Increasing the size of a minipage proportional to the contain

Question

I am trying to create a simple environment. The enviroment contains a minipage that is surrounded but a dashed box.

\NewEnviron{Notes}{
  \par
  \begin{tikzpicture}
    \node[rectangle,minimum width=0.95\textwidth] (m) {
      \begin{minipage} {0.75\textwidth}     
        \color{red}\BODY
      \end{minipage}
    };
    \draw[dashed] (m.south west) rectangle (m.north east);
  \end{tikzpicture}\\
}

Essentially, I would like to increase the size of the box proportional to its contain. So, something like: \vspace{0.2*\BODYHeight}

What's the best way of doing this?

Answer 1

What you can do is to enclose the \BODY with the necessary spacing. Here is a MWE.

\documentclass{article}
\usepackage{environ}
\usepackage{tikz}
\usepackage{lipsum}
\begin{document}
\NewEnviron{Notes}{
  \par
  \begin{tikzpicture}
    \node[rectangle,minimum width=0.95\textwidth] (m) {
      \begin{minipage} {0.75\textwidth}     
        \vspace*{0.1\textwidth}
        \color{red}\BODY
        \vspace{0.1\textwidth}
      \end{minipage}
    };
    \draw[dashed] (m.south west) rectangle (m.north east);
  \end{tikzpicture}\\
}

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

A better approach is to rather use a fixed amount of padding:

\documentclass{article}
\usepackage{environ}
\usepackage{tikz}
\usepackage{lipsum}
\begin{document}
\NewEnviron{Notes}{
  \par
  \begin{tikzpicture}
    \node[rectangle,minimum width=0.5\textwidth] (m) {
      \fbox{\begin{minipage} {0.5\textwidth}     
           \color{red}\BODY
       \end{minipage}}
    };
    \draw[dashed] (m.south west) rectangle (m.north east);
  \end{tikzpicture}\\
}

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

if you add \fboxsep0pt, the inner rule will not be shown. Padding can be increased using a suitable value of \fboxsep. I think this is a much better solution in terms of typography and scales well. Non-linear scaling of the vertical spacing is also possible and one could employ a technique I first encountered in amsgen, latex amsgen.dtx and look up the definition of \compute@ex@. The difficulty is to find an acceptable formula to describe the aesthetics of such spacing. The formula should include for such variables as textwidth, height, font-size and the relationships to the rest of the text.

Answer 2

Not exactly proportional because eI added 2pt to avoid very small values . It's possible to change .05\htbox with .1\htbox but now the problem comes from big values.

\documentclass{article}
\usepackage{environ}
\usepackage{tikz}
\usepackage{lipsum}
\begin{document} 

\newbox\mybox 
\newdimen\htbox
\newdimen\innersep   
\NewEnviron{Notes}{%
 \setbox\mybox=\vbox{%
 \begin{minipage} {0.75\textwidth}     
   \color{red}\BODY
 \end{minipage}}% 
 \htbox\ht\mybox
 \advance\htbox by \dp\mybox
 \innersep=.05\htbox
 \advance\innersep by 2pt  
\par
\begin{tikzpicture}
\node[draw,inner sep=\innersep,rectangle,
      text width=0.95\textwidth-2\innersep] (m) {\unvcopy\mybox}; 
\end{tikzpicture}\\
}

\begin{Notes}
Texte
\end{Notes}

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

\end{document}