Using ligatures from Linux Libertine for numbering sections and in TOC

Question

The old Libertine package, which worked with pdfTeX, included a command \libertineGlyph{}. \libertineGlyph{Fourroman} printed

Ⅳ

But how can I get these roman numbers used for numbering sections and even in the TOC?

I found Using ligatures from libertine for roman numerals in pdftex , but I do not know how to make it work.

MWE:

\documentclass[ngerman]{article}
\usepackage[T1]{fontenc}\usepackage[utf8]{inputenc}
\usepackage{babel,blindtext}
 \usepackage{libertine}


\newcommand*{\libertineRoman}[1]{%
    \def\Romantemp{}%
    \ifnum\value{#1}>0\relax%
        \ifnum\value{#1}<13\relax%
            \edef\Romantemp{\ifcase\value{#1}\or One\or Two\or Three\or Four\or Five\or Six\or Seven\or Eight\or Nine\or Ten\or Eleven\or Twelve\fi}%
            \libertineGlyph{\Romantemp roman}%
        \else\Roman{#1}\fi%
    \else\Roman{#1}\fi%
}
\newcommand*{\libertineroman}[1]{%
    \def\Romantemp{}%
    \ifnum\value{#1}>0\relax%
        \ifnum\value{#1}<13\relax%
            \edef\Romantemp{\ifcase\value{#1}\or one\or two\or three\or four\or five\or six\or seven\or eight\or nine\or ten\or eleven\or twelve\fi}%
            \libertineGlyph{\Romantemp roman}%
        \else\roman{#1}\fi%
    \else\roman{#1}\fi%
}


%%% Roman numbers
\renewcommand{\thesection}{\Roman{section}}

%%% Roman ligatures from Linux Libertine?
%\renewcommand{\thesection}{\libertineRoman{section}}
%%% DOES NOT WORK


\begin{document}
\tableofcontents{}

{\libertineGlyph{Fourroman}} 

\blinddocument

\end{document}

Cave: I use the old libertine package from years ago, which provides \libertineGlyph for pdfTeX. However, maybe somebody can give me a hint.

Answer 1

The new libertine package also provides \libertineGlyph if XeLaTeX or LuaLaTeX is used. This made it possible for me to come up with a solution without installing the old package. The code should also work for the old package.

A counter representation command such as \arabic should be expandable if you don't want to run into troubles. Your commands are not expandable, though.

Below I define five commands:

• \LibertineRomanByName{<name>} -- a shortcut for \libertineGlyph{<name>roman}.
• \LibertineUCRomanByInt{<integer>} -- gives the uppercase libertine glyph for the given integer (as long as the integer is in the range of 1--12).
• \LibertineLCRomanByInt{<integer>} -- gives the lowercase libertine glyph for the given integer (as long as the integer is in the range of 1--12).
• \lbtRoman{<counter>} -- gives the uppercase libertine glyph for the corresponding counter value or the usual result of \Roman if the counter is out of range.
• \lbtroman{<counter>} -- gives the lowercase libertine glyph for the corresponding counter value or the usual result of \roman if the counter is out of range.

The Code

Uppercase: \lbtRoman{section}, lowercase: \lbtroman{section}

\setcounter{section}{7}
Uppercase: \lbtRoman{section}, lowercase: \lbtroman{section}

\setcounter{section}{13}
Uppercase: \lbtRoman{section}, lowercase: \lbtroman{section}

\LibertineUCRomanByInt{1} \LibertineLCRomanByInt{1}\par
\LibertineUCRomanByInt{2} \LibertineLCRomanByInt{2}\par
\LibertineUCRomanByInt{3} \LibertineLCRomanByInt{3}\par
\LibertineUCRomanByInt{4} \LibertineLCRomanByInt{4}\par
\LibertineUCRomanByInt{5} \LibertineLCRomanByInt{5}\par
\LibertineUCRomanByInt{6} \LibertineLCRomanByInt{6}\par
\LibertineUCRomanByInt{7} \LibertineLCRomanByInt{7}\par
\LibertineUCRomanByInt{8} \LibertineLCRomanByInt{8}\par
\LibertineUCRomanByInt{9} \LibertineLCRomanByInt{9}\par
\LibertineUCRomanByInt{10} \LibertineLCRomanByInt{10}\par
\LibertineUCRomanByInt{11} \LibertineLCRomanByInt{11}\par
\LibertineUCRomanByInt{12} \LibertineLCRomanByInt{11}

