Measure viewportRef's element (or accept an explicit viewport size),
resolve the strategy registered for the container's strategyId, and
return a NodeId-keyed map of placements for the container's visible
children. Updates on resize, container config changes, and child changes.
Measure
viewportRef's element (or accept an explicit viewport size), resolve the strategy registered for the container'sstrategyId, and return a NodeId-keyed map of placements for the container's visible children. Updates on resize, container config changes, and child changes.