[cairo] How to draw two parallel polylines?

[archee@126]

Hi, All,

I'm startting to use Cairo to draw roads in a city. Each road can be represented as a polyline with multiple points. To draw a simple road, just create a path with these points and then stroke the path. But if I want to draw both directions of a road, how to create two parallel paths according to the polyline? Is there any facility provided in Cairo doing that?

Thanks in advance!

Regards,
Archee
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