How to specify start and end date of \chronoperiode in a dd/mm/yyyy format
A further modified version of chronos which aims to provide a flexible alternative to chronosys. Note that the preamble is this long only because the code is designed to draw a variety of different kinds of timelines with different date formats etc.
The date and year formats are now specified with ! before each element e.g. !Y rather than just Y. (That is, Joseph Wright was right, as usual.)
The example from the question does not illustrate the drawing of the period very well as it is very short in comparison with the length of the timeline. However, you can see that draw=gray is drawing the period on the timeline itself. Omit if this is not desired.
\documentclass[border=10pt,multi,tikz]{standalone}
\usepackage{pgfcalendar}
\usepackage{datenumber,xparse,fp}
\usetikzlibrary{arrows.meta,backgrounds,fixedpointarithmetic}
\makeatletter
\ExplSyntaxOn
\tl_new:N \l_chronos_date_tl
\tl_new:N \l_chronos_dateformat_tl
\tl_new:N \l_chronos_year_tl
\tl_new:N \l_chronos_yearformat_tl
\tl_set:Nn \l_chronos_dateformat_tl { !d/!m/!Y }
\tl_set:Nn \l_chronos_yearformat_tl { !Y }
% YY yn lle YYYY
\cs_new_protected_nopar:Npn \chronos_year_shorten:n #1
{
\chronos_year_shorten_aux:w #1 \q_stop % expl3 manuaal, 46
}
\cs_new_protected_nopar:Npn \chronos_year_shorten_aux:w #1 #2 #3 #4 \q_stop
{
#3 #4
}
\cs_generate_variant:Nn \chronos_year_shorten:n { V , c }
\cs_generate_variant:Nn \int_abs:n { c }
\cs_generate_variant:Nn \tl_replace_all:Nnn { Nnx }
% dangos dyddiadau
\cs_new_protected_nopar:Npn \chronos_show_date:n #1
{% ateb Joseph Wright: http://tex.stackexchange.com/a/327642/
\tl_set_eq:NN \l_chronos_date_tl \l_chronos_dateformat_tl
\tl_replace_all:Nnx \l_chronos_date_tl { !a } { \pgfcalendarweekdayshortname{\thechronos@weekday} }
\tl_replace_all:Nnx \l_chronos_date_tl { !A } { \pgfcalendarweekdayname{\thechronos@weekday} }
\tl_replace_all:Nnx \l_chronos_date_tl { !b } { \pgfcalendarmonthshortname{\csname chronos@#1month\endcsname} }
\tl_replace_all:Nnx \l_chronos_date_tl { !B } { \pgfcalendarmonthname{\csname chronos@#1month\endcsname} }
\tl_replace_all:Nnx \l_chronos_date_tl { !d } { \csname chronos@#1day\endcsname }
\tl_replace_all:Nnx \l_chronos_date_tl { !E } { \chronos_dateformat_era:c { chronos@#1year } }
\tl_replace_all:Nnx \l_chronos_date_tl { !m } { \csname chronos@#1month\endcsname }
\tl_replace_all:Nnx \l_chronos_date_tl { !q } { \chronos_dateformat_sign:c { chronos@#1year } }
\tl_replace_all:Nnx \l_chronos_date_tl { !Q } { \chronos_dateformat_signs:c { chronos@#1year } }
\tl_replace_all:Nnx \l_chronos_date_tl { !y } { \chronos_year_shorten:c { chronos@#1year } }
\tl_replace_all:Nnx \l_chronos_date_tl { !Y } { \int_abs:c { chronos@#1year } }
\l_chronos_date_tl
}
\cs_new_protected_nopar:Npn \chronos_show_year:n #1
{% ateb Joseph Wright: http://tex.stackexchange.com/a/327642/
\tl_set_eq:NN \l_chronos_year_tl \l_chronos_yearformat_tl
\tl_replace_all:Nnx \l_chronos_year_tl { !E } { \chronos_dateformat_era:n { #1 } }
\tl_replace_all:Nnx \l_chronos_year_tl { !q } { \chronos_dateformat_sign:n { #1 } }
\tl_replace_all:Nnx \l_chronos_year_tl { !Q } { \chronos_dateformat_signs:n { #1 } }
\tl_replace_all:Nnx \l_chronos_year_tl { !y } { \chronos_year_shorten:n { #1 } }
\tl_replace_all:Nnx \l_chronos_year_tl { !Y } { \int_abs:n { #1 } }
\l_chronos_year_tl
}
