new command, pfgkeys within pfgplots axis environment

Question

I am trying to setup an command to create technical drawing dimensions (inspiration from Dimensioning of a technical drawing in TikZ).

I would like to use pgfkeys for that, in order to pass multiple optional arguments in the same spirit of TikZ.

I works pretty fine (at least I can get what I need) except within an axis environment (from pgfplots). I seems that all pgfkeys from all dimline calls are overridden by the last one.

I am using last MacTex for MacOSX.

I am compiling the source using:

/usr/texbin/xelatex -interaction nonstopmode -shell-escap -output-directory . test3.tex

Any idea why the axis environment zaps all dimline options?

Here is my code:

\documentclass{article}
\usepackage{tikz}
\usepackage{pgfplots}
\usetikzlibrary{calc}

\pgfkeys{
  dimline/.is family,
  dimline,
  dimcolor/.initial = black,
  start line/.initial=1cm,
  start line width/.initial=0.01,
  end line/.initial=1cm,
  end line width/.initial=0.01,
  label pos/.initial={},
}

% #1: optional keys parameters
% #2: start point
% #3: end point
% #4: text

\newcommand{\dimline}[4][]{%

  \pgfkeys{
    dimline,
    #1,
    start line width/.get=\dimlinestartlinewidth,
    start line/.get=\dimlinestartline,
    end line/.get=\dimlineendline,
    end line width/.get=\dimlineendlinewidth,
    label pos/.get=\labelpos,
  }

  \begin{scope}[
    dimrecall/.style={\pgfkeysvalueof{/dimline/dimcolor}},
    dimline/.style={\pgfkeysvalueof{/dimline/dimcolor}},
    ]

    \node (a) at #2 {};
    \node (b) at #3 {};

    \draw [/tikz/dimrecall, line width=\dimlinestartlinewidth]
    (a.center) -- ($(a)!\dimlinestartline!-90:(b)$);
    \draw [dimrecall, line width=\dimlineendlinewidth]
    (b.center) -- ($(b)!\dimlineendline!90:(a)$);

    \draw[|<->|, dimline,] (a.center) -- (b.center)
    node[fill=white, sloped, midway] {\tiny{#4}};
  \end{scope}
}


\begin{document}

Correct without \texttt{axis} environment:

\begin{tikzpicture}
  \draw  (0,0) -- (0,4) -- (.5,4) -- (.5,5) -- (1.,5) -- (1.,4) -- (1.5,4) -- (1.5,0) -- cycle;
  \dimline[dimcolor=blue,start line=-0.25, end line=-0.25]{(3,0)}{(3,4)}{4.0};
  \dimline[dimcolor=red,start line=0.85, end line=0.85]{(0,6)}{(1.5,6)}{1.5};
\end{tikzpicture}


Incorrect within \texttt{axis} environment \texttt{pgfkeys} are overriden:

\begin{tikzpicture}
  \begin{axis} [
    xmin = -1,
    xmax = 8,
    ymin = -1,
    ymax = 8]

    \addplot[mark=none,  color=black] coordinates {
      (0,0)  (0,4) (.5,4) (.5,5) (1.,5) (1.,4) (1.5,4) (1.5,0) (0,0)
    };

    \dimline[dimcolor=blue,start line=-0.25, end line=-0.25]{(axis cs: 3,0)}{(axis cs:3,4)}{4.0};
    \dimline[dimcolor=red,start line=0.85, end line=0.85]{(axis cs: 0,6)}{(axis cs: 1.5,6)}{1.5};

  \end{axis}

\end{tikzpicture}

\end{document}

and the result

Answer 1

While Jake's answer is the actual solution to the problem, here is a slight improvement on the UI. Let the macro \dimline deal with

• if you need to use (axis cs: x, y) or (x, y),
• if the \pgfplotsextra needs to be applied or not.

The, both the axis and tikzpicture solutions use an identical format:

\dimline[dimcolor=blue,start line=-0.25, end line=-0.25]{3,0}{3,4}{4.0};
\dimline[dimcolor=red,start line=0.85,   end line=0.85 ]{0,6}{1.5,6}{1.5};

to yield:

---

References:

• Determine if within a PGF axis environment

Notes:

• The way the coordinates are specified has been changed in that the () around them have been removed. Perhaps there is a way to allow for that as well.

---

Code:

\documentclass{article}
\usepackage{tikz}
\usepackage{pgfplots}
\usetikzlibrary{calc}

\pgfkeys{
  dimline/.is family,
  dimline,
  dimcolor/.initial = black,
  start line/.initial=1cm,
  start line width/.initial=0.01,
  end line/.initial=1cm,
  end line width/.initial=0.01,
  label pos/.initial={},
}

% #1: optional keys parameters
% #2: start point
% #3: end point
% #4: text


\newcommand{\DoNothing}[1]{#1}%
\newcommand{\dimline}[4][]{%
\pgfplotsifinaxis{%
    \coordinate (a) at (axis cs: #2) {};
    \coordinate (b) at (axis cs: #3) {};
    \let\MyPgfplotsextra\pgfplotsextra%
}{%
    \coordinate (a) at (#2) {};
    \coordinate (b) at (#3) {};
    \def\MyPgfplotsextra#1{#1}%
    \let\MyPgfplotsextra\DoNothing%
}%

