raster_magick: Rasterize the ggplot layers

In ggalign: A 'ggplot2' Extension for Consistent Axis Alignment

Rasterize the ggplot layers

Description

The function rasterizes input graphical objects (e.g., grob, layer, ggplot) and optionally processes the resulting raster using magick, a powerful image manipulation library. This allows for advanced graphical transformations directly within the plotting pipeline.

Usage

raster_magick(
  x,
  magick = NULL,
  ...,
  res = NULL,
  interpolate = FALSE,
  vp = NULL
)

Arguments

x	An object to rasterize, can be a grob(), layer(), ggplot(), or a list of such objects.
magick	A function (purrr-style formula is accepted) that takes an image_read() object as input and returns an object compatible with as.raster(). You can use any of the ⁠image_*()⁠ functions from the magick package to process the raster image.
...	These dots are for future extensions and must be empty.
res	An integer sets the desired resolution in pixels.
interpolate	A logical value indicating whether to linearly interpolate the image (the alternative is to use nearest-neighbour interpolation, which gives a more blocky result).
vp	A Grid viewport object (or NULL).

Value

An object with the same class of the input.

See Also

magickGrob()

Examples

# Currently, `magick` package require R >= 4.1.0
if (requireNamespace("magick")) {
    # data generated code was copied from `ComplexHeatmap`
    set.seed(123)
    small_mat <- matrix(rnorm(56), nrow = 7)
    rownames(small_mat) <- paste0("row", seq_len(nrow(small_mat)))
    colnames(small_mat) <- paste0("column", seq_len(ncol(small_mat)))
    ggheatmap(small_mat, aes(.x, .y), filling = NULL) +
        raster_magick(geom_tile(aes(fill = value)), res = 20)

    ggheatmap(small_mat, aes(.x, .y), filling = NULL) +
        # Use `magick::filter_types()` to check available `filter` arguments
        raster_magick(
            geom_tile(aes(fill = value)),
            magick = function(image) {
                magick::image_resize(image,
                    geometry = "50%x", filter = "Lanczos"
                )
            }
        )
}

ggalign documentation built on June 8, 2025, 11:25 a.m.