On 20 Aug, 2013, at 8:36 AM, Rick Mann <rm...@latencyzero.com> wrote:

> 
> On Aug 19, 2013, at 17:25 , Roland King <r...@rols.org> wrote:
> 
>> 
>> On 20 Aug, 2013, at 8:03 AM, Rick Mann <rm...@latencyzero.com> wrote:
>> 
>>> I'm drawing a couple of arcs and then calling ClosePath() to close up the 
>>> shape I drew. This works great. But then I repeat the process in a 
>>> different place, and stroke the whole thing. Unfortunately, Core Graphics 
>>> adds a line from the last point in the closed path to the first point of 
>>> the new arc I add. From my reading of the docs, this line shouldn't happen.
>>> 
>>> "After closing the subpath, your application can begin a new subpath 
>>> without first calling CGContextMoveToPoint. In this case, a new subpath is 
>>> implicitly created with a starting and current point equal to the previous 
>>> subpath’s starting point."
>>> 
>> 
>> From my reading that's exactly what should happen. You close the subpath 
>> then you implicitly start one because you didn't call CGContextMoveToPoint() 
>> when you add the next arc, that path starts from the original starting point 
>> of the old subpath (which is functionally exactly the same as the endpoint). 
>> So the new subpath starts with a line to the start of your new arc from the 
>> start of the previous path. If you don't want that, do the move. 
>> 
>> There's a difference between a context with no path at all and a context 
>> which already contains subpaths, closed or not. 
> 
> Oh, I think you're right. Pity. It makes working with arcs a real pain. I 
> have to compute the arc's starting point and move to it. Unless I'm missing 
> something?
> 


So many ways to attack that. Stroke the segments one-by-one. Or instead of 
going right to the context, create a CGMutablePathRef() for each arc , draw to 
that, then add it to the context path. Heck if you are drawing the same shape 
each time you can even reuse the path and change the CTM to move it around when 
you add then then you only even have to draw it once. 
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