[cairo] Horizontal artifacts rendering to an image surface

[Floyd May]

-----Original Message-----
From: Søren Sandmann [mailto:sandmann at cs.au.dk] 
Sent: Friday, July 27, 2012 4:43 PM
To: Floyd May
Cc: cairo at cairographics.org
Subject: Re: [cairo] Horizontal artifacts rendering to an image surface

Floyd May <FMay at sstsoftware.com>> writes:

>> I've been able to boil this down to a reproducible, small case.
>> Basically, two four-point polygons where one edge from each is 
>> collinear.  Using even-odd rendering, I'm getting these artifacts:
>>
>> http://imagebin.org/222354
>>
>> Again, this is based on v 1.10.2, on Windows (both x86 and x64 exhibit 
>> the issue), based on a recent download of GTK+ binaries.
>>
>> Here is C# source (using Mono.Cairo; should be able to adapt to C code 
>> relatively easily):

> FWIW, here is a C variant that shows the same artefact and also 
> demonstrates that it doesn't happen with the X backend. 
> (To use the X backend, set the "const int image" variable to 0).

So it seems that this is limited to the backend for image surfaces. Is this a pixman thing? Is this fixed in a later version of Cairo?