Clarification Re: [cairo] Mac Tiger Core Image

[mental at rydia.net]

Quoting mental at rydia.net:

> I'm going to attach a simple SVG that provides an example of the
> rendering problems I am trying to avoid -- namely the four
> hairlines that separate the segments of the ring, despite their
> meeting perfectly from a geometric perspective.

FWIW, it's specifically intended to illustrate a case where I don't
understand how rendering on separate surfaces could solve the
problem entirely.

Ideally you'd want to render all the ring segments together, since
they share edges, but the star figure that interleaves with them
complicates matters.

Maybe there is some trick using different compositing operators that
I'm missing, though.  Can you or someone else on the list suggest a
sequence of cairo operations that could render this without
hairlines?

(Then, if that sequence of operations is nontrivial, I'd still need
an algorithm to derive such a compositing sequence automatically,
given an arbitrary arrangement of shapes...)

-mental