Using savebox around the BODY of environ

Question

I tried to use a \savebox around the \BODY macro of \NewEnviron. Can I keep the linebreaks somehow (they are gone, in the MWE)?

\documentclass{article}

\usepackage{environ}

\newsavebox{\mybox}

\NewEnviron{myenv}{%
    \savebox{\mybox}{\BODY}
    \usebox{\mybox}
}

\begin{document}

\begin{myenv}
A

B
\end{myenv}

\end{document}

The problem is probably independent from the environ package but that is what I'm trying to use.

Or: Is there a way to determine the vertical and horizontal size of the \BODY?

Unrelated to the question: you should move \newsavebox{\mybox} outside of the environment's definition (try using the environment twice to see why) — cgnieder, Nov 10 '13 at 16:02
The line breaks are lost because they're converted into spaces (or \par) as part of the tokenization stage. Moreover \savebox typesets its contents in horizontal mode, so you'll get a long line. Maybe you can expand your question telling what's your aim. — egreg, Nov 10 '13 at 16:05
@egreg. I'm trying to determine the vertical and horizontal size of the output of \BODY. \savebox seemed to be the closest to this aim. — masu, Nov 10 '13 at 16:13
There's no "natural" horizontal size: you have to specify what you want or it will be the current \linewidth. — egreg, Nov 10 '13 at 16:15
The adjustbox package should help you here. You need to use the varwidth key to get a variable width. An alternative is to use the lrbox environment with a varwidth environment inside it (needs the varwidth package). — Martin Scharrer, Nov 10 '13 at 16:16
Side note: if you try to use the box outside the environment you'll need to do something else: boxes - Why is a box seemingly emptied after closing an environment - TeX - LaTeX Stack Exchange — user202729, Jun 08 '22 at 12:22

egreg · Accepted Answer · 2013-11-10T16:27:27.333

There's no notion of “natural width” of a text, when paragraphs are being built: TeX will use what you specify or \linewidth in case you don't.

However there's the varwidth environment that can help:

\documentclass{article}
\usepackage{environ,varwidth}

\newsavebox{\mybox}

\NewEnviron{myenv}{%
  \sbox{\mybox}{\begin{varwidth}{\linewidth}\BODY\end{varwidth}}%
  The box is \texttt{\the\wd\mybox} wide
  and \texttt{\the\dimexpr\ht\mybox+\dp\mybox} high.
}

\begin{document}

\begin{myenv}
A

B
\end{myenv}

\end{document}

It depends on you what to do with those dimensions.

enter image description here

Using \NewEnviron is not necessary:

\documentclass{article}
\usepackage{varwidth}

\newsavebox{\mybox}

\newenvironment{myenv}
 {\begin{lrbox}{\mybox}
  \begin{varwidth}{\linewidth}}
 {\end{varwidth}%
  \end{lrbox}%
  The box is \texttt{\the\wd\mybox} wide and
  \texttt{\the\dimexpr\ht\mybox+\dp\mybox} high.
}

\begin{document}

\begin{myenv}
A

B
\end{myenv}

\end{document}

Using savebox around the BODY of environ

1 Answers1

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