Restored and undeprecated gladtex for HTML math.

- Added `GladTeX` constructor to `Text.Pandoc.Options.HTMLMathMethod`
  [API change, reverts removal in v2.2]
- Restored and undeprecated `--gladtex` option, removed in v2.2.

Closes #4607.

3 files changed, 15 insertions, 1 deletions

diff --git a/src/Text/Pandoc/App.hs b/src/Text/Pandoc/App.hs
index 920462d48..a59fd9bbe 100644
--- a/src/Text/Pandoc/App.hs
+++ b/src/Text/Pandoc/App.hs
@@ -1403,6 +1403,12 @@ options =
                   "URL")
                   "" -- Use KaTeX for HTML Math
 
+    , Option "" ["gladtex"]
+                 (NoArg
+                  (\opt ->
+                      return opt { optHTMLMathMethod = GladTeX }))
+                 "" -- "Use gladtex for HTML math"
+
     , Option "" ["abbreviations"]
                 (ReqArg
                  (\arg opt -> return opt { optAbbreviations = Just arg })
diff --git a/src/Text/Pandoc/Options.hs b/src/Text/Pandoc/Options.hs
index 4797a3094..e5ca1764c 100644
--- a/src/Text/Pandoc/Options.hs
+++ b/src/Text/Pandoc/Options.hs
@@ -107,6 +107,7 @@ data EPUBVersion = EPUB2 | EPUB3 deriving (Eq, Show, Read, Data, Typeable, Gener
 
 data HTMLMathMethod = PlainMath
                     | WebTeX String               -- url of TeX->image script.
+                    | GladTeX
                     | MathML
                     | MathJax String              -- url of MathJax.js
                     | KaTeX String                -- url of KaTeX files
diff --git a/src/Text/Pandoc/Writers/HTML.hs b/src/Text/Pandoc/Writers/HTML.hs
index 535071ae2..a09ad2fda 100644
--- a/src/Text/Pandoc/Writers/HTML.hs
+++ b/src/Text/Pandoc/Writers/HTML.hs
@@ -58,7 +58,7 @@ import qualified Data.Text.Lazy as TL
 import Network.HTTP (urlEncode)
 import Network.URI (URI (..), parseURIReference, unEscapeString)
 import Numeric (showHex)
-import Text.Blaze.Internal (customLeaf, MarkupM(Empty))
+import Text.Blaze.Internal (customLeaf, customParent, MarkupM(Empty))
 #if MIN_VERSION_blaze_markup(0,6,3)
 #else
 import Text.Blaze.Internal (preEscapedString, preEscapedText)
@@ -1029,6 +1029,13 @@ inlineToHtml opts inline = do
               return $ case t of
                         InlineMath  -> m
                         DisplayMath -> brtag >> m >> brtag
+           GladTeX ->
+              return $
+                customParent (textTag "eq") !
+                  customAttribute "env"
+                    (toValue $ if t == InlineMath
+                                  then ("math" :: Text)
+                                  else "displaymath") $ strToHtml str
            MathML -> do
               let conf = useShortEmptyTags (const False)
                            defaultConfigPP