LaTeX template: support font fallback

* LuaLaTeX-specific (uses luaotfload)
* Configured in YAML metadata
* Sans/main/mono fonts have separate fallback chains

1 files changed, 27 insertions, 3 deletions

diff --git a/data/templates/default.latex b/data/templates/default.latex
index 6d062af19..72b22896c 100644
--- a/data/templates/default.latex
+++ b/data/templates/default.latex
@@ -139,13 +139,37 @@ $endif$
 \ifPDFTeX\else
   % xetex/luatex font selection
 $if(mainfont)$
-  \setmainfont[$for(mainfontoptions)$$mainfontoptions$$sep$,$endfor$]{$mainfont$}
+  $if(mainfontfallback)$
+    \ifLuaTeX
+      \usepackage{luaotfload}
+      \directlua{luaotfload.add_fallback("mainfontfallback",{
+        $for(mainfontfallback)$"$mainfontfallback$"$sep$,$endfor$
+      })}
+    \fi
+  $endif$
+  \setmainfont[$for(mainfontoptions)$$mainfontoptions$$sep$,$endfor$$if(mainfontfallback)$,RawFeature={fallback=mainfontfallback}$endif$]{$mainfont$}
 $endif$
 $if(sansfont)$
-  \setsansfont[$for(sansfontoptions)$$sansfontoptions$$sep$,$endfor$]{$sansfont$}
+  $if(sansfontfallback)$
+    \ifLuaTeX
+      \usepackage{luaotfload}
+      \directlua{luaotfload.add_fallback("sansfontfallback",{
+        $for(sansfontfallback)$"$sansfontfallback$"$sep$,$endfor$
+      })}
+    \fi
+  $endif$
+  \setsansfont[$for(sansfontoptions)$$sansfontoptions$$sep$,$endfor$$if(sansfontfallback)$,RawFeature={fallback=sansfontfallback}$endif$]{$sansfont$}
 $endif$
 $if(monofont)$
-  \setmonofont[$for(monofontoptions)$$monofontoptions$$sep$,$endfor$]{$monofont$}
+  $if(monofontfallback)$
+    \ifLuaTeX
+      \usepackage{luaotfload}
+      \directlua{luaotfload.add_fallback("monofontfallback",{
+        $for(monofontfallback)$"$monofontfallback$"$sep$,$endfor$
+      })}
+    \fi
+  $endif$
+  \setmonofont[$for(monofontoptions)$$monofontoptions$$sep$,$endfor$$if(monofontfallback)$,RawFeature={fallback=monofontfallback}$endif$]{$monofont$}
 $endif$
 $for(fontfamilies)$
   \newfontfamily{$fontfamilies.name$}[$for(fontfamilies.options)$$fontfamilies.options$$sep$,$endfor$]{$fontfamilies.font$}