\cs_new_protected_nopar:Npn \chronos_dateformat_sign:n #1
{
\int_compare:nT { #1 < 0 } { - }
}
\cs_generate_variant:Nn \chronos_dateformat_sign:n { c }
\cs_new_protected_nopar:Npn \chronos_dateformat_signs:n #1
{
\int_compare:nTF
{ #1 < 0 } { - }
{
\int_compare:nT { #1 > 0 }
{
\ifchronos@yearzero\relax
\else
\int_compare:nT { #1 > 1} { + }
\fi
}
}
}
\cs_generate_variant:Nn \chronos_dateformat_signs:n { c }
\cs_new_protected_nopar:Npn \chronos_dateformat_era:n #1
{
\int_compare:nTF
{ #1 < 0 } { \chronos@yearbce }
{
\int_compare:nT { #1 > 0 }
{
\ifchronos@yearzero\relax
\else
\int_compare:nT { #1 > 1} { \chronos@yearce }
\fi
}
}
}
\cs_generate_variant:Nn \chronos_dateformat_era:n { c }
\cs_new_protected_nopar:Npn \chronos_set_dateformat:n #1
{
\tl_set:Nn \l_chronos_dateformat_tl { #1 }
\tl_replace_all:Nnn \l_chronos_dateformat_tl { ~ } { \c_space_token }
}
\cs_new_protected_nopar:Npn \chronos_set_yearformat:n #1
{
\tl_set:Nn \l_chronos_yearformat_tl { #1 }
\tl_replace_all:Nnn \l_chronos_yearformat_tl { ~ } { \c_space_token }
}
% user interface
\NewDocumentCommand \chronos@setdateformat { m }
{
\chronos_set_dateformat:n { #1 }
}
\NewDocumentCommand \chronos@setyearformat { m }
{
\chronos_set_yearformat:n { #1 }
}
% for pgf/tikz convenience
\NewDocumentCommand \chronos@showdate { o m }
{
\group_begin:
\IfValueT { #1 }
{
\chronos_set_dateformat:n { #1 }
}
\pgfcalendarjuliantoweekday{\csname thechronos@#2date\endcsname}{\c@chronos@weekday}%
\chronos_show_date:n { #2 }
\group_end:
}
\NewDocumentCommand \chronos@showyear { o m }
{
\group_begin:
\IfValueT { #1 }
{
\chronos_set_yearformat:n { #1 }
}
\chronos_show_year:n { #2 }
\group_end:
}
\ExplSyntaxOff
\newlength\chronos@tempdima
\newcounter{chronos@date}
\newcounter{chronos@startdate}
\newcounter{chronos@enddate}
\newcounter{chronos@startyear}
\newcounter{chronos@endyear}
\newcounter{chronos@yeardate}
\newcounter{chronos@thingdate}
\newcounter{chronos@otherthingdate}
\newcounter{chronos@weekday}
\newcounter{chronos@tempcnta}
\newif\ifchronos@marks
\chronos@marksfalse
\newif\ifchronos@timeline@showyears
\chronos@timeline@showyearstrue
\newif\ifchronos@eventyearsonline
\chronos@eventyearsonlinefalse
\newif\ifchronos@yearzero
\chronos@yearzerofalse
\newif\ifchronos@onlytext
\chronos@onlytextfalse
\newif\ifchronos@markeras
\chronos@markerasfalse
\newif\ifchronos@yearsonline
\chronos@yearsonlinefalse
\newif\ifchronos@eventdatessplit
\chronos@eventdatessplitfalse
\pgfkeys{/pgf/number format,
int detect,
set thousands separator={},
}
\tikzset{%
/handlers/.chronos too/.code={%
\edef\chronos@tempc{\pgfkeyscurrentpath}%
\edef\chronos@tempd{#1}%
\tikzset{%
\pgfkeyscurrentpath @too/.code={%
\tikzset{%
/chronos/\chronos@tempd/.append style={##1},
}%
},
\chronos@tempc/.forward to=\chronos@tempc @too,
}%
},
chronos/.code={% http://tex.stackexchange.com/a/159856/ - Claudio Fiandrino
\tikzset{%
align=center,
anchor=mid,
fixed point arithmetic,
/chronos/.cd,
#1,
timeline config,
timeline config/.code={},
}%
\ifnum\chronos@startyear=\chronos@endyear
\tikzset{%
/chronos/timeline no years,
}%
\fi
\setlength\chronos@tempdima{\chronos@timelinemargin}%
\ifchronos@markeras
{%
\chronos@timelinefont
\pgfmathsetmacro\chronos@tempe{((width("\chronos@bce"))>(width("\chronos@ce"))) ? (width("\chronos@bce")) : (width("\chronos@ce"))}%
\xdef\chronos@tempf{\chronos@tempe}%
}%
\addtolength\chronos@tempdima{\chronos@tempf pt}%
\fi
