snellen.tex

%! TEX program = XeLaTeX

\documentclass{article}

% Factor = 3m/6m.
% This is obtained by dividing the distance at which the chart is kept
% by 6 m.  Note that this sometimes needs to be slightly tweaked to get
% the required optotype width.
\def\factor{0.5}

\usepackage{fontspec}
\usepackage{graphicx}
\usepackage{color}
\usepackage[pass]{geometry}
\usepackage{longtable}
\setlength\LTpre{0pt} % space before table

\newfontfamily\optsans{Optician-Sans.otf}[LetterSpace=40]
\def\optotype#1#2{\begin{tabular}{c}\resizebox{!}{#1}{\selectfont\optsans#2}\end{tabular}}

% https://tex.stackexchange.com/q/172234
\newcommand{\deflen}[2]{%
  \expandafter\newlength\csname #1\endcsname
  \expandafter\setlength\csname #1\endcsname{#2}%
}

\input{|python3 snellen.py --defs}

\definecolor{smoke}{rgb}{0.6,0.6,0.6}
\deflen{acuitylen}{0.25in}
\def\acuity#1#2{\resizebox{!}{\acuitylen}{$#1^{\,\color{smoke}(#2)}$}}

\makeatletter
\def\colorrule#1#2{\color{#1}\leavevmode\leaders\hrule height #2\hfill\kern\z@}
\makeatother

\pagestyle{empty}

\begin{document}

\newgeometry{margin=0.5in}

\input{|python3 snellen.py 10}

\end{document}