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
Test with U+0CB0,U+200D,U+0CCD,U+0C95,U+0CBF and tunga.ttf.
Improves some scripts. Improves Bengali too, but numbers
are up because we produce better results than Uniscribe for some
sequences now.
New numbers:
BENGALI: 353724 out of 354188 tests passed. 464 failed (0.131004%)
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: 1048140 out of 1048334 tests passed. 194 failed (0.0185056%)
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%)
Lohit-Punjabi has a upem of 769! We were losing one unit in our
code, and FreeType is losing another one... Test with U+0A06.
Has an advance of 854 in the font. We were producing 852.
Now we do 853, which is what FreeType is telling us.
See comments from caveat! Seems to work fine.
This is useful for Javanese which has an atomically encoded pre-base
reordering Ra which should only be reordered if it was substituted
by the pref feature.
For scripts without an old/new spec distinction, use zero-context=false.
This changes behavior in Sinhala / Khmer, but doesn't seem to regress.
This will be useful and used in Javanese.
Whic means these twp are applied per-syllable now. Apparently
in some Khmer fonts the clig interacts with presentation features.
Test case: U+1781,U+17D2,U+1789,U+17BB,U+17C6 with Mondulkiri-R.ttf
should produce one big ligature.
Commit 6b65a76b40. "end" was becoming
negative. Was trigerred by Lohit-Kannada 2.5.3 and the sequence:
U+0CB0,U+200D,U+0CBE,U+0CB7,U+0CCD,U+0C9F,U+0CCD,U+0CB0,U+0C97,U+0CB3
Two glyphs were being duplicated.
First, we were abusing OT_VD instead of OT_A. Fix that
but moving OT_A in the grammar where it belongs (which
is different from what the spec says).
Also, only allow medial consonants after all other
consonants. This doesn't affect any current character.
Finally, fix Halant attachment in presence of medial
consonants. Again, this currently doesn't affect any
sequence.
I lied. There's Gurmukhi U+0A75 which is Consonant_Medial.
Uniscribe allows one of those in each of these positions:
before matras, after matras and before syllable modifiers,
and after syllable modifiers! We currently just allow
unlimited numbers of it, before matras.
Unicode 6.2.0 Section 16.2 / Figure 16.3 says:
"For backward compatibility, between Arabic characters a ZWJ acts just
like the sequence <ZWJ, ZWNJ, ZWJ>, preventing a ligature from forming
instead of requesting the use of a ligature that would not normally be
used. As a result, there is no plain text mechanism for requesting the
use of a ligature in Arabic text."
As such, we flip internal zwj to zwnj flags for GSUB matching, which
means it will block ligation in all features, unless the font
explicitly matches U+200D glyph. This doesn't affect joining behavior.
Behdad Esfahbod