This function is currently not documented; only the argument list is available.
This function is EXPERIMENTAL. The behaviour of this function, the name of this function, and anything else documented about this function may change without notice in a future release of PHP. Use this function at your own risk.
Adds a path element to the current path which closes the current subpath by drawing a straight line from the current point to the current subpath's most recent starting point (usually, the most recent moveto point).