# grobCoords: Calculate Points on the Perimeter of a Grob

## Description

These functions calculate points along the perimeter (or length) of
a grob.

## Usage

grobCoords(x, closed, …)
grobPoints(x, closed, …)
emptyCoords
isEmptyCoords(coords)

## Arguments

closed

Whether we are asking for points along the perimeter of
a closed object or points along the length of an open object.
Some grobs (e.g., X-splines) can do both.

…

Arguments to be used by methods.

coords

A set of grob coordinates (as generated by `grobCoords`

).

## Value

A list of lists with components `x`

and `y`

.
All locations are in inches relative to the current grid viewport.

## Details

Custom grobs can write their own methods for `grobPoints`

.

The `emptyCoords`

object can be used to return a "null"
result (e.g., when asking for `closed`

coordinates on an
open line) and the `isEmptyCoords`

function can be used to check for
"null" results.