[cairo] Problem clearing edge of a clip region

[Ian Britten]

       [ bump ]
Any comments?  Sorry to re-ask - I know everyone is busy...  :P
Thanks,
Ian

> Hi all,
>   [ cairo v1.8.8, pixman 0.14.0 ]
> I'm having a problem when trying to clear the contents of a
> clip region - Specifically the border pixels - and was wondering
> if anyone can offer any insight?
> 
> In the attached sample, I define a clip region, draw to it, then
> clear it.  However, after doing the clear, the edge pixels are
> still (partially) visible, and seemingly weren't cleared.
> 
> Am I doing something wrong?  Might this be a bug?  Or is this
> somehow due to subpixel/AA rendering?
> If it's a problem with my technique/understanding, can anyone
> offer any suggestions about how to proceed?  Or point me to
> something to read?  My code is based on
> http://cairographics.org/FAQ/#clear_a_surface, but that doesn't
> discuss this particular case.
> 
> Many thanks for any info!
> Ian