[cairo] high-fidelity anti-aliasing in Cairo/libpixman?

[Leon Woestenberg]

Hello,

I have been doing some reading on high-fidelity anti-aliasing in a set 
of articles
and in "Computer Graphics - Principles and Practice, 2nd Edition in C" 
by Foley,
van Dam, Feiner, Hughes.

Especially the sections on un-weighted area sampling (aka box filter) versus
weighted area sampling (aka cone filter) where the latter has higher
fidelity.

I tried to see how Cairo and libpixman cope with the problem of 
calculating pixel
alpha values, but could not derive an algorithm out of the C code.

I assume the stuff sits in "libpixman/ictrap.c/IcRasterizeTrapezoid() 
and PixelAlpha()"
for most of it.

In a more general sense, I had a hard time seeing the algorithms past 
the cleverly pieces
of C code, and I think much of the underlying algorithms are fully known 
to those who
wrote it, or perform nothing but computer graphics arithmetics during 
the week.

Can anyone enlighten me a bit?

Thanks,

Leon Woestenberg.