编辑投影机标题页上的框的宽度

Question

我想将以下演示文稿的标题页上author和date字段周围的白色框缩小到其内容的宽度beamer：

\documentclass{beamer}

\usetheme{Malmoe}
\usecolortheme{beaver}

\title{The tediously long title of my presentation}
\author{Me}
\date{\today}

\setbeamercolor{author}{bg=white}
\setbeamercolor{date}{bg=white}

\begin{document}
    {\usebackgroundtemplate{
            \includegraphics[width=\paperwidth,height=\paperheight]{example-image-a}
        }
        \begin{frame}
            \titlepage
        \end{frame}
    }
\end{document}

这该怎么做？手动调整宽度就可以了。

Answer 1

快速破解：重新定义标题页，并将beamercolorboxes 包装在所需宽度的小页中：

\documentclass{beamer}

\usetheme{Malmoe}
\usecolortheme{beaver}

\title{The tediously long title of my presentation}
\author{Me}
\date{\today}

\setbeamercolor{author}{bg=white}
\setbeamercolor{date}{bg=white}


\makeatletter
\setbeamertemplate{title page}{
  \vbox{}
  \vfill
  \begingroup
    \centering
    \begin{minipage}{.9\textwidth}
    \begin{beamercolorbox}[sep=8pt,center]{title}
      \usebeamerfont{title}\inserttitle\par%
      \ifx\insertsubtitle\@empty%
      \else%
        \vskip0.25em%
        {\usebeamerfont{subtitle}\usebeamercolor[fg]{subtitle}\insertsubtitle\par}%
      \fi%     
    \end{beamercolorbox}%
    \end{minipage}

    \vskip1em\par
    \begin{minipage}{.15\textwidth}
    \begin{beamercolorbox}[sep=8pt,center]{author}
      \usebeamerfont{author}\insertauthor
    \end{beamercolorbox}
    \end{minipage}

    \begin{minipage}{.5\textwidth}
    \begin{beamercolorbox}[sep=8pt,center]{institute}
      \usebeamerfont{institute}\insertinstitute
    \end{beamercolorbox}
    \end{minipage}

    \begin{minipage}{.3\textwidth}
    \begin{beamercolorbox}[sep=8pt,center]{date}
      \usebeamerfont{date}\insertdate
    \end{beamercolorbox}
    \end{minipage}
    \vskip0.5em
    {\usebeamercolor[fg]{titlegraphic}\inserttitlegraphic\par}
  \endgroup
  \vfill
}
\makeatother



\begin{document}
    {\usebackgroundtemplate{
            \includegraphics[width=\paperwidth,height=\paperheight]{example-image-a}
        }
        \begin{frame}
            \titlepage
        \end{frame}
    }
\end{document}