Timeline.tileBuilder constructor
- {Key? key,
- required TimelineTileBuilder builder,
- Axis? scrollDirection,
- bool reverse = false,
- ScrollController? controller,
- bool? primary,
- ScrollPhysics? physics,
- bool shrinkWrap = false,
- EdgeInsetsGeometry? padding,
- double? cacheExtent,
- int? semanticChildCount,
- DragStartBehavior dragStartBehavior = DragStartBehavior.start,
- ScrollViewKeyboardDismissBehavior keyboardDismissBehavior = ScrollViewKeyboardDismissBehavior.manual,
- String? restorationId,
- Clip clipBehavior = Clip.hardEdge,
- TimelineThemeData? theme}
Creates a scrollable, linear array of widgets that are created on demand.
This constructor is appropriate for list views with a large (or infinite) number of children because the builder is called only for those children that are actually visible.
Providing a non-null itemCount
improves the ability of the Timeline to
estimate the maximum scroll extent.
The itemBuilder
callback will be called only with indices greater than
or equal to zero and less than itemCount
.
The itemBuilder
should always return a non-null widget, and actually
create the widget instances when called.
Avoid using a builder that returns a previously-constructed widget; if the
timeline view's children are created in advance, or all at once when the
Timeline itself is created, it is more efficient to use the Timeline
constructor. Even more efficient, however, is to create the instances on
demand using this constructor's itemBuilder
callback.
The addAutomaticKeepAlives
argument corresponds to the
SliverChildBuilderDelegate.addAutomaticKeepAlives property. The
addRepaintBoundaries
argument corresponds to the
SliverChildBuilderDelegate.addRepaintBoundaries property. The
addSemanticIndexes
argument corresponds to the
SliverChildBuilderDelegate.addSemanticIndexes property. None
may be null.
Timeline.builder by default does not support child reordering. If you are planning to change child order at a later time, consider using Timeline or Timeline.custom.
Implementation
factory Timeline.tileBuilder({
Key? key,
required TimelineTileBuilder builder,
Axis? scrollDirection,
bool reverse = false,
ScrollController? controller,
bool? primary,
ScrollPhysics? physics,
bool shrinkWrap = false,
EdgeInsetsGeometry? padding,
// double itemExtent, TODO: fixedExtentTileBuilder?
double? cacheExtent,
int? semanticChildCount,
DragStartBehavior dragStartBehavior = DragStartBehavior.start,
ScrollViewKeyboardDismissBehavior keyboardDismissBehavior =
ScrollViewKeyboardDismissBehavior.manual,
String? restorationId,
Clip clipBehavior = Clip.hardEdge,
TimelineThemeData? theme,
}) {
assert(builder.itemCount >= 0);
assert(
semanticChildCount == null || semanticChildCount <= builder.itemCount);
return Timeline.custom(
key: key,
childrenDelegate: SliverChildBuilderDelegate(
builder.build,
childCount: builder.itemCount,
// TODO: apply some fields if needed.
),
scrollDirection: scrollDirection,
reverse: reverse,
controller: controller,
primary: primary,
physics: physics,
shrinkWrap: shrinkWrap,
padding: padding,
// itemExtent: itemExtent,
cacheExtent: cacheExtent,
semanticChildCount: semanticChildCount ?? builder.itemCount,
dragStartBehavior: dragStartBehavior,
keyboardDismissBehavior: keyboardDismissBehavior,
restorationId: restorationId,
clipBehavior: clipBehavior,
theme: theme,
);
}