How to add subfigures in own list of figures

Question

I want to add subfigure captions (like "61(a)") in my own list of figures. My code (see example document below) works fine, but as soon as I load the caption or subcaption package additionally my code results in an empty list.

What I need is that my \tableoffigures command has to get along with the following command:

\usepackage[...,list=true]{subcaption}

Example document:

\documentclass{report}
%\usepackage{caption} %figure caption
%\usepackage[list=true,lofdepth=2]{subcaption} %subfigure caption
\usepackage{longtable,letltxmacro}

\newcounter{fullfigurecounter}
\newcounter{fulltablecounter}

\makeatletter

\newcommand*\@starttof[2]{%
    \begingroup
    \renewcommand{\arraystretch}{1.5}
    % Table format may be changed%%%
    \begin{longtable}{|p{2cm}|p{6cm}|p{7cm}|}
%       \hline
        \multicolumn{3}{c}{}\tabularnewline
        \multicolumn{3}{c}{\Large \bfseries #2}\tabularnewline
        \multicolumn{3}{c}{}\tabularnewline
%       \hline
        \multicolumn{3}{c}{}\tabularnewline[0.5ex]
        \hline
        \large Table No.  & \large Title of the Table & \large Source \tabularnewline
        \hline
        \endhead % Repeating head
        \@input{\jobname.#1}%  Input the ToF or ToT file 
        \tabularnewline
        \hline
    \end{longtable}
    \setcounter{table}{0}%
    \if@filesw
    \expandafter\newwrite\csname tf@#1\endcsname
    \immediate\openout \csname tf@#1\endcsname \jobname.#1\relax
    \fi
    \endgroup
}

\newcommand{\tableoffigures}{%
    \cleardoublepage
    \@starttof{tof}{Abbildungs- und Quellenverzeichnis}
}%

\newcommand{\tableoftables}{%
    \clearpage
    \@starttof{tot}{LIST OF TABLES}%
}%

\def\temp@@a{figure}%
\def\temp@@b{table}%

\LetLtxMacro\captionpkg@caption\caption

\newcommand{\writetofline}[3]{%
    \ifnum\value{fullfigurecounter} > 1
    \tabularnewline
    \protect\hline
    \fi
    \figurename\ #1 & #2 & #3 
}

\newcommand{\writetotline}[3]{%
    \ifnum\value{fulltablecounter} > 1
    \tabularnewline
    \protect\hline
    \fi
    \tablename\ #1 & #2 & #3 
}

\RenewDocumentCommand{\caption}{somO{Eigene Darstellung}}{%
    \IfBooleanTF{#1}{%
        \captionpkg@caption{#3}%
    }{%
        \ifx\@currenvir\temp@@a
        \stepcounter{fullfigurecounter}%
        \else
        \ifx\@currenvir\temp@@b
        \stepcounter{fulltablecounter}%
        \fi
        \fi
        \IfValueTF{#2}{%
            \captionpkg@caption[#2]{#3}%
            \ifx\@currenvir\temp@@a
            \addtocontents{tof}{\writetofline{\thefigure}{#2}{#4}}%
            \else
            \ifx\@currenvir\temp@@b
            \addtocontents{tot}{\writetotline{\thetable}{#2}{#4}}%
            \fi
            \fi
        }{%
            \captionpkg@caption{#3}%
            \ifx\@currenvir\temp@@a
            \addtocontents{tof}{\writetofline{\thefigure}{#3}{#4}}%
            \else%
            \ifx\@currenvir\temp@@b
            \addtocontents{tot}{\writetotline{\thetable}{#3}{#4}}%
            \fi
            \fi
        }%
    }%
}

\makeatother

\begin{document}

\tableoffigures
\clearpage
\tableoftables 
\clearpage

\chapter{A sample for multicol table of contents}
\begin{table}
    \caption[A nice table]{A nice table}[Me!]
\end{table}
\clearpage
\begin{figure}
    \caption{Irgendein Bild}
\end{figure}
\begin{figure}
    \caption[Die Sonnenblumen]{Irgendein Bild}[Vincent van Gogh]
\end{figure}
\clearpage
\begin{table}[!ht]
    \caption[List of $ \theta $ signature]{$\theta$ signature}
    \label{theta}
    \centering
    \begin{tabular}{|c|*{6}{c|}}
        \hline
%       \backslashbox{$ \boldsymbol{\theta} $}{signature}& \textbf{1} & \textbf{2} & \textbf{3} & \textbf{4} & $ \boldsymbol{\cdots} $ & $ \boldsymbol{t} $\\ \hline
        \textbf{1} & 1 &    2 & 3&  4&  $ \ldots $ &    1+c \\
        \hline
        \textbf{4} &    5 & 6 &     \multicolumn{3}{c|}{$ \ldots $} & 7\\ \cline{4-5}
        \hline
        $ \vdots $ &    \multicolumn{6}{c|}{$ \ldots $} \\ \cline{2-6}
        \hline
    \end{tabular}
\end{table}

\ifx\subfigure\undefined\else

\begin{figure}
    \begin{subfigure}{.5\linewidth}
        \caption[flower]{}
    \end{subfigure}
\end{figure}
\begin{figure}\ContinuedFloat
    \begin{subfigure}{.5\linewidth}
        \caption[animal]{}
    \end{subfigure}
\end{figure}

\fi

\end{document}

Answer 1

Since \caption is subject to re-definition for many environments (subfigure, longtable, ...), this approach patches the caption package instead, forwarding the burden of dealing with all the different \caption implementations to it.

