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rlatexr-markdownmarkdownbeamer

Remove additional blank slides after ToC and insert black slides in rmarkdown::beamer_presentation with custom beamer theme

I use a custom LaTex beamer theme in an rmarkdown::beamer_presentation. As per these SO answers (LaTex theme, colon, theme path), I used several modifications of the YAML header and beamerthemeTHEMENAME.sty. These LaTex hacks are necessary to apply the LaTex Beamer theme smoothly in the rmarkdown::beamer_presentation.

However, currently, a blank slide is inserted by LaTex before and after the table of contents (ToC) slide (see fig 1 below).

  • How can I get rid of these slides?
  • Instead, I would ideally have a completely black slide before the ToC and at other instances during the presentation (i.e., to briefly interrupt and "switch off" the presentation in between)

Note: if I use the option toc: true to generate the ToC (instead of using the \tocframedefined in beamerouterthemeTHEMENAME.sty), markdown messes up the vertical alignment of the ToC and it comes without any headline (see fig 2 below).

Fig 1: using Tocframe from LaTex Template to generate ToC (toc:false in YAML header)

Fig1 - MWE - with tocframe from LaTex Template

Fig 2: using toc:true in YAML header to generate ToC

Fig2 - MWE - with ToC from Rmarkdown

MWE.Rmd

---
# COMMENT out "title" in YAML header: else markdown generates a second title slide
# ==> if title contains no special characters: feed it straight into LaTex at the end of the YAML header
# ==> if title contains special characters, like ":", feed it in "preamble.tex" sourced in "LaTex Hacks"
subtitle: "Beamer presentation with R-markdown"
institute: "some place"
date: "`r format(Sys.time(), '%B %d, %Y')`"
output:
  # beamer_presentation: default
  bookdown::pdf_book:
    base_format: rmarkdown::beamer_presentation
    # Source below in "LaTex Hacks", if want theme to be stored in subfolder (else rmarkdown does not find it)
    # theme: "THEMENAME"
    # Source "includes" below in "LaTex Hacks" if using custom theme with custom title page
    # => else, markdown places the includes at inadequate position in LaTex file, which then either does not show the title or throws an error
    # includes: ...
    latex_engine: xelatex
    toc: false # use LaTex TOC (else vertical alignment is messed up and not headline)
    slide_level: 2
classoption: aspectratio=169 # fix aspect ratio of presentation (169 => 16:9, 149 => 14:9, default: 4:3)
#
# LaTex Hacks
# --------------------------
compact-title: false # to remove markdown generated title frame
header-includes:
  # - \title{Title if no special characters} 
  - \input{beamer_files/beamerthemeTHEMENAME.sty}
  - \input{beamer_files/preamble}       # feed title to LaTex in preamble.tex due to ":"
  - \def\titlefigure{img/my_bg}
  - \AtBeginDocument{\titleframe} # add title frame defined in beamerouterthemeTHEMENAME
  - \makeatletter\beamer@ignorenonframefalse\makeatother
  ---


​```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = FALSE)
​```

<!-- TOC - Table of Contents -->
<!-- ======================================================== -->

``` {=latex}
\end{frame}
\tocframe
\begin{frame}
```

## Slide with Bullets
<!-- ======================================================== -->

- Bullet 1
- Bullet 2
- Bullet 3

<!-- Appendix -->
<!-- ======================================================== -->
``` {=latex}
\end{frame}
\appendix
\begin{frame}
```

beamerthemeTHEMENAME.sty

\mode<presentation>

% Tizk, textpos, graphics
\RequirePackage{tikz}
\RequirePackage{textpos}
\RequirePackage{booktabs}

% Beamer settings
\input{beamer_files/beamercolorthemeTHEMENAME.sty}
\input{beamer_files/beamerouterthemeTHEMENAME.sty}

\setbeamertemplate{navigation symbols}{}

\mode<all>

beamerouterthemeTHEMENAME.sty

\mode<presentation>

% Redefine \insertshortinstitute to allow multiple lines
\makeatletter
\renewcommand{\insertshortinstitute}{\beamer@shortinstitute}
\makeatother

