2

My question Drawing an ellipse around an edge in forest resulted in the following code with a forest style circle edge. I want to show and hide this edge for presentations with beamerbut cannot figure out how to do this. I already found visible on but I cannot combine this with the forest style.

\documentclass{beamer}

\usepackage[linguistics]{forest}

\usetikzlibrary{shapes.geometric,fit}

\forestset{%
  circle edge/.style={
    tikz+={
          \node [fit=(.child anchor) (!u.parent anchor), draw=red, ellipse, inner ysep=1.5pt, line
            width=0.25mm] {};
        }
  },
}

\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}} % \pgfkeysalso doesn't change the path
    },
}
\forestset{
  visible on/.style={
    for ancestors'={
      /tikz/visible on={#1},
      edge={/tikz/visible on={#1}}}}}



\begin{document}

\frame{

\begin{forest}
[S
  [NP$_x$ [he,tier=words]]
  [VP
    [V x z y
      [V x y, circle edge={/tikz/visible on=<3>}
        [baked]]]
    [NP$_z$ [her,tier=words]]
    [NP$_y$ [a cake,roof,tier=words]]]]
\end{forest}

\pause\pause\pause



}

\end{document}

Edit: My solution below works for simple cases like <3->but it fails for <2,4>because of the comma. Is there a way to get the comma through to beamer?

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Stefan Müller
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2 Answers2

5

Found the answer here Using beamer overlays with forest generated trees. One can call the visible on style in circle edge and pass the <3-> information as an argument. An open issue is how to pass <2,4>. The comma is a problem.

The only disadvantage of this is that one cannot pass the color argument for the color of the ellipse without having two arguments.

\documentclass{beamer}

\usepackage[linguistics]{forest}

\usetikzlibrary{shapes.geometric,fit}

\forestset{%
  circle edge/.style={
    tikz+={
          \node [fit=(.child anchor) (!u.parent anchor), draw=red, visible on=#1, ellipse, inner ysep=1.5pt, line
            width=0.25mm] {};
        }
  },
}

\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}} % \pgfkeysalso doesn't change the path
    },
}

\begin{document}

\frame{

\begin{forest}
[S
  [NP$_x$ [he,tier=words]]
  [VP
    [V x z y
      [V x y, circle edge=<3->
        [baked]]]
    [NP$_z$ [her,tier=words]]
    [NP$_y$ [a cake,roof,tier=words]]]]
\end{forest}

\pause\pause\pause



}

\end{document}
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Stefan Müller
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  • You don't actually need the \forestset visible on part here - you aren't using it at all. – cfr Feb 25 '17 at 01:15
  • I am very sorry. This is really embarrassing. Usually I do this and I also have the URL in the code I use. I removed it from the code here since it does not belong there, but I should have provided it in the description. Did this now. – Stefan Müller Feb 26 '17 at 08:26
  • Do you know a way to deal with <2,4>? – Stefan Müller Feb 26 '17 at 08:33
  • 1
    Please see my answer below. You can declare a toks for the colour and just need curly brackets to deal with the comma. – cfr Feb 26 '17 at 23:19
  • I tried the curly brackets everywhere but inside the angle brackets. Thanks! – Stefan Müller Feb 27 '17 at 08:32
3

You can deal with the comma in an overlay specification by using curly brackets around it. 

          [V x y, circle edge=<{2,4}>

You can control the colour of the ellipse, without use of a second argument, by declaring a toks option.

For example, use circle edge colour for the colour and then use this option as the value for draw when drawing the node.

\forestset{%
  circle edge/.style={
    tikz+={
      \node [fit=(.child anchor) (!u.parent anchor), visible on=#1, ellipse, inner ysep=1.5pt, line
      width=0.25mm, draw=\foresteoption{circle edge colour}] {};
    },
  },

Declare the option and set the default for a red ellipse.

  declare toks={circle edge colour}{red},
}

Putting this together, we can create a blue ellipse on slides 2 and 4.

          [V x y, circle edge=<{2,4}>, circle edge colour=blue

ellipse on slides 2 and 4 in non-default blue

Complete code (note that the \pause\pause\pause is superfluous as far as I can tell):

% addaswyd o ateb (a chwestiwn) Stefan Müller: http://tex.stackexchange.com/a/355485/
\documentclass{beamer}
\usepackage[linguistics]{forest}
\usetikzlibrary{shapes.geometric,fit}
\forestset{%
  circle edge/.style={
    tikz+={
      \node [fit=(.child anchor) (!u.parent anchor), visible on=#1, ellipse, inner ysep=1.5pt, line
      width=0.25mm, draw=\foresteoption{circle edge colour}] {};
    },
  },
  declare toks={circle edge colour}{red},
}

\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
  },
}
\begin{document}

\begin{frame}
  \centering
  \begin{forest}
    [S
      [NP$_x$ [he,tier=words]]
      [VP
        [V x z y
          [V x y, circle edge=<{2,4}>, circle edge colour=blue
            [baked]]]
        [NP$_z$, calign with current [her,tier=words]]
        [NP$_y$ [a cake,roof,tier=words]]]]
  \end{forest}
\end{frame}

\end{document}
cfr
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