How to modify the headline of beamertheme-focus so as to usage a logo at a custom position

Question

I am using beamertheme focus for an upcoming presentation.

I need to customise the default theme as follows

I already know how to change the default colour of the headline in my theme. However, I don't know how to insert the logo (a vector graphic) such that it aligns in-flush with the bottom line of the headline shading, and shall appreciate help in achieving this (if possible in every slide, not just the title slide of the presentation).

Answer 1

In the same folder of your document you should create a file called beamerouterthemefocus.sty with the following content:

  % Copyright (C) 2018-2019 Pasquale Claudio Africa and the LaTeX community.
% A full list of contributors can be found at
%
%     https://github.com/elauksap/focus-beamertheme
% 
% This file is part of beamerthemefocus.
% 
% beamerthemefocus is free software: you can redistribute it and/or modify
% it under the terms of the GNU General Public License as published by
% the Free Software Foundation, either version 3 of the License, or
% (at your option) any later version.
% 
% beamerthemefocus is distributed in the hope that it will be useful,
% but WITHOUT ANY WARRANTY; without even the implied warranty of
% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
% GNU General Public License for more details.
% 
% You should have received a copy of the GNU General Public License
% along with beamerthemefocus. If not, see <http://www.gnu.org/licenses/>.

\mode<presentation>

\RequirePackage{appendixnumberbeamer} % Don't number appendix frames.
% Fix hyperref warning caused by \appendix
% (https://tex.stackexchange.com/questions/192686/hyperref-warning-caused-by-beamer-appendix).
\newcommand*{\bkmtranslateto}{\languagename}
\newcommand*{\bkmtranslate}[1]{%
    \ifcsname tr@@@\bkmtranslateto @#1\endcsname
    \csname tr@@@\bkmtranslateto @#1\endcsname
    \else
    #1%
    \fi
}
\pdfstringdefDisableCommands{\let\translate\bkmtranslate}
\RequirePackage{bookmark}

\RequirePackage{etoolbox} % \BeforeBeginEnvironment.
\RequirePackage{tikz}


% FRAMETITLE TEMPLATES. --------------------------------------------------------
\defbeamertemplate*{frametitle}{focus}{%
    % If not title page.
    \ifnum\value{framenumber}>0%
%        \vspace{-1pt}%
%        \begin{beamercolorbox}[wd=\paperwidth,leftskip=0.55cm,rightskip=0.55cm,sep=0.2cm]{frametitle}%
%            \strut\insertframetitle\strut%
%\hfill\includegraphics[scale=0.3]{logoUCL}\vskip0pt
%        \end{beamercolorbox}%
\usebeamercolor{frametitle}\colorlet{focus@@temp}{bg}
\tikz[remember picture, overlay] {
\fill[color=focus@@temp] (current page.north west) rectangle ([yshift=-1.5cm]current page.north east) node[anchor= south east,inner sep=0pt]{\includegraphics[scale=0.3]{logoUCL}};
\node[anchor=north west] at ([shift={(0.55cm,-0.55cm)}]current page.north west) {\insertframetitle};
}
    \fi%
}

% Plain header.
\defbeamertemplate*{frametitle}{plain}{%
    % If not title page.
    \ifnum\value{framenumber}>0%
        \vspace{-1pt}%
        \begin{beamercolorbox}[wd=\paperwidth,leftskip=0.55cm,rightskip=0.55cm,sep=0.2cm,ignorebg]{frametitle}%
            \strut%
        \end{beamercolorbox}%
    \fi%
}


% FOOTLINE TEMPLATES. ----------------------------------------------------------
% Lenghts for the progress bar footline.
\newlength{\focus@pbar@height}% Progress bar height.
\newlength{\focus@pbar@leftoffset}
\newlength{\focus@pbar@rightoffset}

\defbeamertemplate*{footline}{progressbar}{%
    % If not appendix.
    \ifnum\mainend<0% From package appendixnumberbeamer.
        %
        \settowidth{\focus@pbar@leftoffset}{1}%
        \addtolength{\focus@pbar@leftoffset}{1.5em}%
        %
        \settowidth{\focus@pbar@rightoffset}{\inserttotalframenumber}%
        \addtolength{\focus@pbar@rightoffset}{1.5em}%
        %
        % If not title page.
        \ifnum\c@framenumber>0%
            \ifnum\c@framenumber<\inserttotalframenumber%
                \begin{tikzpicture}[inner xsep=0.5em, inner ysep=0.5ex]\usebeamerfont{footline}
                    \pgfmathsetmacro{\focus@pbar@progress}%
                        {(\paperwidth-\focus@pbar@leftoffset-\focus@pbar@rightoffset)*(\insertframenumber/\inserttotalframenumber)}