Disadvantages:

1. This solution works only if the caption package is loaded.
2. This solution patches an internal command of the caption package.
3. Since we do not patch \caption we need an extra command to specify the source. (I have called it \source in my example code below.)

\documentclass{report}
\usepackage[listformat=simple]{caption} %figure caption
\usepackage[list=true,lofdepth=2]{subcaption} %subfigure caption
\usepackage{longtable}

\makeatletter

\newcommand*\@starttof[2]{% (not altered)
    \begingroup
    \renewcommand{\arraystretch}{1.5}
    % Table format may be changed%%%
    \begin{longtable}{|p{2cm}|p{6cm}|p{7cm}|}
%       \hline
        \multicolumn{3}{c}{}\tabularnewline
        \multicolumn{3}{c}{\Large \bfseries #2}\tabularnewline
        \multicolumn{3}{c}{}\tabularnewline
%       \hline
        \multicolumn{3}{c}{}\tabularnewline[0.5ex]
        \hline
        \large Table No.  & \large Title of the Table & \large Source \tabularnewline
        \hline
        \endhead % Repeating head
        \@input{\jobname.#1}%  Input the ToF or ToT file 
    \end{longtable}
%   \setcounter{table}{0}% What is this line good for?
    \if@filesw
    \expandafter\newwrite\csname tf@#1\endcsname
    \immediate\openout \csname tf@#1\endcsname \jobname.#1\relax
    \fi
    \endgroup
}

\newcommand{\tableoffigures}{% (not altered)
    \cleardoublepage
    \@starttof{tof}{Abbildungs- und Quellenverzeichnis}
}%

\newcommand{\tableoftables}{% (not altered)
    \clearpage
    \@starttof{tot}{LIST OF TABLES}%
}%

\newcommand{\writetofline}[4]{% (one argument added)
    #1~#2 & #3 & #4%
    \tabularnewline
    \protect\hline
}

% New \source{...} command (avoiding patching \caption)
\newcommand*\our@source{}
\newcommand*\source[1]{\renewcommand\our@source{#1}}

% Patch the caption package code which actually writes an entry into the list of figures/tables
% WARNING: We are patching an internal command of the caption package here
\let\caption@@@addcontentsline@ORI\caption@@@addcontentsline
\renewcommand*\caption@@@addcontentsline[4]{%
  % #1 = "lof" / "lot"
  % #2 = "figure" / "table" / "subfigure" / "subtable"
  % #3 = caption list number (content could be altered using option "listformat=...")
  % #4 = caption list entry (as given in \caption)
  % \@captype = "figure" / "table"
  %
  % Make entry in regular List of Figures/Tables (this could be dropped if no regular lof/lot is desired)
  \caption@@@addcontentsline@ORI{#1}{#2}{#3}{#4}%
  % lof -> tof / lot -> tot
  \edef\our@ext{#1}\edef\our@ext{t\expandafter\@gobble\our@ext}%
  % Set default source, if none was set by the user
  \ifx\our@source\@empty
      \def\our@source{Eigene Darstellung}%
  \fi
  % Add contents line to tof/tot
  \addtocontents{\our@ext}{\writetofline{\@nameuse{\@captype name}}{#3}{#4}{\our@source}}%
}

\makeatother

\begin{document}

\tableoffigures
\clearpage
\tableoftables 
\clearpage

\chapter{A sample for multicol table of contents}
\begin{table}
    \source{Me!}
    \caption[A nice table]{A nice table}
\end{table}
\clearpage
\begin{figure}
    \caption{Irgendein Bild}
\end{figure}
\begin{figure}
    \source{Vincent van Gogh}
    \caption[Die Sonnenblumen]{Irgendein Bild}
\end{figure}
\clearpage
\begin{table}[!ht]
    \caption[List of $ \theta $ signature]{$\theta$ signature}
    \label{theta}
    \centering
    \begin{tabular}{|c|*{6}{c|}}
        \hline
%       \backslashbox{$ \boldsymbol{\theta} $}{signature}& \textbf{1} & \textbf{2} & \textbf{3} & \textbf{4} & $ \boldsymbol{\cdots} $ & $ \boldsymbol{t} $\\ \hline
        \textbf{1} & 1 &    2 & 3&  4&  $ \ldots $ &    1+c \\
        \hline
        \textbf{4} &    5 & 6 &     \multicolumn{3}{c|}{$ \ldots $} & 7\\ \cline{4-5}
        \hline
        $ \vdots $ &    \multicolumn{6}{c|}{$ \ldots $} \\ \cline{2-6}
        \hline
    \end{tabular}
\end{table}

\ifx\subfigure\undefined\else

\begin{figure}
    \begin{subfigure}{.5\linewidth}
        \caption[flower]{}
    \end{subfigure}
\end{figure}
\begin{figure}\ContinuedFloat
    \begin{subfigure}{.5\linewidth}
        \caption[animal]{}
    \end{subfigure}
\end{figure}

\fi

\end{document}