[Tex/LaTex] Change theme mid-presentation using metropolis package

beamerbeamer-metropolispresentations

I am using beamer with metropolis theme.
According to manual (page 6) metropolis offers option for background, namely dark and light, which can be set anytime, i.e. even mid-presentation, with the \metroset macro.

As expected, setting \metroset{background=dark} in preamble results in dark background and light normal text.

However, using \metroset{background=dark} in mid-document does not work as expected. The \metroset{background=dark} indeed sets the background of next slide to dark, but does not change the color of the normal text from dark to light. Hence, the text on dark background is invisible.

\documentclass{beamer}
\usetheme[progressbar=frametitle,block=fill]{metropolis}

\begin{document}
\begin{frame}{Light Theme}
    Hello, world!
\end{frame}

\metroset{background=dark} % change background theme according to manual

\begin{frame}{Dark Theme}
    Hello, world! % invisible
\end{frame}
\end{document}

Best Answer

The theme doesn't take sufficient account of the way Beamer's colours work. In particular, when you change the colour, the code uses \setbeamercolor but not \usebeamercolor, which is necessary for the change to take effect.

For example, the following works.

\documentclass{beamer}
\usetheme[progressbar=frametitle,block=fill]{metropolis}
\begin{document}
\begin{frame}{Light Theme}
    Hello, world!
\end{frame}

\metroset{background=dark} % change background theme according to manual
\usebeamercolor[fg]{normal text}
\begin{frame}{Dark Theme}
    Hello, world! % invisible
\end{frame}
\end{document}

Should you run into any weird spacing issues when using this theme, consider the possibility that it is introducing spurious spaces as the code suggests it may be quite keen to do so.

For things to work as expected, you could redefine the commands as follows.

\documentclass{beamer}
\usetheme[progressbar=frametitle,block=fill]{metropolis}
\makeatletter
\renewcommand{\metropolis@colors@dark}{%
  \setbeamercolor{normal text}{%
    fg=black!2,
    bg=mDarkTeal
  }%
  \usebeamercolor[fg]{normal text}%
}
\renewcommand{\metropolis@colors@light}{%
  \setbeamercolor{normal text}{%
    fg=mDarkTeal,
    bg=black!2
  }%
  \usebeamercolor[fg]{normal text}%
}
\makeatother
\begin{document}
\begin{frame}{Light Theme}
    Hello, world!
\end{frame}
\metroset{background=dark} % change background theme according to manual
\begin{frame}{Dark Theme}
    Hello, world! % invisible
\end{frame}
\metroset{background=light} % change background theme according to manual
\begin{frame}{Light Again}
    Hello, world! % invisible
\end{frame}
\end{document}

Related Solutions

[Tex/LaTex] How to use beamer colors in beamerarticle

Having just wanted to do this in answer to another question, I can tell you that this is Not Intended To Be Done! A lot of the theming and colour commands are simply set to "do nothing" when the article version of beamer is used. However, using a bit of trickery we can reload the commands and so make the colours available. This should be used with Extreme Caution as it might break something that I haven't tested (which is about everything).

Here's a picture based on a slightly modified version of your example:

beamer colours in article mode

And here's the code:

\documentclass{standalone}
%\url{http://tex.stackexchange.com/q/22768/86}
\PassOptionsToPackage{svgnames}{xcolor}
\usepackage{beamerarticle}
\usepackage{tikz}

\makeatletter

\def\beamer@currentmode{beamer}
\def\beamer@colorhook{}
\newskip\beamer@lastskip
\let\beamercolorbox=\relax
\let\endbeamercolorbox=\relax
\let\usetheme=\relax
\let\usecolortheme=\relax
\let\usefonttheme=\relax
\let\useoutertheme=\relax
\let\useinnertheme=\relax

\input{beamerbasethemes.sty}
\input{beamerbasecolor.sty}
\usecolortheme{default}
\usecolortheme{beaver}
\makeatother

\setbeamercolor{example text}{bg=Maroon}

\begin{document}

This is some text outside any frame.

\begin{frame}{Frame}
\begin{alertblock}{Block}
\usebeamercolor{example text}%
\begin{tikzpicture}
\filldraw[color=fg, fill=bg!50!white] (0,0) rectangle (5,3);
\draw[line width=5mm] (1,1)--(2,2);
\end{tikzpicture}
\end{alertblock}
\end{frame}
\end{document}

The main part is the stuff between \makeatletter and \makeatother. We need to load in the beamer colour management. Unfortunately, the file containing the commands checks the mode and skips most stuff in article mode. So we need to temporarily change to beamer mode to persuade it that we really do want to define this stuff. But as the files have already been read in (via the \usepackage{beamerarticle}) we can't \usepackage them again but have to \input them (this produces a couple of warnings in the log, but ignore them). We load in the themes set and the color set. There are a couple of things that are defined in beamer.cls that these depend on so we have to set them up: \beamer@colorhook and \beamer@lastskip. Also, some things are defined by \newcommand and were defined (to the wrong things) on the first read. So we need to set them all to \relax to avoid errors. After that, it's plain sailing!

[Tex/LaTex] Numerical conditional within tikz keys

I am definitely unfamiliar with both beamer and tikz (do not quite get what the \only are supposed to do) but perhaps this could go in the direction you want:

\documentclass{beamer}
\usepackage{tikz}
\usetikzlibrary{chains}
\newcounter{count}

% helper macro:
\long\def\GobToSemiColon #1;{}

\newcommand\myPicture{
\begin{tikzpicture}
  \begin{scope}[start chain = going below]
  \ifnum\value{count}<1 \expandafter\GobToSemiColon\fi
  \ifnum\value{count}>3 \expandafter\GobToSemiColon\fi
  \node[draw, rectangle, on chain] {display only when counter is between
    1 and 3};

  \ifnum\value{count}>-1 \expandafter\GobToSemiColon\fi
  \node[draw, rectangle, on chain] {display only when counter is
    negative}; 

  \ifnum\value{count}<100 \expandafter\GobToSemiColon\fi
  \ifnum\value{count}>200 \expandafter\GobToSemiColon\fi  
  \node[draw, rectangle, on chain] {display only if counter is between
    100 and 200};

  \ifnum\value{count}<3 \expandafter\GobToSemiColon\fi
  \ifnum\value{count}>20 \expandafter\GobToSemiColon\fi
  \node[draw, circle, on chain] {only when counter is in the range 3 to 20};
  \end{scope}
\end{tikzpicture}
}

\begin{document}
\begin{frame}
\only{\setcounter{count}{-3}\myPicture}
\only{\setcounter{count}{105}\myPicture}
\only{\setcounter{count}{39}\myPicture}
\only{\setcounter{count}{2}\myPicture}
\only{\setcounter{count}{5}\myPicture}
\end{frame}
\end{document}

beamer

Best Answer

Related Solutions

[Tex/LaTex] How to use beamer colors in beamerarticle

[Tex/LaTex] Numerical conditional within tikz keys

Related Question