Added a Scale=MatchAveragecase option (#490)

Co-authored-by: Will Robertson <[email protected]>

CHANGES.md

@@ -3,6 +3,7 @@ Change history
 
 ## Unreleased
 
+  * Added a `Scale=MatchAveragecase` paramater which averages `Scale=MatchLowercase` and `Scale=MatchUppercase`.
   * switched options to LaTeX keyval handler
   * added option verbose to undo silent/quiet
   * euenc/tuenc options are obsolete

fontspec-code-keyval.dtx

@@ -485,17 +485,19 @@
 %
 % \paragraph{Scale}
 % If the input isn't one of the pre-defined string options, then
-% it's gotta be numerical. \cs{fontspec_calc_scale:n} does all the work in
-% the auto-scaling cases.
+% it's gotta be numerical. \cs{fontspec_calc_scale:n} and \cs{fontspec_calc_scale:nn}
+% do all the work in the auto-scaling cases.
 %    \begin{macrocode}
 \@@_keys_define_code:nnn {fontspec} {Scale}
   {
     \str_case:nnF {#1}
       {
         {MatchLowercase} { \@@_calc_scale:n {5} }
         {MatchUppercase} { \@@_calc_scale:n {8} }
+        {MatchAveragecase} { \@@_calc_scale:nn {5} {8} }
       }
       { \tl_set:Nx \l_@@_scale_tl {#1} }
+      \@@_info:n {set-scale}
   }
 %    \end{macrocode}
 %
@@ -542,7 +544,6 @@
                        \dim_to_fp:n {\l_@@_tmpb_dim}   }
         }
 
-      \@@_info:n {set-scale}
       \exp_args:NNNx
     \group_end:
     \tl_set:Nx \l_@@_scale_tl { \l_@@_scale_tl }
@@ -551,6 +552,26 @@
 % \end{macro}
 %
 %
+% \begin{macro}{\@@_calc_scale:nn}
+% This macro calls \cs{fontspec_calc_scale:n} twice
+% and then sets the scale to the average of the two results.
+%    \begin{macrocode}
+\cs_new:Nn \@@_calc_scale:nn
+{
+    \group_begin:
+      \__fontspec_calc_scale:n {#1}
+      \tl_set_eq:NN \l_@@_tmp_tl \l_@@_scale_tl
+      \__fontspec_calc_scale:n {#2}
+      \tl_set:Nx \l_@@_scale_tl
+        {
+          \fp_eval:n { (\l_@@_tmp_tl + \l_@@_scale_tl)/2 }
+        }
+      \exp_args:NNNx
+    \group_end:
+    \tl_set:Nx \l_@@_scale_tl { \l_@@_scale_tl }
+  }
+%    \end{macrocode}
+% \end{macro}
 % \begin{macro}{\@@_set_font_dimen:NnN}
 % This function sets the dimension |#1| (for font |#3|) to `fontdimen' |#2|
 % for either font dimension 5 (x-height) or 8 (cap-height). If, for some

fontspec-doc-featset.tex

@@ -411,26 +411,30 @@ \subsection{Scale}
 \cmdbox{
  \feat{Scale} = \meta{number} \\
  \feat{Scale} = \opt{MatchLowercase} \\
- \feat{Scale} = \opt{MatchUppercase}
+ \feat{Scale} = \opt{MatchUppercase} \\
+ \feat{Scale} = \opt{MatchAveragecase}
 }
 
 In its explicit form, \feat{Scale} takes a single
 numeric argument for linearly scaling the font, as demonstrated
 in \exref{fontload}.
 
