空间条目如何

Question

如何将每个项目之间的间距设置为 2ex、子项目之间的间距设置为 1ex、项目与其子项目之间的间距设置为 1ex、子项目与下一个项目之间的间距设置为 2ex？

我尝试按照以下方式进行：

\documentclass{beamer}
\makeatletter
\def\@listii{\leftmargin\leftmarginii
              \topsep    1ex
              \parsep    0\p@   \@plus\p@
              \itemsep   \parsep}
\makeatother
\begin{document}
    \begin{frame}
        \begin{itemize}
            \item Here are two interesting things:
            \begin{itemize}
                \item Here are two interesting things:
                \item Here are two interesting things:
            \end{itemize}
                \item Here are two interesting things:
                \item Here are two interesting things:
        \end{itemize}
    \end{frame}
\end{document}

提前致谢！

Answer 1

一个选项重新定义\itemize（如 中所定义），根据 的值beamerbaselocalstructure.sty有条件地设置（新代码由、表示）：\itemsep\@itemdepth% start change% end change

\documentclass{beamer}

\makeatletter
\renewcommand{\itemize}[1][]{%
  \beamer@ifempty{#1}{}{\def\beamer@defaultospec{#1}}%
  \ifnum \@itemdepth >2\relax\@toodeep\else
\advance\@itemdepth\@ne
\beamer@computepref\@itemdepth% sets \beameritemnestingprefix
\usebeamerfont{itemize/enumerate \beameritemnestingprefix body}%
\usebeamercolor[fg]{itemize/enumerate \beameritemnestingprefix body}%
\usebeamertemplate{itemize/enumerate \beameritemnestingprefix body begin}%
\list
  {\usebeamertemplate{itemize \beameritemnestingprefix item}}
  {\def\makelabel##1{%
  {%
\hss\llap{{%
\usebeamerfont*{itemize \beameritemnestingprefix item}%
\usebeamercolor[fg]{itemize \beameritemnestingprefix item}##1}}%
  }%
}%
% start change
\ifnum\@itemdepth=1\relax
\setlength\itemsep{2ex}
\else
\ifnum\@itemdepth=2\relax
\setlength\itemsep{1ex}
\fi\fi%
% end change
  }
  \fi%
  \beamer@cramped%
  \raggedright%
  \beamer@firstlineitemizeunskip%
}
\makeatother

\begin{document}

\begin{frame}
\begin{itemize}
\item Here are two interesting things:
  \begin{itemize}
  \item Here are two interesting things:
  \item Here are two interesting things:
  \item Here are two interesting things:
  \end{itemize}
\item Here are two interesting things:
\item Here are two interesting things:
\end{itemize}
\end{frame}

\end{document}

借助xpatch我们可以修补\itemize并且代码可以简化一些：

\documentclass{beamer}
\usepackage{xpatch}

\xpatchcmd{\itemize}
  {\def\makelabel}
  {\ifnum\@itemdepth=1\relax
     \setlength\itemsep{2ex}
   \else
     \ifnum\@itemdepth=2\relax
   \setlength\itemsep{1ex}
   \fi\fi\def\makelabel
  }
 {}
 {}

\begin{document}

\begin{frame}
\begin{itemize}
\item Here are two interesting things:
  \begin{itemize}
  \item Here are two interesting things:
  \item Here are two interesting things:
  \item Here are two interesting things:
  \end{itemize}
\item Here are two interesting things:
\item Here are two interesting things:
\end{itemize}
\end{frame}

\end{document}