# TikZ - Resize, Externalize AND tikzsetnextfilename Figures

I have a document (two-column article) with several TikZ images, and I want to:

1. Scale the figures to half of the column width, without changing the text's font size
2. Externalize the figures inside the folder ./tikz_output
3. Set externalized filenames, avoiding automatically generated names by externalize, using tikzsetnextfilename

I found the code below from this old question, which fulfills points 1 and 2, but fails to work when setting externalized filenames:

% Automagically scale a Tikz picture, so it has the desired (given) width.
% Does NOT scale line width/text width! Needs the package "environ"!
%
% Usage:
%
% \begin{myscaletikzwidth}{\textwidth}
%   \begin{tikzpicture}[scale=\tikzscale]
%     ..
%   \end{tikzpicture}
% \end{myscaletikzwidth}
%
\makeatletter
\newsavebox{\measure@tikzpicture}
\NewEnviron{myscaletikzwidth}[1]{%
\tikzifexternalizingnext{%
\def\tikz@width{#1}%
\def\tikzscale{1}\begin{lrbox}{\measure@tikzpicture}%
\tikzset{external/export next=false,external/optimize=false}% force translation of this BODY (and do not optimize it away as it would usually do):
\BODY
\end{lrbox}%
\pgfmathparse{#1/\wd\measure@tikzpicture}%
\edef\tikzscale{\pgfmathresult}%
\BODY
}{% this will re-use an existing external graphics:
\BODY
}%
}
\makeatother

\usepackage{todonotes}
\makeatletter
\renewcommand{\todo}[2][]{%
\tikzexternaldisable\@todo[#1]{#2}\tikzexternalenable%
}
\makeatother


When not setting any externalized filenames, everything works well; when setting externalized filenames, it crashes, displaying the following:

Package tikz Error: Sorry, the system call 'pdflatex -shell-escape -halt-on-error -interaction=batchmode -jobname "tikz_output/mynd_1" \def\tikzexternalrealjob{main}\input{main}"' did NOT result in a usable output file 'tikz_output/mynd_1' (expected one of .pdf:.jpg:.jpeg:.png:). Please verify that you have enabled system calls. For pdflatex, this is 'pdflatex -shell-escape'. Sometimes it is also named 'write 18' or something like that. Or maybe the command simply failed? Error messages can be found in 'tikz_output/mynd_1.log'. If you continue now, I'll try to typeset the picture.

See the tikz package documentation for explanation.
Type  H <return>  for immediate help.
...

l.72 \end{myscaletikzwidth}


How can this be fixed?

My code looks like this (I am currently testing this in Overleaf):

\documentclass[twocolumn]{article}

\usepackage{epstopdf}

\usepackage[hypcap=true]{subcaption}

\usepackage{lipsum}

\usepackage{tikz}
\usetikzlibrary{shapes,arrows,arrows.meta,positioning,calc,fit}
\usepackage{tikzscale}
\usepackage{circuitikz}

\usetikzlibrary{external}
\tikzexternalize[prefix=tikz_output/]

\usepackage{environ}

% Automagically scale a Tikz picture, so it has the desired (given) width.
% Does NOT scale line width/text width! Needs the package "environ"!
%
% Usage:
%
% \begin{myscaletikzwidth}{\textwidth}
%   \begin{tikzpicture}[scale=\tikzscale]
%     ..
%   \end{tikzpicture}
% \end{myscaletikzwidth}
%
\makeatletter
\newsavebox{\measure@tikzpicture}
\NewEnviron{myscaletikzwidth}[1]{%
\tikzifexternalizingnext{%
\def\tikz@width{#1}%
\def\tikzscale{1}\begin{lrbox}{\measure@tikzpicture}%
\tikzset{external/export next=false,external/optimize=false}% force translation of this BODY (and do not optimize it away as it would usually do):
\BODY
\end{lrbox}%
\pgfmathparse{#1/\wd\measure@tikzpicture}%
\edef\tikzscale{\pgfmathresult}%
\BODY
}{% this will re-use an existing external graphics:
\BODY
}%
}
\makeatother

\usepackage{todonotes}
\makeatletter
\renewcommand{\todo}[2][]{%
\tikzexternaldisable\@todo[#1]{#2}\tikzexternalenable%
}
\makeatother

\begin{document}

\begin{figure}[!h]
\centering
\begin{subfigure}[b]{0.49\columnwidth}
\centering
\tikzsetnextfilename{mynd_1}
\begin{myscaletikzwidth}{\textwidth}
\begin{tikzpicture}[scale=\tikzscale]
\draw[->] (0,0) -- (4.5,0) node[right] {$t$};
\draw[->] (0,0) -- (0,3) node[above] {$\ddot{s}\left(t\right)$};
\draw plot[domain=0:4.5,smooth] (\x,{1 + cos(\x r)});
\end{tikzpicture}
\end{myscaletikzwidth}
\caption{}
\end{subfigure}%
\begin{subfigure}[b]{0.49\columnwidth}
\centering
\tikzsetnextfilename{mynd_2}
\begin{myscaletikzwidth}{\textwidth}
\begin{tikzpicture}[scale=\tikzscale]
\draw[->] (0,0) -- (4.5,0) node[right] {$t$};
\draw[->] (0,0) -- (0,3) node[above] {$s\left(t\right)$};
\draw plot[domain=0:4.5,smooth] (\x,{1 + sin(\x r)});
\end{tikzpicture}
\end{myscaletikzwidth}
\caption{}
\end{subfigure}

\end{figure}

\lipsum[1]

\end{document}

• Cymraeg? ('mynd' yw 'go'.) – cfr Feb 4 '18 at 19:22
• Ah, indeed. Is there a vowel in it for you? ('y' is a vowel for me.) – cfr Feb 4 '18 at 19:55
• It is pronounced "mint" – erik Feb 4 '18 at 20:22