[cairo] downscaling capabilities

[Vladimir Vukicevic]

On Apr 19, 2008, at 8:23 PM, Frédéric Plourde wrote:
>
> By the way,
>
> Does anybody know what was the first intented uses for filtering  
> modes CAIRO_FILTER_BILINEAR,
> CAIRO_FILTER_GOOD and CAIRO_FILTER_BEST ??
>
> down to pixman, all three are considered equal to the same bilinear  
> sampling technique, so we're not making any smart use of them.
> I would suggest, since we're turning ourselves toward sampling  
> issues, that we make use of these "GOOD" and "BEST" modes in a more  
> clever way.
>
> For example :
>
>  CAIRO_FILTER_BILINEAR : our current bilinear filter
>  CAIRO_FILTER_GOOD :       true downscaling to nearest mipmap level  
> + bilinear filtering
>  CAIRO_FILTER_BEST :         trilinear filtering.

GOOD, BEST, and FAST are supposed to be 'generic' names that don't  
imply a specific algorithm, but instead allow the surface backend to  
choose an algorithm based on the desired characteristics (goodness,  
bestness, fastness :).  We can certainly add new enums here if they're  
necessary to identify specific techniques to allow them to be selected  
explicitly.

    - Vlad