Beamer - 将多行标题合并为一个标题

Question

我正在尝试将多行标题调整为单行。我找到了文本的长度并检查它是否大于\linewidth或\textwidth。两个维度都给出了比预期更大的值。经过修改后，我意识到250pt是神奇的值。我不知道如何以编程方式找到它。

\documentclass{beamer}

\newcommand{\mytitle}{A very very very very very very very very very long title}
\newlength{\mytitlewidth}
\settowidth{\mytitlewidth}{\mytitle}

\ifdim\mytitlewidth > \linewidth % 250pt
  \title{\resizebox{\dimexpr\textwidth}{!}{\centering{\mytitle}}}
\else
  \title{\mytitle}
\fi

\author{\the\mytitlewidth, \the\linewidth}
\institute{}
\date{January 31st, 2023}

\begin{document}

\frame{\titlepage}
\end{document}