R/pattern-array-plasma.R

In gridpattern: 'grid' Pattern Grobs

#' Plasma patterned grobs
#'
#' `grid.pattern_plasma()` draws a plasma pattern onto the graphic device.
#'
#' @inheritParams grid.pattern_gradient
#' @param scale Extra scaling
#' @return A grid grob object invisibly.  If `draw` is `TRUE` then also draws to the graphic device as a side effect.
#' @examples
#'   if (requireNamespace("magick")) {
#'     x_hex <- 0.5 + 0.5 * cos(seq(2 * pi / 4, by = 2 * pi / 6, length.out = 6))
#'     y_hex <- 0.5 + 0.5 * sin(seq(2 * pi / 4, by = 2 * pi / 6, length.out = 6))
#'     grid.pattern_plasma(x_hex, y_hex, fill = "green")
#'   }
#' @seealso [grid.pattern_ambient()] provides a noise pattern using the `ambient` package.
#'          Pseudorandom seeds for the plasma pattern may be set via [magick::magick_set_seed()].
#' @export
grid.pattern_plasma <- function(
	x = c(0, 0, 1, 1),
	y = c(1, 0, 0, 1),
	id = 1L,
	...,
	fill = gp$fill %||% "grey80",
	scale = 1,
	alpha = gp$alpha %||% NA_real_,
	aspect_ratio = 1,
	key_scale_factor = 1,
	res = getOption("ggpattern_res", 72),
	default.units = "npc",
	name = NULL,
	gp = gpar(),
	draw = TRUE,
	vp = NULL
) {
	grid.pattern(
		"gridpattern::plasma",
		x,
		y,
		id,
		fill = fill,
		scale = scale,
		alpha = alpha,
		aspect_ratio = aspect_ratio,
		key_scale_factor = key_scale_factor,
		res = res,
		default.units = default.units,
		name = name,
		gp = gp,
		draw = draw,
		vp = vp
	)
}

#' Read a user specified filename as an image
#'
#' @inheritParams create_gradient_as_array
#'
#' @return array
#' @noRd
create_magick_plasma_as_array <- function(width, height, params, legend) {
	assert_suggested("magick", "plasma")

	colour <- as.character(params$pattern_fill)

	img <- create_magick_plasma_img(
		width = width,
		height = height,
		colour = colour
	)

	convert_img_to_array(img)
}

#' Create plasma using imagemagick
#'
#' Ref: \url{https://usage.imagemagick.org/canvas/}
#'
#' @param width,height image dimensions
#' @param colour colour
#'
#' @noRd
create_magick_plasma_img <- function(width = 100, height = 100, colour) {
	colour <- convert_r_colour_to_magick_colour(colour)

	#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
	# Create a pattern image of the required size
	#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
	pseudo <- "plasma:"
	img <- magick::image_blank(width, height, pseudo_image = pseudo)
	img <- magick::image_convert(img, colorspace = 'gray', depth = 8)
	img <- magick::image_blur(img, radius = 2)

	#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
	# Make the white transparent
	# Colorize the black pixels into the desired colour
	#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
	img <- magick::image_transparent(img, 'white')
	img <- magick::image_colorize(img, opacity = 50, colour)

	img
}