grobX                  package:grid                  R Documentation

Create a Unit Describing a Grob Boundary Location

Description:

     These functions create a unit object describing a location
     somewhere on the boundary of a grob.  They are generic.

Usage:

     grobX(x, theta)
     grobY(x, theta)

Arguments:

       x: A grob, or gList, or gTree, or gPath.

   theta: An angle indicating where the location is on the grob
          boundary.  Can be one of '"east"', '"north"', '"west"', or
          '"south"', which correspond to angles 0, 90, 180, and 270,
          respectively.

Details:

     The angle is anti-clockwise with zero corresponding to a line with
     an origin centred between the extreme points of the shape, and
     pointing at 3 o'clock.

     If the grob describes a single shape, the boundary value should
     correspond to the exact edge of the shape.

     If the grob describes multiple shapes, in most cases, the boundary
     value will correspond to the edge of a bounding box around all of
     the shapes.  The exception to this is a polygon grob describing
     multiple polygons;  in that case, the edge corresponds to a convex
     hull around all points of all polygons described by the grob.

Value:

     A unit object.

Author(s):

     Paul Murrell

See Also:

     'unit' and 'grobWidth'

