Beamer 中的树形侧边栏

Question

我一直在寻找，似乎侧边栏格式是 Beamer 的内置格式。我该如何更改格式，以便将其表示为tree类似输出？

编辑：MWE如下：

\documentclass[presentation]{beamer}
\usepackage[english]{babel}
\usetheme{Singapore}
\useoutertheme{sidebar}
\usecolortheme{rose}
\setbeamercovered{transparent}
\beamertemplatenavigationsymbolsempty
\begin{document}
\section{Section1}
\subsection{Subsection1}
\begin{frame}
First frame without title.
\end{frame}
\subsection{Subsection2}
\begin{frame}
Second frame without title.
\end{frame}
\section{Section2}
\subsection{Subsection1}
\begin{frame}
Third frame without title.
\end{frame}
\subsection{Subsection2}
\begin{frame}
Fourth frame without title.
\end{frame}
\end{document}

这完美地完成了两件事 - 它在每张幻灯片的侧面显示所有标题和副标题。它还将当前幻灯片设置为粗体。

不过，也出现了一些问题。首先，它只显示章节和子章节（而不是子子章节）。其次，它没有左侧的栏来创建树。我也见过树型，但在幻灯片顶部就像这里一样。以下是我想在侧边栏获取的内容：

├── blank
│   ├── defaults
│   ├── files
│   ├── handlers
│   ├── LICENSE
│   ├── meta
│   ├── README.md
│   ├── tasks
│   ├── templates
│   └── vars
└── Blank
    ├── ansible.cfg
    ├── dev
    │   ├── group_vars
    │   │   └── all
    │   └── hosts
    ├── LICENSE
    ├── plays
    ├── prod
    │   ├── group_vars
    │   │   └── all
    │   └── hosts
    ├── README.md
    ├── requirements.yml
    ├── roles
    │   ├── external
    │   └── internal
    │       └── blank
    └── site.yml

Answer 1

\documentclass{beamer}

% total number of sections %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\usepackage{totcount}
\newcounter{totalsection}
\regtotcounter{totalsection}

\AtBeginDocument{%
  \pretocmd{\section}{\refstepcounter{totalsection}}{}{}%
}%

% number of subsections per section %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\usepackage{xcntperchap}
\RegisterCounters{section}{subsection}
\newcounter{totalsubsection}
\setcounter{totalsubsection}{0}

% creating automatic label %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% based on https://tex.stackexchange.com/a/386557/36296
\AtBeginSection[]{\label{sec:\thesection}}
\AtBeginSubsection[]{\label{subsec:\thesection:\thesubsection}}
\newcounter{currentsub}
\newcounter{totsection}

% Creating the sidebar
\usepackage{pmboxdraw}

\useoutertheme[height=0pt,left,width=.22\textwidth]{sidebar}
\setbeamercolor{sidebar}{use=structure,bg=structure.fg!20!white}

\setbeamercolor{section in sidebar}{fg=alerted text.fg}
\setbeamercolor{section in sidebar shaded}{fg=structure}

\setbeamercolor{subsection in sidebar}{fg=alerted text.fg!30!bg}
\setbeamercolor{subsection in sidebar shaded}{fg=structure}
\setbeamercolor{current subsection in sidebar}{fg=alerted text.fg}


\usepackage{pgffor}
\makeatletter
\setbeamertemplate{sidebar left}{%
    \begin{beamercolorbox}[wd=\beamer@sidebarwidth,sep=2em]{sidebar}%
        \usebeamerfont{section in sidebar}%
        %
        % parent = title %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
        \insertshorttitle\newline%
        %
        % first level = section %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
        \foreach \i in {1,...,\totvalue{totalsection}}{%
            % get number of subsections in current section
            \setcounter{currentsub}{\ObtainTrackedValueExp[\i]{section}{subsection}}%
            % insert vertical line + line to right |-
            \ifnum\i=\totvalue{totalsection}%
                \textSFii%
            \else% shorter line for final section
                \textSFviii%
            \fi%
            % insert horzonal line - or T if there are subsection
            \ifnum\thecurrentsub>0%
                \textSFvi%
            \else%
                \textSFx%
            \fi%
            % insert hoziontal line -
            \textSFx~%
            % insert hyperline to section
            {%
                \ifnum\i=\value{section}%
                    \usebeamercolor[fg]{section in sidebar}%
                \else%
                    \usebeamercolor[fg]{section in sidebar shaded}%
                \fi%
                \mbox{\hyperlink{sec:\i}{\nameref{sec:\i}}}\newline%
            }%
            %
            %   secon level = subsection %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
            \ifnum\thecurrentsub>0%
                \foreach \j in {1,...,\thecurrentsub}{%
                    % vertical line to connect section | 
                    \ifnum\i<\totvalue{totalsection}%
                        \textSFxi%
                    \else%
                        \textcolor{bg}{\textSFxi}% not for the last section
                    \fi%
                    % 
                    % insert vertical line + line to right |-
                    \ifnum\j=\thecurrentsub%
                        \textSFii%
                \else% shorter line for final section
                    \textSFviii%
                \fi%
                % insert hoziontal line -
                \textSFx\textSFx~%
                % insert hyperline to section
                {%
                    \ifnum\i=\value{section}%
                        \ifnum\j=\value{subsection}%
                            \usebeamercolor[fg]{current subsection in sidebar}%
                        \else%
                            \usebeamercolor[fg]{subsection in sidebar}%
                        \fi%
                    \else%
                        \usebeamercolor[fg]{subsection in sidebar shaded}%
                    \fi%
                    \mbox{\hyperlink{subsec:\i:\j}{\nameref{subsec:\i:\j}}}\newline%
                }%
            }%
        \fi%        
        }%
    \end{beamercolorbox}%
}%
\makeatother

\title{Some Title}

\begin{document}

\section{Section One}
\frame{abc}

\section{Section Two}
\frame{abc}

\subsection{subsection a}
\frame{abc}

\subsection{subsection b}
\frame{abc}

\subsection{subsection c}
\frame{abc}

\section{Section Three}
\frame{abc} 

\section{Section Three}
\frame{abc} 

\subsection{subsection a}
\frame{abc}

\subsection{subsection b}
\frame{abc}

\subsection{subsection c}
\frame{abc}        

\end{document}