Can be -1 for NUL-terminated string. This is useful for passing parts
of a larger string to a function without having to copy or modify the
string first.
Affected functions:
hb_tag_t hb_tag_from_string()
hb_direction_from_string()
hb_language_from_string()
hb_script_from_string()
For two reasons:
1. User can always call hb_buffer_pre_allocate() themselves, and
2. Now we do a pre_alloc in add_utfX anyway, so the total number of
reallocs is limited to a small number (~3) anyway. This just makes the
API cleaner.
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.
This includes HB_DIRECTION_INVALID and HB_SCRIPT_INVALID.
The INVALID will cause a "guess whatever from the text" in hb_shape().
While it's not ideal, it works better than the previous defaults at
least (HB_DIRECTION_LTR and HB_SCRIPT_COMMON).
The --features parsing handles errors now. More importantly, it
allos limiting individual features to specific byte ranges. The
format is Python-esque. Here is how it all works:
Syntax: Value: Start: End:
Setting value:
"kern" 1 0 ∞ # Turn feature on
"+kern" 1 0 ∞ # Turn feature off
"-kern" 0 0 ∞ # Turn feature off
"kern=0" 0 0 ∞ # Turn feature off
"kern=1" 1 0 ∞ # Turn feature on
"kern=2" 2 0 ∞ # Choose 2nd alternate
Setting index:
"kern[]" 1 0 ∞ # Turn feature on
"kern[:]" 1 0 ∞ # Turn feature on
"kern[5:]" 1 5 ∞ # Turn feature on, partial
"kern[:5]" 1 0 5 # Turn feature on, partial
"kern[3:5]" 1 3 5 # Turn feature on, range
"kern[3]" 1 3 3+1 # Turn feature on, single char
Mixing it all:
"kern[3:5]=0" 1 3 5 # Turn feature off for range
Accepts values like:
--features="-mkmk,aalt=2,calt=1,+cswh"
A minus sign means "=0", a plus sign means "=1". Default is "=1".
A minus sign overrides an explicit value.
Also adds --script support to hb-view.
If a script tag is not known to us, we pass the ISO 15924 tag around.
Right now, the OT layer ignores that, but we can fix it to blindly
convert that to an OT script tag.
Behdad Esfahbod
Ryan Lortie