[cairo] Non-antialiased rendering in image surface

[cu]

I'll try to get a trace, but the issue is so common I don't think
specific trace is needed. Essentially any polygon drawn using non-pixel
aligned and non-axis-aligned edges causes this issue. All you need is
two polygons that share a portion of their outline, draw one and fill,
draw the other and fill. It's most visible when colors are the same.

Attached is the image of two polygons sharing part of outline drawn with
antialiasing turned on. Same area with antialiasing turned off looks
like a square of plain uniform color, so I didn't bother attaching it -
there is nothing there to see.



Siarhei Siamashka wrote:
> On Saturday 26 June 2010 18:18:03 cu wrote:
>   
>> I see. That's unfortunate. I use non-antialiased rendering for certain
>> objects when it's important that their edges match perfectly (without a
>> thin line that seems to appear when fill is made in antialiased mode).
>>
>> Guess I need to measure the impact and compare.
>>     
>
> Submitting a relevant cairo-trace for your use case may help to ensure that it 
> performs well. Adding new fast paths to pixman for more a1 compositing 
> operations should be technically possible.
>
>   
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