[Pixman] New separable filter generator

[Bill Spitzak]

On 06/23/2014 08:05 PM, Krzysztof Kosiński wrote:

> This looks way better and more comprehensive than my attempts at
> fixing the downscaling problem. I would support getting this into
> trunk, preferably along with the rest of your patches, before the 1.14
> release.

I am also looking into the identical patch for pixman instead. The 
result is that PIXMAN_GOOD/BEST would do exactly the same thing. This 
may be a better method to get all backends (such as xlib) to use the 
filtering. I am unclear on the political or technical limitations of 
this approach and what cairo would do with an "old" pixman backend.

> It looks like the magic value 1.35 used in
> _pixman_image_set_properties is undocumented - was it derived
> experimentally?

Yes. This was done with an image of alternating B&W 1-pixel stripes. 
Both BILINEAR and BOX produced artifacts on downscaling and I tried to 
choose a scale where they were about equally objectionable.

>
> Unfortunately I won't have time to test how this works with Inkscape
> for the next 2-3 weeks.
>
> Regards, Krzysztof
>