locator(n=512)
locator
reads the position of the graphics cursor when
the (first) mouse button is pressed. Unless the process
is terminated prematurely by the user (see below) at most
n
positions are determined.
The input process can be terminated prematurely by pressing any mouse button other than the first, or by clicking outside the graphics window.
x
and y
components which are
the coordinates of the identified points.