[Drawkit] Handling full circles with DKArcPath

[Graham Cox]

On 16 Oct 2008, at 9:09 pm, Alastair Houghton wrote:

> A better approach to solving this problem would be to alter the code  
> that handles interaction with the user so that it keeps track of  
> what they're actually doing with the end angle.  That way you can  
> make arbitrarily small arcs *and* full circles without having  
> problems where one turns into the other unexpectedly.


Yes, I agree this would be better behaviour.

I'll take a look at this - I'm thinking that simply setting a max  
angle limit of 360 and not wrapping to 0 should work, rather that  
trying to detect clockwise or anti-clockwise rotation which could be  
gnarly.

Note that if you want a circle and only a circle, you can set the  
arcType to kDKArcPathCircle and that's what you get, though using the  
arc's interactive dragging behaviours. Depending on your needs that  
can be a better choice than an ordinary shape with a circular path,  
since that is readily distorted into an oval, etc whereas the arc  
implementation is a circle and always will be a circle no matter what  
you do to it.

cheers, Graham