word_cloud_grob.R

library(grid)
word_cloud_grob = function(text, fontsize, 
	line_space = unit(4, "pt"), word_space = unit(4, "pt"), max_width = unit(80, "mm"), 
	col = function(fs) circlize::rand_color(length(fs), luminosity = "dark"),
	test = FALSE) { # width in mm

	if(length(text) != length(fontsize)) {
		stop("`text` and `fontsize` should the same length.")
	}
	
	od = order(fontsize, decreasing = TRUE)
	text = text[od]
	fontsize = fontsize[od]

	if(Sys.info()["sysname"] == "Darwin" && dev.interactive()) {
		ComplexHeatmap:::dev.null()
		on.exit(ComplexHeatmap:::dev.off2())
	}

	n = length(text)
	text_gb_lt = lapply(seq_len(n), function(i) textGrob(text[i], gp = gpar(fontsize = fontsize[i])))
	text_width = vapply(text_gb_lt, function(gb) convertWidth(grobWidth(gb), "mm", valueOnly = TRUE), 0)
	text_height = vapply(text_gb_lt, function(gb) convertHeight(grobHeight(gb), "mm", valueOnly = TRUE), 0)

	if(is.unit(line_space)) line_space = convertHeight(line_space, "mm", valueOnly = TRUE)
	if(is.unit(word_space)) word_space = convertWidth(word_space, "mm", valueOnly = TRUE)

	x = numeric(n)
	y = numeric(n)
	current_line_height = 0
	current_line_width = 0

	# the first text
	current_line_height = text_height[1]
	current_line_width = text_width[1]
	x[1] = 0
	y[1] = 0

	w = text_width[1]
	h = text_height[1]

	if(is.unit(max_width)) {
		max_width = convertWidth(max_width, "mm", valueOnly = TRUE)
	} 

	for(i in seq_len(n)[-1]) {
		# the next text can be put on the same line
		if(current_line_width + text_width[i] <= max_width) {
			x[i] = current_line_width + word_space
			y[i] = y[i-1] # same as previous one
			current_line_width = x[i] + text_width[i]
			w = max(w, current_line_width)
			h = max(h, y[i] + text_height[i])
		} else { # the next text need to be put on the next line
			x[i] = 0
			y[i] = current_line_height + line_space
			current_line_width = text_width[i]
			current_line_height = y[i] + text_height[i]
			w = max(w, current_line_width)
			h = max(h, current_line_height)
		}
	}

	if(is.character(col) || is.numeric(col)) {
		if(length(col) == 1) col = rep(col, n)
		col_fun = function(fontsize) return(col)
	} else if(is.function(col)) {
		col_fun = col
	} else {
		stop("`col` can only be a function or a character vector.")
	}

	if(test) {
		gl = gList(
			rectGrob(),
			textGrob(text, x = x, y = y, gp = gpar(fontsize = fontsize, col = col_fun(fontsize)), 
				default.units = "mm", just = c(0, 0)),
			rectGrob(x = x, y = y, width = text_width, height = text_height, default.units = "mm", just = c(0, 0))

		)
	} else {
		gl = gList(
			textGrob(text, x = x, y = y, gp = gpar(fontsize = fontsize, col = col_fun(fontsize)), 
				default.units = "mm", just = c(0, 0))
		)
	}

	gb = gTree(children = gl, cl = "word_cloud", vp = viewport(width = unit(w, "mm"), height = unit(h, "mm")))
	return(gb)
}

widthDetails.word_cloud = function(x) {
	x$vp$width
}

heightDetails.word_cloud = function(x) {
	x$vp$height
}

scale_fontsize = function(x, rg = c(1, 30), fs = c(4, 16)) {
	k = (fs[2] - fs[1])/(rg[2] - rg[1]) 
	b = fs[2] - k*rg[2]
	y = k*x + b
	y[y < fs[1]] = fs[1]
	y[y > fs[2]] = fs[2]
	round(y)
}