R: Boundary of a grid grob

xDetails {grid} | R Documentation

## Boundary of a grid grob

### Description

These generic functions are used to determine a location on the boundary of a grid grob.

### Usage

    xDetails(x, theta)
    yDetails(x, theta)

### Arguments

`x` | A grid grob.
`theta` | A numeric angle, in degrees, measured anti-clockwise from the 3 o'clock or one of the following character strings: `"north"`, `"east"`, `"west"`, `"south"`.

### Details

The location on the grob boundary is determined by taking a line from the centre of the grob at the angle `theta` and intersecting it with the convex hull of the grob (for the basic grob primitives, the centre is determined as half way between the minimum and maximum values in x and y directions).

These functions are called in the calculation of `"grobx"` and `"groby"` units as produced by the `grobX` and `grobY` functions. Methods should be written for classes derived from grob or gTree where the boundary of the grob can be determined.

### Value

A unit object.

### Author(s)

Paul Murrell

### See Also

`grobX`, `grobY`.

[Package grid version 2.8.1 Index]