在 Beamer 中，块内和块外部的条目使用不同的颜色吗？

Question

我希望获得我在以下 MWE 中描述的内容，即符号itemize应该是

• 黑色外部块；
• 蓝色普通的块；
• 警报块中为红色；
• 示例块中为绿色。

梅威瑟：

\documentclass{beamer}
\begin{document}
\begin{frame}
\begin{itemize} 
\item Here in blue, I'd like it in black. 
\end{itemize}
\begin{block}{A block}
  \begin{itemize} 
  \item Here in blue, I'd like keep it in blue. 
  \end{itemize}
\end{block}
\begin{alertblock}{An alert block}
  \begin{itemize} 
  \item Here in red, I'd like keep it in red. 
  \end{itemize}
\end{alertblock}
\begin{exampleblock}{An example block}
  \begin{itemize} 
  \item Here in green, I'd like keep it in green. 
  \end{itemize}
\end{exampleblock}
\end{frame}
\end{document}

如果我查看beamercolorthemedefault.sty，我会看到items 使用以下颜色进行着色local structure：

• 如果我把 改为local structure黑色，普通的块变黑；
• 如果我直接将item颜色改为黑色，那么所有块都是黑色。

那么，获得期望结果的正确方法是什么？

Answer 1

我会将普通文本的颜色设置local structure为黑色，然后在启动普通块时将其更改为再次匹配的颜色structure。这可以通过将颜色的重新定义添加到 beamer 模板来实现block begin：

\documentclass{beamer}

\setbeamercolor{local structure}{parent=normal text}
\addtobeamertemplate{block begin}{\setbeamercolor{local structure}{parent=structure}}{}

\begin{document}
\begin{frame}
\begin{itemize} 
\item Here in blue, I'd like it in black. 
\end{itemize}
\begin{block}{A block}
  \begin{itemize} 
  \item Here in blue, I'd like keep it in blue. 
  \end{itemize}
\end{block}
\begin{alertblock}{An alert block}
  \begin{itemize} 
  \item Here in red, I'd like keep it in red. 
  \end{itemize}
\end{alertblock}
\begin{exampleblock}{An example block}
  \begin{itemize} 
  \item Here in green, I'd like keep it in green. 
  \end{itemize}
\end{exampleblock}
\end{frame}
\end{document}

Answer 2

一种可能性是设置itemize item颜色设置为黑色。这将影响全部环境itemize，然后借助包，etoolbox您可以恢复块内的所需颜色：

\usepackage{etoolbox}
\setbeamercolor{itemize item}{fg=black}
\AtBeginEnvironment{block}{\setbeamercolor{itemize item}{fg=structure}}
\AtBeginEnvironment{alertblock}{\setbeamercolor{itemize item}{fg=block title alerted.fg}}
\AtBeginEnvironment{exampleblock}{\setbeamercolor{itemize item}{fg=block title example.fg}}

完整示例：

\documentclass{beamer}
\usepackage{etoolbox}

\setbeamercolor{itemize item}{fg=black}
\AtBeginEnvironment{block}{\setbeamercolor{itemize item}{fg=structure}}
\AtBeginEnvironment{alertblock}{\setbeamercolor{itemize item}{fg=block title alerted.fg}}
\AtBeginEnvironment{exampleblock}{\setbeamercolor{itemize item}{fg=block title example.fg}}

\begin{document}
\begin{frame}
\begin{itemize} 
\item Here in black, as desired. 
\end{itemize}
\begin{block}{A block}
  \begin{itemize} 
  \item Here in blue, I'd like keep it in blue. 
  \end{itemize}
\end{block}
\begin{alertblock}{An alert block}
  \begin{itemize} 
  \item Here in red, I'd like keep it in red. 
  \end{itemize}
\end{alertblock}
\begin{exampleblock}{An example block}
  \begin{itemize} 
  \item Here in green, I'd like keep it in green. 
  \end{itemize}
\end{exampleblock}
\end{frame}
\end{document}