the cluster to end applying this feature setting (exclusive).
the cluster to start applying this feature setting (inclusive).
a feature tag
0 disables the feature, non-zero (usually 1) enables the feature.
For features implemented as lookup type 3 (like 'salt') the value is a one
based index into the alternates.
Converts a #hb_feature_t into a %NULL-terminated string in the format
understood by hb_feature_from_string(). The client in responsible for
allocating big enough size for buf, 128 bytes is more than enough.
The #hb_feature_t is the structure that holds information about requested feature application. The feature will be applied with the given value to all glyphs which are in clusters between
start(inclusive) andend(exclusive). Setting start toHB_FEATURE_GLOBAL_STARTand end toHB_FEATURE_GLOBAL_ENDspecifies that the feature always applies to the entire buffer.