在 Beamer 中将幻灯片背景设为可选项

Question

我的自定义模板中有背景，我想在某些幻灯片中关闭它。理想情况下，我会使用 选项来执行此\begin{frame}操作。我的模板大致基于Claudio Fiandrino 对“从头开始设计自定义 Beamer 主题”的回答。

我见过如何在投影仪框架中插入背景图像？和如何将背景图像仅包含在投影仪演示文稿的一页中？；我所寻找的本质上是后者的反面，但是干净利落（如果我正确使用这个模板，我不会是唯一使用它的人，所以我希望它是强大的）。

这对于 MWE 来说就是相当多的代码。最相关的部分可能是第一个，beaminnerthemecf.sty：

\mode<presentation>

\setbeamertemplate{background}{
\begin{tikzpicture}
  \useasboundingbox[inner sep=0] (0,0) rectangle(\paperwidth,\paperheight);
  \node[anchor=north,opacity=0.25] (bkg) at (current page.north) {\includegraphics[width=\paperwidth,height=\paperheight]{example-image-a}};
  \fill[color=red,anchor=north west] (0,\the\paperheight) rectangle(\the\paperwidth,0.85\paperheight);
  \node[anchor= south east, red,align=right] at (0.975\paperwidth,0.025\paperheight){\normalsize\insertauthor\\[0.2em]\normalsize\insertdate};  
  \ifnum\thepage>1\relax%
    \ifx\insertframesubtitle\@empty%
      {\node[anchor=north west, white,font=\Large] at (0.025\paperwidth,0.975\paperheight){\insertframetitle};}
      \else{%
        \node[anchor=north west, white,font=\Large] at (0.025\paperwidth,0.985\paperheight){\insertframetitle};%
        \node[anchor=north west, white,font=\large] at (0.025\paperwidth,0.925\paperheight){\insertframesubtitle};%
      }%
     \fi
   \fi
  \end{tikzpicture}
}

% Title page
\defbeamertemplate*{title page}{cf}[1][]{%
    \begin{tikzpicture}[overlay, remember picture, shift={(current page.south west)}]
        \useasboundingbox (current page.south west) rectangle(\paperwidth,\paperheight);
        \node[anchor=center, red,inner sep=0,align=center,text width=0.8\paperwidth] at (0.5\paperwidth,0.5\paperheight){\inserttitle};
    \end{tikzpicture}
}
% Items
\setbeamertemplate{items}[square]
\setbeamertemplate{sections/subsections in toc}[square]
\mode<all>

为了测试它，我们可以编译dummy.tex：

\documentclass{beamer}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\title{\Large{\textbf{There Is No Largest Prime Number}}}
\date[ISPN ’80]{27th International Symposium of Prime Numbers}
\author[Euclid]{Euclid of Alexandria \texttt{[email protected]}}
\usetheme{cf}

\begin{document}

\begin{frame}
\titlepage
\end{frame}

\begin{frame} % This is where I'd like to turn off the background image
\frametitle{There Is No Largest Prime Number} 
\framesubtitle{The proof uses \textit{reductio ad absurdum}.} 
This is a test
\begin{enumerate}
\item Suppose $p$ were the largest prime number. 
\item Let $q$ be the product of the first $p$ numbers. 
\item Then $q+1$ is not divisible by any of them. 
\item But $q + 1$ is greater than $1$, thus divisible by some prime
number not in the first $p$ numbers.
\end{enumerate}
\end{frame}

\end{document}

还需要beamerouterthemecf.sty：

\mode<presentation>
% Frame title
\defbeamertemplate*{frametitle}{cf}[1][]{
}
\mode<all>

和beamercolorthemecf.sty：

\mode<presentation>
% Settings
\setbeamercolor*{title page header}{fg=white}
\setbeamercolor*{author}{fg=white}
\setbeamercolor*{date}{fg=white}
\setbeamercolor*{item}{fg=red}
\setbeamercolor*{normal text}{fg=black}
\mode<all>

Answer 1

您始终可以声明一个本地空背景。

\documentclass{beamer}

\setbeamertemplate{background}{
   \includegraphics[height=\paperheight,width=\paperwidth]{example-image-a}
}

\begin{document}

\begin{frame}
Background image
\end{frame}

{%-> Starts scope where to apply following template
\setbeamertemplate{background}{}
\begin{frame}
No background image
\end{frame}
}%-> Ends scope where particular template has been applied. 

\begin{frame}
Background image, again.
\end{frame}

\end{document}