[cairo] Curve drawing question (from GUADEC)

[Liam Girdwood]

I had the good fortune to bump into Carl and Keith at GUADEC recently
and asked them a cairo curve drawing question. I said I would repeat my
question for the list (as there was no example code and I'd also
probably forget the answer).

I asked what was the best sequence of cairo function calls to draw a
scaled curve in cairo (e.g. lines of longitude/latitude on a spherical
projection of the Earth). Iirc, Carl mentioned that getting the ordering
of cairo function calls wrong in this case could cause the line
thickness to vary slightly from one end of the curve to the other.

Thanks

Liam