grobX                  package:grid                  R Documentation

_C_r_e_a_t_e _a _U_n_i_t _D_e_s_c_r_i_b_i_n_g _a _G_r_o_b _B_o_u_n_d_a_r_y _L_o_c_a_t_i_o_n

_D_e_s_c_r_i_p_t_i_o_n:

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

_U_s_a_g_e:

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

_A_r_g_u_m_e_n_t_s:

       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.

_D_e_t_a_i_l_s:

     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, the boundary value will
     either correspond to the edge of a bounding box around all of the
     shapes described by the grob (for multiple rectangles, circles,
     xsplines, or text), or to a  convex hull around all vertices of
     all shapes described by the grob (for multiple polygons, points,
     lines, polylines,  and segments).

     Points grobs are currently a special case because the convex hull
     is based on the data symbol _locations_ and does not take into
     account the extent of the data symbols themselves.

     The extents of any arrow heads are currently _not_ taken into
     account.

_V_a_l_u_e:

     A unit object.

_A_u_t_h_o_r(_s):

     Paul Murrell

_S_e_e _A_l_s_o:

     'unit' and 'grobWidth'

