close #29: make it possible to refer to files in other directories

NEWS.md

@@ -4,6 +4,8 @@
 
 - A class `title-slide` was added to the automatically generated title slide (`moon_reader(seal = TRUE)`) so that you can customize the this slide using CSS (thanks, @ekstroem, #7).
 
+- Added an argument `cast_from` to `infinite_moon_reader()` to specify the root directory of the server. Previously the root directory is the directory of the Rmd input file, which makes it impossible for the Rmd document to use resources in upper-level directories (e.g. `![](../gif/cute-kittens.gif)`). Now you can set the working directory to the upper-level directory and call `inf_mr('relative/path/to/input.Rmd')`, so that `input.Rmd` can use any files under the current working directory `./` (thanks, @pat-s, #29).
+
 ## BUG FIXES
 
 - A local copy of MathJax should work with `moon_reader()` (thanks, @bnicenboim, #13).

R/render.R

@@ -155,17 +155,20 @@ tsukuyomi = function(...) moon_reader(...)
 #' \code{inf_mr()} is an alias of \code{infinite_moon_reader()}.
 #'
 #' The Rmd document is compiled continuously to trap the world in the Infinite
-#' Tsukuyomi.
+#' Tsukuyomi. The genjutsu is cast from the directory specified by
+#' \code{cast_from}, and the Rinne Sharingan will be reflected off of the
+#' \code{moon}.
 #' @param moon The input Rmd file path (if missing and in RStudio, the current
 #'   active document is used).
+#' @param cast_from The root directory of the server.
 #' @references \url{http://naruto.wikia.com/wiki/Infinite_Tsukuyomi}
 #' @note This function is not really tied to the output format
 #'   \code{\link{moon_reader}()}. You can use it to serve any single-HTML-file R
 #'   Markdown output.
 #' @seealso \code{servr::\link{httw}}
 #' @export
 #' @rdname inf_mr
-infinite_moon_reader = function(moon) {
+infinite_moon_reader = function(moon, cast_from = '.') {
   # when this function is called via the RStudio addin, use the dir of the
   # current active document
   if (missing(moon) && requireNamespace('rstudioapi', quietly = TRUE)) {
@@ -183,14 +186,25 @@ infinite_moon_reader = function(moon) {
       basename(moon), '".'
     )
   }
-  moon = normalizePath(moon, mustWork = TRUE)
+  moon = normalize_path(moon)
   rebuild = function(...) {
     if (moon %in% normalizePath(c(...))) rmarkdown::render(
       moon, envir = globalenv(), encoding = 'UTF-8'
     )
   }
-  html = rebuild(moon)  # render slides initially
-  servr::httw(dirname(moon), initpath = basename(html), handler = rebuild)
+  html = normalize_path(rebuild(moon))  # render slides initially
+  d = normalize_path(cast_from)
+  f = rmarkdown::relative_to(d, html)
+  # see if the html output file is under the dir cast_from
+  if (f == html) {
+    d = dirname(html)
+    f = basename(html)
+    warning(
+      "Cannot use '", cast_from, "' as the root directory of the server because ",
+      "the HTML output is not under this directory. Using '", d, "' instead."
+    )
+  }
+  servr::httw(d, initpath = f, handler = rebuild)
 }
 
 #' @export

R/utils.R

@@ -11,6 +11,10 @@ example_css = function() htmltools::htmlDependency(
   'remark-css', '0.0.1', pkg_resource(), stylesheet = 'example.css', all_files = FALSE
 )
 
+normalize_path = function(path) {
+  normalizePath(path, winslash = '/', mustWork = TRUE)
+}
+
 # a simple JSON serializer
 tojson = function(x) {
   if (is.null(x)) return('null')