如何使用之前的几张幻灯片制作动画

Question

我想用之前的几张幻灯片制作动画，我该怎么做？

\transduration不影响\againframe，如何避免

\documentclass{beamer}

\begin{document}
\begin{frame}[label=bob]

\begin{enumerate}[<+->]

\item a
\item b
\item c

\end{enumerate}
\end{frame}

\transduration<4->{.2}
\againframe<2->{bob}

\end{document}

Answer 1

\transduration没有效果；可能是 bug。所以让我们手动操作一下：

\documentclass{beamer}

\begin{document}
\begin{frame}[label=bob]

\begin{enumerate}[<+->]

\item a
\item b
\item c

\end{enumerate}
\end{frame}

\typeout{***** before \string\transduration:\the\pdfpageattr *****}
\transduration{.2} %doesn't work, why?
\typeout{***** after \string\transduration:\the\pdfpageattr *****}

% save current value of \pdfpageattr
\edef\pdfpageattrOrig{\the\pdfpageattr}
% append page duration to the page attributes (do it manually)
\begingroup
\edef\x{\endgroup
  \pdfpageattr{\the\pdfpageattr /Dur 0.2}%
}%
\x

\againframe<1->{bob} %auto-advancing frames

%reset page attributes to saved value
\begingroup
\edef\x{\endgroup
  \pdfpageattr{\pdfpageattrOrig}%
}%
\x

\againframe<1->{bob} %frames don't auto-advance any more

\end{document}