This better emulates Unicode grapheme clusters.
Note that Uniscribe does NOT do this, but should be harmless with most clients,
and improve fallback with clients that use HarfBuzz cluster as unit of fallback.
Fixes https://github.com/behdad/harfbuzz/issues/217
This is what Microsoft's implementation does. Marks that need advance
need to add it back using 'dist' or other feature in GPOS. Update tests to
match.
Fixes https://github.com/behdad/harfbuzz/issues/211
What happens in that bug is that a mark is attached to base first,
then a second mark is cursive-chained to the first mark. This only
"works" because it's in the Indic shaper where mark advances are
not zeroed.
Before, we didn't allow cursive to run on marks at all. Fix that.
We also where updating mark major offsets at the end of GPOS, such
that changes in advance of base will not change the mark attachment
position. That was superior to the alternative (which is what Uniscribe
does BTW), but made it hard to apply cursive to the mark after it
was positioned. We could track major-direction offset changes and
apply that to cursive in the post process, but that's a much trickier
thing to do than the fix here, which is to immediately apply the
major-direction advance-width offsets... Ie.:
https://github.com/behdad/harfbuzz/issues/211#issuecomment-183194739
If this breaks any fonts, the font should be fixed to do mark attachment
after all the advances are set up first (kerning, etc).
Finally, this, still doesn't make us match Uniscribe, for I explained
in that bug. Looks like Uniscribe applies minor-direction cursive
adjustment immediate as well. We don't, and we like it our way, at
least for now. Eg. the sequence in the test case does this:
- The first subscript attaches with mark-to-base, moving in x only,
- The second subscript attaches with cursive attachment to first subscript
moving in x only,
- A final context rule moves the first subscript up by 104 units.
The way we do, the final shift-up, also shifts up the second subscript
mark because it's cursively-attached. Uniscribe doesn't. We get:
[ttaorya=0+1307|casubscriptorya=0@-242,104+-231|casubscriptnarroworya=0@20,104+507]
while Uniscribe gets:
[ttaorya=0+1307|casubscriptorya=0@-242,104+-211|casubscriptnarroworya=0+487]
note the different y-offset of the last glyph. In our view, after cursive,
things move together, period.
This test font had a upem of 769, which results in rounding-related errors with
the FreeType font funcs. Change the upem to 1024 to fix that.
Fixes https://github.com/behdad/harfbuzz/issues/201
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
Before, we were just checking the use_category(). This detects as
halant a ligature that had the halant as first glyph (as seen in
NotoSansBalinese.) Change that to use the is_ligated() glyph prop
bit. The font is forming this ligature in ccmp, which is before
the rphf / pref tests. So we need to make sure the "ligated" bit
survives those tests. Since those only check the "substituted" bit,
we now only clear that bit for them and "ligated" survives.
Fixes https://github.com/behdad/harfbuzz/issues/180
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
To fully test what these are supposed to test, they should be run
against libharfbuzz-fuzzing.la instead of libharfbuzz.la, but for
now just record the files.
The feature is enabled for any character in the Arabic shaper.
We should experiment with using it for Arabic subtending marks.
Though, that has a directionality problem as well, since those
are used with digits...
Fixes https://github.com/behdad/harfbuzz/issues/141
This resurrects the space fallback feature, after I disabled
the compatibility decomposition. Now I can release HarfBuzz
again without breaking Pango!
It also remembers which space character it was, such that later
on we can approximate the width of this particular space
character. That part is not implemented yet.
We normalize all GC=Zs chars except for U+1680 OGHA SPACE MARK,
which is better left alone.
Also route fuzzing-related tests through hb-ot-font, to reduce dependency
on FreeType behavior for badly-broken fonts. Fixes failing test with
FreeType master.
Behdad Esfahbod