[Tex/LaTex] Boxed text inside tcolorbox tcblisting

Question

I am writing a text which includes lots of programming snippets which I've put into environments which use tcolorbox/tcblisting:

\usepackage[pdftex]{xcolor}
\definecolor{vlgray}{gray}{0.9}
\definecolor{lgray}{gray}{0.7}

\usepackage{tcolorbox,fancyvrb}
\tcbuselibrary{skins,breakable,listings,breakable}

\newenvironment{shk}{%
  \tcblisting{listing only,colback=vlgray,colframe=vlgray,enlarge
  top by=0mm,top=-2mm,bottom=2mm,enhanced,
  after={\par\vspace{0.5\baselineskip}\noindent},
  overlay={\node[draw,fill= black,yshift=4pt,xshift=-10pt,left,text=white,
         anchor=east,font=\footnotesize\bfseries] at (frame.south east)
         {Shakespeare};}, 
  listing options={basicstyle=\small\ttfamily,breaklines=true,
    language=HTML},}}
{\endtcblisting}

This means that in my document:

\begin{shk}
Now is the winter of our discontent
Made glorious summer by this sun of York;
\end{shk}

looks like this:

which is exactly what I want.

However! Suppose I want to box one word, say "winter", in my listing. How do I do that? I can't merely write \fbox{winter} as that will simply be listed, rather than escaped to LaTeX. The mathescape option of the listings package doesn't seem to work in tcblisting.

I know I could use tikzpicture with [remember picture,overlay] to position a box on the page, but that seems a little inelegant… is there a way of boxing text within tcblisting itself?

Answer 1

I don't know about mathescape, but presumably you don't want/need to enter math mode anyway, since you just want to make a box.

So use escapechar=<char> instead. I've turned your code snippets into an MWE to more clearly show the solution, but the same escapechar=| (or some other character not used anywhere in the listing) is equally valid inside listing options in your environment's definition.

\documentclass{article}

\usepackage{tcolorbox}
\tcbuselibrary{listings}

\begin{document}
\begin{tcblisting}{listing only,listing options={basicstyle=\ttfamily,escapechar=|}}
Now is the |\fbox{winter}| of our discontent
Made glorious summer by this sun of York;
\end{tcblisting}
\end{document}

Here's the full code made into a compilable example:

\documentclass[11pt]{article}

\usepackage[pdftex]{xcolor}
\definecolor{vlgray}{gray}{0.9}
\definecolor{lgray}{gray}{0.7}

\usepackage{tcolorbox}
\tcbuselibrary{skins,breakable,listings}

\newenvironment{shk}{%
  \tcblisting{listing only,colback=vlgray,colframe=vlgray,enlarge
  top by=0mm,top=-2mm,bottom=2mm,enhanced,
  after={\par\vspace{0.5\baselineskip}\noindent},
  overlay={\node[draw,fill= black,yshift=4pt,xshift=-10pt,left,text=white,
         anchor=east,font=\footnotesize\bfseries] at (frame.south east)
         {Shakespeare};}, 
  listing options={basicstyle=\small\ttfamily,breaklines=true,
    language=HTML,escapechar=|},}}
{\endtcblisting}


\begin{document}
\begin{shk}
Now is the |\fbox{winter}| of our discontent
Made glorious summer by this sun of York;
\end{shk}
\end{document}