[ft] Rendering a filled contour inside an unfilled one

[Shriramana Sharma]

Hello. I am new to this list. I searched for this info in the docs but
couldn't seem to find it there so am asking here. Sorry if I
overlooked anything.

In common to TrueType and PostScript style outlines (i.e. whichever
combination of clockwise/anticlockwise/filled/unfilled is used) I
would like to know how a filled contour inside an unfilled one (which
in turn would of course be inside a filled one) such as in the case of
© is provided by the font and handled by the rasterizer. Is it just
that whichever is first in storage order is done first? For example,
in the case of © the outer filled circle should be placed first in the
font storage, then the inner unfilled circle, then the innermost
filled C?

Again, for ®, there is an unfilled contour (belly of R) inside a
filled one inside an unfilled one inside a filled one. How is that
handled?

Or is a fillrule is used to determine filled/unfilled areas
irrespective of the order of clockwise/anticlockwise contours?
http://fontforge.org/overview.html seems to suggest that the nonzero
rule is what is followed. Is that correct?

Somehow I am not sure it is correct because (for example) as per the
nonzero rule, a standalone contour will always be filled irrespective
of its orientation. If a particular standard prescribes that
anticlockwise contours should be unfilled, then they should be
unfilled always, no?

Or have I seriously got the wrong hang of things?

I am trying to implement boolean operations on glyph contours, which
is why I ask.

Thanks for your time and patience.

-- 
Shriramana Sharma