Passing parameters to tikz picture?

Question

I wrote a tikz diagram, which resides in its own dedicated file. I would like to include this file several times in my document, each time highlighting a different node in it. I tried defining a macro that would check for the argument, but alas, macro expansion within a path does not work. Any other ideas?

Here is my code:

  {
  \usetikzlibrary{arrows}
  \usetikzlibrary{mindmap}
  \begin{tikzpicture}[level 1/.append style={level distance=5ex,sibling angle=90}]
  \small\it
  \tikzstyle{show}=[draw,rectangle,thin,rounded corners]
  \node[show] {} 
    child {node[show] {Monomorphism} }
    child[missing]
    child {node[show] {Polymorphism}
      child { node[show] {Ad hoc}
    child {node[show] {Overloading} }
    child [missing]
    child {node[show] {Coercion}} 
    child [missing]
      }
      child [missing]
      child [missing]
      child [missing]
      child {node[show] {Universal}
    child {node[show] {Parametric} 
      child {node[show] {Polymorphic Functions}}
      child [missing]
      child [missing]
      child {node[show] {Polytypes}}
    }
    child[missing]
    child[missing]
    child {node[show] {Inclusion} child {node[show] {Subtype}}}
      }
    }
  ;
  \end{tikzpicture}
  }

Answer 1

First you have to give names to each node, with the syntax

node[<options>] (<name>) {<node text}

I define a macro \HighlightedNode that holds the name of the node to be highlighted, and a second one \Highlight to change the node to be highlighted. The highlighting is simply a thick red ellipse drawn around the centre of the node, please advise if you want something different. The \TikzFig node contains your tree and the additional

\draw [ultra thick,red] (\HighlightedNode.center) circle [x radius=5em,y radius=1.5em];

which creates the highlighting.

Using a macro defined by Martin Scharrer in How can I know if a node is already defined? I check for whether the node defined by \HighlightedNode exists, and only then draw the highlight. By defining \HighlightedNode to a string that is not a node name in the picture, this effectively turns off the highlighting.

I also changed from \tikzstyle to \tikzset, the latter is recommended. And don't use \it, these two-letter font switching macros are deprecated, use \itshape instead. Finally, rather than adding \small\itshape as you've done, I think I would use every node/.style={font=\small\itshape}.

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

\newcommand\HighlightedNode{none}
\newcommand\Highlight[1]{\renewcommand\HighlightedNode{#1}}

\makeatletter % https://tex.stackexchange.com/questions/37709/how-can-i-know-if-a-node-is-already-defined
\long\def\ifnodedefined#1#2#3{%
    \@ifundefined{pgf@sh@ns@#1}{#3}{#2}%
}
\makeatother

\newcommand\TikzFig{
  \begin{tikzpicture}[level 1/.append style={level distance=5ex,sibling angle=90},
  every node/.append style={font=\small\itshape}]
  \tikzset{show/.style={draw,rectangle,thin,rounded corners}}
  \node[show] {} 
    child {node[show] (mono) {Monomorphism} }
    child[missing]
    child {node[show] (poly) {Polymorphism}
      child { node[show] (adhoc) {Ad hoc}
    child {node[show] (overload) {Overloading} }
    child [missing]
    child {node[show] (coerce) {Coercion}} 
    child [missing]
      }
      child [missing]
      child [missing]
      child [missing]
      child {node[show] (uni) {Universal}
    child {node[show] (para) {Parametric} 
      child {node[show] (polyfunc) {Polymorphic Functions}}
      child [missing]
      child [missing]
      child {node[show] (polytype) {Polytypes}}
    }
    child[missing]
    child[missing]
    child {node[show] (inclusion) {Inclusion} child {node[show](subtype) {Subtype}}}
      }
    }
  ;
  \ifnodedefined{\HighlightedNode}{
    \draw [ultra thick,red] (\HighlightedNode.center) circle [x radius=5em,y radius=1.5em];}{}

  \end{tikzpicture}}
\begin{document}    

\TikzFig

\Highlight{poly}

\vspace{2cm}

\TikzFig

\Highlight{coerce}

\vspace{2cm}

\TikzFig

\end{document}

Answer 2

Maybe a node-name-based style that activates a highlight style?

By the way, it looks like if you are using missing childs to correct the spacing of the tree. You might be interested in the forest package forest that automatically positions the nodes with a proper spacing between them (and much more). Though, I don’t think that this solution will work then.

Code

\begin{filecontents*}{\jobname.tikz}
\begin{tikzpicture}[
  level 1/.append style={level distance=+5ex, sibling angle=90},
  show/.style={draw,rectangle,thin,rounded corners}]
\small\itshape
\path[nodes=show] node (r) {} 
  child {node {Monomorphism} } child [missing]
  child {node  {Polymorphism}
    child {node  {Ad hoc}
      child {node  {Overloading}}  child [missing]
      child {node  {Coercion}}     child [missing] }
    child [missing] child [missing] child [missing]
    child {node {Universal}
      child {node {Parametric} 
        child {node {Polymorphic Functions}}
        child [missing] child [missing]
        child {node {Polytypes}}}
      child[missing] child[missing]
      child {node {Inclusion} child {node {Subtype}}}}};
\end{tikzpicture}
\end{filecontents*}
\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{mindmap}
\tikzset{highlight/.style={draw=red, text=blue, fill=green!25}}
\makeatletter
\usepackage{etoolbox}
\patchcmd\tikz@@fig@main{\tikzset{every \tikz@shape\space node/.try}}{%
  \tikzset{every \tikz@shape\space node/.try}%
  \tikzset{every node named \tikz@fig@name/.try}%
}{}{}
\newcommand*\inpTikZ[2][]{%
  \begingroup
    \def\tikz@temp{#1}% is #1 empty?
    \ifx\tikz@temp\pgfutil@empty\else
      \tikzset{every node named #1/.append style=highlight}%
    \fi
    \input{#2}%
  \endgroup}
\makeatother
\begin{document}
\inpTikZ[r-1]{\jobname.tikz}

% r-2 is "missing"
\inpTikZ[r-3]{\jobname.tikz}

\inpTikZ[r-3-5]{\jobname.tikz}
\end{document}