Kalendervorlage wie auf Kalenderpedia

\documentclass[fontsize=10pt,DIV=12,paper=landscape,svgnames]{scrartcl}

\usepackage[ngerman]{babel}
\usepackage[table]{xcolor}
\usepackage{scrdate}

\newcounter{newyeardaynumber}
\newcounter{firstweekstartoffset}
\newcommand*{\startdate}{}
\newif\ifleepyear
\newcounter{weeksperyear}

\newcommand*{\InitKW}[1]{%
  \setcounter{newyeardaynumber}{\DayNumber{#1}{1}{1}}%
  \setcounter{weeksperyear}{52}%
  \expandafter\ifcase\value{newyeardaynumber}
    \setcounter{firstweekstartoffset}{1}%
    \edef\startdate{#1-1-2}%
  \or
    \setcounter{firstweekstartoffset}{0}%
    \edef\startdate{#1-1-1}%
  \or
    \setcounter{firstweekstartoffset}{-1}%
    \edef\startdate{\the\numexpr#1-1\relax-12-31}%
  \or
    \setcounter{firstweekstartoffset}{-2}%
    \edef\startdate{\the\numexpr#1-1\relax-12-30}%
  \or
    \setcounter{firstweekstartoffset}{-3}%
    \edef\startdate{\the\numexpr#1-1\relax-12-29}%
    \setcounter{weeksperyear}{53}%
  \or
    \setcounter{firstweekstartoffset}{3}%
    \edef\startdate{#1-1-4}%
  \or
    \setcounter{firstweekstartoffset}{2}%
    \edef\startdate{#1-1-3}%
  \fi
  \expandafter\ifnum\value{weeksperyear}=52
    \expandafter\ifnum\DayNumber{\numexpr #1+1\relax}{1}{1}=5
      \setcounter{weeksperyear}{53}%
    \fi
  \fi
  \expandafter\ifnum\DayNumber{#1}{2}{29}\expandafter=\DayNumber{#1}{3}{1}
    \leepyearfalse
  \else
    \leepyeartrue
  \fi
}
\makeatletter
\newcommand*\splitdate{}
\def\splitdate#1-#2-#3\@nil{\year=#1\relax \month=#2\relax \day=#3\relax}
\newcommand*{\@calcdate}[1]{%
  \@tempcnta=#1\relax
  \@whilenum \@tempcnta>0\do {%
    \@tempcntb=\ifcase \month
      \or 31
      \or \ifleepyear 29 \else 28 \fi
      \or 31
      \or 30
      \or 31
      \or 30
      \or 31
      \or 31
      \or 30
      \or 31
      \or 30
      \or 31
    \fi
    \ifnum \day>\@tempcntb
      \advance\day by -\@tempcntb
      \advance\month by 1
      \ifnum \month>12\relax \month=1\relax\advance\year by 1\relax\fi
    \fi
    \advance\@tempcnta by -1
    \ifnum\@tempcnta>0 \advance\day by 7\relax\fi      
  }%
}
\newcommand*{\KWStartdate}[1]{%
  \begingroup
    \expandafter\splitdate\startdate\@nil
    \@calcdate{#1}%
    \the\day. \csname month@\languagename\endcsname
  \endgroup
}
\newcommand*{\KWEnddate}[1]{%
  \begingroup
    \expandafter\splitdate\startdate\@nil
    \advance\day by 6\relax
    \@calcdate{#1}%
    \the\day. \csname month@\languagename\endcsname
  \endgroup
}
\newcommand*{\KWFirst}[1]{%
  \begingroup
    \expandafter\splitdate\startdate\@nil
    \advance\day by 0\relax
    \@calcdate{#1}%
    \the\day. \the\month. \DayName{\year}{\month}{\day}%
  \endgroup
}
\newcommand*{\KWSecond}[1]{%
  \begingroup
    \expandafter\splitdate\startdate\@nil
    \advance\day by 1\relax
    \@calcdate{#1}%
    \the\day. \the\month. \DayName{\year}{\month}{\day}%
  \endgroup
}
\newcommand*{\KWThird}[1]{%
  \begingroup
    \expandafter\splitdate\startdate\@nil
    \advance\day by 2\relax
    \@calcdate{#1}%
    \the\day. \the\month. \DayName{\year}{\month}{\day}%
  \endgroup
}
\newcommand*{\KWForth}[1]{%
  \begingroup
    \expandafter\splitdate\startdate\@nil
    \advance\day by 3\relax
    \@calcdate{#1}%
    \the\day. \the\month. \DayName{\year}{\month}{\day}%
  \endgroup
}
\newcommand*{\KWFifth}[1]{%
  \begingroup
    \expandafter\splitdate\startdate\@nil
    \advance\day by 4\relax
    \@calcdate{#1}%
    \the\day. \the\month. \DayName{\year}{\month}{\day}%
  \endgroup
}
\newcommand*{\KWSixth}[1]{%
  \begingroup
    \expandafter\splitdate\startdate\@nil
    \advance\day by 5\relax
    \@calcdate{#1}%
    \the\day. \the\month. \DayName{\year}{\month}{\day}%
  \endgroup
}
\newcommand*{\KWSeventh}[1]{%
  \begingroup
    \expandafter\splitdate\startdate\@nil
    \advance\day by 6\relax
    \@calcdate{#1}%
    \the\day. \the\month. \DayName{\year}{\month}{\day}%
  \endgroup
}
\makeatother
\newcommand*{\KWshowweek}[1]{%
  \newpage
  \begingroup
    \raggedright
    \sffamily
    KW #1, \KWStartdate{#1}--\KWEnddate{#1}

    \begin{tabular}{|*4{p{\dimexpr \linewidth/4-2\tabcolsep\relax}|}}
      \cellcolor{IndianRed}
      \KWFirst{#1} &
      \cellcolor{Gold}
      \KWSecond{#1} &
      \cellcolor{Khaki}
      \KWThird{#1} &
      \cellcolor{PaleGreen}
      \KWForth{#1} \\\hline
      & & & \\[12\normalbaselineskip]
      \hline
      \cellcolor{PaleTurquoise}
      \KWFifth{#1} &
      \cellcolor{DarkTurquoise}
      \KWSixth{#1} &
      \cellcolor{MediumOrchid}
      \KWSeventh{#1} &
      \cellcolor{LightGrey}
      Notizen: \\\hline                                             
      & & & \\[12\normalbaselineskip]
      \hline
    \end{tabular}

  \endgroup
}

\InitKW{\the\year}

\newcounter{week}

\begin{document}

Der 1. Januar \the\year{} ist ein \DayNameByNumber{\value{newyeardaynumber}} und
das Jahr ist \ifleepyear\else kein \fi Schaltjahr.
Die erste KW beginnt nach ISO~8601 am \startdate{} und das Jahr hat
\arabic{weeksperyear} Wochen.

\setcounter{week}{0}
\csname @whilenum\endcsname\value{week}<\value{weeksperyear}\do {
  \stepcounter{week}%
  \KWshowweek{\arabic{week}}%
}

\InitKW{2019}
Der 1. Januar 2019 ist ein \DayNameByNumber{\value{newyeardaynumber}} und
das Jahr ist \ifleepyear\else kein \fi Schaltjahr.
Die erste KW beginnt nach ISO~8601 am \startdate{} und das Jahr hat
\arabic{weeksperyear} Wochen.

\setcounter{week}{0}
\csname @whilenum\endcsname\value{week}<\value{weeksperyear}\do {
  \stepcounter{week}%
  \KWshowweek{\arabic{week}}%
}

\end{document}