Set \fontdimen10|11 for math fonts

This gives macro packages access to (Script)ScriptPercentScaleDown math
constants, see wspr/unicode-math#112.

1 files changed, 17 insertions, 0 deletions

diff --git a/luaotfload.dtx b/luaotfload.dtx
index 6c3dafd..0cb371e 100644
--- a/luaotfload.dtx
+++ b/luaotfload.dtx
@@ -678,6 +678,23 @@ local function def_font(...)
             mc["FractionDelimiterDisplayStyleSize"] = 2.39 * size
 
             fontdata.MathConstants = mc
+%    \end{macrocode}
+%
+%    \LuaTeX\ does not provide interface to accessing
+%    \texttt{(Script)ScriptPercentScaleDown} math constants, so we emulate
+%    \XeTeX\ behaviour by setting \cs{fontdimen10} and \cs{fontdimen11}.
+%
+%    \begin{macrocode}
+            if mc["ScriptPercentScaleDown"] then
+                fontdata.parameters[10] = mc["ScriptPercentScaleDown"]
+            else -- resort to plain TeX default
+                fontdata.parameters[10] = 70
+            end
+            if mc["ScriptScriptPercentScaleDown"] then
+                fontdata.parameters[11] = mc["ScriptScriptPercentScaleDown"]
+            else -- resort to plain TeX default
+                fontdata.parameters[11] = 50
+            end
         end
 
     end