Mount a statistics table that keeps itself current.
filter may be a value or a getter — a getter, because the usual filter is a drawn region that
changes independently of the layer. The layer emits nothing when a region is drawn, so call
update() after that; everything the LAYER can know about is already automatic.
Mount a statistics table that keeps itself current.
filtermay be a value or a getter — a getter, because the usual filter is a drawn region that changes independently of the layer. The layer emits nothing when a region is drawn, so callupdate()after that; everything the LAYER can know about is already automatic.