Display engine images in the exercise caption

NEWS.md

@@ -28,7 +28,7 @@ learnr (development version)
 * Added error handling when user specifies a non-existent label for `exercise.setup` option with an error message. ([#390](https://github.com/rstudio/learnr/pull/390))
 * We no longer forward the checker code to browser (in html), but instead cache it. ([#390](https://github.com/rstudio/learnr/pull/390))
 * We no longer display an invisible exercise result warning automatically. Instead, authors must set the exercise chunk option `exercise.warn_invisible = TRUE` to display an invisible result warning message. ([#373](https://github.com/rstudio/learnr/pull/373))
-* With the addition of multi-language support, the default caption for an exercise has been switched to the combination of the exercise engine and `" code"`. This can be overwritten by setting the chunk option `exercise.cap`. ([#397](https://github.com/rstudio/learnr/pull/397))
+* `exercise.cap` now accepts HTML input. If no `exercise.cap` is provided, an icon of the exercise engine will be displayed. If no icon is known, the `exercise.cap` will default to the combination of the exercise engine and `" code"`. ([#397](https://github.com/rstudio/learnr/pull/397), [#429](https://github.com/rstudio/learnr/pull/429))
 * `engine` is now passed to the `exercise.checker` to help distinguish what language is being checked in the exercise. ([#397](https://github.com/rstudio/learnr/pull/397))
 * Hitting the `TAB` key in an exercise has always opened the auto-completion drop down. Now, hitting the `TAB` key will also complete the currently selected code completion. ([#428](https://github.com/rstudio/learnr/pull/428))
 

R/knitr-hooks.R

@@ -234,10 +234,8 @@ install_knitr_hooks <- function() {
         completion  <- as.numeric(options$exercise.completion %||% 1 > 0)
         diagnostics <- as.numeric(options$exercise.diagnostics %||% 1 > 0)
         startover <- as.numeric(options$exercise.startover %||% 1 > 0)
-        caption <- options[["exercise.cap"]] %||% paste0(options$engine, " code")
         paste0('<div class="tutorial-', class,
                '" data-label="', options$label,
-               '" data-caption="', caption,
                '" data-completion="', completion,
                '" data-diagnostics="', diagnostics,
                '" data-startover="', startover,
@@ -313,9 +311,26 @@ install_knitr_hooks <- function() {
         )
 
         # script tag with knit options for this chunk
+        caption <-
+          if (!is.null(options$exercise.cap)) {
+            as.character(options$exercise.cap)
+          } else {
+            cap_engine <- knitr_engine(options$engine)
+
+            cap_engine_file <- system.file(file.path("internals", "icons", paste0(cap_engine, ".svg")), package = "learnr")
+            if (file.exists(cap_engine_file)) {
+              as.character(htmltools::div(
+                class = "tutorial_engine_icon",
+                htmltools::HTML(readLines(cap_engine_file))
+              ))
+            } else {
+              paste0(options$engine, " code")
+            }
+          }
         ui_options <- list(
           engine = options$engine,
-          has_checker = !is.null(check_chunk) || !is.null(code_check_chunk)
+          has_checker = (!is.null(check_chunk) || !is.null(code_check_chunk)),
+          caption = caption
         )
         extra_html <- c('<script type="application/json" data-ui-opts="1">',
                         jsonlite::toJSON(ui_options, auto_unbox = TRUE),

R/options.R

@@ -4,7 +4,7 @@
 #' Set various tutorial options that control the display and evaluation of
 #' exercises.
 #'
-#' @param exercise.cap Caption for exercise chunk (defaults to \code{"Code")}.
+#' @param exercise.cap Caption for exercise chunk (defaults to the engine's icon or the combination of the engine and \code{" code"}).
 #' @param exercise.eval Whether to pre-evaluate the exercise so the reader can
 #'   see some default output (defaults to \code{FALSE}).
 #' @param exercise.timelimit Number of seconds to limit execution time to
@@ -20,7 +20,7 @@
 #' @param exercise.startover Show "Start Over" button on exercise.
 #'
 #' @export
-tutorial_options <- function(exercise.cap = "Code",
+tutorial_options <- function(exercise.cap = NULL,
                              exercise.eval = FALSE,
                              exercise.timelimit = 30,
                              exercise.lines = NULL,