\MyPgfplotsextra{
  \pgfkeys{
    dimline,
    #1,
    start line width/.get=\dimlinestartlinewidth,
    start line/.get=\dimlinestartline,
    end line/.get=\dimlineendline,
    end line width/.get=\dimlineendlinewidth,
    label pos/.get=\labelpos,
  }


  \begin{scope}[
    dimrecall/.style={\pgfkeysvalueof{/dimline/dimcolor}},
    dimline/.style={\pgfkeysvalueof{/dimline/dimcolor}},
    ]


    \coordinate (a to b) at ($(a)!\dimlinestartline!-90:(b)$);
    \coordinate (b to a) at ($(b)!\dimlineendline!90:(a)$);

    \draw [dimrecall, line width=\dimlinestartlinewidth]
    (a.center) -- (a to b);
    \draw [dimrecall, line width=\dimlineendlinewidth]
    (b.center) -- (b to a);

    \draw[|<->|, dimline,] (a.center) -- (b.center)
    node[fill=white, sloped, midway] {\tiny{#4}};
  \end{scope}
 }
}


\begin{document}

%Correct without \texttt{axis} environment:

\begin{tikzpicture}
  \draw  (0,0) -- (0,4) -- (.5,4) -- (.5,5) -- (1.,5) -- (1.,4) -- (1.5,4) -- (1.5,0) -- cycle;
  \dimline[dimcolor=blue,start line=-0.25, end line=-0.25]{3,0}{3,4}{4.0};
  \dimline[dimcolor=red,start line=0.85, end line=0.85]{0,6}{1.5,6}{1.5};
\end{tikzpicture}
%
%
%Incorrect within \texttt{axis} environment \texttt{pgfkeys} are overriden:
%
\begin{tikzpicture}
  \begin{axis} [
    xmin = -1,
    xmax = 8,
    ymin = -1,
    ymax = 8]

    \addplot[mark=none,  color=black] coordinates {
      (0,0)  (0,4) (.5,4) (.5,5) (1.,5) (1.,4) (1.5,4) (1.5,0) (0,0)
    };

    \dimline[dimcolor=blue,start line=-0.25, end line=-0.25]{3,0}{3,4}{4.0};
    \dimline[dimcolor=red,start line=0.85, end line=0.85]{0,6}{1.5,6}{1.5};

  \end{axis}

\end{tikzpicture}

\end{document}

Answer 2

In an axis environment, TikZ commands that are reasonably complicated (invoking other macros, for example) should be wrapped inside \pgfplotsextra{...} to make sure that they're executed correctly:

\documentclass{article}
\usepackage{tikz}
\usepackage{pgfplots}
\usetikzlibrary{calc}

\pgfkeys{
  dimline/.is family,
  dimline,
  dimcolor/.initial = black,
  start line/.initial=1cm,
  start line width/.initial=0.01,
  end line/.initial=1cm,
  end line width/.initial=0.01,
  label pos/.initial={},
}

% #1: optional keys parameters
% #2: start point
% #3: end point
% #4: text

\newcommand{\dimline}[4][]{%

  \pgfkeys{
    dimline,
    #1,
    start line width/.get=\dimlinestartlinewidth,
    start line/.get=\dimlinestartline,
    end line/.get=\dimlineendline,
    end line width/.get=\dimlineendlinewidth,
    label pos/.get=\labelpos,
  }

  \begin{scope}[
    dimrecall/.style={\pgfkeysvalueof{/dimline/dimcolor}},
    dimline/.style={\pgfkeysvalueof{/dimline/dimcolor}},
    ]

    \node (a) at #2 {};
    \node (b) at #3 {};

    \draw [/tikz/dimrecall, line width=\dimlinestartlinewidth]
    (a.center) -- ($(a)!\dimlinestartline!-90:(b)$);
    \draw [dimrecall, line width=\dimlineendlinewidth]
    (b.center) -- ($(b)!\dimlineendline!90:(a)$);

    \draw[|<->|, dimline,] (a.center) -- (b.center)
    node[fill=white, sloped, midway] {\tiny{#4}};
  \end{scope}
}


\begin{document}

\begin{tikzpicture}
  \begin{axis} [
    xmin = -1,
    xmax = 8,
    ymin = -1,
    ymax = 8]

    \addplot[mark=none,  color=black] coordinates {
      (0,0)  (0,4) (.5,4) (.5,5) (1.,5) (1.,4) (1.5,4) (1.5,0) (0,0)
    };


    \pgfplotsextra{
            \dimline[dimcolor=blue,start line=-0.25, end line=-0.25]{(axis cs: 3,0)}{(axis cs:3,4)}{4.0};
            \dimline[dimcolor=red,start line=0.85, end line=0.85]{(axis cs: 0,6)}{(axis cs: 1.5,6)}{1.5};
        }

  \end{axis}

\end{tikzpicture}

\end{document}