segmentPropertiesOverlay

void segmentPropertiesOverlay(harfbuzz.segment_properties.SegmentProperties p,  harfbuzz.segment_properties.SegmentProperties src)

Fills in missing fields of p from src in a considered manner.

First, if p does not have direction set, direction is copied from src.

Next, if p and src have the same direction (which can be unset), if p does not have script set, script is copied from src.

Finally, if p and src have the same direction and script (which either can be unset), if p does not have language set, language is copied from src.

Parameters

`p`	#hb_segment_properties_t to fill in.
`src`	#hb_segment_properties_t to fill in from.