'rclt' is "Required Contextual Forms" being proposed by Microsoft.
It's like 'calt', but supposedly always on. We apply 'calt' anyway,
and now apply this too.
At this point, the GDEF glyph synthesis looks pointless. Not that I
have many fonts without GDEF lying around.
As for mark advance zeroing when GPOS not available, that also is being
replaced by proper fallback mark positioning soon.
We need the font for glyph lookup during GSUB pauses in Indic shaper.
Could perhaps be avoided, but at this point, we don't mean to support
separate substitute()/position() entry points (anymore), so there is
no point in not providing the font to GSUB.
If there is no GPOS, zero mark advances.
If there *is* GPOS and the shaper requests so, zero mark advances for
attached marks.
Fixes regression with Tibetan, where the font has GPOS, and marks a
glyph as mark where it shouldn't get zero advance.
When we removed the separate Hangul shaper, the specific normalization
preference of Hangul was lost. Fix that. Also, the Thai shaper was
copied from Hangul, so had the fully-composed normalization behavior,
which was unnecessary. So, fix that too.
Also remove shaper_options argument to hb_shape_full(). That was
unused and for "future". Let it go.
More shaper API coming in preparation for plan/planned API.
hb_shape() now accepts a shaper_options and a shaper_list argument.
Both can be set to NULL to emulate previous API. And in most situations
they are expected to be set to NULL.
hb_shape() also returns a boolean for now. If shaper_list is NULL, the
return value can be ignored.
shaper_options is ignored for now, but otherwise it should be a
NULL-terminated list of strings.
shaper_list is a NULL-terminated list of strings. Currently recognized
strings are "ot" for native OpenType Layout implementation, "uniscribe"
for the Uniscribe backend, and "fallback" for the non-complex backend
(that will be implemented shortly). The fallback backend never fails.
The env var HB_SHAPER_LIST is also parsed and honored. It's a
colon-separated list of shaper names. The fallback shaper is invoked if
none of the env-listed shapers succeed.
New API hb_buffer_guess_properties() added.
Behdad Esfahbod