Label TikZ spath3 components by their number

spath3-number-components.png

spath3-number-components.tex

\documentclass{standalone}
\usepackage{tikz}
\usetikzlibrary{intersections}
\usetikzlibrary{spath3}

\tikzset{
    every spath component/.style={draw,->,thick,green},
    every spath component label/.style={every spath component,draw=none,fill=white, fill opacity=1, circle,text opacity=1,
      node contents={\spathname\spathcomponentnumber}
    },
    spath/label components/.code={
        \tikzset{
          spath/get components of={#1}\cpts}
        \def\spathname{#1}
        \foreach[count=\spathcomponentnumber] \cpt in \cpts {
            \node[at={(spath cs:{\cpt} .5)},
                every spath component label];
            }
        },
    spath/render components with labels/.style={
        render components={#1},
        label components={#1}
    }
}
\begin{document}
\begin{tikzpicture}
    \draw[spath/save=A] circle(2cm);
    \draw[spath/save=B] ellipse(3cm and 1cm);
    \tikzset{
        spath/.cd,
        split at intersections={A}{B},
        label components=A,
        /tikz/every spath component/.append style={red},
        render components with labels=B,
    }
\end{tikzpicture}
\end{document}