[Tex/LaTex] How to “execute at begin node” be used with special characters like curly braces? (or: how to raise node content)

hookstikz-pgftikz-styles

I'd like to define the following style:

test/.style={
    execute at begin node={\raisebox\{-0.2cm\}\{},
    execute at end node={\}}
}

and use it like

\documentclass{article} 
\usepackage{tikz}

\tikzset{
    test/.style={
        execute at begin node={\raisebox\{-0.2cm\}\{},
        execute at end node={\}}
    }
}

\begin{document}

    \begin{tikzpicture}
        \node[test,circle,draw] {g};    
    \end{tikzpicture}

\end{document}

But it seems to be wrong, as I get errors like "! Extra }, or forgotten \endgroup" or "Missing number, treated as zero".

I guess the problem is due to the braces. How can I escape them properly?

EDIT: From the answers it became clear that \raisebox alone (like I tried in my broken solution) would've somehow worked in my case (because the dimension was so small that it didn't change the node size (at least I can't see it), which is what I wanted). So I consider all answers correct that only handled this specific/simple case. Answers using \smash and \phantom solved the problem I had actually in mind (but which I didn't clearly formulate as a question). Thanks again for all the great answers! 🙂

WARNING: As already said by percusse, if one only wants to align the text baselines, don't use this! Instead, as described in the "Putting a Diagram in Chains" tutorial of the manual, use text height and text depth on all nodes to be aligned, e.g. text height=1.5ex,text depth=.25ex.

Best Answer

If I want to do something with the node’s content (which, to my recollection, cannot be accessed by a key), I collect it in a savebox via the lrbox environment.

In the following example, the text is saved in the savebox \qrrTikzNodeContent and then, still in the execute at end node key, used.

Firstly it is typeset in \phantom so that the node gets re-sized appropriately (as if the content would be typeset as usual). The following \usebox command is firstly \llaped to occupy the same horizontal space like its phantom-ed version, and than \smashed so that it doesn’t occupy any vertical space.

I added some hopefully useful keys, that should help how \raisebox may affect the node:

phantom re-sizes the node as if the content would be typeset in the usual way;
smash deactivates re-sizing of the node as forced by \raisebox.

This does not work with the keys text width and align as \tikz@atbegin@node is executed after the minipage is applied that is used to realize those keys.

For this special use-case I want to point out that there’s also the text depth key. For <content> without a depth setting this to <value> is like a \raisebox{<value>}{<depth>}.

The following code procudes a matrix of nodes:

  normal        raise            raise + phantom
text depth  raise + smash    raise + phantom + smash

Additionally it shows the baseline of the node.

Code

\documentclass[tikz]{standalone}
\newsavebox\qrrTikzNodeContent
\newif\ifphantom% remove for 'clean' version
\newif\ifsmash  % remove for 'clean' version
\tikzset{
  nodes={draw,circle},
  bl/.style={append after command={\pgfextra{\draw[very thin] (\tikzlastnode.base west) -- (\tikzlastnode.base east);}}},% debug, remove for 'clean' version
  phantom/.is if=phantom,% remove for 'clean' version
  smash/.is if=smash,    % remove for 'clean' version
  raise/.style={
    execute at begin node={\begingroup\begin{lrbox}{\qrrTikzNodeContent}},
    execute at end node={\end{lrbox}% remove for 'clean' version
      \ifphantom
          \phantom{\usebox\qrrTikzNodeContent}%
      \fi
      \ifsmash\smash{\fi
        \ifphantom\llap{\fi
          \raisebox{#1}{\usebox\qrrTikzNodeContent}%
        \ifphantom}\fi
      \ifsmash}\fi
      \endgroup
    },
%    execute at end node={\end{lrbox}% 'clean' version
%      \phantom{\usebox\qrrTikzNodeContent}%
%      \smash{%
%        \llap{%
%          \raisebox{#1}{\usebox\qrrTikzNodeContent}%
%        }%
%      }%
%      \endgroup
%    }
  },
}
\begin{document}
  \begin{tikzpicture}
    \matrix[draw=none, append after command={}, row sep=1ex, column sep=1ex] {
      \node[bl,                            ] {g}; &
      \node[bl, raise=-.2cm,               ] {g}; &  % only raisebox
      \node[bl, raise=-.2cm,        phantom] {g}; \\ % phantom
      \node[bl, text depth=-.2cm           ] {g}; &  % text depth
      \node[bl, raise=-.2cm, smash,        ] {g}; &  % smash
      \node[bl, raise=-.2cm, smash, phantom] {g}; \\ % smash + phantom
    };
  \end{tikzpicture}

