produces some interesting behavior,
but since we don't want to support fonts missing GDEF more than we have
to, I went for this simpler fix which is to always mark
default-ignorables as base when synthesizing GDEF.
Micro-test added.
Fixes rest of https://bugs.freedesktop.org/show_bug.cgi?id=65258
If pre-base reordering Ra is NOT formed (or formed and then
broken up), we should consider that Ra as base. This is
observable when there's a left matra or dotreph that positions
before base.
Now, it might be that we shouldn't do this if the Ra happend
to form a below form. We can't quite deduce that right now...
Micro test added. Also at:
https://code.google.com/a/google.com/p/noto-alpha/issues/detail?id=186#c29
Normally if you want to, say, conditionally prevent a 'pref', you
would use blocking contextual matching. Some designers instead
form the 'pref' form, then undo it in context. To detect that
we now also remember glyphs that went through MultipleSubst.
In the only place that this is used, Uniscribe seems to only care
about the "last" transformation between Ligature and Multiple
substitions. Ie. if you ligate, expand, and ligate again, it
moves the pref, but if you ligate and expand it doesn't. That's
why we clear the MULTIPLIED bit when setting LIGATED.
Micro-test added. Test: U+0D2F,0D4D,0D30 with font from:
[1]
https://code.google.com/a/google.com/p/noto-alpha/issues/detail?id=186#c29
Bug 70509 - Candrabindu+Visarga doesn't work in Devanagari
https://bugs.freedesktop.org/show_bug.cgi?id=70509
We categorize both bindus and visarga as syllable-modifiers.
OT spec doesn't actually say what characters go in the syllable
modifier category, and allows one. We just allow up to two now.
Test case: U+0930,U+0941,U+0901,U+0903
Uniscribe currently doesn't support that and produces a
dotted circle.
More like Uniscribe... We still allow user-defined features to
work across syllables, but not pres,blws,abs,psts,etc.
This "regressed" Sinhala numbers by 11. These are cases were
there's Consonant followed by Ra,Halant,ZWJ at the of text.
The Ra,Halant,ZWJ ends up forming reph, which is wrong...
But before we were also ligating that reph with the previous
consonant. That's even more wrong. That's also what Uniscribe
does.
Current numbers:
BENGALI: 353732 out of 354188 tests passed. 456 failed (0.128745%)
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: 951030 out of 951913 tests passed. 883 failed (0.0927606%)
KHMER: 299070 out of 299124 tests passed. 54 failed (0.0180527%)
MALAYALAM: 1048140 out of 1048334 tests passed. 194 failed (0.0185056%)
ORIYA: 42320 out of 42329 tests passed. 9 failed (0.021262%)
SINHALA: 271655 out of 271847 tests passed. 192 failed (0.070628%)
TAMIL: 1091753 out of 1091754 tests passed. 1 failed (9.15957e-05%)
TELUGU: 970555 out of 970573 tests passed. 18 failed (0.00185457%)
The new test suite runs tests included under
hb/test/shaping/tests/*.tests, which themselves reference
font files stored by sha1sum under hb/test/shaping/fonts/sha1sum.
The fonts are produced using a subsetter to only include glyphs
needed to run the test.
Four initial tests are added for (Chain)Context matching,
of which three currently fail.
After the Ngapi hackfest work, we were assuming that fonts
won't use presentation features to choose specific forms
(eg. conjuncts). As such, we were using auto-joiner behavior
for such features. It proved to be troublesome as many fonts
used presentation forms ('pres') for example to form conjuncts,
which need to be disabled when a ZWJ is inserted.
Two examples:
U+0D2F,U+200D,U+0D4D,U+0D2F with kartika.ttf
U+0995,U+09CD,U+200D,U+09B7 with vrinda.ttf
What we do now is to never do magic to ZWJ during GSUB's main input
match for Indic-style shapers. Note that backtrack/lookahead are still
matched liberally, as is GPOS. This seems to be an acceptable
compromise.
As to the bug that initially started this work, that one needs to
be fixed differently:
Bug 58714 - Kannada u+0cb0 u+200d u+0ccd u+0c95 u+0cbe does not
provide same results as Windows8
https://bugs.freedesktop.org/show_bug.cgi?id=58714
New numbers:
BENGALI: 353689 out of 354188 tests passed. 499 failed (0.140886%)
DEVANAGARI: 707305 out of 707394 tests passed. 89 failed (0.0125814%)
GUJARATI: 366349 out of 366457 tests passed. 108 failed (0.0294714%)
GURMUKHI: 60706 out of 60747 tests passed. 41 failed (0.067493%)
KANNADA: 951030 out of 951913 tests passed. 883 failed (0.0927606%)
KHMER: 299070 out of 299124 tests passed. 54 failed (0.0180527%)
LAO: 53611 out of 53644 tests passed. 33 failed (0.0615167%)
MALAYALAM: 1048102 out of 1048334 tests passed. 232 failed (0.0221304%)
ORIYA: 42320 out of 42329 tests passed. 9 failed (0.021262%)
SINHALA: 271666 out of 271847 tests passed. 181 failed (0.0665816%)
TAMIL: 1091753 out of 1091754 tests passed. 1 failed (9.15957e-05%)
TELUGU: 970555 out of 970573 tests passed. 18 failed (0.00185457%)
TIBETAN: 208469 out of 208469 tests passed. 0 failed (0%)
The code was confused because it was expecting left matra to have
POS_PRE_M, like we do in the Myanmar shaper, but that is not what
we were doing in this shaper. Rewrite to rely on category only.
Test case: U+AA06,U+AA34,U+AA2F
Ouch, how did things ever work without this?! The added test that has a
dot-reph as well as a pre-base reordering Ra perfectly demonstrates the
bug (tested with Nirmala font from Win8 for example). Testing suggests
that Win8 shaper has the *exact* same bug / behavior that we used to
have. Odd.
Behdad Esfahbod