blag/templates/tikz.tex

\documentclass{article}
\usepackage[pdftex,active,tightpage]{preview}
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{mathrsfs}
\usepackage{tikz}
\usetikzlibrary{matrix}
\usetikzlibrary{calc}
\usetikzlibrary{fit}
\usetikzlibrary{arrows}
\usetikzlibrary{arrows.meta}
\usetikzlibrary{decorations.pathreplacing}
\usepackage{xcolor}
\definecolor{red}{RGB}{235, 77, 75}
\definecolor{blue}{RGB}{9, 123, 227}

\tikzset{
    ncbar angle/.initial=90,
    ncbar/.style={
        to path=(\tikztostart)
        -- ($$(\tikztostart)!#1!\pgfkeysvalueof{/tikz/ncbar angle}:(\tikztotarget)$$)
        -- ($$(\tikztotarget)!($$(\tikztostart)!#1!\pgfkeysvalueof{/tikz/ncbar angle}:(\tikztotarget)$$)!\pgfkeysvalueof{/tikz/ncbar angle}:(\tikztostart)$$)
        -- (\tikztotarget)
    },
    ncbar/.default=0.5cm,
}

\tikzset{square left brace/.style={ncbar=0.5cm}}
\tikzset{square right brace/.style={ncbar=-0.5cm}}

\tikzset{round left paren/.style={ncbar=0.5cm,out=120,in=-120}}
\tikzset{round right paren/.style={ncbar=0.5cm,out=60,in=-60}}

\begin{document}
\begin{preview}
  \begin{tikzpicture}[auto]
    $body$
  \end{tikzpicture}
\end{preview}
\end{document}