%%
%% Copyright (c) 2022-2023 by Friedemann Bartels
%%
%% This file may be distributed and/or modified under the
%% conditions of the LaTeX Project Public License, either
%% version 1.3c of this license or (at your option) any later
%% version.  The latest version of this license is in:
%%
%%    http://www.latex-project.org/lppl.txt
%%
%% and version 1.3c or later is part of all distributions of
%% LaTeX version 2008/05/04 or later.
%%

\documentclass{standalone}
\usepackage{tikz}
\usepackage{xcolor}

\makeatletter
\newcommand{\dimentonumber}[1]{\strip@pt\dimexpr #1*65536/\number\dimexpr 1\unitlength}
\makeatother

\definecolor{cyan}{rgb}{0, 1, 1}
\definecolor{magenta}{rgb}{1, 0, 1}
\definecolor{yellow}{rgb}{1, 1, 0}

\newdimen\strokewidth
\newdimen\width
\newdimen\height

\width=1500pt
\height=1000pt
\strokewidth=1pt
\def\strokecolor{black}
\def\strokeopacity{0.3}
\def\bgcolor{cyan}
\def\bgopacity{0.3}

\begin{document}
  \begin{picture}(\dimentonumber{\width},\dimentonumber{\height})%
    \put(0,0){%
      \begin{tikzpicture}%
        \pgflowlevelsynccm
        \fill[\bgcolor,opacity=\bgopacity] (0,0) rectangle ++(\width,\height);%
        \draw[line width=\strokewidth,draw=\strokecolor,opacity=\strokeopacity](0pt,0pt) -- (\width,\height);%
        \draw[line width=\strokewidth,draw=\strokecolor,opacity=\strokeopacity](0pt,\height) -- (\width,0pt);%
        \draw[line width=\strokewidth,draw=\strokecolor,opacity=\strokeopacity](0pt,\height / 2) -- (\width,\height / 2);%
        \draw[line width=\strokewidth,draw=\strokecolor,opacity=\strokeopacity](\width / 2,0pt) -- (\width / 2,\height);%
        \ifdim\width>\height
          \draw[line width=\strokewidth,draw=\strokecolor,opacity=\strokeopacity](\width / 2,\height / 2) circle (\height / 2 - \strokewidth / 2);%
        \else
          \draw[line width=\strokewidth,draw=\strokecolor,opacity=\strokeopacity](\width / 2,\height / 2) circle (\width / 2 - \strokewidth / 2);%
        \fi
      \end{tikzpicture}
    }%
  \end{picture}
\end{document}
