| % File src/library/grid/man/grid.null.Rd |
| % Part of the R package, https://www.R-project.org |
| % Copyright 1995-2007 R Core Team |
| % Distributed under GPL 2 or later |
| |
| \name{grid.null} |
| \alias{grid.null} |
| \alias{nullGrob} |
| \title{ Null Graphical Object } |
| \description{ |
| These functions create a NULL graphical object, |
| which has zero width, zero height, and draw nothing. |
| It can be used as a place-holder or as an invisible |
| reference point for other drawing. |
| } |
| \usage{ |
| nullGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"), |
| default.units = "npc", |
| name = NULL, vp = NULL) |
| grid.null(...) |
| } |
| \arguments{ |
| \item{x}{A numeric vector or unit object specifying x-location.} |
| \item{y}{A numeric vector or unit object specifying y-location.} |
| \item{default.units}{A string indicating the default units to use |
| if \code{x}, \code{y}, \code{width}, or \code{height} |
| are only given as numeric vectors.} |
| \item{name}{ A character identifier. } |
| \item{vp}{A Grid viewport object (or NULL).} |
| \item{\dots}{Arguments passed to \code{nullGrob()}.} |
| } |
| \value{ |
| A null grob. |
| } |
| \author{Paul Murrell} |
| \seealso{ |
| \link{Grid}, |
| \code{\link{viewport}} |
| } |
| \examples{ |
| grid.newpage() |
| grid.null(name="ref") |
| grid.rect(height=grobHeight("ref")) |
| grid.segments(0, 0, grobX("ref", 0), grobY("ref", 0)) |
| } |
| \keyword{dplot} |