% Title frame
\def\titlefigure{img/my_bg}
\newlength\titleboxwidth
\setlength{\titleboxwidth}{0.43\textwidth}
\newcommand{\titleframe}{%
    {
        \setbeamertemplate{background}{
            \begin{tikzpicture}
            \useasboundingbox (0,0) rectangle(\the\paperwidth,\the\paperheight);
            \ifx\titlefigure\empty
                \fill[titlebgcolor] (6.3mm,6.4mm) rectangle (\the\paperwidth-8.3mm,\the\paperheight-13mm);
            \else
                \node at (current page.center) [anchor=center,yshift=-3.5mm] {\includegraphics[width=\the\paperwidth-19mm]{\titlefigure}};
            \fi
            \node at (current page.north east) [anchor=base east, xshift=-8.3mm, yshift=-6.3mm, align=left, inner sep=0mm, font=\fontsize{5.5}{6.6}\selectfont] {
                \insertshortinstitute
            }; 
            \node at (current page.north west) [anchor=south west, inner sep=0mm, xshift=8.3mm, yshift=-8.6mm] {
                \includegraphics[height=3.8mm]{img/my_logo}
            }; 
            \end{tikzpicture}
        }
        \setbeamertemplate{footline}{}
        \begin{frame}[noframenumbering]
            \begin{tikzpicture}
                \useasboundingbox (0,0) rectangle(\the\paperwidth,\the\paperheight);
                \node [
                    shift={(-11.5mm,-1.8mm)},
                    fill=titlefgcolor!50!white,
                    minimum width=0.46\paperwidth,
                    minimum height=18mm,
                    anchor=west,
                    inner sep=4mm
                    ] at (current page.west) {
                        \hspace*{9mm}
                        \begin{minipage}{\titleboxwidth}
                            \raggedright
                            \usebeamerfont{title}\usebeamercolor[fg]{title}\inserttitle\par
                            \usebeamerfont{author}\usebeamercolor[fg]{author}\insertauthor\par
                            \usebeamerfont{date}\usebeamercolor[fg]{date}\insertdate
                        \end{minipage}          
                    };
            \end{tikzpicture}
        \end{frame}
    }
}

% TOC frame
\newcommand{\tocframe}{%
    \begin{frame}
      \frametitle{Outline}
      \tableofcontents
    \end{frame}
}

% Section title frame
\AtBeginSection[]
{
    \begin{frame}
      \frametitle{Outline}
      \large
      \tableofcontents[currentsection] 
    \end{frame}
}

% Frame title
\setbeamertemplate{frametitle}{
    \vspace{2mm}
    \insertframetitle \\
    \usebeamerfont{framesubtitle}\insertframesubtitle
    \vspace{2.5mm}
}

% Footline
\setbeamertemplate{footline}{
    \leavevmode%
    \hyperlink{toc---table-of-contents}{\includegraphics[width=12mm,trim=0mm 0.4mm 0mm 0mm]{img/my_logo.png}}   
    \hfill
    \hyperlinkappendixstart{\insertframenumber/\inserttotalframenumber}
    \vspace{3mm}
}

\mode<all>

preamble.tex

% "title" is commented out in YAML header: else markdown generates a second title slide
% if title contains no special characters: feed it straight into LaTex at the end of the YAML header
% if title contains special characters, like ":", feed it to LaTex here:
\title[short version]{First line of the title:\\ second line of the title}
Solution

    • The additional frames are inserted by markdown because it will automatically start unnecessary frames even if none of the content is actually printed to the frame. You can avoid the empty frame between the title and your toc frame by placing the \tocframe after your \titleframe.

    • for black frames, you can define a new macro, e.g.

      \newcommand{\blackframe}{{\setbeamercolor{background canvas}{bg=black}\begin{frame}[plain]\end{frame}}}

    ---
subtitle: "Beamer presnetation with R-markdown"
institute: "some place"
date: "`r format(Sys.time(), '%B %d, %Y')`"
author: "Donald Duck"
output:
  # beamer_presentation: default
  bookdown::pdf_book:
    base_format: rmarkdown::beamer_presentation
    # includes:
    #   in_header: preamble.tex
    theme: "THEMENAME"
    latex_engine: xelatex
    toc: false
    slide_level: 2
    keep_tex: true 
header-includes:
  - \newcommand{\blackframe}{{\setbeamercolor{background canvas}{bg=black}\begin{frame}[plain]\end{frame}}}
  - \AtBeginDocument{\title{MWE}\titleframe\blackframe\tocframe}    
  - \AtEndDocument{\begin{closingframe}lalala\end{closingframe}}
  - \makeatletter\beamer@ignorenonframefalse\makeatother
---

```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = FALSE)
```

# section

## Slide with Bullets
<!-- ======================================================== -->

- Bullet 1
- Bullet 2
- Bullet 3

``` {=latex}
\end{frame}
\blackframe
\begin{frame}
```

<!-- Appendix -->
<!-- ======================================================== -->
``` {=latex}
\end{frame}
\appendix
\begin{frame}
```

    enter image description here