R/lcbc-logo.R

In LCBC-UiO/MOAS: MOAS convenience functions

#' LCBC logo graphics object
#'
#' @param type type of logo to get
#' @param alpha opacity of logo
#'
#' @return graphics object (grob)
lcbc_logo_grob <- function(type = "main", alpha = 0.4){

  logo_dir <- system.file("logos", package = "MOAS")


  logos <- list.files(logo_dir)
  logos <- gsub("LCBC_|\\.png", "", logos)

  type <- match.arg(type, logos)

  img <- png::readPNG(list.files(logo_dir, pattern = type, full.names = TRUE),
                      FALSE, FALSE)

  img <- matrix(grDevices::rgb(img[,,1], img[,,2], img[,,3],
                    img[,,4] * alpha), nrow=dim(img)[1])

  grid::rasterGrob(img, interpolate=TRUE)
}

#' Add LCBC logo to plot
#'
#' in a ggplot, adding the logo should be added
#' early in the plot building
#'
#' @inheritParams lcbc_logo_grob
#' @param ... arguments to \code{annotation_custom}
#'
#' @export
#'
#' @examples
#' library(ggplot2)
#' ggplot(mtcars, aes(x = wt, y = disp, colour = cyl)) +
#'   geom_point() +
#'   add_lcbc_logo()
add_lcbc_logo <- function(type = "main", alpha = .4,
                          ...){
  g <- lcbc_logo_grob(type, alpha = alpha)

  ggplot2::annotation_custom(grob = g, ...)
}