Fixes https://github.com/harfbuzz/harfbuzz/issues/2567
New API:
+hb_blob_create_or_fail()
+hb_blob_create_from_file_or_fail()
Use these in util/ to distinguish empty file from not-found file.
Only err on the latter.
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.
Remove hb_ft_get_font_funcs() as it cannot be used by the user anyway.
Add hb_ft_font_set_funcs(). Which will make the font internally use
FreeType. That is, no need for the font to have created using the
hb-ft API. Just create using hb_face_create()/hb_font_create() and
then call this on the font (after having set font scale). This
internally creates an FT_Face and attached to the font.
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.