Creates region that describes covers the area where the given surface is more than 50% opaque.
This function takes into account device offsets that might be set with Surface.setDeviceOffset.
a cairo surface
A cairo_region_t; must be freed with Region.destroy
Creates region that describes covers the area where the given surface is more than 50% opaque.
This function takes into account device offsets that might be set with Surface.setDeviceOffset.