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