 As well as a numerical argument, the \feat{Scale} feature
-also accepts options \opt{MatchLowercase}
-and \opt{MatchUppercase}, which will scale the font being selected to match
-the current default roman font to either the height of the lowercase or
-uppercase letters, respectively; these features are shown in \exref{scale}.
+also accepts options \opt{MatchLowercase}, \opt{MatchUppercase},
+and \opt{MatchAveragecase}, which will scale the font being selected to match
+the current default roman font to either the height of the lowercase,
+the height of the uppercase letters, or the average of the two,
+respectively; these features are shown in \exref{scale}.
 The amount of scaling used in each instance is reported in the \texttt{.log} file.
 
 \begin{Xexample}{scale}{Automatically calculated scale values.}
   \setmainfont{Georgia}
   \newfontfamily\lc[Scale=MatchLowercase]{Verdana}
    The perfect match {\lc is hard to find.}\\
   \newfontfamily\uc[Scale=MatchUppercase]{Arial}
-   L O G O \uc F O N T
+   L O G O {\uc F O N T}\\
+  \newfontfamily\ac[Scale=MatchAveragecase]{Fira Math}
+   Lower {\ac and UPPER} CASE
 \end{Xexample}
 
 Additional calls to the \feat{Scale} feature overwrite the settings of the former.
@@ -442,7 +446,8 @@ \subsection{Scale}
   [ Scale = 1.1 , ScaleAgain = 1.2 ] % -> scale of 1.32
 \end{Verbatim}
 
-Note that when |Scale=MatchLowercase| is used with |\setmainfont|, the new `main'
+Note that when |Scale=MatchLowercase|, |Scale=MatchUppercase|, or |Scale=MatchAverageCase|
+is used with |\setmainfont|, the new `main'
 font of the document will be scaled to match the old default.
 If you wish to automatically scale all fonts except have the main font use `natural'
 scaling, you may write

testfiles/feat-scale-match.luatex.tlg

@@ -31,5 +31,14 @@ TU/texgyrecursor-regular.otf(2)/m/n:
   [texgyrecursor-regular.otf]:mode=node;script=latn;language=dflt; at 10.79132pt
 font dimen 5: 4.49998pt
 font dimen 8: 6.07552pt
+MATCH AVERAGECASE
+TU/texgyreheros-regular.otf(3)/m/n:
+  [texgyreheros-regular.otf]:mode=node;script=latn;language=dflt; at 8.83438pt
+font dimen 5: 4.62921pt
+font dimen 8: 6.44026pt
+TU/texgyrecursor-regular.otf(3)/m/n:
+  [texgyrecursor-regular.otf]:mode=node;script=latn;language=dflt; at 11.27487pt
+font dimen 5: 4.70161pt
+font dimen 8: 6.34775pt
 ***************
 Compilation 1 of test file completed with exit status 0

testfiles/feat-scale-match.lvt

@@ -22,4 +22,8 @@
 \fontspec[Scale=MatchLowercase]{texgyreheros-regular.otf}  \X
 \fontspec[Scale=MatchLowercase]{texgyrecursor-regular.otf} \X
 
+\MSG{MATCH AVERAGECASE}
+\fontspec[Scale=MatchAveragecase]{texgyreheros-regular.otf}  \X
+\fontspec[Scale=MatchAveragecase]{texgyrecursor-regular.otf} \X
+
 \end{document}

testfiles/feat-scale-match.tlg

@@ -31,5 +31,14 @@ TU/texgyrecursor-regular.otf(2)/m/n:
   "[texgyrecursor-regular.otf]/OT:script=latn;language=dflt;" at 10.79132pt
 font dimen 5: 4.49998pt
 font dimen 8: 6.07552pt
+MATCH AVERAGECASE
+TU/texgyreheros-regular.otf(3)/m/n:
+  "[texgyreheros-regular.otf]/OT:script=latn;language=dflt;" at 8.83438pt
+font dimen 5: 4.62921pt
+font dimen 8: 6.44026pt
+TU/texgyrecursor-regular.otf(3)/m/n:
+  "[texgyrecursor-regular.otf]/OT:script=latn;language=dflt;" at 11.27487pt
+font dimen 5: 4.70161pt
+font dimen 8: 6.34775pt
 ***************
 Compilation 1 of test file completed with exit status 0