\pgfmathsetmacro\chronos@unit{(\chronos@width-2*\chronos@tempdima)/(\thechronos@enddate-\thechronos@startdate)}%
\draw [/chronos/timeline@line, line width=\chronos@height] (-\chronos@tempdima,0) coordinate (chronos pre) -- +(\chronos@width,0) coordinate (chronos post);
\coordinate (chronos base) at (0,-.5*\chronos@height);
\coordinate (chronos top) at (0,.5*\chronos@height);
\coordinate (chronos foot) at (0,{-.5*\chronos@height-\chronos@borderheight});
\coordinate (chronos head) at (0,{.5*\chronos@height+\chronos@borderheight});
\coordinate (chronos start) at (0,0);
\coordinate (chronos end) at ([xshift=-\chronos@tempdima]chronos post);
\ifdim\chronos@borderheight>0pt
\fill [bottom color=chronos@borderinner, top color=chronos@borderouter] (chronos pre |- chronos head) rectangle (chronos post |- chronos top);
\fill [top color=chronos@borderinner, bottom color=chronos@borderouter] (chronos pre |- chronos base) rectangle (chronos post |- chronos foot);
\fi
\ifchronos@timeline@showyears
\pgfmathsetcounter{chronos@startyear}{\chronos@startyear}%
\pgfmathsetcounter{chronos@endyear}{\chronos@endyear}%
\def\tempa{none}%
\ifx\chronos@stepfrom\tempa
\def\tempa{01}%
\ifx\chronos@startmonth\tempa
\ifx\chronos@startday\tempa
\else\stepcounter{chronos@startyear}%
\fi
\else\stepcounter{chronos@startyear}%
\fi
\else
\pgfmathsetcounter{chronos@startyear}{\chronos@stepfrom}%
\fi
\def\tempa{12}%
\def\tempb{31}%
\ifx\chronos@endmonth\tempa
\ifx\chronos@endday\tempb
\stepcounter{chronos@endyear}%
\fi
\fi
\ifnum\value{chronos@endyear}<\value{chronos@startyear}\setcounter{chronos@endyear}{\thechronos@startyear}\fi
\pgfmathsetmacro\chronos@nextstep{int(((\thechronos@startyear+\chronos@stepyears)>\thechronos@endyear) ? \thechronos@endyear : (\thechronos@startyear+\chronos@stepyears))}%
\ifchronos@yearzero\setcounter{chronos@tempcnta}{1}\else\setcounter{chronos@tempcnta}{0}\fi
\foreach \b [evaluate=\b as \i using {((\b==0)&&(\thechronos@tempcnta==0)) ? 1 : int(\b)}, remember=\i as \ilast (initially \pi)] in {\thechronos@startyear,\chronos@nextstep,...,\thechronos@endyear} {%
\ifnum\i=\ilast\relax
\else
\pgfcalendardatetojulian{{\i}-01-01}{\c@chronos@yeardate}%
\ifchronos@yearzero\relax\else\ifnum0<\i\addtocounter{chronos@yeardate}{-366}\fi\fi
\pgfmathsetmacro\chronos@tempa{(\thechronos@yeardate-\thechronos@startdate)*\chronos@unit}%
\ifchronos@yearsonline
\node (chronos@year@\i) [/chronos/.cd, timeline@years, timeline year on line] at (\chronos@tempa pt,0) {\chronos@timelinefont\chronos@showyear{\i}};
\ifchronos@marks
\path [/chronos/timeline mark on line] (chronos@year@\i.south) -- (chronos@year@\i |- chronos base);
\path [/chronos/timeline mark on line] (chronos@year@\i.north) -- (chronos@year@\i |- chronos top);
\fi
\ifchronos@markeras
\path (chronos pre) +(\chronos@timelinemargin,0) node (chronos@bce) [/chronos/.cd, timeline@years, timeline year on line] {\chronos@timelinefont\chronos@bce};
\path (chronos post) +(-\chronos@timelinemargin,0) node (chronos@ce) [/chronos/.cd, timeline@years, timeline year on line] {\chronos@timelinefont\chronos@ce};
\fi
\else
\node (chronos@year@\i) [/chronos/.cd, timeline@years, timeline year off line] at (\chronos@tempa pt,0) {\chronos@timelinefont\chronos@showyear{\i}};
\ifchronos@marks
\path [shorten <=.5*\chronos@height, /chronos/timeline mark off line] (\chronos@tempa pt, 0) -- (chronos@year@\i);
\fi
\ifchronos@markeras
