| Allegro CL version 8.2 This page is new in 8.2. |
Arguments: point box &optional pos-to-return &key margin
Returns the point on the edge of a box
where it is crossed by a line that passes through the center of the
box and through an arbitrary
point. Returns nil
if the box center and the arbitrary point are the same.
The first argument is a position object for the arbitrary point, and
the second argument is a box object. Returns a position object or
nil
.
If pos-to-return
is nil
or unspecified, then a new position
object is created and returned. Otherwise
pos-to-return should be a position object, which
will be modified and returned.
The margin argument is somewhat
obscure. If specified, it should be a real number indicating a
distance. If the real intersection point is less than this distance
from a corner of the box, then the returned point will be adjusted so
that it is this distance from the corner. (This is used by one
application to avoid drawing a connecting line to a rounded corner of
a rounded box.) If you specify a value for margin, you must also
specify a value for the pos-to-return optional
argument. Specify nil
if you do not want to
specify a position.
As usual, position and box objects should contain integers. See make-position and make-box. See also radial-line-box-intersection-x-y and radial-line-circle-intersection.
Copyright (c) 1998-2016, Franz Inc. Oakland, CA., USA. All rights reserved.
This page is new in the 8.2 release.
Created 2016.6.21.
| Allegro CL version 8.2 This page is new in 8.2. |