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.
Add into the NMake Makefiles to build the DirectWrite shaping backend,
but as PR #134 mentions, this is considered to be in an experimental state,
so don't include this in the build by default for now. This is most probably
going to replace the Uniscribe backend eventually, since DirectWrite is meant
to be Uniscribe's replacement, and is needed for Windows Store apps if a
system shaping API is to be used.
This adds a set of NMake Makefiles that can be used to build HarfBuzz, from
the standard basic build building the minimal HarfBuzz DLL (consisting
of OpenType, fallback and Uniscribe support only), to a full fledged build
consisting of GLib and FreeType support, as well as building the utilities,
the test programs in src/ and test/api, and HarfBuzz-ICU and
HarfBuzz-GObject, and up to building the introspection files. This means a
flexible build mechanism is supported here, so anything that is supported
for a Windows build (code-wise), should all be supported by this build
system.
As in an earlier commit, the source listings are shared with the autotools
builds with the various Makefile.sources in src/, src/hb-ucdn and util/, and
this set of NMake Makefiles will transform these lists into the form they
want.
In the current form, all the test programs in test/api pass, and this has
been checked successfully with 'make -j8 distcheck'.
This adds a pre-configured config.h template that can be used for Visual
Studio builds, where autotools is not normally available. This has the
configs that are suitable for Visual Studio builds, as well as all the
features used for Windows builds enabled (HAVE_OT, HAVE_FALLBACK and
HAVE_UNISCRIBE).
Note that the optional features are not enabled here, they are enabled by
/D's (or -D's) in the NMake Makefiles as requested.
This moves all the source listings in src/Makefile.am,
src/hb-ucdn/Makefile.am and util/Makefile.am into separate Makefile
snippets, so that they may be shared between different Makefile-based
build systems, such as NMake for Visual Studio.
This speeds up shaping the Amiri font by over 15%.
This was primarily needed for my work on OpenType GX, since
we will be collecting only sublookups that are "active" for
current font instance; but it's a nice boost in general as
well.
We might, in the future, collect subtables in the lookup_accel.
That would also allow us to do a per-subtbale set-digest, which
should speed things up some more, specially for ContextChainFormat3
lookups... Amiri, for example, contains one lookup with 53
subtables!
The font Garamond Premier Pro Caption (and possibly many other
Adobe fonts), have many FeatureParamsSize tables with the old
wrong offset. We handle fixing those up, but they were still
contributing to edit_count, and when I reduced HB_SANITIZE_MAX_EDIT
from 100 to 8 in 14c2de3218, these
fonts were now getting GPOS dropped and hence kerning disabled.
Fix, by not counting edits made towareds offset fix-up. I'll
also increase edit count again, in the next commit.
Behdad Esfahbod
Chun-wei Fan
n8willis
Martin Hosken