  \begin{tikzpicture}
    \matrix[draw=none, append after command={}, row sep=1ex, column sep=1ex] {
      \node[bl,                            ] {h}; &
      \node[bl, raise=-.2cm,               ] {h}; &  % only raisebox
      \node[bl, raise=-.2cm,        phantom] {h}; \\ % phantom
      \node[bl, text depth=-.2cm           ] {h}; &  % text depth
      \node[bl, raise=-.2cm, smash,        ] {h}; &  % smash
      \node[bl, raise=-.2cm, smash, phantom] {h}; \\ % smash + phantom
    };
  \end{tikzpicture}
\end{document}

Output

enter image description here

Related Solutions

[Tex/LaTex] Using execute at begin node with \phantom and \pgfuseimage in TikZ

There's a lot of information buried in the comments so I'm going to try to extract my contributions into some form of answer. My recommended solution is to use pgfkeys. The key lengths can be short - single letter if really wanted - so the number of key strokes needed to use them is not really that much more than putting the picture name in the node text. Indeed, if you are going to use names that match some pattern (as in the example), there's no need to specify the picture name at all whereupon it isn't necessary to use any key in the actual node commands. Or you could patch into the unknown key handler so that an unknown key is taken to the the name of a picture. The pgfkeys method is the most robust, I think, and the most flexible. For example, it will work with matrix of nodes.

Second in my list of solutions would be Jake's solution of defining an entirely new macro. The only downside to this is that it doesn't work transparently with matrix of nodes (that is, you can always put the new macro into the cells but you can't take advantage of the automatically inserted nodes).

Way, way down at the bottom of my list is a hack that allows you to actually do what you originally asked: use the node text as the argument to a macro. This is a Very Bad Idea for lots of reasons. Firstly, it involves modifying the TikZ node processing commands directly rather than via hooks. Secondly, the opening bracket of the node text is actually removed before TikZ starts its node machinery (this is what TikZ looks for to know to start processing the text and the test is destructive) so we have to put it back again and this means More Hackery. It is not possible to insert stuff in the begin node/end node hooks for two reasons: Firstly, what appears between those two hooks is not just the node text. It is:

\bgroup%
  \aftergroup\unskip%
  \ifx\tikz@textcolor\pgfutil@empty%
  \else%
   \pgfutil@colorlet{.}{\tikz@textcolor}%
  \fi%
  \pgfsetcolor{.}%
  \setbox\tikz@figbox=\box\pgfutil@voidb@x%
  \tikz@uninstallcommands%
  \aftergroup\tikz@fig@collectresetcolor%
  \tikz@halign@check%
  \ignorespaces%

followed by the node text. There's even more junk after the node text and before the end hook is called. So if we want to get at the actual node text we need to add something after that \ignorespaces and it has to have a genuine opening brace.

Here's code illustrating all the above-mentioned solutions.

\documentclass{article}

\usepackage{tikz}

\pgfdeclareimage{firstpicture}{vignettes.pdf}
\pgfdeclareimage{secondpicture}{vignettes.pdf}
\pgfdeclareimage{thirdpicture}{vignettes.pdf}
\pgfdeclareimage{fourthpicture}{vignettes.pdf}

\makeatletter
\newif\if@pgfimagefound
\tikzset{
  dummy image with key/.style={
    every node/.append style={%
      execute at end
node=\phantom{\pgfuseimage{\pgfkeysvalueof{/tikz/pname}}}
    },
  },
  pname/.initial={},
  dummy image/.style={
    every node/.append style={%
      execute at end
node=\phantom{\pgfuseimage{\pgfkeysvalueof{/tikz/pname}}},
    /tikz/.unknown/.add code=%
    {%
      \@ifundefined{pgf@image@\pgfkeyscurrentname!}{\@pgfimagefoundfalse}{%
        \let\tikz@key=\pgfkeyscurrentname
        \tikzset{pname/.expand once=\tikz@key}%
        \@pgfimagefoundtrue
      }%
      \if@pgfimagefound
      \else
    }%
    {
      \fi
    }
    }
  }
}

