circle_fill_pattern.R

#| dev: ragg_png

library(grid)
library(ggplot2)

# gpar everywhere to rule out an "invisible lines" issue
gp <- gpar(col = "black", fill = "transparent", lwd = 2, lty = "solid")

mm_rel <- function(...) {
  unit(0.5, "npc") + unit((base::c(...) - 0.5) * 10, "mm")
}

circle_pattern <- function(r) {
  pattern(
    circleGrob(x = mm_rel(c(1, 3, 5) / 6), y = mm_rel(c(1, 3, 5) / 6), r = unit(r, "mm"), gp = gp),
    width = unit(10, "mm"), height = unit(10, "mm"), extend = "repeat", gp = gp
  )
}

d <- tempfile()
dir.create(d)
ragg::agg_png(file.path(d, "plot%03d.png"))

for (i in 1:200) {
  p <- ggplot(mpg, aes(factor(cyl), fill = factor(cyl))) +
    geom_bar() +
    scale_fill_manual(values = lapply(c(3.3, 4.4, 5.5, 6.6) * (0.2 + 0.01 * i)^2, circle_pattern))
  
  plot(p)
}
dev.off()

gifski::gifski(list.files(d, full.names = TRUE), delay = 0.01)