Tikz: conditional style depending on width/height of content

Question

I'd like to apply different styles depending on the height/width of the text inside (before applying any style of course):

For now I defined the 3 styles, but I'm not sure how to have access to the node's content (or why not directly to the height/width of the node's content).

MWE

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{backgrounds,positioning}
\usetikzlibrary{shapes,shapes.geometric,shapes.misc}
\begin{document}
\tikzset{
  nodeEmpty/.style={minimum width=.3mm, circle, fill=green},
  nodeSmall/.style={minimum width=.3mm, circle, fill=green!70!black},
  nodeLong/.style={minimum width=1cm, rounded rectangle, fill=green!50!black, inner xsep=3mm},
  nodeAuto/.code={
    %%% Goal: apply automatically the good style depending on the width of the text inside. Something like: if empty, apply nodeEmpty, if height is smaller than 2em and if ratio height/width > 0.5, apply nodeSmall, else apply nodeLong.
    % ???
  }
}
\begin{tikzpicture}
  \node[nodeEmpty] at (0,0) {};
  \node[nodeSmall] at (2,0) {$\frac{\pi}{2}$};
  \node[nodeLong] at (4,0) {$a+b+c+d$};
\end{tikzpicture}
\end{document}

Really? Even with multiple compilations? Too bad :( People manage to do crazy things with tikz, I tought it was possible https://tex.stackexchange.com/questions/107227/dependent-node-size-in-tikz — tobiasBora, Oct 05 '21 at 20:40
The post you're refering to is very interesting and could lead to a solution in your case. We have to study that. Someone would probably come with an answer. — SebGlav, Oct 05 '21 at 21:19

score 2 · Answer 1 · answered Oct 18 '21 at 19:29

As suggested it is possible to define a command for the purpose:

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{backgrounds,positioning}
\usetikzlibrary{shapes,shapes.geometric,shapes.misc,math,calc}
\begin{document}
\tikzset{
  nodeEmpty/.style={minimum width=.3mm, circle, fill=green},
  nodeSmall/.style={minimum width=.3mm, circle, fill=green!70!black},
  nodeLong/.style={minimum width=1cm, rounded rectangle, fill=green!50!black, inner xsep=3mm},
  nodeAuto/.code={
    %%% Goal: apply automatically the good style depending on the width of the text inside. Something like: if empty, apply nodeEmpty, if height is smaller than 2em and if ratio height/width > 0.5, apply nodeSmall, else apply nodeLong.
    % ???
  }
}
\newcommand{\NodeWithVariableStyle}[2]{\tikzmath{ 
        if width("#2") == 0
        then {let \st=nodeEmpty;}
        else {if height("#2") < scalar(2em)&&
            height("#2")/width("#2") > 0.5
            then {let \st=nodeSmall;}
            else {let \st=nodeLong;};
        };
        {
            \node[\st] at #1 {#2}; 
        }; 
}}%\NodeWithVariableStyle{position}{content}
\begin{tikzpicture}
\NodeWithVariableStyle{(0,0)}{}
  \NodeWithVariableStyle{(2,0)}{$\frac{\pi}{2}$}
  \NodeWithVariableStyle{(4,0)}{$a+b+c+d$}
\end{tikzpicture}
\end{document}

Thanks for your answer. I could indeed write a separate command (and it's what I do in practice), but I wanted to use a style also to be compatible with other softwares, like tikzit which only know about styles. Also, creating a new command makes it hard to combine multiple styles. But +1 for the nice usage of tikzmath! — tobiasBora, Oct 22 '21 at 07:34

Tikz: conditional style depending on width/height of content

1 Answers1