Apparently some clients have reference-table callbacks that copy the table.
As such, avoid loading 'glyf' table which is only needed if fallback positioning
happens.
Fixes https://github.com/behdad/harfbuzz/issues/237
Note that Uniscribe enforces a certain syllable order. We don't.
But with this change, I get all of the tibetan contractions pass
with Microsoft Himalaya font.
Previously we only synthesized GDEF glyph classes if the glyphClassDef
array in GDEF was null. This worked well enough, and is indeed what
OpenType requires: "If the font does not include a GlyphClassDef table,
the client must define and maintain this information when using the
GSUB and GPOS tables." That sentence does not quite make sense since
one needs Unicode properties as well, but is close enough.
However, looks like Arial Unicode as shipped on WinXP, does have GDEF
glyph class array, but defines no classes for Hebrew. This results
in Hebrew marks not getting their widths zeroed. So, with this change,
we synthesize glyph class for any glyph that is not specified in the
GDEF glyph class table. Since, from our point of view, a glyph not
being listed in that table is a font bug, any unwanted consequence of
this change is a font bug :).
Note that we still don't get the same rendering as Uniscribe, since
Uniscribe seems to do fallback positioning as well, even though the
font does have a GPOS table (which does NOT cover Hebrew!). We are
not going to try to match that though.
Test string for Arial Unicode:
U+05E9,U+05B8,U+05C1,U+05DC
Before: [gid1166=3+991|gid1142=0+737|gid5798=0+1434]
After: [gid1166=3+991|gid1142=0+0|gid5798=0+1434]
Uniscribe: [gid1166=3+991|gid1142=0@348,0+0|gid5798=0+1434]
Note that our new output matches what we were generating until July
2014, because the Hebrew shaper used to zero mark advances based on
Unicode, NOT GDEF. That's 9e834e29e0.
Reported by Greg Douglas.
API changes:
- If NDEBUG is defined, define HB_NDEBUG
- Disable costlier sanity checks if HB_NDEBUG is defined.
In 1.2.3 introduced some code to disable costly sanity checks if
NDEBUG is defined. NDEBUG, however, disables all assert()s as
well. With HB_NDEBUG, one can disable costlier checks but keep
assert()s.
I'll probably add a way to define HB_NDEBUG automatically in
release tarballs. But for now, production systems that do NOT
define NDEBUG, are encouraged to define HB_NDEBUG for our build.
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.
That commit moved the advance adjustment for mark positioning to
be applied immediately, instead of doing late before. This breaks
if mark advances are zeroed late, like in Arabic. Also, easier to
hit it in RTL scripts since a single mark with non-zero advance is
enough to hit the bug, whereas in LTR, at least two marks are needed.
This reopens https://github.com/behdad/harfbuzz/issues/211
The cursive+mark interaction is broken again. To be fixed in a
different way.
Behdad Esfahbod
Arthur Reutenauer
Konstantin Ritt
Ebrahim Byagowi
Kal Conley