Add mathjax support via cdn

Author: cpsievert

R/layout.R

@@ -117,7 +117,7 @@ rangeslider <- function(p, start = NULL, end = NULL, ...) {
 #' config(p, locale = "zh-CN")
 #' 
 
-config <- function(p, ..., collaborate = TRUE, cloud = FALSE, locale = NULL) {
+config <- function(p, ..., collaborate = TRUE, cloud = FALSE, locale = NULL, mathjax = FALSE) {
 
   if (!is.null(locale)) {
     p$dependencies <- c(
@@ -127,6 +127,13 @@ config <- function(p, ..., collaborate = TRUE, cloud = FALSE, locale = NULL) {
     p$x$config$locale <- locale
   }
 
+  if (!identical(mathjax, FALSE)) {
+    p$dependencies <- c(
+      list(mathjax_dependency()),
+      p$dependencies
+    )
+  }
+  
   p$x$config <- modify_list(p$x$config, list(...))
 
   nms <- sapply(p$x$config[["modeBarButtonsToAdd"]], "[[", "name")

R/mathjax.R

@@ -0,0 +1,40 @@
+mathjax_cdn <- function() {
+  htmltools::htmlDependency(
+    name = "mathjax",
+    version = "2.7.4",
+    src = c(file = depPath("mathjax")),
+    script = "cdn.js"
+  )
+}
+
+# TODO: wait until there is a more official way to include query parameters
+# https://github.com/rstudio/htmltools/issues/98
+mathjax_local <- function() {
+  htmltools::htmlDependency(
+    name = "mathjax",
+    version = "2.7.4",
+    src = c(file = mathjax_path()),
+    script = "MathJax.js?config=TeX-AMS-MML_SVG"
+  )
+}
+
+
+mathjax_path <- function() {
+  path <- Sys.getenv("PLOTLY_MATHJAX_PATH", NA)
+  if (!is.na(path)) {
+    mj <- file.path(path, "MathJax.js")
+    if (!file.exists(mj)) stop("Couldn't find 'MathJax.js' file in local directory")
+    return(path)
+  }
+  
+  if (system.file(package = "rmarkdown") != "") {
+    # Note, this should throw an informative error if the path isn't found
+    return(getFromNamespace("pandoc_mathjax_local_path", "rmarkdown")())
+  } 
+  
+  stop(
+    "To use a local version of MathJax with plotly, either set the PLOTLY_MATHJAX_PATH",
+    "environment variable to the location of MathJax or install rmarkdown.",
+    call. = FALSE
+  )
+}

R/orca.R

@@ -71,19 +71,3 @@ orca <- function(p, file = "plot.png", format = tools::file_ext(file),
   try_library("processx", "orca")
   invisible(processx::run("orca", args, echo = TRUE, spinner = TRUE))
 }
-
-
-mathjax_path <- function() {
-  if (is_rstudio()) {
-    try_library("rmarkdown", "orca")
-    return(getFromNamespace("pandoc_mathjax_local_path", "rmarkdown")())
-  }
-  path <- Sys.getenv("PLOTLY_MATHJAX_PATH", Sys.getenv("RMARKDOWN_MATHJAX_PATH", NA))
-  if (!is.na(path)) return(normalizePath(path, mustWork = TRUE))
-  stop(
-    "Please set either the RMARKDOWN_MATHJAX_PATH or PLOTLY_MATHJAX_PATH ",
-    "environment variable to the location of MathJax. ",
-    "On Linux systems you can also install MathJax using your system package manager.",
-    call. = FALSE
-  )
-}

inst/htmlwidgets/lib/mathjax/cdn.js

@@ -0,0 +1,4 @@
+var script = document.createElement("script");
+script.type = "text/javascript";
+script.src  = "https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.4/MathJax.js?config=TeX-AMS-MML_SVG";
+document.getElementsByTagName("head")[0].appendChild(script);