[cairo] Howto draw quadratic curves with cairo?

[Bill Spitzak]

All variables are vectors with 2 or more points.

To turn quad(p0, p1, p2) into cubic(q0, q1, q2, q3):

	q0 = p0
	q1 = (p0+2*p1)/3
	q2 = (p2+2*p1)/3
	q3 = p2

Ascii diagram, q1 and q2 are 2/3 the distance along the lines:

	p0         p2
	 \         /
	  \       /
	   \     /
	    q1  q2
	     \ /
	      p1

Sebastien Pouliot wrote:
> Hello Clemens,
> 
> We have such code inside Moonlight
> http://anonsvn.mono-project.com/viewvc/trunk/moon/src/moon-path.c?revision=127537&view=markup
> 
> Sebastien
> 
> On Fri, 2009-10-16 at 12:25 -0400, Clemens Eisserer wrote:
>> Hi,
>>
>> I would like to use cairo for drawing quadratic bezier curves, however
>> as as far as I saw cairo only supports cubic curves.
>> I guess its not hard, but could anybody help me out howto create cubic
>> curve parameters out of quadratic ones?
>>
>> Thank you in advance, Clemens