                    \clip (0,0) rectangle ++(\paperwidth,\the\focus@pbar@height);
                    \fill[footline.bg] (0,0) rectangle ++(\the\focus@pbar@leftoffset,\the\focus@pbar@height);

                    \fill[footline.bg] (\the\focus@pbar@leftoffset,0) rectangle ++(\focus@pbar@progress pt,\the\focus@pbar@height)
                                       ++(0,{-0.5*\the\focus@pbar@height}) node[anchor=east, text=footline.fg] {\strut\insertframenumber};

                    \fill[footline.bg] (\paperwidth,0) rectangle ++(-\the\focus@pbar@rightoffset,\the\focus@pbar@height)
                                       ++(0,{-0.5*\the\focus@pbar@height}) node[anchor=west, text=footline.fg] {\strut\inserttotalframenumber};
                \end{tikzpicture}%
            \else%
                \begin{tikzpicture}[inner xsep=0.5em, inner ysep=0.5ex]
                    \clip (0,0) rectangle ++(\paperwidth,\the\focus@pbar@height);
                    \fill[footline.bg] (0,0) rectangle ++(\paperwidth,\the\focus@pbar@height);

                    \node[anchor=east, footline.fg] at ({\paperwidth-\the\focus@pbar@rightoffset},{0.5*\focus@pbar@height}) {\strut\insertframenumber};
                    \node[footline.fg] at ({\paperwidth-\the\focus@pbar@rightoffset},{0.5*\focus@pbar@height}) {\strut/};
                    \node[anchor=west, footline.fg] at ({\paperwidth-\the\focus@pbar@rightoffset},{0.5*\focus@pbar@height}) {\strut\inserttotalframenumber};
                \end{tikzpicture}%
            \fi%
        \fi%
    \fi%
}

% Full bar footline.
\defbeamertemplate*{footline}{fullbar}{%
    % If not appendix.
    \ifnum\mainend<0% From package appendixnumberbeamer.
        %
        \settowidth{\focus@pbar@leftoffset}{1}%
        \addtolength{\focus@pbar@leftoffset}{1.5em}%
        %
        \settowidth{\focus@pbar@rightoffset}{\inserttotalframenumber}%
        \addtolength{\focus@pbar@rightoffset}{1.5em}%
        %
        % If not title page.
        \ifnum\c@framenumber>0%
            \begin{tikzpicture}[inner xsep=0.5em, inner ysep=0.5ex]
                \clip (0,0) rectangle ++(\paperwidth,\the\focus@pbar@height);
                \fill[footline.bg] (0,0) rectangle ++(\paperwidth,\the\focus@pbar@height);

                \node[anchor=east, footline.fg] at ({\paperwidth-\the\focus@pbar@rightoffset},{0.5*\focus@pbar@height}) {\strut\insertframenumber};
                \node[footline.fg] at ({\paperwidth-\the\focus@pbar@rightoffset},{0.5*\focus@pbar@height}) {\strut/};
                \node[anchor=west, footline.fg] at ({\paperwidth-\the\focus@pbar@rightoffset},{0.5*\focus@pbar@height}) {\strut\inserttotalframenumber};
            \end{tikzpicture}%
        \fi%
    \fi%
}

% Empty footline.
\defbeamertemplate*{footline}{none}{}

\DeclareOptionBeamer{numbering}{\def\beamer@focus@numbering{#1}}
\ExecuteOptionsBeamer{numbering=progressbar}
\ProcessOptionsBeamer

\def\beamer@focus@numberingprogressbar{progressbar}
\def\beamer@focus@numberingfullbar{fullbar}
\def\beamer@focus@numberingnone{none}


% BACKGROUND CANVAS TEMPLATES. -------------------------------------------------
\defbeamertemplate*{background canvas}{focus}{%
    \begin{tikzpicture}
        \clip (0,0) rectangle ++(\paperwidth,\paperheight);
        \fill[normal text.bg] (0,0) rectangle ++(\paperwidth,\paperheight);
    \end{tikzpicture}%
}

\defbeamertemplate*{background canvas}{focusplain}{%
    \begin{tikzpicture}
        \clip (0,0) rectangle ++(\paperwidth,\paperheight);
        \fill[normal text.bg] (0,0) rectangle ++(\paperwidth,\paperheight);
    \end{tikzpicture}%
}

\defbeamertemplate*{background canvas}{focusframe}{%
    \begin{tikzpicture}
        \clip (0,0) rectangle ++(\paperwidth,\paperheight);
        \fill[frametitle.bg] (0,0) rectangle ++(\paperwidth,\paperheight);        
    \end{tikzpicture}%
}


