packShapes

Pack shapes into a tight block, in place.

Shapes are laid out left to right in rows inside a square-ish area centred on where they already are, keeping their reading order, with gap between them. Sizes are never changed — packing is about removing whitespace, and a layout that also resized things would be a different operation with a different undo expectation.

SEMANTICS-ASSUMED: rows, ordered by the shapes' existing reading order, in a block whose target width is the square root of the total area. Row packing is the only layout that is stable — nudging one shape does not reshuffle the rest — which is what makes repeated packing idempotent.