| % File src/library/grid/man/grobX.Rd |
| % Part of the R package, https://www.R-project.org |
| % Copyright 1995-2007 R Core Team |
| % Distributed under GPL 2 or later |
| |
| \name{grobX} |
| \alias{grobX} |
| \alias{grobY} |
| \title{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{ |
| \item{x}{A grob, or gList, or gTree, or gPath.} |
| \item{theta}{An angle indicating where the location is |
| on the grob boundary. Can be one of \code{"east"}, |
| \code{"north"}, \code{"west"}, or \code{"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, 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 \emph{locations} and does not take |
| into account the extent of the data symbols themselves. |
| |
| The extents of any arrow heads are currently \emph{not} taken into account. |
| } |
| \value{ |
| A unit object. |
| } |
| \author{Paul Murrell} |
| \seealso{ |
| \code{\link{unit}} and |
| \code{\link{grobWidth}} |
| } |
| \keyword{dplot} |