Use total number of pages in beamer as counter

Question

I'm trying to set a count in latex on the total number of pages:

\newcount\mypagecount
\mypagecount=\insertpresentationendpage

But whenver I do this, it auto "prints" the total number of pages instead of putting the number as a count. Is there a way to set it as a count?

Here is more precisely what I'm trying to do:

\newcount\mypagenum
\newcount\mypagecount
\newdimen\barwidth

\mypagenum=\insertpagenumber
\mypagecount=\insertpresentationendpage
\barwidth=\paperwidth

\multiply\barwidth by \mypagenum                                       
\divide\barwidth by \mypagecount

I tried with counters, but that threw errors as well:

\newcounter{mypagecount}
\setcounter{mypagecount}{\insertpresentationendpage}

Any ideas how I can do the division at the end if I can't use these numbers and/or how to actually use these numbers?

Answer 1

The following does essentially the same as the current version of \insertpresentationendpage of beamer, but in a way such that your counter is set instead of the result printed. I also included a proof of concept progress bar output.

\documentclass[]{beamer}

\newlength\barwidth
\newlength\tmpbarwidth
\newcount\mypagecount

\makeatletter
\newcommand*\progressbar
  {%
    \ifnum\mypagecount=0
      \ifx\beamer@startpageofappendix\@empty
        \mypagecount=\beamer@endpageofdocument\relax
      \else
        \mypagecount=\beamer@startpageofappendix\relax
        \advance\mypagecount\m@ne
      \fi
      \ifnum\mypagecount=0
        \global\mypagecount=1
      \else
        \global\mypagecount=\mypagecount
      \fi
    \fi
    \begingroup
      \tmpbarwidth\insertpagenumber\barwidth
      \divide\tmpbarwidth\mypagecount
      \rule{\tmpbarwidth}{5pt}%
      \advance\barwidth-\tmpbarwidth
      \textcolor{gray}{\rule{\barwidth}{5pt}}%
    \endgroup
  }
\makeatother

\setlength\barwidth{5cm}

\begin{document}
\begin{frame}
  \progressbar
\end{frame}
\begin{frame}
  \progressbar
\end{frame}
\begin{frame}
  \progressbar
\end{frame}
\begin{frame}
  \progressbar
\end{frame}

\end{document}