Largest clipped normalized-device area, from 0 through 4, of any visible
leaf that references the chunk. It is the area of the leaf's projected
bounding rectangle, so it over-estimates a slanted box and attributes a
whole leaf to each chunk the leaf references; it ranks demand, it does not
measure a chunk's own pixels.
Largest clipped normalized-device area, from 0 through 4, of any visible leaf that references the chunk. It is the area of the leaf's projected bounding rectangle, so it over-estimates a slanted box and attributes a whole leaf to each chunk the leaf references; it ranks demand, it does not measure a chunk's own pixels.