Automatic scaling of side by side figures

Question

I'm using a quite satisfying solution for side by side independent caption figures, a solution by which images are sized automatically to same height and to text width, see MWE below.

\documentclass{article}
\usepackage{mwe}
\usepackage{floatrow}

\begin{document}
\blindtext

\begin{figure*}
\CommonHeightRow{\begin{floatrow}
\ffigbox[\FBwidth]{\includegraphics[height=\CommonHeight]{example-image-16x10}}{\caption{A caption.}\label{fig:01}}
\ffigbox[\FBwidth]{\includegraphics[height=\CommonHeight]{example-image-10x16}}{\caption{Another caption.}\label{fig:02}}
\end{floatrow}}
\end{figure*}

\blindtext
\end{document}

However sometimes I would like to limit the overall width of the two figures to something less (say 80%) than text width (retaining the uniform height), but I couldn't find a way to achieve it. (For some reason the naive solution of adding a scalar prefix to \CommonHeight, such as 0.8\CommonHeight, gives an error.)

Thanks in advance for any clue.

Solutions using a package other than floatrow are welcomed, as long as they automatically size images height and overall width by a given percentage of text width, as required.

Answer 1

The floatrow package has two macros, \FRleftmargin and \FRrightmargin which are, by default, \hfill. You can redefine each of them to be \hspace{0.1\textwidth} so the space left for the figures will be 0.8\textwidth.

(rule for scale :)

The definition must be before \begin{floatrow}. If you put it inside \begin{figure} it will be valid for the current figure only, otherwise it will take effect until you redefine it.

I made a little command that will take as argument the desired width of the figures. The command will then balance it and pass to \FRleftmargin and \FRrightmargin. Just call \ThisWidth{0.8\textwidth} after \begin{figure} (or \begin{figure*}, of course :)

\documentclass{article}
\usepackage{mwe}
\usepackage{floatrow}

\makeatletter
\def\ThisWidth#1{%
  \@tempdima\dimexpr(\textwidth-#1)/2\relax
  \edef\FRleftmargin{\noexpand\hspace*{\the\@tempdima}}%
  \edef\FRrightmargin{\noexpand\hspace*{\the\@tempdima}}%
  \ignorespaces}
\makeatother

\begin{document}
\pagenumbering{gobble}
\blindtext

\begin{figure*}
\ThisWidth{0.8\textwidth}
\CommonHeightRow{\begin{floatrow}
\ffigbox[\FBwidth]{\includegraphics[height=\CommonHeight]{example-image-16x10}}{\caption{A caption.}\label{fig:01}}
\ffigbox[\FBwidth]{\includegraphics[height=\CommonHeight]{example-image-10x16}}{\caption{Another caption.}\label{fig:02}}
\end{floatrow}}
\rule{0.8\textwidth}{2pt}
\end{figure*}

\blindtext
\end{document}