Adjust font size on-the-fly

Question

In my document I want to emphasize some key points by placing them in a box with rounded corners. This I do using the following code:

\documentclass{report}
\usepackage{fancybox}

\begin{document}

\ovalbox{
\begin{minipage}[c][.35\textwidth]{.5\textwidth} % [text in box][height][width]
\begin{center}
\begin{minipage}[c]{.9\textwidth}
This text might be too large to fit into the (.35x.50)$\cdot$textwidth box,
in which case the font size should be decreased to make it fit.
\end{minipage}
\end{center}
\end{minipage}
}

\end{document}

The dimensions of the box I would like to have fixed. When the text now becomes too big for the box, can I let LateX notice that and have it adjust the font size such that it does fit?

I was made aware of this fit-text-into-given-box-by-adjusting-the-fontsize question, but have not been able to transform the answer it into a workable solution for me (i.e. getting an \ovalbox around it).

Further have I noticed that paragraphs in the proposed solutions are not indented anymore, how can that be avoided?

Answer 1

\documentclass{report}
\usepackage{lmodern}
\usepackage{fancybox,environ}

\NewEnviron{textinoval}
  {\def\trysize{10.5pt}\def\tryblskip{12.5pt}%
   \retry}
\makeatletter
\def\retry{%
  \ifdim\trysize<5.5pt
    \WARNING\expandafter\@gobble
  \else
    \expandafter\@firstofone
  \fi
  {\edef\trysize{\the\dimexpr\trysize-0.5pt\relax}%
   \edef\tryblskip{\the\dimexpr\tryblskip-0.5pt\relax}%
   \sbox0{\begin{minipage}{.45\textwidth}
   \begingroup\edef\x{\endgroup
     \noexpand\fontsize{\trysize}{\tryblskip}\noexpand\selectfont}\x
   \BODY\end{minipage}}%
  }%
  \dimen0=\dimexpr\ht0+\dp0\relax
  \ifdim\dimen0>.3\textwidth
    \expandafter\retry
  \else
    \expandafter\outputoval
  \fi}
\makeatletter

\def\WARNING{\sbox{0}{WARNING}}

\def\outputoval{\ovalbox{\begin{minipage}[c][.35\textwidth]{.5\textwidth}
  \begin{center}\usebox{0}\end{center}\end{minipage}}}
\begin{document}

\begin{textinoval}
This text might be too large to fit into the (.35x.50)$\cdot$textwidth box,
in which case the font size should be decreased to make it fit.
\end{textinoval}

\begin{textinoval}
This text might be too large to fit into the (.35x.50)$\cdot$textwidth box,
in which case the font size should be decreased to make it fit.
This text might be too large to fit into the (.35x.50)$\cdot$textwidth box,
in which case the font size should be decreased to make it fit.
\end{textinoval}

\begin{textinoval}
This text might be too large to fit into the (.35x.50)$\cdot$textwidth box,
in which case the font size should be decreased to make it fit.
This text might be too large to fit into the (.35x.50)$\cdot$textwidth box,
in which case the font size should be decreased to make it fit.
This text might be too large to fit into the (.35x.50)$\cdot$textwidth box,
in which case the font size should be decreased to make it fit.
\end{textinoval}

\begin{textinoval}
This text might be too large to fit into the (.35x.50)$\cdot$textwidth box,
in which case the font size should be decreased to make it fit.
This text might be too large to fit into the (.35x.50)$\cdot$textwidth box,
in which case the font size should be decreased to make it fit.
This text might be too large to fit into the (.35x.50)$\cdot$textwidth box,
in which case the font size should be decreased to make it fit.
This text might be too large to fit into the (.35x.50)$\cdot$textwidth box,
in which case the font size should be decreased to make it fit.
\end{textinoval}

\end{document}

Here are some explanations. First of all, the \NewEnviron-defined environment gathers its contents. This contents is typeset in a "private" box and if it fits the size requirements it's passed for final typesetting; otherwise we try at a size half a point less and redo until the requirements are respected. One can redefine \WARNING as wished; it will be come into action when the recursion is started and the font is already at 5pt size.

Answer 2

For the general case please see Fit text into given box by adjusting the fontsize. For your specific case you could use the following way, which scales the content if required. I'm not saying that will give nice results in all cases.

Note that the use of minipage modifies the \textwidth so that length can be different at different places. Keep also in mind that later adjustbox keys can effect earlier one because of this:

\documentclass{report}
\usepackage{fancybox}
\usepackage{adjustbox}

\newenvironment{myovalbox}{%
    \noindent
    \adjustbox{minipage=[c]{.45\textwidth},margin=1ex,max totalsize={\textwidth}{.7\textwidth},center=.5\textwidth,
    env={minipage}[c][.35\textwidth]{.5\textwidth},
    precode=\ovalbox}\bgroup
}{%
    \egroup
}

\begin{document}

\begin{myovalbox}
This text is small enough to fit in the box.
\end{myovalbox}

\begin{myovalbox}
This text might be too large to fit into the (.35x.50)$\cdot$textwidth box,
in which case the font size should be decreased to make it fit.
\end{myovalbox}

\begin{myovalbox}
This text might be too large to fit into the (.35x.50)$\cdot$textwidth box,
in which case the font size should be decreased to make it fit.
This text might be too large to fit into the (.35x.50)$\cdot$textwidth box,
in which case the font size should be decreased to make it fit.
\end{myovalbox}

\begin{myovalbox}
This text might be too large to fit into the (.35x.50)$\cdot$textwidth box,
in which case the font size should be decreased to make it fit.
This text might be too large to fit into the (.35x.50)$\cdot$textwidth box,
in which case the font size should be decreased to make it fit.
This text might be too large to fit into the (.35x.50)$\cdot$textwidth box,
in which case the font size should be decreased to make it fit.
\end{myovalbox}

\begin{myovalbox}
This text might be too large to fit into the (.35x.50)$\cdot$textwidth box,
in which case the font size should be decreased to make it fit.
This text might be too large to fit into the (.35x.50)$\cdot$textwidth box,
in which case the font size should be decreased to make it fit.
This text might be too large to fit into the (.35x.50)$\cdot$textwidth box,
in which case the font size should be decreased to make it fit.
This text might be too large to fit into the (.35x.50)$\cdot$textwidth box,
in which case the font size should be decreased to make it fit.
This text might be too large to fit into the (.35x.50)$\cdot$textwidth box,
in which case the font size should be decreased to make it fit.
This text might be too large to fit into the (.35x.50)$\cdot$textwidth box,
in which case the font size should be decreased to make it fit.
\end{myovalbox}

\end{document}