mdframed digressionarrows style with custom header

Question

Using the mdframed package, I've been trying to figure out how to add an option for changing the header in their digression-environment (example 6 here: http://cloud.github.com/downloads/marcodaniel/mdframed/mdframed-example-texsx.pdf).

I imagine using the package like this

\begin{mdframed}[style=digressionarrows]{Header of the environment}

Does anyone know how customize the digressionarrows style to allow that?

Answer 1

Instead of redefining the environment mdframed I suggest the following.

The definition of a new key is very simple. So I recommend the definition of a new key e.g. digressiontitle This can be done by:

\mdf@do@stringoption{digressiontitle=={Digression}}

whereby the word Digression is the default value. You can change it.

The value of this option is saved in the macro \mdf@digressiontitle and can be used inside the definition of the style. This is done in the example.

In the next step I suggest the using of \newmdenv with a specific digressiontitle. (For more information about the command \newmdenv see the documentation.

So you can write:

\newmdenv[style=digressionarrows,digressiontitle=Info]{info}
\newmdenv[style=digressionarrows,digressiontitle=Side note]{sidenote}

And use:

\begin{info}
\lipsum[1]
\end{info}

\begin{sidenote}
\lipsum[1]
\end{sidenote}

which leads to the following output:

\documentclass{article}
\usepackage[framemethod=tikz]{mdframed}
\usetikzlibrary{calc,arrows}
\makeatletter
\mdf@do@stringoption{digressiontitle=={Digression}}
\tikzset{
  excursus arrow/.style={%
       line width=2pt,
      draw=gray!40,
      rounded corners=2ex,
      },
   excursus head/.style={
      fill=white,
      font=\bfseries\sffamily,
      text=gray!80,
      anchor=base west,
  },
}
\mdfdefinestyle{digressionarrows}{%
   singleextra={%
            \path let \p1=(P), \p2=(O) in (\x2,\y1) coordinate (Q);
            \path let \p1=(Q), \p2=(O) in (\x1,{(\y1-\y2)/2}) coordinate (M);
            \path [excursus arrow, round cap-to]
                        ($(O)+(5em,0ex)$) -| (M) |- %
                        ($(Q)+(12em,0ex)$) .. controls +(0:16em) and +(185:6em) .. %
                        ++(23em,2ex);
            \node [excursus head] at ($(Q)+(2.5em,-0.75pt)$) {\mdf@digressiontitle};},
   firstextra={%
            \path let \p1=(P), \p2=(O) in (\x2,\y1) coordinate (Q);
            \path [excursus arrow,-to] (O) |- %
                        ($(Q)+(12em,0ex)$) .. controls +(0:16em) and +(185:6em) .. %
                        ++(23em,2ex);
            \node [excursus head] at ($(Q)+(2.5em,-2pt)$) {\mdf@digressiontitle};},
   secondextra={%
            \path let \p1=(P), \p2=(O) in (\x2,\y1) coordinate (Q);
            \path [excursus arrow,round cap-]($(O)+(5em,0ex)$) -| (Q);},
   middleextra={%
            \path let \p1=(P), \p2=(O) in (\x2,\y1) coordinate (Q);
            \path [excursus arrow](O) -- (Q);},
   middlelinewidth=2.5em,middlelinecolor=white,
   hidealllines=true,topline=true,
   innertopmargin=0.5ex,
   innerbottommargin=2.5ex,
   innerrightmargin=2pt,
   innerleftmargin=2ex,
   skipabove=0.87\baselineskip,
   skipbelow=0.62\baselineskip,
}
\makeatother

\newmdenv[style=digressionarrows,digressiontitle=Info]{info}
\newmdenv[style=digressionarrows,digressiontitle=Side note]{sidenote}

\usepackage{lipsum}
\begin{document}

\begin{info}
\lipsum[1]
\end{info}

\begin{sidenote}
\lipsum[1]
\end{sidenote}
\end{document}