\path (chronos pre) +(\chronos@timelinemargin,0) node (chronos@bce) [/chronos/.cd, timeline@years, timeline year off line] {\chronos@timelinefont\chronos@bce};
\path (chronos post) +(-\chronos@timelinemargin,0) node (chronos@ce) [/chronos/.cd, timeline@years, timeline year off line] {\chronos@timelinefont\chronos@ce};
\fi
\fi
\fi
}%
\else
\ifchronos@markeras
\path (chronos pre) +(\chronos@timelinemargin,0) node (chronos@bce) [/chronos/.cd, timeline@years, timeline year off line] {\chronos@timelinefont\chronos@bce};
\path (chronos post) +(-\chronos@timelinemargin,0) node (chronos@ce) [/chronos/.cd, timeline@years, timeline year off line] {\chronos@timelinefont\chronos@ce};
\fi
\fi
\ifchronos@eventyearsonline
\tikzset{%
/chronos/timeline years=on line,
}%
\fi
},
chronos set date/.code args={#1:#2:#3:#4}{%
\pgfcalendardatetojulian{{#1}-#2-#3}{\c@chronos@date}%
\setcounter{chronos@#4date}{\thechronos@date}%
\ifchronos@yearzero\relax
\else
\setcounter{chronos@tempcnta}{#1}%
\ifnum0<\value{chronos@tempcnta}%
\addtocounter{chronos@#4date}{-366}%
\fi
\fi
\expandafter\def\csname chronos@#4year\endcsname{#1}%
\expandafter\def\csname chronos@#4month\endcsname{#2}%
\expandafter\def\csname chronos@#4day\endcsname{#3}%
},
chronos date/.style args={#1-#2-#3}{%
/tikz/chronos set date/.expanded={#1:#2:#3:thing}%
},
chronos period date/.style args={#1-#2-#3}{%
/tikz/chronos set date/.expanded={#1:#2:#3:otherthing}%
},
/chronos/.search also={/tikz},
/chronos/.cd,
timeline config/.code={},
date format/.code={%
\chronos@setdateformat{#1}%
},
year format/.code={%
\chronos@setyearformat{#1}%
},
step years/.store in=\chronos@stepyears,
step from year/.store in=\chronos@stepfrom,
start date/.style args={#1-#2-#3}{%
/chronos/timeline config/.append code={%
\tikzset{/tikz/chronos set date/.expanded={#1:#2:#3:start}}%
},
},
end date/.style args={#1-#2-#3}{%
/chronos/timeline config/.append code={%
\tikzset{/tikz/chronos set date/.expanded={#1:#2:#3:end}}%
},
},
ce year label/.store in=\chronos@yearce,
bce year label/.store in=\chronos@yearbce,
timeline ce label/.store in=\chronos@ce,
timeline bce label/.store in=\chronos@bce,
timeline width/.store in=\chronos@width,
timeline height/.store in=\chronos@height,
width/.forward to=/chronos/timeline width,
height/.forward to=/chronos/timeline height,
timeline border height/.store in=\chronos@borderheight,
timeline border inner colour/.code={\colorlet{chronos@borderinner}{#1}},
timeline border outer colour/.code={\colorlet{chronos@borderouter}{#1}},
timeline mark eras/.is if=chronos@markeras,
timeline margin/.store in=\chronos@timelinemargin,
timeline font/.store in=\chronos@timelinefont,
timeline years set/.store in=\chronos@timelineyears,
timeline years/.is choice,
timeline years/.forward to=/chronos/timeline years set,
timeline years/above/.code={%
\tikzset{%
/chronos/timeline@years/.style={above, anchor=south, yshift=.5*\chronos@height},
}%
},
timeline years/below/.code={%
\tikzset{%
/chronos/timeline@years/.style={below, anchor=north, yshift=-.5*\chronos@height},
}%
},
timeline years/on line/.code={%
\chronos@yearsonlinetrue
\tikzset{%
/chronos/timeline@years/.style={anchor=center},
}%
},
only years/.code={%
\edef\tempa{}%
\edef\tempb{#1}%
\ifx\tempa\tempb\chronos@setdateformat{!Y}\else\chronos@setdateformat{#1}\fi
\tikzset{%
/tikz/chronos date/.style={%
/tikz/chronos set date/.expanded={##1:01:01:thing}%
},
