How do I make break in chronology?

Question

This is my code

\documentclass[10pt]{beamer}

\usetheme[progressbar=frametitle]{metropolis}
\usepackage{appendixnumberbeamer}
\usepackage{chronology}
\begin{frame}{Timeline}
\begin{center}
\begin{chronology}[10]{1810}{2020}{63ex}[\textwidth]
\event{\decimaldate{}{}{1812}}{\small Beginnings of Gerrymandering}
\event{\decimaldate{26}{3}{1962}}{\small Baker v. Carr}
\event{\decimaldate{15}{12}{1964}}{\small Reynold v. Sims}
\event{\decimaldate{2}{10}{1985}}{\small Bandermer v. Davis}
\event{\decimaldate{}{}{1991}}{\small Third Criterion}
\event{\decimaldate{}{}{2004}}{\small Vieth v. Jubelirer}
\event{\decimaldate{31}{12}{2006}}{\small LULAC v. Perry}
\event{\decimaldate{}{}{2015}}{\small Efficiency Gap}
\event{\decimaldate{}{}{2018}}{\small Gill v. Whitford}
\end{chronology}
\end{center}
\end{frame}
\end{document}

Since the events go from 1812-2018, the timeline get so small you cant see them on my frame. I want there to be a break in between the first two events. Does anyone know how to do this?

Answer 1

After having a lot of fun (this package is !#$&), adjusting the very internals by copying and improving the code, you can use the code below. This is far from perfect, e.g. the label from long events aren't shifted, spacing is not optimal etc. But at least something you can work with. You could still add sub-ticks and do more fancy stuff. But in general I would recommend to use another package. This is not general enough, well documented enough, ...

\documentclass[10pt]{beamer}

\usetheme[progressbar=frametitle]{metropolis}
\usepackage{appendixnumberbeamer}
\usepackage{chronology}

\newlength{\myunit}
\makeatletter%
\newif\ifchronology@star%
\renewenvironment{chronology}{%
    \@ifstar{\chronology@startrue\chronology@i*}{\chronology@starfalse\chronology@i*}%
}{%
\end{tikzpicture}%
\end{lrbox}%
\usebox{\timelinebox}
}%
\def\chronology@i*{%
\@ifnextchar[{\chronology@ii*}{\chronology@ii*[{5}]}%
}%
\def\chronology@ii*[#1]#2#3#4#5{%
\newif\ifflipped%
\ifchronology@star%
\flippedtrue%
\else%
\flippedfalse%
\fi%
\setcounter{step}{#1}%
\setcounter{yearstart}{#2}\setcounter{yearstop}{#3}%
\setcounter{deltayears}{\theyearstop-\theyearstart}%
\setlength{\timelinewidth}{#4}%
\setlength{\myunit}{#5}%
\pgfmathsetcounter{stepstart}{\theyearstart-mod(\theyearstart,\thestep)}%
\pgfmathsetcounter{stepstop}{\theyearstop-mod(\theyearstop,\thestep)}%
\addtocounter{step}{\thestepstart}%
\begin{lrbox}{\timelinebox}%
\begin{tikzpicture}[baseline={(current bounding box.north)}]%,x=\timelinewidth,y=\p@]%
\draw [|->] (0,0) -- (\timelinewidth, 0);%
%\foreach \x in {1,...,\thedeltayears}%
%\draw[xshift=\x/\thedeltayears*\timelinewidth] (0,-.5\myunit) -- (0,.5\myunit);%
\addtocounter{deltayears}{1}%
\foreach \x in {\thestepstart,\thestep,...,\thestepstop}{%
    \pgfmathsetlength\xstop{(\x-\theyearstart)/\thedeltayears*\timelinewidth}%
    \draw[xshift=\xstop] (0,-\myunit) -- (0,\myunit);%
    \ifflipped%
    \node[chrontickslabel] at (\xstop,0) [above=\myunit] {\x};%
    \else%
    \node[chrontickslabel] at (\xstop,0) [below=\myunit] {\x};%
    \fi%
}%
}%
\makeatother%

\RenewDocumentCommand{\event}{o m m}{%
    \pgfmathsetlength\xstop{(#2-\theyearstart)/\thedeltayears*\timelinewidth}%
    \IfNoValueTF {#1} {%
        \ifflipped%
        \draw[chronevent]%
        (\xstop, 0) circle (.7\myunit);%
        \draw[chronevent]
        (\xstop,-.5\myunit+2pt) node[flippedeventlabel] {#3};%
        \else%
        \draw[chronevent]%
        (\xstop, 0) circle (.7\myunit);%
        \draw[chronevent]
        (\xstop,.5\myunit-2pt) node[eventlabel] {#3} ;%
        \fi%
    }{%
        \pgfmathsetlength\xstart{(#1-\theyearstart)/\thedeltayears*\timelinewidth}%
        \ifflipped%
        \draw[chronevent,rounded corners=.7\myunit]%
        (\xstart,-.7\myunit) rectangle%
        node[flippedeventlabel] {#3} (\xstop,.7\myunit) [below=\myunit];%
        \else%
        \draw[chronevent,rounded corners=.7\myunit]%
        (\xstart,-.7\myunit) rectangle%
        node[eventlabel] {#3} (\xstop,.7\myunit);%
        \fi%
    }%
}


\begin{document}
\begin{frame}{Timeline}
\vspace*{-5ex}
\begin{chronology}[50]{1800}{2020}{.9\linewidth}{1ex}
    \event{\decimaldate{}{}{1812}}{\small Beginnings of Gerrymandering}
    \event[\decimaldate{}{}{1960}]{\decimaldate{}{}{2020}}{}
\end{chronology}
\par
\begin{chronology}[10]{1960}{2020}{.9\linewidth}{1ex}
    \event{\decimaldate{26}{3}{1962}}{\small Baker v. Carr}
    \event{\decimaldate{15}{12}{1964}}{\small Reynold v. Sims}
    \event{\decimaldate{2}{10}{1985}}{\small Bandermer v. Davis}
    \event{\decimaldate{}{}{1991}}{\small Third Criterion}
    \event{\decimaldate{}{}{2004}}{\small Vieth v. Jubelirer}
    \event{\decimaldate{31}{12}{2006}}{\small LULAC v. Perry}
    \event{\decimaldate{}{}{2015}}{\small Efficiency Gap}
    \event{\decimaldate{}{}{2018}}{\small Gill v. Whitford}
\end{chronology}
\end{frame}
\end{document}