TikZ image with overlaid pins

Question

In the below TikZ image I'd like the two pins to not extend the bounding box but still be displayed in their entirety (even if parts of them fall outside the bounding box).

Using the overlay option on either the nodes or the pins themselves (as suggested by percusse in the comments to this answer) unfortunately crops the pins to the bounding box. The same is true if we instead enclose the nodes in a pgfinterruptboundingbox or scope environment (the latter again with option overlay).

\documentclass[tikz]{standalone}

\usetikzlibrary{patterns}

\tikzset{
    cross/.style={path picture={\draw[black]
        (path picture bounding box.south east) -- (path picture bounding box.north west)
        (path picture bounding box.south west) -- (path picture bounding box.north east);}}
}

\begin{document}
\begin{tikzpicture}

    % Loop
    \def\radius{1.5}
    \draw[very thick] (0,0) circle (\radius);
    \draw[fill=white,cross] (0,\radius) circle (0.175*\radius) node[above=5pt] {$\partial_k R_{k,ij}(p_1,p_2)$};
    \node at (-1.35*\radius,0.75*\radius) {$G_{ij}(p_1,p_2)$};
    \node at (1.35*\radius,0.75*\radius) {$G_{jk}(p_2,p_3)$};
    \node[below] at (0,-\radius) {$G_{ef}(p_3,p_4)$};

    % External lines
    \draw (-2*\radius,0) -- (-\radius,0) node[pos=0.4,below] {$\varphi_a$};
    \draw[->,semithick,yshift=5pt,shorten >=5pt,shorten <=5pt] (-2*\radius,0) -- (-1.25*\radius,0) node[midway,above] {$q_1$};
    \draw (\radius,0) -- (2*\radius,0) node[pos=0.6,below] {$\varphi_b$};
    \draw[->,semithick,yshift=5pt,shorten >=5pt,shorten <=5pt] (1.25*\radius,0) -- (2*\radius,0) node[midway,above] {$q_2$};

    % Vertices
    \node[draw,circle,minimum size=16pt,fill=white,postaction={pattern=north east lines},pin={260:$\Gamma_{k,ail}^{(3)}(q_1,\!p_1,\!p_4\!)$}] at (-\radius,0) {};
    \node[draw,circle,minimum size=16pt,fill=white,postaction={pattern=north east lines},pin={280:$\Gamma_{k,bde}^{(3)}(q_2,\!p_3,\!p_4\!)$}] at (\radius,0) {};


\end{tikzpicture}
\end{document}

Answer 1

If pin doesn't produce the result that you want, don't use it and search for alternatives. This is one, two independent nodes for Gamma ... with an smaller font and two lines joining them to circles like pin.

Note: Probably pin can produce a similar results, but I didn't want to consult the documentation right now.

\documentclass[tikz]{standalone}

\usetikzlibrary{patterns}

\tikzset{
    cross/.style={path picture={\draw[black]
        (path picture bounding box.south east) -- (path picture bounding box.north west)
        (path picture bounding box.south west) -- (path picture bounding box.north east);}}
}

\begin{document}
\begin{tikzpicture}

    % Loop
    \def\radius{1.5}
    \draw[very thick] (0,0) circle (\radius);
    \draw[fill=white,cross] (0,\radius) circle (0.175*\radius) node[above=5pt] {$\partial_k R_{k,ij}(p_1,p_2)$};
    \node at (-1.35*\radius,0.75*\radius) {$G_{ij}(p_1,p_2)$};
    \node at (1.35*\radius,0.75*\radius) {$G_{jk}(p_2,p_3)$};
    \node[below] at (0,-\radius) (gef) {$G_{ef}(p_3,p_4)$};

    % External lines
    \draw (-2*\radius,0) coordinate (xl) -- (-\radius,0) node[pos=0.4,below] {$\varphi_a$};
    \draw[->,semithick,yshift=5pt,shorten >=5pt,shorten <=5pt] (-2*\radius,0) -- (-1.25*\radius,0) node[midway,above] {$q_1$};
    \draw (\radius,0) -- (2*\radius,0) coordinate (xr) node[pos=0.6,below] {$\varphi_b$};
    \draw[->,semithick,yshift=5pt,shorten >=5pt,shorten <=5pt] (1.25*\radius,0) -- (2*\radius,0) node[midway,above] {$q_2$};

