Fixes https://github.com/behdad/harfbuzz/issues/223
Right now we cannot test this because it has to be tested using hb-fuzzer.
We should move all fuzzing tests from test/shaping/tests/fuzzed.tests to
test/fuzzing/ and have its own test runner. At that point, should add
test from this issue as well.
Say, if we are ligating "A B_C m D", then previously 'm' was being
attached to 'B' in the combined A_B_C_D ligature. Now we attach it
to 'C'. No test for this though :(.
We use three bits for lig_id these days, so we finally got a report of
two separate ligatures with the same lig_id happening adjacent to each
other, and then the component-handling code was breaking things.
Protect against that by ignoring same-lig-id but lig-comp=0 glyphs after
a new ligature.
Fixes https://github.com/behdad/harfbuzz/issues/198
This is just to make it harder to be extremely slow. There definitely
are ways still, just harder. Oh well... how do we tame this problem
without solving halting problem?!
Fixes https://github.com/behdad/harfbuzz/issues/174
This makes a lot of code safer. We only try modifying the object in one
place, after making sure it's safe to do so. So, do a const_cast<> in
that one place...
Otherwise, we might process a lookup thousands of times, with no
benefit. This pathological case was hit by Noto Nastaliq Urdu Draft
in Firefox's code to determine whether space glyph is involved in
any GSUB/GPOS rules. A test page is at http://behdad.org/urdu
See:
https://bugzilla.mozilla.org/show_bug.cgi?id=1090869
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
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
Jonathan Kew