在投影機的 itemize 環境中使用文字作為標籤

Question

我正在嘗試在投影機的逐項環境中使用文字作為標籤。

我用過

\documentclass{beamer}

\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage[english]{babel}
\usepackage{enumitem}

\setitemize{%
    label=\usebeamerfont*{itemize item}
    \usebeamercolor[fg]{itemize item}
    \usebeamertemplate{itemize item}
}

\begin{document}

\begin{frame}

\begin{itemize}
\item \makebox[2.75cm][l]{$a$} iff $a$,
\item \makebox[2.75cm][l]{$b+c$} iff $a$,
\item \makebox[2.75cm][l]{$d$} iff $a$
\item \makebox[2.75cm][l]{$e+f$} iff $a$ and a lot of text which takes up multiple lines without correct alignment
\end{itemize}

\vfill

\begin{itemize}
\item[$a$] iff $a$,
\item[$b+c$] iff $a$,
\item[$d$] iff $a$
\item[$e+f$] iff $a$
\end{itemize}

\end{frame}

\end{document}

生產

第一個 itemize 環境中的問題是我需要第二行與上面一行中的“iff $a$ and ...”對齊。

我嘗試透過在 itemize 環境中使用標籤而不是\makebox.但如果我這樣做，我仍然沒有定義標籤的寬度，並且我丟失了藍色的逐項項目符號/箭頭。

Answer 1

通常，beamer不能很好地配合enumitem，存在著許多相容性問題。這是解決您的問題的（不太乾淨的）技巧。不過，它會破壞覆蓋選項。

\documentclass{beamer}
\usepackage{lmodern}
\usepackage[T1]{fontenc}
\usepackage[english]{babel}
\usepackage{enumitem}

\setitemize{%
    label=\usebeamerfont*{itemize item}
    \usebeamercolor[fg]{itemize item}
    \usebeamertemplate{itemize item}
}


\makeatletter
\def\Myitemize#1{%
  \advance\beamer@descdefault by \labelsep%
  \list
  {}
  {\labelwidth\beamer@descdefault%
  \leftmargin\beamer@descdefault%
  \let\makelabel\beamer@descriptionitem
  \settowidth\labelwidth{\beamer@descriptionitem{#1}}%
  \setlength\leftmargin{\labelwidth}% 
  \addtolength\leftmargin{\labelsep}%
  }%
  \beamer@cramped%
  \raggedright
  \beamer@firstlineitemizeunskip%
}
\def\endMyitemize{\ifhmode\unskip\fi\endlist}
\long\def\beamer@descriptionitem#1{%
  \def\insertdescriptionitem{#1}%
  {\usebeamertemplate**{description item}}\hfil}
\makeatother  


\begin{document}

\begin{frame}

\begin{Myitemize}{$\blacktriangleright$ $b+c$} % <= longest label here
\item [$\blacktriangleright$ $a$  ] iff $a$,
\item [$\blacktriangleright$ $b+c$] iff $a$,
\item [$\blacktriangleright$ $d$  ] iff $a$,
\item [$\blacktriangleright$ $e+f$] iff $a$ and a lot of text which takes up multiple lines without correct alignment
\end{Myitemize}

\end{frame}

\end{document}

編輯：

更好的方法是這樣的：

\begin{itemize}
\item \makebox[2cm][l]{$a$}   iff $a$,
\item \makebox[2cm][l]{$b+c$} iff $a$,
\item \makebox[2cm][l]{$d$}   iff $a$,
\item \makebox[2cm][l]{$e+f$} \begin{minipage}[t]{7cm}
iff $a$ and a lot of text which takes up multiple lines without correct alignment, and a lot of text which takes up multiple lines without correct alignment
\end{minipage}
\end{itemize}