Linked to this previous post, i make some tests to have more elegant sidecaption using memoir class.
I try to reproduce this layout, with two type of caption style :
- a normal centered caption with legend aligned to the title,
- and a sidecaption with possible sidelegend. Title are ragged to the left and aligned with the legend float. Text in the sidelegend float is justified.

I found the \sidelegend command in memoir class documentation, but i found no example of usage in my case.
A MWE :
\documentclass[a4paper, 11pt,twoside, openright]{memoir}
\usepackage{polyglossia}
\setdefaultlanguage{french}
\setotherlanguage{english}
\usepackage{fontspec}
\usepackage{xparse}
\usepackage{graphicx}
\usepackage{ragged2e}
\usepackage{mwe} % just for dummy images
\usepackage{lipsum}
\usepackage{showframe} % just to display frame
\sidecapmargin{outer}
\setsidecappos{t}
\renewcommand*{\sidecapstyle}{%
\ifscapmargleft
\captionstyle{\raggedright\scriptsize}%
\else
\captionstyle{\raggedright\scriptsize}%
\fi}
\makeatletter
\renewcommand{\fnum@figure}{\scriptsize\textbf{Figure~\thefigure~--}}
\makeatother
\begin{document}
\begin{figure}[h]
\begin{sidecaption}[fortoc]{A long graphic title 1 \\[2ex] A very long legend with multiple citations, and multiple authors, and some blablabla }[fig:S_OverviewOptimisation1]
\centering
\includegraphics[width=.9\linewidth]{example-image}
\end{sidecaption}
\end{figure}
\lipsum[1-3]
\begin{figure}[h]
\begin{sidecaption}[fortoc]{A long graphic title 2 \\[2ex] A very long legend with multiple citations, and multiple authors, and some blablabla }[fig:S_OverviewOptimisation2]
\centering
\includegraphics[width=.9\linewidth]{example-image}
\end{sidecaption}
\end{figure}
\lipsum[1-3]
\begin{figure}[h]
\centering
\includegraphics[width=.9\linewidth]{example-image}
\caption{A long graphic title 3}
\legend{A very long legend with multiple citations, and multiple authors, and some blablabla }
\end{figure}
\lipsum[1-3]
\end{document}
I try to reproduce the stylized layout, so i need to understand how can i separate alignement for figure (ragged right or left?), and alignement for legend text (justified)
There is a command nammed \sidelegend in memoir class, but i don't understand how this command work to obtain this behavior, and how can i justify text ?
\usepackage[demo]{graphicx}! – DG' Jan 27 '15 at 13:41