Beamer 覆盖和 Tikz 图层问题

Question

这些角度应该出现在第二张幻灯片上，但是却没有。

\documentclass{beamer}

\usepackage{tikz}
\usetikzlibrary{angles}

\pgfdeclarelayer{background}
\pgfdeclarelayer{foreground}
\pgfsetlayers{background,main,foreground}

\begin{document}
\begin{frame}

\hfill \begin{tikzpicture}


\onslide<+->{
\draw[scale=1.5,rotate=118] (0,0) coordinate (A)
        --++(1,0) coordinate (B)
        --++(120:2) coordinate (C)
        --cycle ;
}

\onslide<+->{%
    \begin{pgfonlayer}{background}
    \draw pic[%
        semithick,
        fill=blue!25,
        angle radius=.7cm
        ] {angle=A--C--B} ;
    \draw pic[%
        semithick,
        fill=red!25,
        angle radius=.7cm
        ] {angle=C--B--A} ;
    \end{pgfonlayer}
    }

\end{tikzpicture}\hfill\strut
\end{frame}
\end{document}

Answer 1

你也可以 \onslide使用visible onhttps://tex.stackexchange.com/a/55849/36296可通过 方便地获取\usetikzlibrary{overlay-beamer-styles}。

\documentclass{beamer}

\usepackage{tikz}
\usetikzlibrary{angles}

\pgfdeclarelayer{background}
\pgfdeclarelayer{foreground}
\pgfsetlayers{background,main,foreground}

\usetikzlibrary{overlay-beamer-styles}

\begin{document}
\begin{frame}

\hfill 
\begin{tikzpicture}

\draw[scale=1.5,rotate=118] (0,0) coordinate (A)
        --++(1,0) coordinate (B)
        --++(120:2) coordinate (C)
        --cycle ;

\begin{pgfonlayer}{background}
\draw pic[%
    semithick,
    fill=blue!25,
    angle radius=.7cm,
    visible on=<+(1)->
    ] {angle=A--C--B} ;
\draw pic[%
    semithick,
    fill=red!25,
    angle radius=.7cm,
    visible on=<+->
    ] {angle=C--B--A} ;
\end{pgfonlayer}

\end{tikzpicture}\hfill\strut
\end{frame}
\end{document}