[Tex/LaTex] UML Statediagram

tikz-pgftikz-uml

I am trying to draw a UML statediagram with TikZ. I tried tikz-uml, but I was not satisfied with the way it handles the state nodes. While I love TikZ for its versatile placement options of nodes (relative placement with above, selecting anchor points), I have no clue how to do this with tikz-uml. Furthermore, it gives me text extending outside the node.

Looking briefly at tikz-uml's implementation (I am still a TeX noob), I learned that actually a rounded rectangle is drawn around a title node and a content node with the fitting library, and subsequently a line separating the statename is added. Thus I tried to have an implementation of my own, drawing the title and the contents in one TikZ picture, which I then put inside a node. That way I hope to preserve the easy placement that I have grown accustomed to from normal TikZ nodes. Here is the code and the problem, the line I draw for separation is misplaced above the nodes (note: render twice to get the same line placement I got):

\documentclass{article}
\usepackage{tikz}
\usepackage{tikz-uml}   
\usepackage[margin=0cm,nohead]{geometry}
\usepackage[active,tightpage]{preview}
\usetikzlibrary{calc}
\usetikzlibrary{positioning}   
\PreviewEnvironment{tikzpicture}
\begin{document}
\begin{tikzpicture}
    \node[draw, rounded corners](box){
        \begin{tikzpicture}[remember picture]
            \node[draw=red](caption) {titel};
            \node[below=0 of caption] {\begin{tabular} ccontent\\more content\end{tabular}};
        \end{tikzpicture}
    };
    \draw (caption.south -| box.west) -- (caption.south -| box.east);
\end{tikzpicture}
\end{document}

To show where the line should be, the title box is drawn in red, the line should be on its lower edge, similar to the tikz-uml output. The line actually is the black bar above the outer black node, drawn above it near the top edge of the image.

line misplaced above box

For comparison here is what I tried with tikz-uml and the result (simply replace everyting inside the outer tikzpicture above with this to test):

\begin{umlstate}[x=-3, y=-4, name=discard, do=clear all valid bits]{discard}
\end{umlstate}

overset text with tikz uml

Best Answer

You could make your state node into a 'multipart' node. For that, you need to load the shapes.multipart TikZ library. You should then be able to use all the placement options that you're used to.

Result:

enter image description here

Code:

\documentclass[border=1cm]{standalone}
\usepackage{tikz}
\usetikzlibrary{shapes.multipart}    
\begin{document}
  \begin{tikzpicture}
    \node[rectangle split, rectangle split parts=2, draw, rounded corners]{%
      \tikz\node[draw=red, rectangle, rounded corners]{titel};
      \nodepart{two}
      \begin{tabular}{c}
      content \\ more content
      \end{tabular}
    };
  \end{tikzpicture}
\end{document}

PS. You might alternatively make your state node into a matrix, but then it's quite hard to get the horizontal line that you want (see this discussion, for instance).

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