\setcounter{section}{7}
\renewcommand*\thesection{\lbtRoman{section}}
\section{Let's see: it works!}

then gives

Here's the complete code:

% arara: lualatex
\documentclass{article}
\usepackage{libertine}

\makeatletter
\newcommand*\LibertineRomanByName[1]{\libertineGlyph{#1roman}}
\newcommand*\LibertineUCRomanByInt[1]{%
  \ifcase#1%
  \or\LibertineRomanByName{One}%
  \or\LibertineRomanByName{Two}%
  \or\LibertineRomanByName{Three}%
  \or\LibertineRomanByName{Four}%
  \or\LibertineRomanByName{Five}%
  \or\LibertineRomanByName{Six}%
  \or\LibertineRomanByName{Seven}%
  \or\LibertineRomanByName{Eight}%
  \or\LibertineRomanByName{Nine}%
  \or\LibertineRomanByName{Ten}%
  \or\LibertineRomanByName{Eleven}%
  \or\LibertineRomanByName{Twelve}%
  \fi
}
\newcommand*\LibertineLCRomanByInt[1]{%
  \ifcase#1%
  \or\LibertineRomanByName{one}%
  \or\LibertineRomanByName{two}%
  \or\LibertineRomanByName{three}%
  \or\LibertineRomanByName{four}%
  \or\LibertineRomanByName{five}%
  \or\LibertineRomanByName{six}%
  \or\LibertineRomanByName{seven}%
  \or\LibertineRomanByName{eight}%
  \or\LibertineRomanByName{nine}%
  \or\LibertineRomanByName{ten}%
  \or\LibertineRomanByName{eleven}%
  \or\LibertineRomanByName{twelve}%
  \fi
}

\newcommand*\lbtRoman[1]{\expandafter\@lbtRoman\csname c@#1\endcsname}
\newcommand*\@lbtRoman[1]{%
  \ifnum#1=0
    0%
  \else
    \ifnum#1<13
      \LibertineUCRomanByInt{#1}%
    \else
      \@Roman{#1}%
    \fi
  \fi
}

\newcommand*\lbtroman[1]{\expandafter\@lbtroman\csname c@#1\endcsname}
\newcommand*\@lbtroman[1]{%
  \ifnum#1=0
    0%
  \else
    \ifnum#1<13
      \LibertineLCRomanByInt{#1}%
    \else
      \@roman{#1}%
    \fi
  \fi
}

\makeatother

\begin{document}

Uppercase: \lbtRoman{section}, lowercase: \lbtroman{section}

\setcounter{section}{7}
Uppercase: \lbtRoman{section}, lowercase: \lbtroman{section}

\setcounter{section}{13}
Uppercase: \lbtRoman{section}, lowercase: \lbtroman{section}

\LibertineUCRomanByInt{1} \LibertineLCRomanByInt{1}\par
\LibertineUCRomanByInt{2} \LibertineLCRomanByInt{2}\par
\LibertineUCRomanByInt{3} \LibertineLCRomanByInt{3}\par
\LibertineUCRomanByInt{4} \LibertineLCRomanByInt{4}\par
\LibertineUCRomanByInt{5} \LibertineLCRomanByInt{5}\par
\LibertineUCRomanByInt{6} \LibertineLCRomanByInt{6}\par
\LibertineUCRomanByInt{7} \LibertineLCRomanByInt{7}\par
\LibertineUCRomanByInt{8} \LibertineLCRomanByInt{8}\par
\LibertineUCRomanByInt{9} \LibertineLCRomanByInt{9}\par
\LibertineUCRomanByInt{10} \LibertineLCRomanByInt{10}\par
\LibertineUCRomanByInt{11} \LibertineLCRomanByInt{11}\par
\LibertineUCRomanByInt{12} \LibertineLCRomanByInt{11}

\setcounter{section}{7}
\renewcommand*\thesection{\lbtRoman{section}}
\section{Let's see: it works!}

\end{document}