cairo:mesh-pattern-set-control-point (pattern point x y)

pattern -- a cairo:pattern-t instance
point -- an unsigned integer for the control point to set the position for
x -- a number coerced to a double float for the x coordinate of the control point
y -- a number coerced to a double float for the y coordinate of the control point

Set an internal control point of the current patch. Valid values for point are from 0 to 3 and identify the control points as explained for the cairo:pattern-create-mesh function. If the pattern argument is not a mesh pattern then pattern will be put into an error status with a status of :pattern-type-mismatch. If point is not valid, pattern will be put into an error status with a status of :invalid-index. If pattern has no current patch, pattern will be put into an error status with a status of :invalid-mesh-construction.