tangle.sty

% *** tangle ***
% A package for drawing string diagrams exported from https://varkor.github.io/tangle.
%
% Version: 1.0.0
% Authors:
% - varkor (https://github.com/varkor)

\NeedsTeXFormat{LaTeX2e}
\ProvidesPackage{tangle}[2022/10/25 tangle]

% `xcolor` is required for `\definecolor`.
\RequirePackage{xcolor}
% `tikz` is necessary to draw string diagrams.
\RequirePackage{tikz}
\usetikzlibrary{calc}
% `etoolbox` is required for `\ifdefequal`.
\RequirePackage{etoolbox}

% An internal command to check whether two colours are equal.
\makeatletter
\newcommand{\tgColourCheck}[3]{%
    \extractcolorspec{#1}{\@spec@A}
    \extractcolorspec{#2}{\@spec@B}
    \ifdefequal{\@spec@A}{\@spec@B}{\renewcommand{#3}{0}}{\renewcommand{#3}{1}}
}
\makeatother

% The `grid` option will draw a grid over every diagram, for debugging purposes.
\newif\ifgrid
\DeclareOption{grid}{\gridtrue}
\ProcessOptions\relax

% \tgColours{colour-list}
\newcounter{tgColourIdx}
\newcommand{\tgColours}[1]{%
    \setcounter{tgColourIdx}{0}
    \renewcommand*{\do}[1]{\definecolor{\tgColour\thetgColourIdx}{HTML}{##1}\stepcounter{tgColourIdx}}
    \docsvlist{#1}
}

% \tgColour{index}
\newcommand{\tgColour}[1]{colour-#1}

% \tgB
% The bleed value to avoid rendering artefacts.
\pgfmathsetmacro{\tgB}{.01}

% Tiles

% \tgBlank{position}{colour}
\newcommand{\tgBlank}[2]{%
    \fill[#2] #1 + (-\tgB,-\tgB) rectangle +(1+\tgB*2,1+\tgB*2);
}

\newcommand{\tgBorderN}{}
\newcommand{\tgBorderE}{}
\newcommand{\tgBorderS}{}
\newcommand{\tgBorderW}{}
% \tgBorderA{position}{colour-NW}{colour-NE}{colour-SE}{colour-SW}
\newcommand{\tgBorderA}[5]{%
    \fill[#2] #1 + (-\tgB,-\tgB) rectangle +(.5+\tgB*2,.5+\tgB*2);
    \fill[#3] ($#1 + (.5-\tgB,-\tgB)$) rectangle +(.5+\tgB*2,.5+\tgB*2);
    \fill[#4] ($#1 + (.5-\tgB,.5-\tgB)$) rectangle +(.5+\tgB*2,.5+\tgB*2);
    \fill[#5] ($#1 + (-\tgB,.5-\tgB)$) rectangle +(.5+\tgB*2,.5+\tgB*2);
    \tgColourCheck{#2}{#3}{\tgBorderN}
    \tgColourCheck{#3}{#4}{\tgBorderE}
    \tgColourCheck{#4}{#5}{\tgBorderS}
    \tgColourCheck{#5}{#2}{\tgBorderW}
    \tgBorder{#1}{\tgBorderN}{\tgBorderE}{\tgBorderS}{\tgBorderW}
}

% \tgBorder{position}{border-N}{border-E}{border-S}{border-W}
\newcommand{\tgBorder}[5]{%
    \ifnum1=0#2\relax \draw ($#1 + (.5,.5)$) -- +(0,-.5-\tgB); \fi
    \ifnum1=0#3\relax \draw ($#1 + (.5,.5)$) -- +(.5+\tgB,0); \fi
    \ifnum1=0#4\relax \draw ($#1 + (.5,.5)$) -- +(0,.5+\tgB); \fi
    \ifnum1=0#5\relax \draw ($#1 + (.5,.5)$) -- +(-.5-\tgB,0); \fi
}

% \tgBorderC{position}{angle}{colour-outer}{colour-inner}
\newcommand{\tgBorderC}[4]{%
    % Reference is SW quadrant of a circle.
    \begin{scope}[shift={($#1 + (.5,.5)$)}, rotate=#2 * 90]
        % Fill outer region, from NW going clockwise.
        \fill[#3] (-.5-\tgB,-.5-\tgB) -- ++(.5+\tgB,0) -- ++(0,\tgB) arc (180:90:.5) -- (.5+\tgB,0) -- ++(0,.5+\tgB) -- ++(-1-\tgB*2,0) -- cycle;
        % Fill inner region, from N going clockwise.
        % We add straight edges at the edges of the arc to account for the bleed.
        \fill[#4] (0,-.5-\tgB) -- ++(0,\tgB) arc (180:90:.5) -- (.5+\tgB,0) -- ++(0,-.5-\tgB) -- cycle;
        \draw (0,-.5-\tgB) -- ++(0,\tgB) arc (180:90:.5) -- (.5+\tgB,0);
    \end{scope}
}

% \tgCell[(width,height)]{position}{text}
\newcommand{\tgCell}[3][(0,0)]{%
    \filldraw[fill=white, rounded corners=.25cm] ($#2 + (.5,.5) - (.25,.25) - .5*#1$) rectangle ($#2 + (.5,.5) + (.25,.25) + .5*#1$);
    \node at ($#2 + (.5,.5)$) {$#3$};
}

% \tgCopy[(width,height)]{position}
\newcommand{\tgCopy}[3][(0,0)]{%
    \filldraw[fill=black] ($#2 + (.5,.5)$) circle (.1);
}

% \tgArrow{position}{angle}
\newcommand{\tgArrow}[2]{%
    \begin{scope}[shift={($#1 + (.5,.5)$)}, rotate=#2 * 90]
        \draw ($({sqrt(2 * .08 ^ 2) / 2}, 0) - (.08,.08)$) -- ++(.08,.08) -- ++(-.08,.08);
    \end{scope}
}

% \tgAxisLabel{position}{anchor}{text}
\newcommand{\tgAxisLabel}[3]{%
    \tgExterior
    \node[anchor=#2, scale=.8] at #1 {$#3$};
}

% trim x [= value], trim y [= value]
\pgfkeys{
    /tangle/.is family, /tangle,
    trim x/.default = .75,
    trim x/.store in = \trimX,
    trim y/.default = .75,
    trim y/.store in = \trimY,
}

\NewDocumentEnvironment{tangle}{mo}{%
    \pgfkeys{/tangle, trim x = 0, trim y = 0}
    \IfValueT{#2}{\pgfkeys{/tangle, #2}}
    \begin{tikzpicture}[baseline={([yshift=-.5ex]current bounding box.center)}, x=1cm, y=-1cm, line width=1]
        \useasboundingbox \IfNoValueTF{#2}{(-.5,-.5)}{($(-.5,-.5) + (\trimX,\trimY)$)} rectangle \IfNoValueTF{#2}{($#1 + (.5,.5)$)}{($#1 + (.5,.5) - (\trimX,\trimY)$)};
        \begin{scope}
        \begin{pgfinterruptboundingbox}
            \clip (\trimX,\trimY) rectangle ($#1 - (\trimX,\trimY)$);
        \end{pgfinterruptboundingbox}
        \gdef\tgExterior{\end{scope}\gdef\tgExterior{}\begin{scope}}
}{%
        \ifgrid
            \draw[xstep=.5,ystep=-.5,lightgray,very thin] (0,0) grid #1;
            \draw[xstep=1,ystep=-1,gray,thin] (0,0) grid #1;
        \fi
    \end{scope}
    \end{tikzpicture}
}

\endinput