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附言

tag-icon • tag-icon tikz-pgf beamer overlays forest
附言

以下代码在 Beamer 框架中逐级揭示森林树。但是，阴影会同时出现，而不是与节点一起出现。我该如何调整代码，使阴影与投射阴影的节点保持一致？

\documentclass{beamer}
\usepackage{forest}
\tikzset{% set up for transitions using tikz with beamer overlays - developed by Daniel (http://tex.stackexchange.com/a/55849/) and, in earlier form, by Matthew Leingang (http://tex.stackexchange.com/a/6155/) and modified for this use, I think by Qrrbrbirlbel (http://tex.stackexchange.com/a/112471/)
    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}} % \pgfkeysalso doesn't change the path
    },
}
\forestset{%
  visible with edge from/.style={% based on visible on, developed by Qrrbrbirlbel (http://tex.stackexchange.com/a/112471/)
    /tikz/visible on=<#1->,
    /tikz/every label/.append style={visible on=<#1->},
    edge={/tikz/visible on=<#1->},
  },
}
\usetikzlibrary{shadows}
\begin{document}

\begin{frame}
  \begin{forest}
    for tree={
      draw,
      fill=white,
      drop shadow,
    },
    before typesetting nodes={
      for tree={
        tempcounta/.option=level,
        tempcounta'+=1,
        visible with edge from/.register=tempcounta,
      }
    }
    [first slide
      [second slide[third slide][third slide]]
      [second slide]
    ]
  \end{forest}
\end{frame}

\end{document}

问题如下：

无节点的阴影

我以为我见过这个代码，但我似乎找不到重复的代码。特别是，我希望至少我以前没有问过这个问题！

答案1

不妨这样：我们不再处理\beamer@slideinframe，而是追踪对象的不透明度，并将该不透明度应用于其阴影。如下所示

\def\tikzshadowopacityregister{1}
\tikzset{
  invisible/.append code={\def\tikzshadowopacityregister{0}},
  every shadow/.style={opacity=\tikzshadowopacityregister}
}

（将此放在后面，\usetikzlibrary{shadows}否则every shadow将被删除。）

这种策略在以下方面更加灵活：即使有一天有人想出了一些\setbeamercovered以复杂的方式设置不透明度的方法，我们只需要通过全局宏走私结果并将其应用于阴影。

附言

我上面的方法与@Dr. Manuel Kuehner 非常相似。为了避免抄袭丑闻，这里有一个更灵活的版本

\makeatletter
\def\tikzopacityregister{1}
\tikzset{
  opacity/.append code={
    \pgfmathsetmacro\tikzopacityregister{#1*\tikzopacityregister}
  },
  opacity aux/.code={ % this is the original definition of opacity
    \tikz@addoption{\pgfsetstrokeopacity{#1}\pgfsetfillopacity{#1}}
  },
  every shadow/.style={opacity aux=\tikzopacityregister}
}

答案2

这是评论以某种我不太理解的方式向我暗示的。也就是说，它实际上似乎与评论中的建议无关，我不理解并且无法使之发挥作用。但我在尝试使其发挥作用后立即想到了这一点，这表明存在着不平凡的联系。

我不喜欢这个解决方案，因为它需要为每个 drop-shadow-like-item 创建额外的样式，然后将其与主覆盖规范分开应用。这很容易出错，而我却很擅长处理错误。

然而，严格来说，它确实回答了我提出的具体问题，所以也许它会启发某人提供更令人满意的方法。

\documentclass{beamer}
\usepackage{forest}
\tikzset{% set up for transitions using tikz with beamer overlays - developed by Daniel (http://tex.stackexchange.com/a/55849/) and, in earlier form, by Matthew Leingang (http://tex.stackexchange.com/a/6155/) and modified for this use, I think by Qrrbrbirlbel (http://tex.stackexchange.com/a/112471/)
    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}} % \pgfkeysalso doesn't change the path
    },
}
\forestset{%
  visible with edge from/.style={% based on visible on, developed by Qrrbrbirlbel (http://tex.stackexchange.com/a/112471/)
    /tikz/visible on=<#1->,
    /tikz/every label/.append style={visible on=<#1->},
    edge={/tikz/visible on=<#1->},
  },
  drop shadow visible from/.style={/tikz/alt=<#1->{drop shadow}{}},
}
\usetikzlibrary{shadows}
\begin{document}

\begin{frame}
  \begin{forest}
    for tree={
      draw,
      fill=white,
    },
    before typesetting nodes={
      for tree={
        tempcounta/.option=level,
        tempcounta'+=1,
        visible with edge from/.register=tempcounta,
        drop shadow visible from/.register=tempcounta,
      }
    }
    [first slide
      [second slide[third slide][third slide]]
      [second slide]
    ]
  \end{forest}
\end{frame}

\end{document}

带节点的阴影

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