Querying the Viewport Tree {grid} | R Documentation

## Get the Current Grid Viewport (Tree)

### Description

`current.viewport()` returns the viewport that Grid is going to draw into.

`current.parent` returns the parent of the current viewport.

`current.vpTree` returns the entire Grid viewport tree.

`current.vpPath` returns the viewport path to the current viewport.

`current.transform` returns the transformation matrix for the current viewport.

`current.rotation` returns the (total) rotation for the current viewport.

### Usage

    current.viewport()
    current.parent(n=1)
    current.vpTree(all=TRUE)
    current.vpPath()
    current.transform()

### Arguments

`n` | The number of generations to go up.
`all` | A logical value indicating whether the entire viewport tree should be returned.

### Details

It is possible to get the grandparent of the current viewport (or higher) using the `n` argument to `current.parent()`.

The parent of the ROOT viewport is `NULL`. It is an error to request the grandparent of the ROOT viewport.

If `all` is `FALSE` then `current.vpTree` only returns the subtree below the current viewport.

### Value

A Grid viewport object from `current.viewport` or `current.vpTree`.

`current.transform` returns a 4x4 transformation matrix.

The viewport path returned by `current.vpPath` is `NULL` if the current viewport is the `ROOT` viewport

### Author(s)

Paul Murrell

### See Also

`viewport`

### Examples

    grid.newpage()
    pushViewport(viewport(width=0.8, height=0.8, name="A"))
    pushViewport(viewport(x=0.1, width=0.3, height=0.6,
      just="left", name="B"))
    upViewport(1)
    pushViewport(viewport(x=0.5, width=0.4, height=0.8,
      just="left", name="C"))
    pushViewport(viewport(width=0.8, height=0.8, name="D"))
    current.vpPath()
    upViewport(1)
    current.vpPath()
    current.vpTree()
    current.viewport()
    current.vpTree(all=FALSE)
    popViewport(0)

[Package grid version 3.3.2 Index]