Introduce bs_with_theme() and bs_local_theme()

R/theme-local.R

@@ -0,0 +1,45 @@
+#' Localized themes
+#'
+#' Tools for using bootstraplib themes in a localized manner. Use
+#' `bs_with_theme()` to scope theming side-effects to the given `expr` and
+#' `bs_local_theme()` to scope within a particular environment. This makes
+#' `bs_local_theme()` handy for theming within a function that returns a shiny
+#' app and `bs_with_theme()` handy for running "top-level" code at the R console
+#' without introducing theming side-effects.
+#'
+#' @param expr theming code to evaluate in a localized fashion
+#' @param .local_envir The environment to use for scoping.
+#' @export
+#' @examples
+#'
+#' theme <- bs_theme_get()
+#' bs_with_theme({
+#'   bs_theme_new()
+#'   bs_theme_base_colors(bg = "black", fg = "white")
+#'   if (interactive()) shiny::runExample("01_hello")
+#' })
+#' identical(theme, bs_theme_get())
+#'
+#' my_app_func <- function() {
+#'   bs_local_theme({
+#'     bs_theme_new(3)
+#'     bs_theme_base_colors(bg = "black", fg = "white")
+#'   })
+#'   shinyApp(fluidPage("Howdy"), function(input, output) {})
+#' }
+#'
+#' my_app_func()
+#' identical(theme, bs_theme_get())
+#'
+bs_local_theme <- function(expr, .local_envir = parent.frame()) {
+  old_theme <- bs_theme_get()
+  withr::defer(bs_theme_set(old_theme), envir = .local_envir)
+  force(expr)
+}
+
+#' @rdname bs_local_theme
+bs_with_theme <- function(expr) {
+  old_theme <- bs_theme_get()
+  on.exit(bs_theme_set(old_theme), add = TRUE)
+  force(expr)
+}