R: Set the Clipping Region

grid.clip {grid} | R Documentation

## Set the Clipping Region

### Description

These functions set the clipping region within the current viewport without altering the current coordinate system.

### Usage

    grid.clip(...)
    clipGrob(x = unit(0.5, "npc"), y = unit(0.5, "npc"),
             width = unit(1, "npc"), height = unit(1, "npc"),
             just = "centre", hjust = NULL, vjust = NULL,
             default.units = "npc", name = NULL, vp = NULL)

### Arguments

`x` | A numeric vector or unit object specifying x-location.
`y` | A numeric vector or unit object specifying y-location.
`width` | A numeric vector or unit object specifying width.
`height` | A numeric vector or unit object specifying height.
`just` | The justification of the clip rectangle relative to its (x, y) location. If there are two values, the first value specifes horizontal justification and the second value specifies vertical justification. Possible string values are: `"left"`, `"right"`, `"centre"`, `"center"`, `"bottom"`, and `"top"`. For numeric values, 0 means left alignment and 1 means right alignment.
`hjust` | A numeric vector specifying horizontal justification. If specified, overrides the `just` setting.
`vjust` | A numeric vector specifying vertical justification. If specified, overrides the `just` setting.
`default.units` | A string indicating the default units to use if `x`, `y`, `width`, or `height` are only given as numeric vectors.
`name` | A character identifier.
`vp` | A Grid viewport object (or NULL).
`...` | Arguments passed to `clipGrob`.

### Details

Both functions create a clip rectangle (a graphical object describing a clip rectangle), but only `grid.clip` enforces the clipping.

Pushing or popping a viewport always overrides the clip region set by a clip grob, regardless of whether that viewport explicitly enforces a clipping region.

### Value

`clipGrob` returns a clip grob.

### Author(s)

Paul Murrell

### See Also

Grid, `viewport`

### Examples

    # draw across entire viewport, but clipped
    grid.clip(x = 0.3, width = 0.1)
    grid.lines(gp=gpar(col="green", lwd=5))
    # draw across entire viewport, but clipped (in different place)
    grid.clip(x = 0.7, width = 0.1)
    grid.lines(gp=gpar(col="red", lwd=5))
    # Viewport sets new clip region
    pushViewport(viewport(width=0.5, height=0.5, clip=TRUE))
    grid.lines(gp=gpar(col="grey", lwd=3))
    # Return to original viewport;  get
    # clip region from previous grid.clip()
    # (NOT from previous viewport clip region)
    popViewport()
    grid.lines(gp=gpar(col="black"))

[Package grid version 2.6.2 Index]