The cpdf_lineto() function draws
a line from the current point to the point with coordinates
(x-coor, y-coor).
The optional parameter
mode determines the unit length. If it's 0 or
omitted the default unit as specified for the page is used.
Otherwise the coordinates are measured in postscript points
disregarding the current unit.
See also cpdf_moveto(),
cpdf_rmoveto(),
cpdf_curveto().