% HOOKS FOR CREATING FRAMES. ---------------------------------------------------
\BeforeBeginEnvironment{frame}{%
    \setbeamertemplate{background canvas}[focus]%
    \setbeamertemplate{frametitle}[focus]%
    %
    % Reset footline height and determine it for the current slide.
    \setlength{\focus@pbar@height}{0cm}%
    \focus@calculatefootheight%
    %
    % If not appendix.
    \ifnum\mainend<0 % From package appendixnumberbeamer.
        \settoheight{\focus@pbar@height}{\usebeamerfont{footline}1234567890/}%
        \addtolength{\focus@pbar@height}{6pt}%
        %
        \ifx\beamer@focus@numbering\beamer@focus@numberingprogressbar%
            \setbeamertemplate{footline}[progressbar]%
        \else%
            \ifx\beamer@focus@numbering\beamer@focus@numberingfullbar%
                \setbeamertemplate{footline}[fullbar]%
            \fi%
        \fi%
        %
        \focus@calculatefootheight%
    \fi%
}

% Enable noframenumbering option.
\define@key{beamerframe}{noframenumbering}[true]{%
    \setbeamertemplate{footline}[none]%
    \setlength{\focus@pbar@height}{0cm}%
    \focus@calculatefootheight%
    %
    \addtocounter{framenumber}{-1}%
}


% Enable plain option.
\define@key{beamerframe}{plain}[true]{%
    \setbeamertemplate{background canvas}[focusplain]%
    \setbeamertemplate{frametitle}[plain]%
    %
    \setbeamertemplate{footline}[none]%
}


% Full vertical centering
% (from https://tex.stackexchange.com/questions/247826/beamer-full-vertical-centering).
\define@key{beamerframe}{c}[true]{%
    \beamer@frametopskip=0pt plus 1fill\relax%
    \beamer@framebottomskip=0pt plus 1fill\relax%
    \beamer@frametopskipautobreak=0pt plus 0.4\paperheight\relax%
    \beamer@framebottomskipautobreak=0pt plus 0.6\paperheight\relax%
    \def\beamer@initfirstlineunskip{}%
}


% Enable focus option.
\providebool{focus@standout}
\define@key{beamerframe}{focus}[true]{%
    \booltrue{focus@standout}%
    \begingroup%
        \setkeys{beamerframe}{noframenumbering}%
        \setbeamertemplate{background canvas}[focusframe]%
        \setbeamertemplate{frametitle}[plain]%
        %
        \setkeys{beamerframe}{c}%
        \centering%
        \usebeamerfont{focusframe}%
        \usebeamercolor[fg]{frametitle}%
}

\apptocmd{\beamer@reseteecodes}
{%
    \ifbool{focus@standout}%
    {%
        \endgroup%
        \boolfalse{focus@standout}%
    }{}%
}{}{}


% Recalculate the footline's size and refresh other parameters.
% Partially copied from the definition of \beamer@calculateheadfoot.
\def\focus@calculatefootheight{%
    \footheight=\focus@pbar@height%
    \advance\footheight by 4pt%
    \sidebarheight=\paperheight%
    \advance\sidebarheight by-\headheight%
    \advance\sidebarheight by\headdp%
    \advance\sidebarheight by-\footheight%
    \advance\sidebarheight by 4pt%
    \footskip=\footheight%
    \textheight=\paperheight%
    \advance\textheight by-\footheight%
    \advance\textheight by-\headheight%
    \@colht\textheight%
    \@colroom\textheight%
    \vsize\textheight%
}

\mode<all>

Always in the same folder you should create a second file called beamerinnerthemefocus.sty with the following content:

% Copyright (C) 2018-2019 Pasquale Claudio Africa and the LaTeX community.
% A full list of contributors can be found at
%
%     https://github.com/elauksap/focus-beamertheme
% 
% This file is part of beamerthemefocus.
% 
% beamerthemefocus is free software: you can redistribute it and/or modify
% it under the terms of the GNU General Public License as published by
% the Free Software Foundation, either version 3 of the License, or
% (at your option) any later version.
% 
% beamerthemefocus is distributed in the hope that it will be useful,
% but WITHOUT ANY WARRANTY; without even the implied warranty of
% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
% GNU General Public License for more details.
% 
% You should have received a copy of the GNU General Public License
% along with beamerthemefocus. If not, see <http://www.gnu.org/licenses/>.

\mode<presentation>

\RequirePackage{tikz}


% CUSTOMIZE STRUCTURE ELEMENTS. ------------------------------------------------
\setbeamertemplate{blocks}[default]

\setbeamertemplate{section in toc}[square]
\setbeamertemplate{subsection in toc}[square]

\setbeamertemplate{itemize items}[square]
\setbeamertemplate{itemize subitem}[triangle]