    % Vertices
    \node[draw,circle,minimum size=16pt,fill=white,postaction={pattern=north east lines}] at (-\radius,0) (cl) {};
    \node[anchor=north east, inner sep=0pt, font=\small] at (-135:\radius) (Gkail) {$\Gamma_{k,ail}^{(3)}(q_1,\!p_1,\!p_4\!)$};
    \draw[thin,gray] (Gkail)--(cl);
    \node[draw,circle,minimum size=16pt,fill=white,postaction={pattern=north east lines}] at (\radius,0) (cr) {};
    \node[anchor=north west, inner sep=0pt, font=\small] at (-45:\radius) (Gkbde) {$\Gamma_{k,bde}^{(3)}(q_2,\!p_3,\!p_4\!)$};
    \draw[thin,gray] (Gkbde)--(cr);

\end{tikzpicture}
\end{document}

Answer 2

This shows how to create a partially overlapped image. The problem with \includestandalone is that you can't pass the \leftoverlap and \rightoverlap values directly. you might write them out and enter them by hand. You could also write them to a file and read them in again.

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

\newlength{\leftoverlap}
\newlength{\rightoverlap}

\tikzset{
    cross/.style={path picture={\draw[black]
        (path picture bounding box.south east) -- (path picture bounding box.north west)
        (path picture bounding box.south west) -- (path picture bounding box.north east);}}
}

\begin{document}

\sbox0{\begin{tikzpicture}
    % Loop
    \def\radius{1.5}
    \draw[very thick] (0,0) circle (\radius);
    \draw[fill=white,cross] (0,\radius) circle (0.175*\radius) node[above=5pt] {$\partial_k R_{k,ij}(p_1,p_2)$};
    \node at (-1.35*\radius,0.75*\radius) {$G_{ij}(p_1,p_2)$};
    \node at (1.35*\radius,0.75*\radius) {$G_{jk}(p_2,p_3)$};
    \node[below] at (0,-\radius) {$G_{ef}(p_3,p_4)$};

    % External lines
    \draw (-2*\radius,0) -- (-\radius,0) node[pos=0.4,below] {$\varphi_a$};
    \draw[->,semithick,yshift=5pt,shorten >=5pt,shorten <=5pt] (-2*\radius,0) -- (-1.25*\radius,0) node[midway,above] {$q_1$};
    \draw (\radius,0) -- (2*\radius,0) node[pos=0.6,below] {$\varphi_b$};
    \draw[->,semithick,yshift=5pt,shorten >=5pt,shorten <=5pt] (1.25*\radius,0) -- (2*\radius,0) node[midway,above] {$q_2$};

    % Vertices
    \node[draw,circle,minimum size=16pt,fill=white,postaction={pattern=north east lines},pin={260:$\Gamma_{k,ail}^{(3)}(q_1,\!p_1,\!p_4\!)$}] at (-\radius,0) {};
    \node[draw,circle,minimum size=16pt,fill=white,postaction={pattern=north east lines},pin={280:$\Gamma_{k,bde}^{(3)}(q_2,\!p_3,\!p_4\!)$}] at (\radius,0) {};

    % compute margins
    \coordinate(A) at (-2*\radius,0);
    \coordinate(B) at (2*\radius,0);
    \pgfextractx{\leftoverlap}{\pgfpointdiff{\pgfpointanchor{current bounding box}{west}}{\pgfpointanchor{A}{center}}}
    \pgfextractx{\rightoverlap}{\pgfpointdiff{\pgfpointanchor{B}{center}}{\pgfpointanchor{current bounding box}{east}}}
    \global\leftoverlap=\leftoverlap
    \global\rightoverlap=\rightoverlap

\end{tikzpicture}}%
\fboxsep=0pt
\fbox{% show minipage border
\begin{minipage}{\dimexpr \wd0-\leftoverlap-\rightoverlap}
\leftskip=-\leftoverlap
\rightskip=-\rightoverlap
\usebox0
\end{minipage}}
\end{document}