[cairo] Avoiding seams (again)

[Vladimir Vukicevic]

On 3/22/06, Timothée Lecomte <timothee.lecomte at ens.fr> wrote:
> Hi !
>
> Do you remember the thread about avoiding seams between paths a months ago ?
> Well, I am still facing this problem with no ideal solution.

We're running in to this problem in mozilla-land as well, in
particular with thick border rendering.  Since CSS borders can have
different colors/patterns/etc. for each side of the border, they tend
to get drawn as trapezoidal wedges for solid colors.  Right now, with
our cairo builds, we end up with a seam there, as seen in the
testcases in bug https://bugzilla.mozilla.org/show_bug.cgi?id=328241 .

We don't really have a good solution yet; I don't think SATURATE is an
option for us, since we're slow enough as it is (though it might be
acceptable for certain situations where we know we're going to run
into this, like thick borders).  We've been considering supersampling,
maybe extending push group/pop group to support supersampling
internally, but we haven't done any investigation down that path yet
either.

     - Vlad