Optional argument in a tikz environment

Question

I use the following resizedtikzpicture environment in order to rescale my tikzpictures. Would it be possible to add an optional argument, taking into account the tikz option? For example the color or baseline.

MWE:

\documentclass[twocolumn]{article}

\usepackage{tikz,tikzpagenodes}

\newsavebox\mybox
\newenvironment{resizedtikzpicture}[1]{%
  \def\mywidth{#1}%
  \begin{lrbox}{\mybox}%
  \begin{tikzpicture}
  }{%
  \end{tikzpicture}%
  \end{lrbox}%
  \resizebox{\mywidth}{!}{\usebox\mybox}%
}

%\newsavebox\mybox
%\newenvironment{wrongresizedtikzpicture}[2][\unskip]{%
%  \def\mywidth{#1}%
%  \begin{lrbox}{\mybox}%
%  \begin{tikzpicture}[ #2]
%  }{%
%  \end{tikzpicture}%
%  \end{lrbox}%
%  \resizebox{\mywidth}{!}{\usebox\mybox}%
%}


\begin{document}
ABCDE

\begin{resizedtikzpicture}{\columnwidth}
\draw [thick,->] (-5,0)--(5,0);
\draw [thick,->] (0,-5)--(0,5);
\draw [very thick, domain=-5:5,samples=200] plot(\x,{\x+0.2});

\draw [very thick, domain=-5:0,samples=200] plot(\x,{\x});
\draw [very thick, domain=0:5,samples=200] plot(\x,{0*\x});

\draw [very thick, domain=-5:0,samples=200] plot(\x,{0*\x});
\draw [very thick, domain=0:5,samples=200] plot(\x,{\x});

\draw (-6,-4.5) node{{\(x \mapsto x\)}};
\end{resizedtikzpicture}

% Goal :
%\begin{resizedtikzpicture}{\columnwidth}[baseline=0]
%\draw [thick,->] (-5,0)--(5,0);
%\draw [thick,->] (0,-5)--(0,5);
%\draw [very thick, domain=-5:5,samples=200] plot(\x,{\x+0.2});
%
%\draw [very thick, domain=-5:0,samples=200] plot(\x,{\x});
%\draw [very thick, domain=0:5,samples=200] plot(\x,{0*\x});
%
%\draw [very thick, domain=-5:0,samples=200] plot(\x,{0*\x});
%\draw [very thick, domain=0:5,samples=200] plot(\x,{\x});
%
%\draw (-6,-4.5) node{{\(x \mapsto x\)}};
%\end{resizedtikzpicture}

\end{document}

Answer 1

My advice would be to learn how to prepare a minimal working example (MWE) and maybe to read the error message when you encounter an error (“it doesn't work” is not an error message; it is not actionable). The following does work, but the method used here is better, as it wouldn't scale fonts.

Note: I used [{#2}] instead of [#2] because only the former works fine if #2 contains square brackets, which is bound to happen sooner or later.

\documentclass[twocolumn]{article}
\usepackage{tikz}
\usepackage{lipsum}

\newsavebox\mybox
\newenvironment{resizedtikzpicture}[2]{%
  \def\mywidth{#1}%
  \begin{lrbox}{\mybox}%
  \begin{tikzpicture}[{#2}]
  }{%
  \end{tikzpicture}%
  \end{lrbox}%
  \resizebox{\mywidth}{!}{\usebox\mybox}%
}

\begin{document}

\twocolumn[{\lipsum[1]}]

\noindent
\makebox[0pt][l]{abcd.}%
\begin{resizedtikzpicture}{\columnwidth}{baseline=0}
  \draw [thick,->] (-5,0)--(5,0);
  \draw [thick,->] (0,-5)--(0,5);
  \draw [very thick, domain=-5:5,samples=200] plot(\x,{\x+0.2});

  \draw [very thick, domain=-5:0,samples=200] plot(\x,{\x});
  \draw [very thick, domain=0:5,samples=200] plot(\x,{0*\x});

  \draw [very thick, domain=-5:0,samples=200] plot(\x,{0*\x});
  \draw [very thick, domain=0:5,samples=200] plot(\x,{\x});

  \draw (-6,-4.5) node{{\(x \mapsto x\)}};
\end{resizedtikzpicture}

\end{document}

Making the second argument optional

If you want to make the second argument optional, this is not straightforward with \newenvironment, but xparse makes it easy:

\documentclass[twocolumn]{article}
\usepackage{tikz}
\usepackage{xparse}
\usepackage{lipsum}

\newsavebox\mybox
\NewDocumentEnvironment{resizedtikzpicture}{mO{}}{%
  \def\mywidth{#1}%
  \begin{lrbox}{\mybox}%
  \begin{tikzpicture}[{#2}]
  }{%
  \end{tikzpicture}%
  \end{lrbox}%
  \resizebox{\mywidth}{!}{\usebox\mybox}%
}

\begin{document}

\twocolumn[{\lipsum[1]}]

\noindent
\makebox[0pt][l]{abcd.}%
\begin{resizedtikzpicture}{\columnwidth}[baseline=0]
  \draw [thick,->] (-5,0)--(5,0);
  \draw [thick,->] (0,-5)--(0,5);
  \draw [very thick, domain=-5:5,samples=200] plot(\x,{\x+0.2});

  \draw [very thick, domain=-5:0,samples=200] plot(\x,{\x});
  \draw [very thick, domain=0:5,samples=200] plot(\x,{0*\x});

  \draw [very thick, domain=-5:0,samples=200] plot(\x,{0*\x});
  \draw [very thick, domain=0:5,samples=200] plot(\x,{\x});

  \draw (-6,-4.5) node{{\(x \mapsto x\)}};
\end{resizedtikzpicture}

\end{document}

(same output as above).

Optional argument without xparse

There is no reason to avoid xparse which is great, but just for the record, you could have your optional argument with \newenvironment if you accept to have this argument in first position:

\newenvironment{resizedtikzpicture}[2][]{%
  \def\mywidth{#2}%
  \begin{lrbox}{\mybox}%
  \begin{tikzpicture}[{#1}]
  }{%
  \end{tikzpicture}%
  \end{lrbox}%
  \resizebox{\mywidth}{!}{\usebox\mybox}%
}

...

\begin{resizedtikzpicture}[baseline=0]{\columnwidth}