Using slanted text (slshape) with newpxtext and tgpagella like with mathpazo (Palatino font packages)

Question

When I use the mathpazo package (Palatino font), the font shapes generated by using the \textit and \textsl commands (or alternatively the \itshape and \slshape commands) look different as intended: The first one produces italic text, the second one produces slanted text.

However, when I use the newpxtext or the tgpagella package (also Palatino font), both \textit and \textsl produce italic text only. You may try this out with the following MWE:

\documentclass{article}

\usepackage{mathpazo}
%\usepackage{newpxtext}
%\usepackage{tgpagella}

\begin{document}
\texttt{itshape}: \textit{The quick brown fox jumps over the sleazy dog.}

\texttt{slshape}: \textsl{The quick brown fox jumps over the sleazy dog.}
\end{document}

By the way: I use MikTeX and pdflatex.

When running this example with tgpagella, a warning shows up, saying that sl is not available and it is used instead:

LaTeX Font Warning: Font shape 'OT1/qpl/m/sl' in size <10> not available (Font) Font shape 'OT1/qpl/m/it' tried instead on input line 10. (taken from the .log file)

However, no warning appears when I use newpxtext. Apparently, sl is just defined to be the same font shape as it for this package.

My question: Is there a way to use the newpxtext package and be able to use actually slanted text? I am particularly interested in using newpxtext instead of the other two packages since I want to use it jointly with the newpxmath package as recommended in many forums.

Answer 1

Here, I redefine \textsl and \slshape to invoke the mathpazo font.

\documentclass{article}

%\usepackage{mathpazo}
%\usepackage{newpxtext}
\usepackage{tgpagella}

\let\svtextsl\textsl
\renewcommand\textsl[1]{\bgroup\fontfamily{ppl}\selectfont\svtextsl{#1}\egroup}
\let\svslshape\slshape
\renewcommand\slshape{\fontfamily{ppl}\selectfont\svslshape}

\begin{document}
\texttt{itshape}: \textit{The quick brown fox jumps over the sleazy dog.}

\texttt{slshape}: \textsl{The quick brown fox jumps over the sleazy dog.}

Normal text and \slshape now in slshape. \upshape Back ``up'' again.
\end{document}

The only pitfall, if you want to call it that, is that if you are operating in this revised \slshape and change the font family, as in \rmfamily, you will return to the italic shape, because (as the OP knows) the slshape is unknown to the default font family, be it nepxtext or tgpagella.

Answer 2

You can substitute the font call for \slshape:

\documentclass{article}

\usepackage{newpxtext}

\makeatletter
\AtBeginDocument{%
  \DeclareFontShape{T1}{zpl\zpl@figurealign\zpl@figurestyle}{m}{sl}{<-> pplro8t}{}%
  \DeclareFontShape{T1}{zpl\zpl@figurealign\zpl@figurestyle}{b}{sl}{<-> pplbo8t}{}%
}
\makeatother

\begin{document}

\texttt{upshape}: \textup{The quick brown fox jumps over the sleazy dog.}

\texttt{itshape}: \textit{The quick brown fox jumps over the sleazy dog.}

\texttt{slshape}: \textsl{The quick brown fox jumps over the sleazy dog.}

\end{document}

Be aware that this will not follow possible choices about oldstyle figures you make when loading newpxtext.

I'd avoid it. I generally agree with Knuth's typographical choices, but definitely not about slanted type that I find essentially indistinguishable from upright type and ugly.