[Tex/LaTex] How to get line width and inner sep values

key-valuepgfkeystikz-pgftikz-styles

I try to get the values of line widths and node inner sep. How to read such a value form own style (if it will be specified during modifications of the picture) or if it is not specified in this style, how to get the value applied by drawing line or node?

Code:

\documentclass{standalone}
\usepackage{tikz}

\begin{document}
\begin{tikzpicture}[
    every node/.style={line width=2pt},
    my line style/.style={very thick},
    my node style1/.style={draw,inner sep=1em},
    my node style2/.style={draw}
]
    \pgfkeys{/pgf/inner xsep/.get=\innerxsep}
    \node at (0,0) [my node style2,anchor=west] {x inner sep = \innerxsep};

    %\pgfkeys{ ????  /.get=\innerxsep} % how to read inner sep value applied while "my node style1" is used,
                                       % independently on if it is specified in this style?
                                       % how to read border width value applied while "my node stylei" is used,
                                       % independently on if it is specified in this style?
    \node at (0,-1) [my node style1,anchor=west] {x inner sep = ?, border width = ?};

    %\pgfkeys{ ????  /.get=\lw} % how to read line width value applied while "my line style" is used,
                                % independently on if it is specified in this style?
    \draw [my line style] (0,-2) -- +(1,0) node [right] {line width=?};
\end{tikzpicture}
\end{document}

I tried follow answers given by @Loop Space (Reading – and effect – of (default) tikz/pgf keys?) and by @Andrew Swann (Check the value of a pgfkey), but without success in my problem.

Best Answer

Your own style doesn't change any intrinsic properties of the line width and inner sep settings. So you can still use the regular key setting/reading ways.

\documentclass[tikz]{standalone}
\begin{document}
\begin{tikzpicture}[
    every node/.style={line width=2pt},
    my line style/.style={very thick},
    my node style1/.style={draw,inner sep=1em},
    my node style2/.style={draw}
]
    \node at (0,0) [my node style2,anchor=west] 
         {x inner sep = \pgfkeysvalueof{/pgf/inner xsep}};
    \node at (0,-1) [my node style1,anchor=west] 
         {x inner sep = \pgfkeysvalueof{/pgf/inner xsep}, border width = \the\pgflinewidth};
    \draw [my line style] (0,-2) -- +(1,0) node [right] {line width=\the\pgflinewidth};
\end{tikzpicture}
\end{document}

enter image description here

Related Solutions

[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}

enter image description here

[Tex/LaTex] Reading – and effect – of (default) tikz/pgf keys

Not every key sets a value.

A key can execute arbitrary code. If we look in tikz.code.tex then we see that when you invoke \tikzset{line width=2pt} then it doesn't set a value, it invokes \tikz@semiaddlinewidth{2pt}. This, in turn, expands to \tikz@addoption{\pgfsetlinewidth{2pt}}\pgfmathsetlength\pgflinewidth{2pt}.

There are two things going on here. One is that \pgfsetlinewidth is set up to be invoked at a later time. The other is that \pgflinewidth is set to the desired width. Now, \pgfsetlinewidth is the Real McCoy here. It sets the line width down in the depths of PGF's subsystem. All the messing around with \pgflinewidth doesn't actually set the real line width. It needs a genuine call to \pgfsetlinewidth to do this.

But the key /tikz/line width does not directly call \pgfsetlinewidth. It sets it up to be invoked at a later time. This is what \tikz@addoption does. These options get invoked once the path has been constructed and before it is rendered. But the option list is blanked at the start of a path construction. So the effect of the \tikz@addoption is nullified by the following \draw command before it has a chance to take effect.

You could do \tikzset{every path/.append style={line width=\pgflinewidth}} to ensure that the ambient line width is used as the default line width for every path. Or you could define a new key, \tikzset{ambient line width/.code={\pgfsetlinewidth{#1}}} (no need to explicitly set \pgflinewidth here).

As Paul Gaborit noted in the comments, you can achieve a change of line width for a group of paths by putting them in a scope and setting the line width in the optional argument to the scope. That is,

\begin{scope}[line width=1cm]
...
\end{scope}

sets the line width to 1cm for all the intervening paths.

The reason for this is that the optional arguments to the scope environment are passed to \tikzset and then immediately after, the token list \tikz@options is expanded. This means that the part of the line width key that is hidden in the \tikz@options token list is actually executed and therefore the line width is set properly deep in the heart of PGF.

Best Answer

Related Solutions

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

[Tex/LaTex] Reading – and effect – of (default) tikz/pgf keys

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