cacheExtent property
The TreeViewport has an area before and after the visible area to cache rows that are about to become visible when the user scrolls.
TreeRows that fall in this cache area are laid out even though they are not (yet) visible on screen. The cacheExtent describes how many pixels the cache area extends before the leading edge and after the trailing edge of the viewport.
See also:
- TwoDimensionalScrollView.cacheExtent, the area beyond the viewport bounds where soon-to-be-visible children are rendered.
Implementation
final double? cacheExtent;