/tikz/chronos period date/.style={%
/tikz/chronos set date/.expanded={##1:01:01:otherthing}%
},
}%
},
only text/.code={%
\tikzset{/chronos/only years}%
\chronos@setdateformat{}%
\chronos@onlytexttrue
},
year zero/.is if=chronos@yearzero,
background/.code={%
\colorlet{chronos@background}{#1}%
},
timeline marks/.is if=chronos@marks,
timeline show years/.is if=chronos@timeline@showyears,
timeline no years/.code={%
\tikzset{%
/chronos/timeline show years=false,
}%
},
lines/.style={draw, {Triangle[width=0pt 3,reversed,length=0pt 1.5]}-{Triangle[width=0pt 3,reversed,length=0pt 1.5]}, shorten <={.5*\chronos@height}},
events/.style={fill=chronos@background, fill opacity=.75, text opacity=1, draw opacity=1, rounded corners, align=center, font=\footnotesize},
period/.style={draw},
period event line/.style={/chronos/lines},
period event/.style={/chronos/events},
event line/.style={/chronos/lines},
event/.style={/chronos/events},
event years on line/.is if=chronos@eventyearsonline,
event year on line/.style={/chronos/timeline@years, /chronos/timeline year on line},
event dates split/.is if=chronos@eventdatessplit,
event date split/.style={/chronos/event},
event distance/.store in=\chronos@eventdistance,
special date/.store in=\chronos@specialdate,
timeline@line/.style={draw},
timeline line/.chronos too=timeline@line,
timeline year off line/.style={fill=chronos@background, text opacity=1, align=center, fill opacity=.75},
timeline mark off line/.style={draw, {Triangle[width=0pt 3,reversed,length=0pt 1.5]}-, thin, shorten >=-2pt},
timeline year on line/.style={text=chronos@background, inner sep=1pt, align=center},
timeline mark on line/.style={draw=chronos@background, shorten >=1.5pt},
timeline mark too/.code={%
\tikzset{%
/chronos/.cd,
timeline mark on line/.append style={#1},
timeline mark off line/.append style={#1},
}%
},
timeline year too/.code={%
\tikzset{%
/chronos/.cd,
timeline year on line/.append style={#1},
timeline year off line/.append style={#1},
}%
},
timeline mark/.forward to=/chronos/timeline mark too,
timeline year/.forward to=/chronos/timeline year too,
start date=1001-10-01,
end date=1003-06-14,
timeline width=100mm,
timeline height=1pt,
timeline border height=0pt,
chronos date=1850-01-01,
chronos period date=1851-01-01,
step years=1,
timeline years=above,
background=white,
timeline border inner colour=black,
timeline border outer colour=chronos@background,
step from year=none,
special date=none,
ce year label={\textsc{ce}},
bce year label={\textsc{bce}},
event distance=-10pt,
timeline ce label={CE},
timeline bce label={BCE},
timeline margin=10pt,
timeline font=\sffamily,
}
\NewDocumentCommand \chronosevent { O {} m O {} +m D () { \chronos@eventdistance } }
{%
\tikzset{%
chronos date/.expanded={#2},
}%
\pgfmathsetmacro\chronos@offset{(#5 < 0pt) ? (#5-.5*\[email protected]*\chronos@borderheight) : (#5+.5*\chronos@height+.5*\chronos@borderheight)}%
\pgfmathsetmacro\chronos@anchor{(#5 < 0pt) ? "north" : "south"}%
\scoped[on background layer]{%
\ifchronos@eventdatessplit
\ifchronos@onlytext\relax
\else
\pgfmathsetmacro\chronos@invanchor{(#5 < 0pt) ? "south" : "north"}%
\path [postaction={/chronos/event line, #1}] ({(\thechronos@thingdate-\thechronos@startdate)*\chronos@unit pt},0) -- +(0,-\chronos@offset pt) node [anchor=\chronos@invanchor, /chronos/event date split, #3] {\chronos@showdate{thing}};
\fi
