Placing anchor before and after text in multipart rectangle

Question

In the following graph, i would like the arrows to be originated inside the box and not in the border, possibly aligned and next to the text (for example, right after the word "Pointer:".

Here is the code i used:

\usetikzlibrary{shapes.multipart,arrows}
\newcommand{\npd}{\nodepart{two}}
\newcommand{\npt}{\nodepart{three}}
\newcommand{\npq}{\nodepart{four}}
\newcommand{\npc}{\nodepart{five}}

\tikzstyle{fnode}=[rectangle split, rectangle split part align={left,left,left,center,left}, rectangle split parts=5, draw, minimum width =2.75cm, rounded corners]

\begin{tikzpicture}
  \node[fnode] (r1) at (0,0) {Pointer:  \npd Key \npt Text text \npq Pointers \npc text};
  \draw [*->] (r1.one east) to (-2,2);
  \draw [*->] (r1.four east) to (3,0);
  \draw [*->] (r1.four west) to (-3,0);
\end{tikzpicture}

I would also like (if possible) to use a syntax similar to the anchor one. There are no predefined anchors to do this in the manual. What is the easiest way to achive this result?

Answer 1

Here is a possible solution.

You should specify an anchormark on the left or on the right of your pointer by means of \anchormark; its definition is:

\NewDocumentCommand{\anchormark}{O{0.15 cm} m O{0.05}}{%
        \tikz[overlay,remember picture,baseline=-0.5ex,xshift=#1] \node[draw,fill=black,circle,scale=#3] (#2) {};
}

Each anchormark should be uniquely identified (the mandatory argument of the command) and could be shifted (the first argument, optional, of the command) or the circle could be scaled (the third argument, optional again, of the command).

Notice that with this kind of approach you should logically divide the moment in which you deploy the fnode and the markers and the moment in which you create the connections. You should also compile twice.

The complete example:

\documentclass{article}
\usepackage{xparse}
\usepackage{tikz}

\usetikzlibrary{shapes.multipart,arrows}
\newcommand{\npd}{\nodepart{two}}
\newcommand{\npt}{\nodepart{three}}
\newcommand{\npq}{\nodepart{four}}
\newcommand{\npc}{\nodepart{five}}

\NewDocumentCommand{\anchormark}{O{0.15 cm} m O{0.05}}{%
        \tikz[overlay,remember picture,baseline=-0.5ex,xshift=#1] \node[draw,fill=black,circle,scale=#3] (#2) {};
}

\tikzset{fnode/.style={rectangle split, rectangle split part align={left,left,left,center,left}, rectangle split parts=5, draw, minimum width =2.75cm, rounded corners}}

\tikzset{label style/.style={draw, rounded corners}}

\begin{document}
% node deployment
\begin{tikzpicture}
  \node[fnode] (r1) at (0,0) {Pointer:\anchormark{first pointer}[0.075]  \npd Key  \npt Text text \npq \anchormark[-0.15cm]{pointer left}Pointers \anchormark{pointer right}\npc text};  
\end{tikzpicture}
% connection deployment
 \begin{tikzpicture}[remember picture,overlay,-stealth] 
  \draw (first pointer.center) to (2,2.75) node[right,label style]{label};
  \draw (pointer right.center) to (2,1) node[right,label style]{label};
  \draw (pointer left.center) to (-5,1)node[left,label style]{label};
\end{tikzpicture}

\end{document}

The result:

---

This advanced example shows how to deal with more modules. As said in the comment, by adding a [remember picture] to the tikzpicture where the nodes are deployed, in the connection phase it is possible to access their anchors. Another feature of the example is the use of the calc library to avoid absolute positioning in the connection phase.

\documentclass{article}
\usepackage{xparse}
\usepackage{tikz}

\usetikzlibrary{shapes.multipart,arrows,calc}
\newcommand{\npd}{\nodepart{two}}
\newcommand{\npt}{\nodepart{three}}
\newcommand{\npq}{\nodepart{four}}
\newcommand{\npc}{\nodepart{five}}

\NewDocumentCommand{\anchormark}{O{0.15 cm} m O{0.05}}{%
        \tikz[overlay,remember picture,baseline=-0.5ex,xshift=#1] \node[draw,fill=black,circle,scale=#3] (#2) {};
}

\tikzset{fnode/.style={rectangle split, rectangle split part align={left,left,left,center,left}, rectangle split parts=5, draw, minimum width =2.75cm, rounded corners}}

\tikzset{label style/.style={draw, rounded corners}}

\begin{document}
\begin{tikzpicture}[remember picture]
  \node[fnode] (r1) at (0,0) {Pointer:\anchormark{first pointer}[0.075]  \npd Key  \npt Text text \npq \anchormark[-0.15cm]{pointer left}Pointers \anchormark{pointer right}\npc text};  
  \node[fnode] (r2) at (5,0) {Pointer:\anchormark{second pointer}[0.075]  \npd Key  \npt Text text \npq \anchormark[-0.05cm]{second pointer left}Second pointer\npc text};  
  \end{tikzpicture}
 \begin{tikzpicture}[remember picture,overlay,-stealth] 
  \draw (first pointer.center) to ($(first pointer.center)+(2,1)$) node[right,label style] (mylabel){label};
  \draw (pointer right.center) to (second pointer left);
  \draw (pointer left.center) to ($(pointer left.center)+(-1,1)$)node[left,label style]{label};
  \draw (second pointer.center) |-(mylabel);
  % just to connect r1 and r2
  \draw(r1.south)|- ($(r1.south)!0.5!(r2.south)-(0,1)$)-|(r2.south);
\end{tikzpicture}
\end{document}

The result: