How to Center a BeamerColorBox

Question

The question is, how to horizontally center a beamercolorbox on the page?

I put it in the center environment, but that doesn't work.

\setbeamercolor{bgcolor}{fg=black,bg=blue}
\begin{center}
    \begin{beamercolorbox}[rounded=true, center=true, shadow=true, wd=6cm]{bgcolor}
        Some text goes here...
    \end{beamercolorbox}
\end{center}

Answer 1

wd=<dimen> not only sets the width of the beamercolorbox to <dimen>, it sets the \hsize to <dimen>. So you're centering a box in a line which has the same width as the box, resulting in nothing.

So to force centering, use some \hfills:

\documentclass{beamer}
\setbeamercolor{bgcolor}{fg=black,bg=blue}

\begin{document}

\begin{frame}
\hfill
    \begin{beamercolorbox}[rounded=true, center, shadow=true,wd=6cm]{bgcolor}
        Some text goes here...
    \end{beamercolorbox}
\hfill\hfill
\end{frame}

\end{document}

I'm not sure why you need two at the end—it seems like one at the front and back would do the centering. But instead you just get a box flush right. So an extra one does the trick.

Answer 2

Here's an answer that keeps the center environment:

\documentclass{beamer}
\setbeamercolor{bgcolor}{fg=black,bg=blue}

\begin{document}

\begin{frame}

\begin{center}
~
    \begin{beamercolorbox}[rounded=true, center, shadow=true,wd=6cm]{bgcolor}
        Some text goes here...
    \end{beamercolorbox}
~
\end{center}
\end{frame}

\end{document}

Matthew's answer gave me the hint. The trick is to ensure that the colour box is not the only thing on the line that is being centred. Then it isn't treated as a box by itself, but as a component of something larger. So then the search is on for something to put on the line that won't be seen in the final output. If it has non-zero width, then it needs to be put before and after to ensure that the centring is still central. A non-breaking space (~) seemed the simplest thing to do.

Answer 3

A simple solution, which is slightly less messy for my taste, is to create a single column, which is automatically centered:

\begin{frame}
\begin{columns}
\column{.7\linewidth}
  \begin{beamercolorbox}[rounded=true, center, shadow=true]{bgcolor}
    Some text goes here...
  \end{beamercolorbox}
\end{columns}
\end{frame}

Experience shows that one needs at least one more column eventually, anyway ;)