[cairo] Survey of polygon rasterization techniques

[David Turner]

Hello Zack,

> Rendering to QImage (or just rendering on Qt/Windows) invokes software
> rasterizer that is a mixture of freetype2/agg rasterization techniques
> and  should be faster than both. 

Could you elaborate on this "should be faster than both" ? I'm interested
to know what kind of improvement you made. 

I just had a quick look at src/gui/painting/qgrayraster.c in Qt 4.3 and
I don't see much differences from a relatively old version of the
FreeType anti-aliasing rasterizer. Maybe some details escape me ?

Also, you may find interesting that the current FreeType rasterizer sources
use a scanline-bucket scheme now, instead of QSort, to sort the cells. I've
done this because in some relatively common cases, it provided a x1.25 speedup
in rendering time.

Hope this helps,

- David Turner
- The FreeType Project  (www.freetype.org)