ListWheelChildBuilderDelegate class Null safety

A delegate that supplies children for ListWheelScrollView using a builder callback.

ListWheelScrollView lazily constructs its children to avoid creating more children than are visible through the Viewport. This delegate provides children using an IndexedWidgetBuilder callback, so that the children do not have to be built until they are displayed.



ListWheelChildBuilderDelegate({required NullableIndexedWidgetBuilder builder, int? childCount})
Constructs the delegate from a builder callback.


builder NullableIndexedWidgetBuilder
Called lazily to build children.
childCount int?
If non-null, childCount is the maximum number of children that can be provided, and children are available from 0 to childCount - 1.
estimatedChildCount int?
Returns an estimate of the number of children this delegate will build.
read-only, override
hashCode int
The hash code for this object.
read-only, inherited
runtimeType Type
A representation of the runtime type of the object.
read-only, inherited


build(BuildContext context, int index) Widget?
Return the child at the given index. If the child at the given index does not exist, return null.
noSuchMethod(Invocation invocation) → dynamic
Invoked when a non-existent method or property is accessed.
shouldRebuild(covariant ListWheelChildBuilderDelegate oldDelegate) bool
Called to check whether this and the old delegate are actually 'different', so that the caller can decide to rebuild or not.
toString() String
A string representation of this object.
trueIndexOf(int index) int
Returns the true index for a child built at a given index. Defaults to the given index, however if the delegate is ListWheelChildLoopingListDelegate, this value is the index of the true element that the delegate is looping to.


operator ==(Object other) bool
The equality operator.