LaTeX Beamer：全局定义 \itemsep

Question

在 LaTeX Beamer 中，我尝试进行\itemsep全局设置。

我已经尝试了以下操作，但是没有效果：

\documentclass[14pt]{beamer}

\setbeamertemplate{itemize/enumerate body begin}{\setlength{\itemsep}{5ex}}

\begin{document}

\begin{frame}
    \begin{itemize}
%       \setlength{\itemsep}{5ex}  % this would work locally..
        \item Test1
        \item Test2
        \item Test3
    \end{itemize}

\end{frame} 

\end{document}

我究竟做错了什么？

编辑：

如果可能的话，我更喜欢一种允许为主体、子主体、子子主体等定义不同间距的解决方案。

Answer 1

您的代码无法运行，因为itemize/enumerate \beameritemnestingprefix body begin模板已被使用前内部\list使用的itemize。

您可以修补\itemize（原始定义在beamerbaselocalstructure.sty）：

\documentclass[14pt]{beamer}
\usepackage{xpatch}

\xpatchcmd{\itemize}
  {\def\makelabel}
  {\setlength{\itemsep}{5ex}\def\makelabel}
  {}
  {}

\begin{document}

\begin{frame}
    \begin{itemize}
        \item Test1
        \item Test2
        \item Test3
    \end{itemize}
\end{frame} 

\end{document}

由于\itemize的定义beamer具有可选参数，因此使用etoolbox可能\patchcmd会产生不良结果。包\xpatchcmd中的xpatch旨在处理这些情况。

更新

在评论中，有人要求能够独立控制三个允许的嵌套级别的分离；这也可以通过使用条件轻松完成\@itemdepth：

\documentclass{beamer}
\usepackage{xpatch}

\xpatchcmd{\itemize}
  {\def\makelabel}
  {\ifnum\@itemdepth=1\relax
     \setlength\itemsep{3ex}% separation for first level
   \else
     \ifnum\@itemdepth=2\relax
       \setlength\itemsep{2ex}% separation for second level
     \else
       \ifnum\@itemdepth=3\relax
         \setlength\itemsep{0.5ex}% separation for third level
   \fi\fi\fi\def\makelabel
  }
 {}
 {}

\begin{document}

\begin{frame}
\begin{itemize}
\item First item.
  \begin{itemize}
  \item First subitem.
  \item Second subitem.
    \begin{itemize}
    \item First subsubitem.
    \item Second subsubitem.
    \item Third subsubitem.
    \end{itemize}
  \item Third subitem.
  \end{itemize}
\item Second item.
\item Third item.
\end{itemize}
\end{frame}

\end{document}

Answer 2

作为补充Gonzalo Medina 的回答，我用的是这个：

\documentclass{beamer}
\usepackage{xpatch}

\makeatletter
\newcommand{\my@beamer@setsep}{%
\ifnum\@itemdepth=1\relax
     \setlength\itemsep{\my@beamer@itemsepi}% separation for first level
   \else
     \ifnum\@itemdepth=2\relax
       \setlength\itemsep{\my@beamer@itemsepii}% separation for second level
     \else
       \ifnum\@itemdepth=3\relax
         \setlength\itemsep{\my@beamer@itemsepiii}% separation for third level
   \fi\fi\fi}
\newlength{\my@beamer@itemsepi}\setlength{\my@beamer@itemsepi}{3ex}
\newlength{\my@beamer@itemsepii}\setlength{\my@beamer@itemsepii}{1.5ex}
\newlength{\my@beamer@itemsepiii}\setlength{\my@beamer@itemsepiii}{1.5ex}
\newcommand\setlistsep[3]{%
    \setlength{\my@beamer@itemsepi}{#1}%
    \setlength{\my@beamer@itemsepii}{#2}%
    \setlength{\my@beamer@itemsepiii}{#3}%
}
\xpatchcmd{\itemize}
  {\def\makelabel}
  {\my@beamer@setsep\def\makelabel}
 {}
 {}

\xpatchcmd{\beamer@enum@}
  {\def\makelabel}
  {\my@beamer@setsep\def\makelabel}
 {}
 {}
\makeatother


\begin{document}

\begin{frame}
    \begin{columns}[onlytextwidth, T]
        \begin{column}{.48\linewidth}
            % First column
            \begin{itemize}
                \item First item.
                    \begin{itemize}
                        \item First subitem.
                        \item Second subitem.
                            \begin{itemize}
                                \item First subsubitem.
                                \item Second subsubitem.
                                \item Third subsubitem.
                            \end{itemize}
                        \item Third subitem.
                    \end{itemize}
                \item Second item.
                \item Third item.
            \end{itemize}
        \end{column}%
        \hfill%
        \begin{column}{.48\linewidth}
            % second column
            \begin{enumerate}
                \item First item.
                    \begin{enumerate}
                        \item First subitem.
                        \item Second subitem.
                            \begin{enumerate}
                                \item First subsubitem.
                                \item Second subsubitem.
                                \item Third subsubitem.
                            \end{enumerate}
                        \item Third subitem.
                    \end{enumerate}
                \item Second item.
                \item Third item.
            \end{enumerate}
        \end{column}
    \end{columns}
\end{frame}

\end{document}

这样我就可以\setlistsep{2ex}{1ex}{1ex}在幻灯片中需要更改值的地方进行操作了。

如果您还想添加子列表中第一个项目的分隔，您可以将其更改\my@beamer@setsep为：

\newcommand{\my@beamer@setsep}{%
\ifnum\@itemdepth=1\relax
     \setlength\itemsep{\my@beamer@itemsepi}% separation for first level
   \else
     \ifnum\@itemdepth=2\relax
       \setlength\itemsep{\my@beamer@itemsepii}% separation for second level
       \setlength\topsep{\my@beamer@itemsepii}% separation for second level
     \else
       \ifnum\@itemdepth=3\relax
         \setlength\itemsep{\my@beamer@itemsepiii}% separation for third level
         \setlength\topsep{\my@beamer@itemsepiii}% separation for second level
   \fi\fi\fi}

获得

...或者也许最好使用以前的 itemsep 作为topsep：

\newcommand{\my@beamer@setsep}{%
\ifnum\@itemdepth=1\relax
     \setlength\itemsep{\my@beamer@itemsepi}% separation for first level
   \else
     \ifnum\@itemdepth=2\relax
       \setlength\itemsep{\my@beamer@itemsepii}% separation for second level
       \setlength\topsep{\my@beamer@itemsepi}% separation for second level
     \else
       \ifnum\@itemdepth=3\relax
         \setlength\itemsep{\my@beamer@itemsepiii}% separation for third level
         \setlength\topsep{\my@beamer@itemsepii}% separation for second level
   \fi\fi\fi}

（只是个人喜好问题）