Convert math in README (#2263)

Fixes #2261

Co-authored-by: Hadley Wickham <[email protected]>

NEWS.md

@@ -1,5 +1,6 @@
 # pkgdown (development version)
 
+* `build_home_index()` now renders math if you use it in your home page (#2263).
 * `build_home()` now correctly escapes special HTML characters in the bibtex citation (#2022).
 * BS5 templates no longer include empty link to logo when none exists (#2536).
 * `build_articles()` now reports if you are missing alt-text for any images (#2357).

R/markdown.R

@@ -118,6 +118,7 @@ convert_markdown_to_html <- function(in_path, out_path, ...) {
       "--indented-code-classes=R",
       "--section-divs",
       "--wrap=none",
+      "--mathjax",
       ...
     ))
   )

R/pkgdown.R

@@ -31,7 +31,9 @@ local_envvar_pkgdown <- function(pkg, scope = parent.frame()) {
   )
 }
 
-local_pkgdown_site <- function(path = NULL, meta = NULL, env = parent.frame()) {
+local_pkgdown_site <- function(path = NULL, meta = NULL, clone = FALSE, env = parent.frame()) {
+  check_bool(clone)
+
   if (is.null(path)) {
     path <- withr::local_tempdir(.local_envir = env)
     desc <- desc::desc("!new")
@@ -40,6 +42,23 @@ local_pkgdown_site <- function(path = NULL, meta = NULL, env = parent.frame()) {
     desc$write(file = path(path, "DESCRIPTION"))
 
     file_create(path(path, "_pkgdown.yml"))
+  } 
+
+  if (clone) {
+    if (is.null(path)) {
+      cli::cli_abort("Can only clone when {.arg path} is set.")
+    } else {
+      src_paths <- dir_ls(path, recurse = TRUE)
+      is_dir <- is_dir(src_paths)
+
+      dst <- withr::local_tempdir("pkgdown", .local_envir = env)
+      dst_paths <- path(dst, path_rel(src_paths, path))
+
+      dir_create(dst_paths[is_dir])
+      file_copy(src_paths[!is_dir], dst_paths[!is_dir])
+
+      path <- dst
+    }
   }
 
   if (is.character(meta)) {

tests/testthat/test-build-home-index.R

@@ -8,6 +8,17 @@ test_that("title and description come from DESCRIPTION by default", {
   expect_equal(data_home(pkg)$opengraph$description, "Y")
 })
 
+test_that("math is handled", {
+  pkg <- local_pkgdown_site(test_path("assets/home-readme-rmd"), clone = TRUE)
+  write_lines(c("$1 + 1$"), path(pkg$src_path, "README.md"))
+
+  suppressMessages(init_site(pkg))
+  suppressMessages(build_home_index(pkg))
+
+  html <- xml2::read_html(path(pkg$dst_path, "index.html"))
+  expect_equal(xpath_text(html, ".//span[contains(@class, 'math')]"), "\\(1 + 1\\)")
+})
+
 test_that("version formatting in preserved", {
   pkg <- local_pkgdown_site(test_path("assets/version-formatting"))
   expect_equal(pkg$version, "1.0.0-9000")