The cairo-filter-t enumeration is used to indicate what filtering should be applied when reading pixel values from patterns. See the function cairo-pattern-set-filter for indicating the desired filter to be used with a particular pattern.

(defcenum cairo-filter-t
  :fast
  :good
  :best
  :nearest
  :bilinear
  :gaussian)  

:fast

A high-performance filter, with quality similar to :nearest.

:good

A reasonable-performance filter, with quality similar to :bilinear.

:best

The highest-quality available, performance may not be suitable for interactive use.

:nearest

Nearest-neighbor filtering.

:bilinear

Linear interpolation in two dimensions.

:gaussian

This filter value is currently unimplemented, and should not be used in current code.