Customize title page on beamer

Question

I found this beamer theme and I only need the title page because I already used the default theme. How can I extract only the title page from this theme?

Answer 1

Here is a proposal extract from my beamer theme mines-albi (needs two compilations):

\documentclass{beamer}

\usepackage{babel}
\usepackage{tikz}
\usetikzlibrary{calc}

\makeatletter
\defbeamertemplate*{part page}{mytheme}
{
  \begin{tikzpicture}[overlay,remember picture,shift={(current page.north west)}]
    \hypersetup{linkcolor=.}%
    \ifbabelshorthand{!}{\shorthandoff*{!}}{}
    \path let
    \p1 = (.8*\paperheight,-1*\paperheight),
    \p2 = (0,{-1*\paperheight + \x1}),
    \p3 = (.8*\paperheight,0),
    \p4 = ($(\p1)!(\p3)!(\p2)$)
    in
    (\p1) coordinate (p1)
    (\p2) coordinate (p2)
    (\p3) coordinate (p3)
    (\p4) coordinate (p4)
    ;

    \fill[fill=cyan,line width=0]
    (current page.south east) -- (p1) -- (p4) -- (p3) -| cycle;
    \fill[fill=orange,line width=0]
    (current page.north west) -- (p3) -- (p4) -- (p2) -- cycle;

    \path let
    \p5 = ($(p4)!.5!(p3)$),
    \p6 = (\p5 |- p4),
    \n1 = {\paperwidth - \x6 - \Gm@rmargin},
    \n2 = {\n1 - 1em}
    in (\p6)
    node[anchor=west,text width=\n2,inner sep=.5em,align=flush right] {%
      \usebeamerfont*{part name}%
      \usebeamercolor[fg]{part name}%
      \iflanguage{french}{\partname}{\partname~\thepart}%
      \par%
      \usebeamerfont*{part title}\insertpart\par%
    };

    \node[at={(current page.south west)},shift={(.1*\paperheight,.1*\paperheight)},
    anchor=south west,inner sep=0]
    {\includegraphics[width=22mm]{example-image}};
    
  \end{tikzpicture}
} 
\makeatother

\setbeamertemplate{part page}[mytheme]
\setbeamercolor{part name}{fg=white}%
\setbeamertemplate{navigation symbols}{}
\AtBeginPart{\frame[plain]{\partpage}}

\begin{document}
\part{Introduction}
\end{document}