[cairo] Adding support for quadratic beziers

[Paul Sladen]

On Thu, 9 Aug 2012, Shriramana Sharma wrote:
> On Thu, Aug 9, 2012 at 4:51 AM, Chris Wilson <chris at chris-wilson.co.uk> wrote:
> > That said we have a number of other convenience functions,
> > and could have easily hid that we only use cubic beziers internally.
> to add [quadratic beziers] to that list of convenience functions?

It is quite useful to keep the low-level library and convenience
functions separate.  Think GLU vs. GL.  The high-level constructs
are built out of low-level primitives.[0]

None-the-less, when there's no difference/disadvantage for the
computer, but there is a large difference for the programmer/user,
then it makes sense to go with what the user thinks in;

So for radians vs. degrees, this is probably something that
Postscript, SVG and and OpenGL got right, and which is sub-optimal in
the API designs of Cairo and Quartz.  Cairo increases the cognitive
load for the user with no benefit to the computer or API overall.

	-Paul


[0] http://lists.cairographics.org/archives/cairo/2003-May/000097.html
regarding why arcs /are/ primitives, but eg. rounded boxes are not.