hf-tikz package: error with custom colors and overlay in beamer class

Question

Consider the following MWE from here:

Solution with the hf-tikz package

\documentclass{beamer}
\usepackage{lmodern,amsmath,amssymb}
\usepackage[beamer]{hf-tikz}
\usetheme{Copenhagen}
\begin{document}
\section{Mysection}
\subsection{A subsection}
\begin{frame}{The equations}
\begin{block}{}
 \begin{align}
   \tikzmarkin<1>{a}a_i\tikzmarkend{a} + b_j = 10 & \forall i\in I, j\in J \
   \tikzmarkin<2>{c}c_j + d_j + \tikzmarkin<1>{b}a_i\tikzmarkend{b} >= 30 & \forall i\in I, j\in J\tikzmarkend{c}
 \end{align}
\end{block}
\end{frame}
\end{document}

If I try to customize the colors of the highlighting box as per the documentation, I get an error. For instance, if I insert the lines

\hfsetfillcolor{blue!10}
\hfsetbordercolor{blue}

right before tikzmarkin<1> I get the error ! Undefined control sequence.

Moreover, I also get an error if I remove overlay specifications <1> i.e. ! Missing number treated as zero. This happens when I remove the marker tikzmarkin<2>{c} completely, and use tikzmarkin<1>{a} without overlay as tikzmarkin{a}. From my understanding of the documentation, overlay specifications are only optional and not compulsory. I am using TeXnicCenter with MiKTeX 2.9.

Thanks for your help.

Answer 1

The problem is twofold here.

First, it looks like you miss the customcolors option. Second, if you want the customization to be global, you have to define it in the preamble. Otherwise,

\hfsetfillcolor{blue!10}
\hfsetbordercolor{blue}

given before a \tikzmarkin customize only that command and not he subsequent ones.

Try:

\documentclass{beamer}
\usepackage{lmodern,amsmath,amssymb}
\usepackage[customcolors,beamer]{hf-tikz}

\usetheme{Copenhagen}

\hfsetfillcolor{blue!10}
\hfsetbordercolor{blue}

\begin{document}

    \section{Mysection}
    \subsection{A subsection}
    \begin{frame}{The equations}
        \begin{block}{}
            \begin{align}
                \tikzmarkin<1>{a}a_i\tikzmarkend{a} + b_j = 10 & \forall i\in I, j\in J \\
                \tikzmarkin<2>{c}c_j + d_j + \tikzmarkin<1>{b}a_i\tikzmarkend{b} >= 30 & \forall i\in I, j\in J\tikzmarkend{c}
            \end{align}
        \end{block}
    \end{frame}

\end{document}

The result:

The overlay specifications are mandatory only for Beamer class having the beamer option enabled. Indeed, the macro is declared as follows:

\NewDocumentCommand{\tikzmarkin}{r<> o m D(){\belowrightoff} D(){\aboveleftoff}}{%

and the r type from xparse allows to declare a required argument with custom delimiters.

Basically, if you do not specify the beamer option and you do not insert overlays, your code works.