A masonry macro is now available, for creating walls of images with a layout that is “meant to be close to what a mason could do when placing stones in a wall”, along the usual description of this kind of layout. It uses currently the famous JavaScript Desandro Masonry library. Other implementations could be provided in the future, including pure CSS.
Thank you @vmassol for suggesting the use of XDOM directly rather than ad’hoc parsing 
Cheers,