在 Beamer 中收到警报时，用方框包围列表项

Question

要逐项提醒列表中的项目，我通常使用<alert@+>。例如，

\documentclass{beamer}
\begin{document}
    \begin{frame}
        \begin{itemize}[<alert@+>]
            \item one
            \item two
            \item three
        \end{itemize}
    \end{frame}
\end{document}

我们可以在每一步中在项目周围画一个框，而不是用警报。就像这样<boxaround@+>。

Answer 1

基于https://tex.stackexchange.com/a/107209/36296你可以做类似的事情：

\documentclass{beamer}
\usepackage{lmodern}
\usepackage{tikz}
\usetikzlibrary{calc}
\usepackage{xparse}

\tikzset{
    invisible/.style={opacity=0,text opacity=0},
    visible on/.style={alt=#1{}{invisible}},
    alt/.code args={<#1>#2#3}{%
        \alt<#1>{\pgfkeysalso{#2}}{\pgfkeysalso{#3}} 
    },
}

\tikzset{
    background fill/.style={fill=#1},
    background fill/.default={white},
    fill on/.style={alt=#1{}{background fill}},
}

\tikzset{
    background draw/.style={draw=#1},
    background draw/.default={white},
    draw on/.style={alt=#1{}{background draw}},
}

\tikzset{
    background filldraw/.style args={#1 filled by #2}{draw=#1, fill=#2},
    background filldraw/.default=white filled by white,
    filldraw on/.style={alt=#1{}{background filldraw}},
}

\pgfkeys{/highlight/.cd,
    above right offset/.initial={0.015,0.065},
    above right offset/.get=\aboverightoffset,
    above right offset/.store in=\aboverightoffset,
    below left offset/.initial={-0.015,-0.1},
    below left offset/.get=\belowleftoffset,
    below left offset/.store in=\belowleftoffset,
}

\tikzset{highlighting/.style={
        append after command={
            \pgfextra{
                \path[rounded corners,
                background filldraw=red filled by red!30,% border+filling
                filldraw on=<#1>, % overlay specification
                overlay] ($(\tikzlastnode.south west)+(\belowleftoffset)$) % to have some offset
                rectangle ($(\tikzlastnode.north east)+(\aboverightoffset)$);
            }   
        }
    }
}

\NewDocumentCommand{\highlight}{O{} m}{%
    \pgfkeys{/highlight/.cd,#1}
    \tikz[baseline=(A.base)] 
    \node[highlighting=.,
    inner sep=0pt] (A) {\textcolor{black}{#2}};%  
}


\begin{document}

    \begin{frame}{Itemize with styles}
        \begin{itemize}[<alert@+>]
            \item \highlight{one}
            \item \highlight{two}
            \item \highlight{three}
        \end{itemize}
    \end{frame}

\end{document}

---

编辑：

使用该库的简化版本overlay-beamer-styles：

\documentclass{beamer}
\usepackage{lmodern}
\usepackage{tikz}
\usetikzlibrary{calc}
\usepackage{xparse}

\usetikzlibrary{overlay-beamer-styles}

\pgfkeys{/highlight/.cd,
    above right offset/.initial={0.015,0.065},
    above right offset/.get=\aboverightoffset,
    above right offset/.store in=\aboverightoffset,
    below left offset/.initial={-0.015,-0.1},
    below left offset/.get=\belowleftoffset,
    below left offset/.store in=\belowleftoffset,
}

\tikzset{highlighting/.style={
        append after command={
            \pgfextra{
                \path[rounded corners,
                background filldraw=red filled by red!30,% border+filling
                filldraw on=<#1>, % overlay specification
                overlay] ($(\tikzlastnode.south west)+(\belowleftoffset)$) % to have some offset
                rectangle ($(\tikzlastnode.north east)+(\aboverightoffset)$);
            }   
        }
    }
}

\NewDocumentCommand{\highlight}{O{} m}{%
    \pgfkeys{/highlight/.cd,#1}
    \tikz[baseline=(A.base)] 
    \node[highlighting=.,
    inner sep=0pt] (A) {\textcolor{black}{#2}};%  
}


\begin{document}

    \begin{frame}{Itemize with styles}
        \begin{itemize}[<alert@+>]
            \item \highlight{one}
            \item \highlight{two}
            \item \highlight{three}
        \end{itemize}
    \end{frame}

\end{document}