(cffi:defcenum extend-t
  :none
  :repeat
  :reflect
  :pad)  

:none

Pixels outside of the source pattern are fully transparent.

:repeat

The pattern is tiled by repeating.

:reflect

The pattern is tiled by reflecting at the edges.

:pad

Pixels outside of the pattern copy the closest pixel from the source.

The cairo:extend-t enumeration is used to describe how pattern color/alpha will be determined for areas "outside" the natural area, of the pattern for example, outside the surface bounds or outside the gradient geometry. Mesh patterns are not affected by the extend mode.

The default extend mode is :none for surface patterns and :pad for gradient patterns.