Make `\emph`ed letters bold italic when they are in `\textbf`

boldemphasisfontspecitalicxetex

I have some emphasised letters in \textbf{}, i.e. \textbf{\emph{abc}}, to bold-italicise the letters. However, the text merely comes to be italic, not bold italic. How can I redefine \emph to get bold italic letters when I have to use \emph in \textbf{}?

I also have to use XeLaTeX and fontspec.

MWE

\documentclass[
  a4paper]{article}
\usepackage{fontspec}
\setmainfont[Scale = MatchUppercase,BoldFont = Libertinus Sans Bold]{Libertinus Serif}
\setsansfont[Scale = MatchUppercase,BoldFont = LinBiolinum_RB.otf,ItalicFont = LinBiolinum_RI.otf,BoldItalicFont = LinBiolinum_RBO.otf]{LinBiolinum_R.otf}

\begin{document}

I want to make \textbf{\emph{abc}} bold italic,
like 
{\sffamily\bfseries\emph{abc}}.

\end{document}

Output of the MWE in my environment

Best Answer

The example from the question works as-is for me with LuaLaTeX, but throws an error with XeLaTeX (dvipdfmx:fatal: Invalid font: -1 (1)).

In my experience loading files with file names instead of font names is usually much more reliable.

So if we replicate what you already did for Biolinum in \setsansfont also for Libertinus in \setmainfont we end up with

\documentclass[a4paper]{article}
\usepackage{fontspec}
\setmainfont[
  Scale = MatchUppercase,
  BoldFont = LibertinusSerif-Bold.otf,
  ItalicFont = LibertinusSerif-Italic.otf,
  BoldItalicFont = LibertinusSerif-BoldItalic.otf,
]{LibertinusSerif-Regular.otf}
\setsansfont[
  Scale = MatchUppercase,
  BoldFont = LinBiolinum_RB.otf,
  ItalicFont = LinBiolinum_RI.otf,
  BoldItalicFont = LinBiolinum_RBO.otf,
]{LinBiolinum_R.otf}

\begin{document}

I want to make \textbf{\emph{abc}} \textbf{bold} \textit{italic},
like
{\sffamily\bfseries\emph{abc}}.

\end{document}

which works fine with XeLaTeX and LuaLaTeX

Related Solutions

[Tex/LaTex] Redefine \emph to be both bold and italic

Rather than redefining \emph in terms of a copy of itself, it's better redefining it from scratch, using the standard definition as model; the standard definition is surprisingly simple:

% latex.ltx, line 3744:
\DeclareTextFontCommand{\emph}{\em}

because it's \em that does the hard work. So we can simply do

\documentclass[11pt]{article}

\let\emph\relax % there's no \RedeclareTextFontCommand
\DeclareTextFontCommand{\emph}{\bfseries\em}

\begin{document}

Here is \emph{emphasized text with something \emph{emphasized} inside}

\end{document}

enter image description here

However, double emphasis is really too much: italic is sufficiently prominent. The advantage of redefining \emph in this way is that you can simply comment out those two lines and return to the default.

Why doesn't your idea work? Because with those definitions, when TeX finds

\emph{text}

it changes it into

\bfemph{text}

and this becomes

\textbf{\emph{text}}

that in turn becomes

{<expansion of \textbf>\emph{text}}

…

Sorry, infinite loop: \emph will restart the machinery.

[Tex/LaTex] How to make a bold and Italic uppercase Greek letter

Do you perhaps want the \varOmega in bold?

\documentclass{article}
\usepackage{mathtools}
\usepackage{bm}

\begin{document}

  $\bm{\varOmega}$

\end{document}

Note that in the following code

$\mathit {\boldmath $\Omega$}$

the first $ switches into maths mode (assuming we were not already typesetting maths) and the second $ switches out of maths mode. Then the next switches into it and the last switches out of it.

This means that \boldmath occurs in maths mode, causing an error, and \Omega occurs outside maths mode, causing another (except that TeX is quite confused by this point).

Compare (simplifying by dropping the italics):

$\Omega$ \boldmath $\Omega$

which produces:

Note that here the \Omegas are in maths mode, while the \boldmath is outside it.

MWE

Output of the MWE in my environment

Best Answer

Related Solutions

[Tex/LaTex] Redefine \emph to be both bold and italic

[Tex/LaTex] How to make a bold and Italic uppercase Greek letter

Related Question