\section{Coloring and highlighting}
%<-------------------------------------------------------------------------->
\subsection{Coloring vertices: \tkzcname{AddVertexColor}}
\begin{NewMacroBox}{AddVertexColor}{\var{color}\var{list of vertices}}
\emph{The vertices of the list, already drawn, are drawn again with this
color as fill color (and without label). The style \tkzname{Welsh} is
designed for this use.}
\end{NewMacroBox}

\begin{tkzexample}[latex=7cm,small]
\begin{tikzpicture}
  \GraphInit[vstyle=Welsh]
  \tkzSetUpGraph[vertex line width=2pt]
  \Vertices[unit=2]{circle}{A,B,C,D,E,F,G}
  \SetVertexNoLabel
  \AddVertexColor{red}{B,F}
  \AddVertexColor{blue}{E,A}
  \AddVertexColor{green}{C,G}
  \AddVertexColor{yellow}{D}
  \Edges(G,E,F,G,B,D,E,C,D,A,C,B,A)
  \Edges(B,E)
\end{tikzpicture}
\end{tkzexample}

A complete example (the Welsh--Powell algorithm) is given in the
section~\ref{sec:welsh}.

\subsection{Highlighting a path: \tkzcname{tkzHighlightPath}}
\begin{NewMacroBox}{tkzHighlightPath}{\oarg{local options}\var{list}}
\begin{tabular}{llc}
\toprule
Options   & Default  & Definition           \\
\midrule
\TOline{color} {red}   {color of the path}
\TOline{lw}    {1.6pt} {line width}
\TOline{style} {\{\}}  {\TIKZ\ options (to follow a bent edge\dots)}
\TOline{cycle} {false} {the last vertex is joined to the first one}
\bottomrule
\end{tabular}

\medskip
\emph{The list is a path \tkzname{A,B,C,D} (the edges A--B, B--C, C--D are
drawn again) or a list of edges \tkzname{A/B,C/D}. The vertices must exist;
the edges are drawn over the graph, so the macro is used at the end of the
picture. With \tkzname{tkz-berge}, it highlights the edges of a graph drawn by
a single macro.}
\end{NewMacroBox}

\begin{tkzexample}[latex=7cm,small]
\begin{tikzpicture}[scale=.6]
  \GraphInit[vstyle=Normal]
  \SetVertexNoLabel
  \grPetersen[RA=3,RB=1.5]
  \tkzHighlightPath[cycle]{a0,a1,a2,a3,a4}
  \tkzHighlightPath[color=blue]{a0/b0,b2/b4}
\end{tikzpicture}
\end{tkzexample}

A bent edge needs the same \tkzname{style}:

\begin{tkzexample}[latex=7cm,small]
\begin{tikzpicture}
  \Vertices[unit=1.5]{line}{A,B,C}
  \Edge[style={bend left=30}](A)(C)
  \Edges(A,B,C)
  \tkzHighlightPath[color=orange,lw=2.5pt,
     style={bend left=30}]{A,C}
\end{tikzpicture}
\end{tkzexample}

\subsubsection{A Hamiltonian cycle of the cube: the Gray code}
With \tkzname{tkz-berge}, \tkzcname{grHypercube} names the vertices of the
cube by their binary word; a Hamiltonian cycle gives the Gray code.

\begin{tkzexample}[latex=7cm,small]
\begin{tikzpicture}[scale=.8]
  \GraphInit[vstyle=Normal]
  \tkzSetUpGraph[medium size=20pt]
  \grHypercube[RA=3.5,prefix={}]{3}
  \tkzHighlightPath[cycle]%
    {000,001,011,010,110,111,101,100}
\end{tikzpicture}
\end{tkzexample}

\endinput