Before, if one called hb_shape() without setting script, language, and
direction on the buffer, hb_shape() was calling
hb_buffer_guess_segment_properties() on the user's behalf to guess
these.
This is very dangerous, since any serious user of HarfBuzz must set
these properly (specially important is direction). So now, we don't
guess properties by default. People not setting direction will get
an abort() now. If the old behavior is desired (fragile, good for
simple testing only), users can call
hb_buffer_guess_segment_properties() on the buffer just before calling
hb_shape().
That's really the logic desired. Except that MONGOLIAN VOWEL SEPARATOR
is not default_ignorable but it really should be. Reported to Unicode.
Based on suggestion from Konstantin Ritt.
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