[cairo] Questions and optimizations in cairo-arc

[Bill Spitzak]

Actually there are *four* possible arcs, the center can be in two 
positions on either side of the line connecting the points.


Jason Dorje Short wrote:
> Behdad Esfahbod wrote:
> 
> 
>>A viable signature would be:
>>
>>void
>>cairo_arc_to (cairo_t *cr,
>>              double x, double y,
>>              double radius);
>>
>>and draws the unique arc with the specified radius that connects
>>the current point to x,y.  This still has the problem that it is
>>not the '_to' version of cairo_arc.
> 
> 
> But that's not sufficient because you need to know in which direction
> the arc arcs.