\let\orig@tikz@do@fig=\tikz@do@fig
\tikzset{
  slurp node text/.code={
    \def\tikz@do@fig{\orig@tikz@do@fig\expandafter\slurp@node\expandafter{\iffalse}\fi}
  },
  slurp node/.style={
    every node/.append style={
      slurp node text
    },
    slurp node command/.code={#1}
  },
}
\def\slurp@node#1{%
\pgfkeys{/tikz/slurp node command={#1}}%
\egroup}

\newcommand\imgnode[2][]{%
  \node[#1] {\phantom{\pgfuseimage{#2}}};}

\makeatletter
\begin{document}
\tikzset{every node/.append style={draw}}
\begin{tikzpicture}
\matrix [dummy image with key]
{
  \node[pname=firstpicture] {}; & \node[pname=secondpicture] {}; \\
  \node[pname=thirdpicture] {}; & \node[pname=fourthpicture] {}; \\
};
\end{tikzpicture}

\begin{tikzpicture}
\matrix [dummy image]
{
  \node[firstpicture] {}; & \node[secondpicture] {}; \\
  \node[thirdpicture] {}; & \node[fourthpicture] {}; \\
};
\end{tikzpicture}

\begin{tikzpicture}
\matrix
{
  \imgnode{firstpicture} & \imgnode{secondpicture} \\
  \imgnode{thirdpicture} & \imgnode{fourthpicture} \\
};
\end{tikzpicture}

\begin{tikzpicture}
\matrix [slurp node={\phantom{\pgfuseimage{#1}}}] {
  \node {firstpicture}; & \node {secondpicture}; \\
  \node {thirdpicture}; & \node {fourthpicture}; \\
};
\end{tikzpicture}
\end{document}

[Tex/LaTex] How to define the default vertical distance between nodes

I don't really get the question so I hope this is what you wanted. If you include a full document (such that we copy paste and see the problem on our systems) things are much more easier.

Here, you can change the default setting within a scope but your block style had a node distance which was resetting every time it is issued. I've made it 2mm such that we can see the difference easier.

\documentclass[tikz]{standalone}
\usetikzlibrary{arrows,shapes.geometric,positioning}

\begin{document}
\begin{tikzpicture}[decision/.style={diamond, draw, text width=4.5em, text badly centered, node distance=3.5cm, inner sep=0pt},
                    block/.style   ={rectangle, draw, text width=6em, text centered, rounded corners, minimum height=4em, minimum height=2em},
                    cloud/.style   ={draw, ellipse, minimum height=2em},
                    line/.style    ={draw,-latex'},
                    node distance = 1cm, 
                    auto]
    \node [block] (1st) {1st};
    \node [block, right= of 1st]  (2nd1) {2nd1};
\begin{scope}[node distance=2mm and 10mm]%Here we change it for everything inside this scope
    \node [block, above= of 2nd1] (2nd2) {2nd2};
    \node [block, below= of 2nd1] (2nd3) {2nd3};
    \node [block, right= of 2nd1] (3rd1) {3rd1};
    \node [block, above= of 3rd1] (3rd2) {3rd2};
    \node [block, above= of 3rd2] (3rd3) {3rd3};
\end{scope}
    \node [block, below= of 3rd1] (3rd4) {3rd4};
    \node [block, below= of 3rd4] (3rd5) {3rd5};

    \path [line] (1st) -- (2nd1);
    \path [line] (2nd1) -- (2nd2);
    \path [line] (2nd1) -- (2nd3);
    \path [line] (2nd2) -- (3rd3);
    \path [line] (2nd1) -- (3rd1);
    \path [line] (1st) -- (2nd1);
\end{tikzpicture}
\end{document}