How to get the number of beamer's frames inside a personal environment?

Question

Suppose I have a beamer presentation with some contiguous frames containing a "special content" that are inside a specialcontent environment. I'd like to introduce this special content with a frame that display both:

the numbers of "special" frames,
the frame (not page) number of the last "special frame,

as in the MCE below (<total number of frames> and <number of last frame of the special content>).

How could I achieve this?

\documentclass{beamer}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{lmodern}

\setbeamertemplate{footline}[frame number]
\setbeamertemplate{navigation symbols}{}

\newenvironment{specialcontent}{%
  \begin{frame}
    \frametitle{Special content}
    The following special content:
    \begin{itemize}
    \item has <total number of frames> frames,
    \item ends frame \# <number of last frame of the special content>.
    \end{itemize}
  \end{frame}
}{%
}

\begin{document}
\begin{frame}
  \frametitle{Foo bar}
  Foo\pause{} bar.
\end{frame}

\begin{specialcontent}

  \begin{frame}
    \frametitle{Foo bar (special content)}
    Foo\pause{} bar.
  \end{frame}

  \begin{frame}
    \frametitle{Foo bar (special content)}
    Foo\pause{} bar.
  \end{frame}

\end{specialcontent}

\begin{frame}
  \frametitle{Foo bar}
  Foo\pause{} bar.
\end{frame}
\end{document}

@samcarter Maybe it would be useful to explain your solution in case of section instead of environment. — Denis Bitouzé, Mar 27 '18 at 15:06
I was thinking of something like this https://tex.stackexchange.com/questions/308343/how-to-create-mini-sections-mini-subsections-and-mini-frames-in-beamer-presenta/313579#313579 — samcarter_is_at_topanswers.xyz, Mar 27 '18 at 15:13

score 2 · Accepted Answer · answered Mar 27 '18 at 15:18

2

Using the totcount package:

\documentclass{beamer}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{lmodern}

\setbeamertemplate{footline}[frame number]
\setbeamertemplate{navigation symbols}{}


\usepackage{totcount}
\newcounter{endspecial}
\newcounter{startspecial}
\regtotcounter{endspecial}


\newenvironment{specialcontent}{%
  \begin{frame}
    \frametitle{Special content}
    The following special content:
    \begin{itemize}
    \setcounter{startspecial}{\totvalue{endspecial}}
    \addtocounter{startspecial}{1}
    \addtocounter{startspecial}{-\insertframenumber}
    \item has \thestartspecial  <total number of frames> frames,
    \item ends frame \total{endspecial} <number of last frame of the special content>.
    \end{itemize}
  \end{frame}
}{%
  \setcounter{endspecial}{\insertframenumber}
}

\begin{document}
\begin{frame}
  \frametitle{Foo bar}
  Foo\pause{} bar.
\end{frame}

\begin{specialcontent}

  \begin{frame}
    \frametitle{Foo bar (special content)}
    Foo\pause{} bar.
  \end{frame}

  \begin{frame}
    \frametitle{Foo bar (special content)}
    Foo\pause{} bar.
  \end{frame}

\end{specialcontent}

\begin{frame}
  \frametitle{Foo bar}
  Foo\pause{} bar.
\end{frame}
\end{document}

answered Mar 27 '18 at 15:18

samcarter_is_at_topanswers.xyz

158,329

Thanks to your comments, I realized the package I was looking for was indeed totcount. Nicely, quickly and efficiently done, as usual :) – Denis Bitouzé Mar 27 '18 at 15:23
@DenisBitouzé Thanks a lot for your kind words! – samcarter_is_at_topanswers.xyz Mar 27 '18 at 15:24
If I'm right, \addtocounter{startspecial}{1} should be removed, otherwise the numbers of special frames is 3 instead of 2. – Denis Bitouzé Mar 27 '18 at 15:40
@DenisBitouzé Depends if you want to count the one with \frametitle{Special content}? – samcarter_is_at_topanswers.xyz Mar 27 '18 at 15:43
1

@DenisBitouzé My count goes like this: 2 frames within the environment + 1 which is created by it = 3 – samcarter_is_at_topanswers.xyz Mar 27 '18 at 15:45
Indeed, it depends on how the count is done :) – Denis Bitouzé Mar 27 '18 at 15:49

score 1 · Answer 2 · answered Mar 29 '18 at 19:09

For the record, I present here a extended solution to samcarter's one which works also in the case where several occurrences of specialcontents environment are to be used (and, say, this environment is not ours but given by a third party package or class -- in my real use case, it comes from the versions package).

The tricky problem was, when defining many "total counters" on the fly, only the last one was created. Thanks to the egreg's trick, the following is working like a charm:

\documentclass{beamer}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{lmodern}
\usepackage{multido}
\usepackage{totcount}

\usetheme{PaloAlto}
\useoutertheme{infolines}

\setbeamertemplate{navigation symbols}{}

\newenvironment{specialcontent}{%
}{%
}

\AtBeginEnvironment{specialcontent}{%
  \stepcounter{specialcontent@cntr}%
  %
  \begingroup\edef\x{\endgroup
    \noexpand\newtotcounter{startspecial@\roman{specialcontent@cntr}}
    \noexpand\newtotcounter{endspecial@\roman{specialcontent@cntr}}%
  }\x
  %
  \begin{frame}
    \frametitle{Special content (begins)}
    %
    \setcounter{startspecial@\roman{specialcontent@cntr}}{\totvalue{endspecial@\roman{specialcontent@cntr}}}%
    \addtocounter{startspecial@\roman{specialcontent@cntr}}{-\insertframenumber}%
    %
    The following special content:
    \begin{itemize}
    \item \alert{has \total{startspecial@\roman{specialcontent@cntr}} frames},
    \item \alert{ends frame \total{endspecial@\roman{specialcontent@cntr}}}.
    \end{itemize}
  \end{frame}
}

\AtEndEnvironment{specialcontent}{%
  \setcounter{endspecial@\roman{specialcontent@cntr}}{\insertframenumber}%
}

\newcounter{specialcontent@cntr}%

\begin{document}

\multido{\i=1+1}{17}{%
  \begin{frame}
    \frametitle{Foo bar}
    Foo\pause{} bar.
  \end{frame}
  %
  \section{Special \i{}}
  %
  \begin{specialcontent}
    \multido{\I=1+1}{\i}{%
      \begin{frame}
        \frametitle{Foo bar (special content)}
        Foo\pause{} bar.
      \end{frame}
    }
  \end{specialcontent}
  %
  \begin{frame}
    \frametitle{Foo bar}
    Foo\pause{} bar.
  \end{frame}
}

\end{document}

How to get the number of beamer's frames inside a personal environment?

2 Answers2