### Beamer customization III: Logos

This is part III of a series of posts on customizing the beamer default theme and circles around the aspect of displaying logos at the right top and left bottom of each slide. Beamer comes with a \logo command that allows for specifying some text or image (for example via \includegraphics) that is displayed as logo. The alignment of the logo depends on the current theme (for the default theme this is the bottom right corner).

My main problem is that I need two logos instead of one in different positions which cannot be achieved with the provided functionality. For at least one of the logos, I needed to write a custom command. For consistency and simplicity of my template, i did this for both logos and ignored the provided \logo command. I choose to display the logos via the not-so-flexible, but convenient solution of specifying the exact position of the logos on each slide. This can be achieved with the help of the textpos package. When loaded with the absolute and overlay options, it allows to specify the exact position of some text relative to the left upper border of the current page and this text is displayed ontop of anything else that happens to be there. So, somewhere in my preamble I have this package import:

% some more packages
\usepackage[absolute,overlay]{textpos}
% some more packages


The commands for printing the logos are now very similar, except for the adjusted sizes and positioning values. Here is an example:

\newcommand{\unilogo}{
\setlength{\TPHorizModule}{1pt}
\setlength{\TPVertModule}{1pt}
% textblock{}{x,y}: pos(x) = leftUpperCorner + (x * \TPHorizModule), pos(y) = leftUpperCorner - (y * \TPVertModule)
\begin{textblock}{1}(8,245)
\includegraphics[width=25pt,height=25pt]{include/uni}
\end{textblock}
}


\TPHorizModule and \TPVertModule are the factors with which the horizontal and vertical alignment of a textblock is calculated. For a fine-grained positioning, I set them to 1pt. The textblock environment can be used to position some text. The first input parameter marks the width of the text which does not matter if the sole content of the textblock is an image. The following two parameters mark the x and y values for its positioning. These parameters are multiplied with the values of \TPHorizModule and \TPVertModule set before. As the block is displayed relative to the upper left corner of the page, the y value goes downward instead of up. Line 6 contains a standard image inclusion. This code works equally well for several different logos. You just have to adjust the name of the command and the exact positioning. Then of course, you have to make sure that the logos are displayed on every page. This can be done by invoking the commands in an overwritten template that is displayed on any page. An example is the footline template as described in the previous post.