(No version information available, might only be in SVN)
Specifies how to render the endpoints of the path when stroking.
       The default line cap style is CairoLineCap::BUTT.
   
CairoLineCap::BUTT
     Start(stop) the line exactly at the start(end) point
CairoLineCap::ROUND
     Use a round ending, the center of the circle is the end point
CairoLineCap::SQUARE
     Use squared ending, the center of the square is the end point