TikZ: halo around text?

Question

I'd like to label my nodes with text that has a 'halo' around it of a different colour. Is this possible?

The reason is that my label text covers different parts of my diagram with different background colours, so no single colour will make the label legible. I'd ideally like the text to be black, with a white halo.

Answer 1

You can use the contour package with the outline option to create a thick outline around your text. Note that this won't work with things like fraction lines or the horizontal lines of root symbols (see How can I put a coloured outline around fraction lines?).

Andrey Vihoy mentioned the option of just filling the node background. I've added this approach for comparison.

Andrew Stacey suggests rounding the corners of the filled node, which does indeed look more elegant. This variation is shown here as well.

\documentclass{article}

\usepackage{tikz}
\usepackage[outline]{contour}
\contourlength{1.2pt}

\begin{document}
    \begin{tikzpicture}
    \draw [fill=gray!10!white](0,0) rectangle (4.5,1) [step=0.1cm] (0,0) grid (4.5,1);
    \node at (0.75,0.5) {\contour{white}{\Large Text!}};
    \node [fill=white,inner sep=1pt] at (2.25,0.5) {\Large Text!};
    \node [fill=white,rounded corners=2pt,inner sep=1pt] at (3.75,0.5) {\Large Text!};
    \end{tikzpicture}
\end{document}

Answer 2

You can add the [fill] parameter to any text node. This doesn't get you a halo around each character, but it might be more readable, depending on what your needs are.

\documentclass[12pt]{article}
\usepackage{tikz}
\begin{document}
\begin{tikzpicture}
\draw[fill,red] (0,0) rectangle (11,2);
\draw[very thick] (1,1) -- node[outer sep=5pt,fill=white,above] {Label} (10,1);
\end{tikzpicture}
\end{document}