Re: [ft-devel] a satisfactory fix for the cubic spline bug

[James Cloos]

>>>>> "GA" == GRAHAM ASHER <address@hidden> writes:

GA> Some reasons this hasn't made very many waves;

GA> 1. My impression is that nearly all actual fonts are TrueType these
GA> days.  TrueType does't use cubic splines. It uses quadratics only.

Cubic fonts remain an important sector, especially for print and for
display of work intended for print.

That notwithstanding:

GA> 2. Font designers very rarely use 'exciting' cubic splines. Splines
GA> with control points on both sides of the line hardly ever occur in
GA> glyphs, and I would expect self-crossing curves never to occur.

That, on the other hand, is very true.  In fact, and IIRC, Adobe
actively promotes those objective to font designers, to ensure that
the fonts work well with their software, including both their desktop
software and their PS/PDF engines.

GA> We must of course be correct for all curves, but we need optimise
GA> heavily only for the common case where p0, p1, p2 and p3 have
GA> r-coordinates (using Hain's notation) in that order, and
GA> s-coordinates with the same sign.

Consequent to your second point, that is also true.

-JimC
-- 
James Cloos <address@hidden>         OpenPGP: 1024D/ED7DAEA6