% STRUCTURE FRAME TEMPLATE DEFINITIONS. ----------------------------------------
% Title page.
\defbeamertemplate*{title page}{focus}{%
    {%
        \usebeamercolor{frametitle}\colorlet{focus@@temp}{bg}%
        \begin{tikzpicture}[overlay, remember picture]
            \fill[color=focus@@temp] (current page.north west) rectangle ([shift = {(0, -0.2\paperheight)}] current page.north east) node[anchor=south east,inner ysep=0 pt] {\includegraphics[scale=0.3]{logoUCL}};
        \end{tikzpicture}
    }
    \begin{beamercolorbox}[sep=1pt,left]{institute}
        \usebeamercolor[fg]{frametitle}
        \usebeamerfont{institute}\insertinstitute
    \end{beamercolorbox}
\vskip4em\par
%    \begin{beamercolorbox}[sep=8pt,left]{title}
%\usebeamercolor[bg]{normal text}
%      \usebeamerfont{title}\inserttitle\par 
%        {\usebeamerfont{subtitle}\insertsubtitle\par}%
%    \end{beamercolorbox}

\begin{minipage}[t]{\textwidth}
\usebeamerfont{title}\inserttitle\par 
        {\usebeamerfont{subtitle}\insertsubtitle\par}%
    \end{minipage}
    %\vspace{-1.65\baselineskip}
%    \begin{minipage}[b][0.35\paperheight]{\textwidth}
%        \vspace{\baselineskip}
%        \usebeamerfont{title}
%        \usebeamercolor[fg]{frametitle}
%        \inserttitle
%    \end{minipage}
%    
%    \begin{minipage}[t][0.1\paperheight]{\textwidth}
%        \usebeamerfont{subtitle}
%        \usebeamercolor[fg]{frametitle}
%        \insertsubtitle
%    \end{minipage}
%    
%    % Set the title graphic in a zero-height box, so that
%    % the position of other elements is not affected.
    {\vfuzz=9999pt\vbox to 0pt {
        \raggedleft
        \inserttitlegraphic
    }}
\vskip4em\par   
    \begin{minipage}[t]{\textwidth}
        \usebeamerfont{author}
        \insertauthor
    \end{minipage}
%    
    %\vspace*{\baselineskip}
%    \begin{minipage}[t]{\textwidth}
%        \usebeamerfont{institute}
%        \insertinstitute
%    \end{minipage}

    \vspace*{\baselineskip}
    \begin{minipage}[t]{\textwidth}
        \usebeamerfont{date}
        \insertdate
    \end{minipage}
    \vspace*{0pt plus 100fill}   
    \addtocounter{framenumber}{-1}
}

% Section page.
\defbeamertemplate*{section page}{focus}{%
    {%
        \usebeamercolor{frametitle}\colorlet{focus@@temp}{bg}%
        \begin{tikzpicture}[overlay, remember picture]
            \fill[color=focus@@temp] (current page.north west) rectangle ([shift = {(0, -0.45\paperheight)}] current page.north east)node[anchor=south east,inner ysep=0 pt] {\includegraphics[scale=0.3]{logoUCL}};
        \end{tikzpicture}%
    }

    \vspace{-2.5\baselineskip}
    \begin{minipage}[b][0.45\paperheight]{\textwidth}
        \usebeamerfont{sectiontitle}
        \usebeamercolor[fg]{frametitle}
        \let\hyperlink\@secondoftwo\insertsection
    \end{minipage}

    \vspace{1.5\baselineskip}
    \begin{minipage}[t][0.55\paperheight]{\textwidth}
        \usebeamerfont{subsectiontitle}
        \usebeamercolor[bg]{frametitle}
        \insertsubsection
    \end{minipage}
}

\AtBeginSection[]{%
    \begin{frame}[plain, noframenumbering]{}
        \sectionpage
    \end{frame}%
}

% Subsection page.
\defbeamertemplate*{subsection page}{focus}{%
    {%
        \usebeamercolor{frametitle}\colorlet{focus@@temp}{bg}%
        \begin{tikzpicture}[overlay, remember picture]
        \fill[color=focus@@temp] (current page.north west) rectangle ([shift = {(0, -0.45\paperheight)}] current page.north east)node[anchor=south east,inner ysep=0 pt] {\includegraphics[scale=0.3]{logoUCL}};
        \end{tikzpicture}%
    }

    \vspace{-2.5\baselineskip}
    \begin{minipage}[b][0.45\paperheight]{\textwidth}
        \usebeamerfont{sectiontitle}
        \usebeamercolor[fg]{frametitle}
        \let\hyperlink\@secondoftwo\insertsection
    \end{minipage}

    \vspace{1.5\baselineskip}
    \begin{minipage}[t][0.55\paperheight]{\textwidth}
        \usebeamerfont{subsectiontitle}
        \usebeamercolor[bg]{frametitle}
        \insertsubsection
    \end{minipage}
}

\AtBeginSubsection[]{%
    \begin{frame}[plain, noframenumbering]{}
        \subsectionpage
    \end{frame}%
}

\mode<all>

The result after setting \setbeamercolor{frametitle}{bg=black} in your document is as follow: