prototypeItem property
If non-null, forces the children to have the same extent as the given widget in the scroll direction.
Specifying an prototypeItem
is more efficient than letting the children
determine their own extent because the scrolling machinery can make use of
the foreknowledge of the children's extent to save work, for example when
the scroll position changes drastically.
See also:
- SliverPrototypeExtentList, the sliver used internally when this property is provided. It constrains its box children to have the same extent as a prototype item along the main axis.
- The
itemExtent
property, which allows forcing the children's extent to a given value. - The
itemExtentBuilder
property, which allows forcing the children's extent to be the value returned by the callback.
Implementation
final Widget? prototypeItem;