\HeaderA{grid.edit}{Edit the Description of a Grid Graphical Object}{grid.edit}
\aliasA{editGrob}{grid.edit}{editGrob}
\keyword{dplot}{grid.edit}
\begin{Description}\relax
Changes the value of one of the slots of a grob
and redraws the grob.
\end{Description}
\begin{Usage}
\begin{verbatim}
grid.edit(gPath, ..., strict = FALSE, grep = FALSE, global = FALSE,
          allDevices = FALSE, redraw = TRUE) 
editGrob(grob, gPath = NULL, ..., strict = FALSE, grep = FALSE,
         global = FALSE) 
\end{verbatim}
\end{Usage}
\begin{Arguments}
\begin{ldescription}
\item[\code{grob}] A grob object.
\item[\code{...}] Zero or more named arguments specifying new slot values.
\item[\code{gPath}] A gPath object. For \code{grid.edit} this
specifyies a grob on the display list.  For \code{editGrob} this
specifies a descendant of the specified grob. 
\item[\code{strict}] A boolean indicating whether the gPath must be
matched exactly. 
\item[\code{grep}] A boolean indicating whether the \code{gPath} should
be treated as a regular expression.  Values are recycled across
elements of the \code{gPath} (e.g., \code{c(TRUE, FALSE)} means
that every odd element of the \code{gPath} will be treated as
a regular expression).

\item[\code{global}] A boolean indicating whether the function should affect
just the first match of the \code{gPath}, or whether all matches
should be affected.

\item[\code{allDevices}] A boolean indicating whether all open devices
should
be searched for matches, or just the current device.
NOT YET IMPLEMENTED.

\item[\code{redraw}] A logical value to indicate whether to redraw the grob. 
\end{ldescription}
\end{Arguments}
\begin{Details}\relax
\code{editGrob} copies the specified grob and returns a modified
grob.

\code{grid.edit} destructively modifies a grob on the display list.
If \code{redraw}
is \code{TRUE} it then redraws everything to reflect the change.

Both functions call \code{editDetails} to allow a grob to perform
custom actions and \code{validDetails} to check that the modified grob
is still coherent.
\end{Details}
\begin{Value}
\code{editGrob} returns a grob object;  \code{grid.edit} returns \code{NULL}.
\end{Value}
\begin{Author}\relax
Paul Murrell
\end{Author}
\begin{SeeAlso}\relax
\code{\LinkA{grob}{grob}}, \code{\LinkA{getGrob}{getGrob}},
\code{\LinkA{addGrob}{addGrob}}, \code{\LinkA{removeGrob}{removeGrob}}.
\end{SeeAlso}
\begin{Examples}
\begin{ExampleCode}
grid.newpage()
grid.xaxis(name = "xa", vp = viewport(width=.5, height=.5))
grid.edit("xa", gp = gpar(col="red"))
# won't work because no ticks (at is NULL)
try(grid.edit(gPath("xa", "ticks"), gp = gpar(col="green")))
grid.edit("xa", at = 1:4/5)
# Now it should work
try(grid.edit(gPath("xa", "ticks"), gp = gpar(col="green")))
\end{ExampleCode}
\end{Examples}

