R: Utility function to resolve the size of a raster grob

resolveRasterSize {grid} | R Documentation

## Utility function to resolve the size of a raster grob

### Description

Determine the width and height of a raster grob when one or both are not given explicitly.

The result depends on both the aspect ratio of the raster image and the aspect ratio of the physical drawing context, so the result is only valid for the drawing context in which this function is called.

### Usage

    resolveRasterSize(x)

### Arguments

`x` | A raster grob

### Details

A raster grob can be specified with width and/or height of `NULL`, which means that the size at which the raster is drawn will be decided at drawing time.

### Value

A raster grob, with explicit width and height.

### See Also

`grid.raster`

### Examples

    # Square raster
    rg <- rasterGrob(matrix(0))
    # Fill the complete page (if page is square)
    grid.newpage()
    resolveRasterSize(rg)$height
    grid.draw(rg)
    # Forced to fit tall thin region
    grid.newpage()
    pushViewport(viewport(width=.1))
    resolveRasterSize(rg)$height
    grid.draw(rg)

[Package grid version 3.1.2 Index]