From ab708607afeb3715c0c64d44569a3166e392409a Mon Sep 17 00:00:00 2001
From: Christophe Dervieux <christophe.dervieux@gmail.com>
Date: Wed, 8 Feb 2023 15:16:46 +0100
Subject: [PATCH] Add support for webtex in blastula_email rmarkodwn format

---
 R/blastula_email_format.R | 14 +++++++++++++-
 man/blastula_email.Rd     |  8 ++++++++
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/R/blastula_email_format.R b/R/blastula_email_format.R
index 2a91784f..1a7170c4 100644
--- a/R/blastula_email_format.R
+++ b/R/blastula_email_format.R
@@ -32,6 +32,12 @@
 #'   default, this is `TRUE`. The standalone HTML file will have no external
 #'   dependencies, it will use URIs to incorporate the contents of linked
 #'   scripts, stylesheets, images, and videos.
+#' @param math_method Passed to `math_method` in [rmarkdown::html_document()].
+#'   Only method `webtex` is supported at the moment to generate math as svg
+#'   image (default), or png (by specifying a url). See details in
+#'   [rmarkdown::html_document()]. Set to `NULL` to deactivate math processing.
+#'   _Note: Using `webtex` requires a internet connection when rendering the
+#'   document as an external service is used.
 #' @param template The Pandoc template to use for rendering. This is the
 #'   `"blastula"` template by default.
 #' @param includes A named list of additional content to include within the
@@ -59,6 +65,7 @@ blastula_email <- function(content_width = "1000px",
                            dev = "png",
                            smart = TRUE,
                            self_contained = TRUE,
+                           math_method = "webtex",
                            template = "blastula",
                            includes = NULL,
                            keep_md = FALSE,
@@ -72,6 +79,10 @@ blastula_email <- function(content_width = "1000px",
     template <- system.file("rmd", "template.html", package = "blastula")
   }
 
+  if (!is.null(math_method) && math_method != "webtex") {
+    stop("Only 'webtex' method is for now supported when math is activated.")
+  }
+
   # Note bash escaping is handled by R Markdown (via shQuote())
   pandoc_args <- paste0("--variable=content-width:", content_width)
   if (isTRUE(connect_footer)) {
@@ -111,7 +122,8 @@ blastula_email <- function(content_width = "1000px",
     self_contained = self_contained,
     theme = "default",
     highlight = "default",
-    mathjax = NULL,
+    math_method = math_method,
+    mathjax = "default",
     template = template,
     extra_dependencies = NULL,
     css = NULL,
diff --git a/man/blastula_email.Rd b/man/blastula_email.Rd
index e213a9f2..4d282d6b 100644
--- a/man/blastula_email.Rd
+++ b/man/blastula_email.Rd
@@ -18,6 +18,7 @@ blastula_email(
   dev = "png",
   smart = TRUE,
   self_contained = TRUE,
+  math_method = "webtex",
   template = "blastula",
   includes = NULL,
   keep_md = FALSE,
@@ -71,6 +72,13 @@ default, this is \code{TRUE}. The standalone HTML file will have no external
 dependencies, it will use URIs to incorporate the contents of linked
 scripts, stylesheets, images, and videos.}
 
+\item{math_method}{Passed to \code{math_method} in \code{\link[rmarkdown:html_document]{rmarkdown::html_document()}}.
+Only method \code{webtex} is supported at the moment to generate math as svg
+image (default), or png (by specifying a url). See details in
+\code{\link[rmarkdown:html_document]{rmarkdown::html_document()}}. Set to \code{NULL} to deactivate math processing.
+_Note: Using \code{webtex} requires a internet connection when rendering the
+document as an external service is used.}
+
 \item{template}{The Pandoc template to use for rendering. This is the
 \code{"blastula"} template by default.}