\path [postaction={/chronos/event line, #1}] ({(\thechronos@thingdate-\thechronos@startdate)*\chronos@unit pt},0) -- +(0,\chronos@offset pt) node [anchor=\chronos@anchor, /chronos/event, #3] {#4};
\else
\path [postaction={/chronos/event line, #1}] ({(\thechronos@thingdate-\thechronos@startdate)*\chronos@unit pt},0) -- +(0,\chronos@offset pt) node [anchor=\chronos@anchor, /chronos/event, #3] {\ifchronos@onlytext\relax\else\chronos@showdate{thing}\\\fi#4};
\fi
}%
\ifchronos@eventyearsonline
\edef\tempa{none}%
\edef\tempb{\chronos@specialdate}%
\ifx\tempa\tempb\else\let\chronos@thingyear\chronos@specialdate\tikzset{/chronos/special date=none}\fi
\node [/chronos/.cd, event year on line] at ({(\thechronos@thingdate-\thechronos@startdate)*\chronos@unit pt},0) {\chronos@thingyear};
\fi
}
\NewDocumentCommand \chronosspecialdate { m }
{%
\tikzset{%
/chronos/special date=#1,
}%
}
\NewDocumentCommand \chronosperiod { O {} m O {} m O {} +m D () { \chronos@eventdistance } }
{%
\tikzset{%
chronos date/.expanded={#2}, chronos period date/.expanded={#4}
}%
\pgfmathsetmacro\chronos@offset{(#7 < 0pt) ? (#7-.5*\[email protected]*\chronos@borderheight) : (#7+.5*\chronos@height+.5*\chronos@borderheight)}%
\pgfmathsetmacro\chronos@anchor{(#7 < 0pt) ? "north" : "south"}%
\ifchronos@yearsonline
\pgfmathsetmacro\chronos@borderoffset{(#7 < 0pt) ? (-.5*\[email protected]*\chronos@borderheight) : (.5*\chronos@height+.5*\chronos@borderheight)}%
\path [postaction={line width=\chronos@borderheight, /chronos/period, blend mode=overlay, #1}] ({(\thechronos@thingdate-\thechronos@startdate)*\chronos@unit pt},\chronos@borderoffset pt) -- ({(\thechronos@otherthingdate-\thechronos@startdate)*\chronos@unit pt},\chronos@borderoffset pt);
\else
\path [postaction={line width=\chronos@height, /chronos/period, #1}] ({(\thechronos@thingdate-\thechronos@startdate)*\chronos@unit pt},0) -- ({(\thechronos@otherthingdate-\thechronos@startdate)*\chronos@unit pt},0);
\fi
\scoped[on background layer]{\path [postaction={/chronos/period event line, #3}] ({(.5*\thechronos@otherthingdate+.5*\thechronos@thingdate-\thechronos@startdate)*\chronos@unit pt},0) -- +(0,\chronos@offset pt) node [anchor=\chronos@anchor, /chronos/period event, #5] {\ifchronos@onlytext\relax\else\chronos@showdate{thing}--\chronos@showdate{otherthing}\\\fi#6};}
}
\makeatother
\begin{document}
\begin{tikzpicture}
[
chronos={%
start date={0-01-01},
end date={2000-01-01},
step years=250,
timeline height=2.5mm,
timeline width=200mm,
timeline line={shorten >={-10mm}, -{Triangle Cap[length=10mm]}},
date format={!d/!m/!Y},
}
]
\chronosperiod[draw=gray]{476-01-01}{476-10-31}{Fall of the\\Roman Empire}
\chronosevent{1492-10-11}{European\\Re-Discovery\\of America}
\chronosevent{1969-07-21}{First Steps\\on the Moon}
\end{tikzpicture}
\end{document}
After an email exchange with Mathieu Long, author and developer of chronosys, he provided me with a modified version of the package that included the requested feature.
Now it's possible to use the command \chronoperiode with a dd/mm/yyyy date format.
Because package maintenance is always time demanding, he only did a quick update to fulfill my request (he was very kind in doing so). So, probably, the new version will not be uploaded on CTAN in a short time (but it's just a supposition I make).
Nevertheless, the modified package is licensed under the LPPL, so I assume I can share it here (as per clause 2 of the license).