R/plot_device.R

In NetSimR: Actuarial Functions for Non-Life Insurance Modelling

################
#Plot device for the Shiny tools
################

# Extra arguments for a grDevices::png() call, such as the report's charts. The default
# device of png() on Windows does not anti-alias, so lines and text come out jagged, and
# it cannot draw semi-transparent pixels: on a transparent background it loses text
# anti-aliasing and faint colours, so charts in the dark theme look smeared. The cairo
# type of png() draws them properly, so it is asked for on Windows when R has cairo, with
# greyscale anti-aliasing: its default, subpixel, gives text coloured fringes. The default
# types elsewhere (quartz on macOS, cairo on Linux) anti-alias already and are left alone.
png_device_args <- function() {
  if (.Platform$OS.type == "windows" && isTRUE(capabilities("cairo"))) {
    list(type = "cairo", antialias = "gray")
  } else {
    list()
  }
}

# Extra device arguments for shiny::renderPlot(). Shiny draws plots with ragg, the macOS
# quartz device or the Cairo package when they are available, and otherwise with
# grDevices::png(), so the png() arguments above apply only in that case (the other
# devices do not take a type argument).
plot_device_args <- function() {
  installed <- function(pkg) nzchar(system.file(package = pkg))
  uses_ragg <- isTRUE(getOption("shiny.useragg", TRUE)) && installed("ragg")
  uses_cairo_package <- isTRUE(getOption("shiny.usecairo", TRUE)) && installed("Cairo")
  uses_png <- !uses_ragg && !isTRUE(capabilities("aqua")) && !uses_cairo_package
  if (uses_png) png_device_args() else list()
}

# shiny::renderPlot() for the tools' charts: redrawn when the output is resized (instead
# of rescaling the old image, which overlaps legends laid out for another width), and drawn
# with the device arguments above. Other arguments (bg, alt, height, ...) are passed on.
netsimr_render_plot <- function(expr, ..., env = parent.frame()) {
  args <- c(
    list(expr = substitute(expr), env = env, quoted = TRUE, execOnResize = TRUE),
    list(...),
    plot_device_args()
  )
  do.call(shiny::renderPlot, args, quote = TRUE)
}