xDetails                package:grid                R Documentation

Boundary of a grid grob

Description:

     These generic functions are used to determine a location on the
     boundary of a grid grob.

Usage:

     xDetails(x, theta)
     yDetails(x, theta)

Arguments:

       x: A grid grob. 

   theta: A numeric angle, in degrees, measured anti-clockwise from the
          3 o'clock _or_ one of the following character strings:
          '"north"', '"east"', '"west"', '"south"'.

Details:

     The location on the grob boundary is determined by taking a line
     from the centre of the grob at the angle 'theta' and intersecting
     it with the convex hull of the grob (for the basic grob
     primitives, the centre is determined as half way between the
     minimum and maximum values in x and y directions).

     These functions are called in the calculation of '"grobx"' and
     '"groby"' units as produced by the 'grobX' and 'grobY' functions.
     Methods should be written for classes derived from grob or gTree
     where the boundary of the grob can be determined.

Value:

     A unit object.

Author(s):

     Paul Murrell

See Also:

     'grobX', 'grobY'.

