Colored background with rounded corners for a text fragment preventing an overflow over the end of line

Question

I have already found some similar solutions, but I was not able to adapt them to my requirements:

• A text fragment (e.g., source code) surrounded by other text should be highlighted with a background color. The background should have slightly rounded corners. A border for the background is nice to have, but not required.
• We can assume, that the text fragment is never longer than a complete line. However, it might happen, that the text fragment does not fit in the remaining width of the current line. I hoped to find one of these solutions for the problem:
  1. As usual text the not fitting part of the text fragment is wrapped to the next line (desired output example: as in the 1st image below, but with rounded corners).
  2. LaTeX determines that the text fragment does not fit in the current line and automatically places the whole text fragment in the next line. Does not look so nice, because it is not perfectly justified anymore, but it is OK. (desired output example: as in the 2nd image below, but with rounded corners).

Related solutions:

• Line breaking, but no rounded corners: https://tex.stackexchange.com/a/6029/61241
• Rounded corners, but no line breaking: https://tex.stackexchange.com/a/36404/61241
• Force complete text fragment to the next line if it does not fit in the current line: https://tex.stackexchange.com/a/62347/61241

Using the suggestions from the 1st link (via soul or via the complex solution) I can get this output. It is almost perfect, but has no rounded corners. This question tells me that it is probably not possible using soul. Any way to modify the other solution?

Combining soul with the solution from the 3rd link works, but without rounded corners, either (\lword is defined in the 3rd link):

\newcommand{\inlinecode}[1]{{\lword{\sethlcolor{veryLightGray}\hl{\small\ttfamily#1}}}}

Answer 1

Here's an answer that gives oval highlighting with linebreaking by combining the rounded corners code and the soul linebreaking.

Edit: Added logic to not round the highlight around linebreaks.

\documentclass{article}
\parindent0pt
\usepackage{fullpage}
\usepackage{tikz}
\usepackage{soul}
\usepackage{tikz}
\usetikzlibrary{calc}
\usetikzlibrary{shapes.misc}
\usetikzlibrary{fit}

\makeatletter
\newbox\mybox
\newcount\test
\test0
\newcommand{\defhighlighter}[3][]{%
    \tikzset{every highlighter/.style={color=#2, fill opacity=#3, #1}}%
}

\defhighlighter[font=\ttfamily]{blue!20}{.3}

\newcommand{\highlight@DoHighlight}[1]{
    \node[outer sep = -13pt, inner sep = 0pt,
        fit=(begin highlight) (end highlight),
        every highlighter, this highlighter,
        rounded rectangle,#1,
        fill
    ]{} ;
}

\newcommand{\highlight@BeginHighlight}[1]{
  \coordinate[yshift=-\dp\mybox-1pt,#1] (begin highlight) at (0,0) ;
}

\newcommand{\highlight@EndHighlight}[1]{
  \coordinate[yshift=\ht\mybox+1pt,#1 ] (end highlight) at (0,0) ;
}

\newdimen\highlight@previous
\newdimen\highlight@current

\DeclareRobustCommand*\highlight[2][]{%
  \setbox\mybox\hbox{#2}
  \tikzset{this highlighter/.style={#1}}%
  \SOUL@setup
  %
  \gdef\ht@possiblenoleftround{}
  \def\SOUL@preamble{%
    \begin{tikzpicture}[overlay, remember picture]
      \highlight@BeginHighlight{xshift=3pt}
      \highlight@EndHighlight{xshift=-3pt}
    \end{tikzpicture}%
  }%
  %
  \def\SOUL@postamble{%
    \begin{tikzpicture}[overlay, remember picture]
      \highlight@EndHighlight{xshift=-3pt}
      \expandafter\highlight@DoHighlight\expandafter{\ht@possiblenoleftround}
    \end{tikzpicture}%
  }%
  %
  \def\SOUL@everyhyphen{%
    \discretionary{%
      \SOUL@setkern\SOUL@hyphkern
      \SOUL@sethyphenchar
      \tikz[overlay, remember picture] \highlight@EndHighlight{} ;%
    }{%
    }{%
      \SOUL@setkern\SOUL@charkern
    }%
  }%
  %
  \def\SOUL@everyexhyphen##1{%
    \SOUL@setkern\SOUL@hyphkern
    \hbox{##1}%
    \discretionary{%
      \tikz[overlay, remember picture] \highlight@EndHighlight{} ;%
    }{%
    }{%
      \SOUL@setkern\SOUL@charkern
    }%
  }%
  %
  \def\SOUL@everysyllable{%
    \begin{tikzpicture}[overlay, remember picture]
      \path let \p0 = (begin highlight), \p1 = (0,0) in \pgfextra
        \global\highlight@previous=\y0
        \global\highlight@current =\y1
      \endpgfextra (0,0) ;
      \ifdim\highlight@current < \highlight@previous
        \expandafter\highlight@DoHighlight\expandafter{\ht@possiblenoleftround,rounded rectangle right arc=none}
        \gdef\ht@possiblenoleftround{rounded rectangle left arc=none}
        \highlight@BeginHighlight{}
      \fi
    \end{tikzpicture}%
    \ttfamily \the\SOUL@syllable
    \tikz[overlay, remember picture] \highlight@EndHighlight{} ;%
  }%
  \SOUL@{#2}
}

\begin{document}
as suggested in a comment, justifies the text within the environment. this would work if there are more ordinary words than long ones, and the long ones don't occur in inconvenient locations within the lines. a test with the affected material, \highlight{trying both techniques side by side, will quickly make it clear which is preferable in a given situation.}s


this is some text \highlight{var files = Directory.EnumerateFiles(myDirectory,''*.txt*);} text
this is some text box text this is some text this is some text texttext \highlight{var files = Directory.EnumerateFiles(myDirectory, ''*.txt*);} hello
\end{document} 

Answer 2

Here is a straight forward combination of David Carlisle's linebreaking code and the rounded corners macro:

\documentclass{article}
\parindent0pt
\usepackage{fullpage}
\usepackage{tikz}

\newenvironment{foo}
{\par
\hyphenpenalty=10000
\exhyphenpenalty=10000
}
{\par}

\newcommand\lword[1]{\leavevmode\nobreak\hskip0pt plus\linewidth\penalty50\hskip0pt plus-\linewidth\nobreak #1}
\newcommand\inlinecode[2][]{\lword{\tikz[overlay]\node[fill=blue!20,inner sep=1pt, anchor=text, rectangle, rounded corners=1mm,#1] {\ttfamily #2};\phantom{\ttfamily #2}}}
\begin{document}
\begin{foo}
this is some text \inlinecode{var files = Directory.EnumerateFiles(myDirectory,''*.txt*);} 
text as suggested in a comment, justifies the text within the environment. this would work 
if there are more ordinary words than long ones, and the long ones don't occur in 
inconvenient locations within the lines. a test with the affected material, 
\inlinecode{trying both techniques side by side, will quickly} make it clear which is 
preferable in a given situation.s
this is some text box text this is some text this is some text texttext 
\inlinecode{var files = Directory.EnumerateFiles(myDirectory, ''*.txt*);} hello
\end{foo}
\end{document}