fav.R

#' Use Font Awesome icons as favicons
#'
#' Generate the html necessary to use a Font Awesome icon as the favicon (the
#' icon that appears on browser tabs) for a shiny app or other HTML document.
#'
#' @inheritParams .fav_encode
#' @inheritDotParams fontawesome::fa
#'
#' @return A `shiny.tag` (see [htmltools::tag()]) that can be used to embed a
#'   favicon in a shiny app or other HTML document.
#' @export
#' @examplesIf interactive()
#' html_page <- htmltools::tags$html(
#'   fav("earth-africa", fill = "blue"),
#'   htmltools::tags$body(
#'     htmltools::tags$h1("Hello world!"),
#'     htmltools::tags$p("(on the browser tab)")
#'   )
#' )
#' htmltools::html_print(html_page, viewer = utils::browseURL)
fav <- function(name, ...) {
  fav_base64 <- .fav_encode(name, ...)
  fav_href <- .fav_as_href(fav_base64)
  htmltools::tags$head(
    htmltools::tags$link(rel = "icon", type = "image/png", href = fav_href)
  )
}

#' Load Font Awesome icon and encode
#'
#' @inheritParams fontawesome::fa
#' @inheritDotParams fontawesome::fa
#'
#' @return A base64-encoded character vector representing the icon png.
#' @keywords internal
.fav_encode <- function(name, ...) {
  jsonlite::base64_enc(
    rsvg::rsvg_png(
      charToRaw(
        fontawesome::fa(name, ...)
      ),
      width = 32,
      height = 32
    )
  )
}

#' Add data URI prefix to base64-encoded icon
#'
#' @param fav_base64 A base64-encoded character vector generated by
#'   [.fav_encode()].
#'
#' @return The base64-encoded icon with the data URI prefix.
#' @keywords internal
.fav_as_href <- function(fav_base64) {
  paste0("data:image/png;base64,", fav_base64)
}