Shrinking text in a node, such that the minimum width and minimum height are the actual width and height of the node

Question

I want to shrink the text in a node such that the minimum height and width are the actual width and height of the node.

I found this Shrinking text to the width of a node within a tikzpicture, but I don't want to first generate the node n in that example.

I need something like:

\begin{tikzpicture} 

    \tikzstyle{D}=[shape=diamond, draw, line width=0.2pt, minimum width=0.8cm,   minimum height=0.8cm,inner sep = 0pt]

      \node [D] (m) {\shrinktofitinnode{AAAAAAAA}{??}...{??};
\end{tikzpicture}

If someone could help me, that would be really good.

Does anyone know a way to calculate the maximal text box that fits into a shape of a certain size?

Answer 1

You can get the value of the minimum width key using \pgfkeysvalueof{/pgf/minimum width} etc. and use it with \resizebox (graphicx package, already loaded by tikz} to resize the content to it. For the diamond shape you might want to reduce the width a little more (e.g. to 90%; for tall texts even down to 50%), otherwise the text will touch the lines.

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{shapes}

\begin{document}

\begin{tikzpicture}[D/.style={shape=diamond, draw, line width=0.2pt, minimum width=0.8cm, minimum height=0.8cm,inner sep=0pt}]

 \node [D] (m) {\setkeys{Gin}{keepaspectratio}\resizebox{\pgfkeysvalueof{/pgf/minimum width}}{\pgfkeysvalueof{/pgf/minimum width}}{AAAAAAAA}};

 \node [D] (k) at (2,0) {\setkeys{Gin}{keepaspectratio}\resizebox{.9\dimexpr\pgfkeysvalueof{/pgf/minimum width}\relax}{.9\dimexpr\pgfkeysvalueof{/pgf/minimum height}\relax}{AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA}};

\end{tikzpicture}

\end{document}

---

You can also use adjustbox for easy further adjustments, e.g. to allow line breaks. The similar TikZ options won't work as normal because \resizebox is used.

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{shapes}

\usepackage{adjustbox}
\begin{document}

\begin{tikzpicture}[D/.style={shape=diamond, draw, line width=0.2pt, minimum width=0.8cm, minimum height=0.8cm,inner sep=0pt}]

 \node [D] (m) {\setkeys{Gin}{keepaspectratio}\resizebox{\pgfkeysvalueof{/pgf/minimum width}}{\pgfkeysvalueof{/pgf/minimum width}}{AAAAAAAA}};

 \node [D] (k) at (2,0) {\adjustbox{varwidth={5cm}\centering,keepaspectratio,width=.9\dimexpr\pgfkeysvalueof{/pgf/minimum width}\relax,height=.9\dimexpr\pgfkeysvalueof{/pgf/minimum height}\relax}{AAAAAAAAAAAAAA\\BBBBBBBBBBBB\\CCCCCCCCC}};

\end{tikzpicture}

\end{document}

---

Finally there is the min size key of \adjustbox which will scale the content down only if required (i.e. it is too large), but keep it the original size otherwise. You might want to define a shortcut macro if you need this more often.

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{shapes}

\usepackage{adjustbox}

\newcommand{\adjsizetonode}{%
  \adjustbox{varwidth={5cm}\centering,keepaspectratio,max size={.9\dimexpr\pgfkeysvalueof{/pgf/minimum width}\relax}{.9\dimexpr\pgfkeysvalueof{/pgf/minimum height}\relax}}%
}
\begin{document}

\begin{tikzpicture}[D/.style={shape=diamond, draw, line width=0.2pt, minimum width=0.8cm, minimum height=0.8cm,inner sep=0pt}]

 \node [D] (A)  at (0,0) {a};
 \node [D] (A2) at (1,0) {\adjsizetonode{a}};
 \node [D] (B)  at (2,0) {\adjsizetonode{BBBBBBBBBBBBBBBBBB}};
 \node [D] (B)  at (3,0) {\adjsizetonode{BBBBBBBBBBBBBBBBBB\\bbbbbbbbbbbbb bbbbbbbb bbbb bbbb\\Bb bbfd  kslkgldf }};

\end{tikzpicture}

\end{document}