grid.force {grid}R Documentation

Force a grob into its components


Some grobs only generate their content to draw at drawing time; this function replaces such grobs with their at-drawing-time content.


grid.force(x, ...)
## Default S3 method:
grid.force(x, redraw = FALSE, ...)
## S3 method for class 'gPath'
grid.force(x, strict = FALSE, grep = FALSE, global = FALSE,
                           redraw = FALSE, ...) 
## S3 method for class 'grob'
grid.force(x, draw = FALSE, ...)
grid.revert(x, ...)
## S3 method for class 'gPath'
grid.revert(x, strict = FALSE, grep = FALSE, global = FALSE,
                            redraw = FALSE, ...) 
## S3 method for class 'grob'
grid.revert(x, draw = FALSE, ...)



For the default method, x should not be specified. Otherwise, x should be a grob or a gPath. If x is character, it is assumed to be a gPath.


A boolean indicating whether the path must be matched exactly.


Whether the path should be treated as a regular expression.


A boolean indicating whether the function should affect just the first match of the path, or whether all matches should be affected.


logical value indicating whether a grob should be drawn after it is forced.


logical value indicating whether to redraw the grid scene after the forcing operation.


Further arguments for use by methods.


Some grobs wait until drawing time to generate what content will actually be drawn (an axis, as produced by grid.xaxis(), with an at or NULL is a good example because it has to see what viewport it is going to be drawn in before it can decide what tick marks to draw).

The content of such grobs (e.g., the tick marks) are not usually visible to or accessible to grid.edit().

The grid.force() function replaces a grob with its at-drawing-time contents. For example, an axis will be replaced by a vanilla gTree with lines and text representing the axis tick marks that were actually drawn. This makes the tick marks visible to and accessible to grid.edit().

The forceGrob() function is the internal work horse for grid.force(), so will not normally be called directly by the user. It is exported so that methods can be written for custom grob classes if necessary.

The grid.revert() function reverses the effect of grid.force(), replacing forced content with the original grob.


Forcing an explicit grob produces a result as if the grob were drawn in the current drawing context. It may not make sense to draw the result in a different drawing context.


These functions only have an effect for grobs that generate their content at drawing time using makeContext() and makeContent() methods (not for grobs that generate their content at drawing time using preDrawDetails() and drawDetails() methods).


Paul Murrell


pushViewport(viewport(width=.5, height=.5))
# Draw xaxis
# Force xaxis
# Revert xaxis
# Draw and force yaxis
grid.force(yaxisGrob(), draw=TRUE)
# Revert yaxis
# Force JUST xaxis
# Force ALL
# Revert JUST xaxis

[Package grid version 4.4.0 Index]