Is there a TikZ equivalent to the PSTricks \ncdiag command?

Question

The pst-node package provides the \ncdiag command, which allows you to connect two nodes with a diagonal line, but with an extra arm parameter which puts a bend in the line and allows the connections at each end to meet the node perpendicularly. Is there a simple way to get this effect in TikZ?

Here's an example (compile with latex or xelatex).

\documentclass{article}
\usepackage{tikz}
\usepackage{pst-node}
\begin{document}

\rput(0,3){\rnode{A}{Foo}}
\rput(2,0){\rnode{B}{Bar}}
\ncdiag[angleA=-90,angleB=90,arm=5mm]{A}{B}
\hspace{2in}
\begin{tikzpicture}
\node at (0,0) (A) {Bar};
\node at (-2,3) (B) {Foo};
\draw[thick] (A) -- (B);
\end{tikzpicture}
\end{document}

Answer 1

Here's my first shot. I do it using a to path, which allows me to replace a path by something else. The first bit of the arm is easy enough, but the second needs the calc library. Also, when applied to nodes then the arm length is relative to the centre of the node, not the length of path that is actually drawn.

Code:

\documentclass{article}
%\url{http://tex.stackexchange.com/q/25474/86}
\usepackage{tikz}
\usetikzlibrary{calc}
\usepackage{pst-node}

\tikzset{
  arm angleA/.initial={0},
  arm angleB/.initial={0},
  arm length/.initial={0mm},
  arm/.style={
    to path={%
      (\tikztostart) -- ++(\pgfkeysvalueof{/tikz/arm
         angleA}:\pgfkeysvalueof{/tikz/arm length}) -- ($(\tikztotarget)+
         (\pgfkeysvalueof{/tikz/arm angleB}:\pgfkeysvalueof{/tikz/arm length})$)
          -- (\tikztotarget)
    }
  },
}

\begin{document}

\rput(0,3){\rnode{A}{Foo}}
\rput(2,0){\rnode{B}{Bar}}
\ncdiag[angleA=-90,angleB=90,arm=5mm]{A}{B}
\hspace{2in}
\begin{tikzpicture}
\node at (0,3) (A) {Foo};
\node at (2,0) (B) {Bar};
\draw[thick] (A) to[arm, arm angleA=-90,arm angleB=90,arm length=5mm] (B);
\end{tikzpicture}
\end{document}

(Note: I changed the node positions in the TikZ one to match the PSTricks specification.)

Picture, PSTricks on left, TikZ on right:

Answer 2

It needs further adjustments but I think this is also a valid yet quick and dirty solution. It can be embedded in a short function.

Also a minor detail about the positioning of the node : you might want to anchor the matrices because the absolute positioning of the text is not exactly aligned to the coordinates where I declare.

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{matrix}
\begin{document}
\begin{tikzpicture}

\matrix[matrix of nodes,row sep = 2mm] (B) at (2,0) 
{
\node[inner sep=1mm] {}; \\
\node {Bar}; \\
};

\matrix[matrix of nodes,row sep = 2mm] (F) at (0,3) 
{
\node {Foo}; \\
\node[inner sep=1mm] {}; \\
};

\draw (B-2-1) -- (B-1-1.north) -- (F-2-1.south) -- (F-1-1.south);
\end{tikzpicture}
\end{document}

You can play with the row sep to extend or shorten the arms.

Cheers,