Notebook and Blackboard canvas don't fill slides when other images are in the slideshow

[Martin1887]

When the slideshow contains any image, Blackboard and Notebook backgrounds don't fill the 100% of the slides.

It can be solved using the workaround below (where $background-image$ is the background path, the same problem was fixed in jgm/pandoc-templates#20), but it only works if the \setbeamertemplate[background canvas]{...} line is removed:

\usebackgroundtemplate{%
\includegraphics[width=\paperwidth]{$background-image$}%
}
% In beamer background-image does not work well when other images are used, so this is the workaround
\pgfdeclareimage[width=\paperwidth,height=\paperheight]{background}{$background-image$}
\usebackgroundtemplate{\pgfuseimage{background}}

I hope that this comments help you to get the cleanest solution (probably simply replace the canvas line by these lines).

Regards,

[kmaed]

I'm sorry but I cannot see what is your problem. Could you provide a MWE?

I've tried the following example, but there is no problem...

\documentclass{beamer}
\usetheme{Blackboard}
\begin{document}
\begin{frame}{Example}
  \includegraphics[width=.5\textwidth]{example.png}
\end{frame}
\end{document}

By the way, if aspectratio=169 is specified for the Blackboard and Notebook theme, then the background image does not fill the slides. Is it your intension to point out?

[Martin1887]

Hello, I think the problem happens when the figure environment is used. However, screenshots of working and not working examples and the corresponding tex file are attached (note that the tex file has an additional .txt extension because GitHub doesn't allow to attach tex files and some boilerplate because I testing this in a Pandoc wrapper I'm developing).
book.beamer.tex.txt

In addition, as you can see in the last screenshot, this workaround also works for 169 mode presentations.

Regards,

[kmaed]

I think that the minimal essential part of your example is

\documentclass{beamer}
\usetheme{Blackboard}
\makeatletter
\def\maxwidth{\ifdim\Gin@nat@width>\linewidth\linewidth\else\Gin@nat@width\fi}
\def\maxheight{\ifdim\Gin@nat@height>\textheight\textheight\else\Gin@nat@height\fi}
\makeatother
% Scale images if necessary, so that they will not overflow the page
% margins by default, and it is still possible to overwrite the defaults
% using explicit options in \includegraphics[width, height, ...]{}
\setkeys{Gin}{width=\maxwidth,height=\maxheight,keepaspectratio}
\begin{document}
\begin{frame}{Frame title}
  text text text text text text text text text text text text text text text text
\end{frame}
\end{document}

This \setkeys{Gin}{width=\maxwidth,height=\maxheight,keepaspectratio} also affects the background image. I added options to \includegraphics of the background image by 9b6dc34. This commit also solves the problem of aspectratio=169 but distorts the background image. I will try to give another solution to the issue if possible.

[Martin1887]

Good job, thanks!