Numbering of citation in beamer with split frame

Question

I have a problem with the numbering of \footfullcite{} command in split frames in beamer. I want to increase the citation counter for every cite-command, even if the commands are not on the same displayed page. If the title was already cited, it should get the same number as the first citation. On the last page, \printbibliography should sort the citations in their citation-order and set the corresponding number as the item. I know, that footline-citations are somehow different to normal citations, anyhow I want to have a similar behaviour for footnote citations than for standard citations in biblatex numeric style.

Here is an example code, where I commented the desired behaviour.

\documentclass[aspectratio=169]{beamer}
\usepackage[language=english, backend=biber, style=authoryear]{biblatex}
\usepackage{filecontents}

\begin{filecontents*}{exampleReferences.bib}
@book{foo1,
  year = {2001},
  title = {Example title 1},
  author = {John One}
}

@book{foo2,
  year = {2002},
  title = {Example title 2},
  author = {John Two}
}
\end{filecontents*}

\addbibresource{exampleReferences.bib}

\begin{document}
\begin{frame}{Example frame 1}
Text on frame that doesn't change.\\

%This citation should be marked with a 1
\only<1>{Special text foo1 to be cited \footfullcite{foo1}}

%This citation should be marked with a 2, as it is the second citation and different from the first citation
\only<2>{Another special text to be cited \footfullcite{foo2}}

%This should be marked once again with 1, as it was already cited before.
\only<3>{Another passage of special text foo1 to be citeted \footfullcite{foo1}}
\end{frame}

\begin{frame}{Example frame 2}
%The reference on a new frame should get the same marker if it was already cited (here it should get a 2)
New frame with reference to already referenced text \footfullcite{foo2}
\end{frame}

\begin{frame}{Bibliography}
%The bibliography of all cited texts. 
%It should be sorted in citation-order and have a citation-number item instead of the image [e.g. [1]~\cite{foo1}].
\printbibliography
\end{frame}
\end{document}

Any suggestions?

Answer 1

It seems easiest to base the style on numeric and its supercite and modify it with a two-pass structure so we get a separate footnote for each citation.

\documentclass[aspectratio=169]{beamer}
\usepackage[backend=biber, style=numeric, sorting=none]{biblatex}

\setbeamertemplate{bibliography item}{\insertbiblabel}

\makeatletter
\newcommand*{\mkblankfootnote}[1]{%
  \begingroup
    \renewcommand\thefootnote{}%
    \footnotetext{\bibfootnotewrapper{#1}}%
  \endgroup
}

\newcommand*{\mkbibsupercite}[1]{%
  \def\cbx@savedcites{\cbx@footfullcite}%
  \mkbibsuperscript{\mkbibbrackets{#1}}%
  \cbx@savedcites}

\DeclareCiteCommand{\supercite}[\mkbibsupercite]
  {\gdef\cbx@savedkeys{}}
  {\usebibmacro{citeindex}%
   \usebibmacro{cite}%
     {}%
   \xappto\cbx@savedkeys{\thefield{entrykey},}}
  {\supercitedelim}
  {\protected@xappto\cbx@savedcites{%
     [\thefield{prenote}][\thefield{postnote}]{\cbx@savedkeys}}}

\DeclareCiteCommand{\cbx@footfullcite}
  {}
  {\mkblankfootnote{%
     \printtext[labelnumberwidth]{%
       \usebibmacro{cite}%
     }%
   \setunit{\addspace}%
   \usedriver
     {\DeclareNameAlias{sortname}{default}}
     {\thefield{entrytype}}}}
  {}
  {}
\makeatother

\usepackage{filecontents}
\begin{filecontents*}{exampleReferences.bib}
@book{foo1,
  year = {2001},
  title = {Example title 1},
  author = {John One}
}

@book{foo2,
  year = {2002},
  title = {Example title 2},
  author = {John Two}
}
\end{filecontents*}

\addbibresource{exampleReferences.bib}

\begin{document}
\begin{frame}{Example frame 1}
Text on frame that doesn't change.

%This citation should be marked with a 1
\only<1>{Special text foo1 to be cited \supercite{foo1}}

%This citation should be marked with a 2, as it is the second citation and different from the first citation
\only<2>{Another special text to be cited \supercite{foo2}}

%This should be marked once again with 1, as it was already cited before.
\only<3>{Another passage of special text foo1 to be citeted \supercite{foo1}}
\end{frame}

\begin{frame}{Example frame 2}
%The reference on a new frame should get the same marker if it was already cited (here it should get a 2)
New frame with reference to already referenced text \supercite{foo2}
\end{frame}

\begin{frame}{Bibliography}
%The bibliography of all cited texts. 
%It should be sorted in citation-order and have a citation-number item instead of the image [e.g. [1]~\cite{foo1}].
\printbibliography
\end{frame}
\end{document}

Answer 2

Just a quick hack, for the disadvantages see moewes comment.

\documentclass[aspectratio=169]{beamer}
\usepackage[language=english, backend=biber, style=numeric]{biblatex}
\usepackage{filecontents}

\begin{filecontents*}{exampleReferences.bib}
@book{foo1,
  year = {2001},
  title = {Example title 1},
  author = {John One}
}

@book{foo2,
  year = {2002},
  title = {Example title 2},
  author = {John Two}
}
\end{filecontents*}

\addbibresource{exampleReferences.bib}
\setbeamertemplate{bibliography item}[text]

\makeatletter
\DeclareCiteCommand{\cite}[\mkbibsuperscript]
  {\usebibmacro{prenote}}
  {\usebibmacro{citeindex}%
   \usebibmacro{cite}}
  {\multicitedelim}
  {\usebibmacro{postnote}}

\renewbibmacro*{cite}{%
  \printtext[bibhyperref]{%
    \printfield{labelprefix}%
    \printfield{labelnumber}%
    \ifbool{bbx:subentry}{%
        \printfield{entrysetcount}
    }{}%
  }%
  \footnotetext[\thefield{labelnumber}]{%
    \usedriver{\DeclareNameAlias{sortname}{default}}{\thefield{entrytype}}
  }%
}
\makeatother
\begin{document}
\begin{frame}{Example frame 1}
Text on frame that doesn't change.\\

%This citation should be marked with a 1
\only<1>{Special text foo1 to be cited \cite{foo1}}

%This citation should be marked with a 2, as it is the second citation and different from the first citation
\only<2>{Another special text to be cited \cite{foo2}}

%This should be marked once again with 1, as it was already cited before.
\only<3>{Another passage of special text foo1 to be citeted \cite{foo1}}
\end{frame}

\begin{frame}{Example frame 2}
%The reference on a new frame should get the same marker if it was already cited (here it should get a 2)
New frame with reference to already referenced text \cite{foo2}
\end{frame}

\begin{frame}{Bibliography}
%The bibliography of all cited texts. 
%It should be sorted in citation-order and have a citation-number item instead of the image [e.g. [1]~\cite{foo1}].
\printbibliography
\end{frame}
\end{document}