KnownExtentsReorderableListView class
A list whose items the user can interactively reorder by dragging.
This class is appropriate for views with a small number of children because constructing the List requires doing work for every child that could possibly be displayed in the list view instead of just those children that are actually visible.
All list items must have a key.
This sample shows by dragging the user can reorder the items of the list. The onReorder parameter is required and will be called when a child widget is dragged to a new position.
{@tool dartpad --template=stateful_widget_scaffold}
final List<int> _items = List<int>.generate(50, (int index) => index);
@override
Widget build(BuildContext context){
final ColorScheme colorScheme = Theme.of(context).colorScheme;
final Color oddItemColor = colorScheme.primary.withOpacity(0.05);
final Color evenItemColor = colorScheme.primary.withOpacity(0.15);
return KnownExtentsReorderableListView(
padding: const EdgeInsets.symmetric(horizontal: 40),
children: <Widget>[
for (int index = 0; index < _items.length; index++)
ListTile(
key: Key('$index'),
tileColor: _items[index].isOdd ? oddItemColor : evenItemColor,
title: Text('Item ${_items[index]}'),
),
],
onReorder: (int oldIndex, int newIndex) {
setState(() {
if (oldIndex < newIndex) {
newIndex -= 1;
}
final int item = _items.removeAt(oldIndex);
_items.insert(newIndex, item);
});
},
);
}
{@end-tool}
- Inheritance
-
- Object
- DiagnosticableTree
- Widget
- StatefulWidget
- KnownExtentsReorderableListView
Constructors
-
KnownExtentsReorderableListView({Key? key, required List<
Widget> children, required ReorderCallback onReorder, required List<double> itemExtents, ReorderItemProxyDecorator? proxyDecorator, bool buildDefaultDragHandles = true, EdgeInsets? padding, Widget? header, Axis scrollDirection = Axis.vertical, bool reverse = false, ScrollController? scrollController, bool? primary, ScrollPhysics? physics, bool shrinkWrap = false, double anchor = 0.0, double? cacheExtent, DragStartBehavior dragStartBehavior = DragStartBehavior.start, ScrollViewKeyboardDismissBehavior keyboardDismissBehavior = ScrollViewKeyboardDismissBehavior.manual, String? restorationId, Clip clipBehavior = Clip.hardEdge}) - Creates a reorderable list from a pre-built list of widgets.
-
KnownExtentsReorderableListView.builder({Key? key, required IndexedWidgetBuilder itemBuilder, required int itemCount, required ReorderCallback onReorder, required List<
double> itemExtents, ReorderItemProxyDecorator? proxyDecorator, bool buildDefaultDragHandles = true, EdgeInsets? padding, Widget? header, Axis scrollDirection = Axis.vertical, bool reverse = false, ScrollController? scrollController, bool? primary, ScrollPhysics? physics, bool shrinkWrap = false, double anchor = 0.0, double? cacheExtent, DragStartBehavior dragStartBehavior = DragStartBehavior.start, ScrollViewKeyboardDismissBehavior keyboardDismissBehavior = ScrollViewKeyboardDismissBehavior.manual, String? restorationId, Clip clipBehavior = Clip.hardEdge}) -
Creates a reorderable list from widget items that are created on demand.
const
Properties
- anchor → double
-
The relative position of the zero scroll offset.
final
- buildDefaultDragHandles → bool
-
If true: on desktop platforms, a drag handle is stacked over the
center of each item's trailing edge; on mobile platforms, a long
press anywhere on the item starts a drag.
final
- cacheExtent → double?
-
The viewport has an area before and after the visible area to cache items
that are about to become visible when the user scrolls.
final
- clipBehavior → Clip
-
The content will be clipped (or not) according to this option.
final
- dragStartBehavior → DragStartBehavior
-
Determines the way that drag start behavior is handled.
final
- hashCode → int
-
The hash code for this object.
no setterinherited
- header → Widget?
-
A non-reorderable header item to show before the items of the list.
final
- itemBuilder → IndexedWidgetBuilder
-
Called, as needed, to build list item widgets.
final
- itemCount → int
-
The number of items in the list.
final
-
itemExtents
→ List<
double> -
final
- key → Key?
-
Controls how one widget replaces another widget in the tree.
finalinherited
- keyboardDismissBehavior → ScrollViewKeyboardDismissBehavior
-
ScrollViewKeyboardDismissBehavior the defines how this ScrollView will
dismiss the keyboard automatically.
final
- onReorder → ReorderCallback
-
A callback used by the list to report that a list item has been dragged
to a new location in the list and the application should update the order
of the items.
final
- padding → EdgeInsets?
-
The amount of space by which to inset the list contents.
final
- physics → ScrollPhysics?
-
How the scroll view should respond to user input.
final
- primary → bool?
-
Whether this is the primary scroll view associated with the parent
PrimaryScrollController.
final
- proxyDecorator → ReorderItemProxyDecorator?
-
A callback that allows the app to add an animated decoration around
an item when it is being dragged.
final
- restorationId → String?
-
Restoration ID to save and restore the scroll offset of the scrollable.
final
- reverse → bool
-
Whether the scroll view scrolls in the reading direction.
final
- runtimeType → Type
-
A representation of the runtime type of the object.
no setterinherited
- scrollController → ScrollController?
-
An object that can be used to control the position to which this scroll
view is scrolled.
final
- scrollDirection → Axis
-
The Axis along which the scroll view's offset increases.
final
- shrinkWrap → bool
-
Whether the extent of the scroll view in the scrollDirection should be
determined by the contents being viewed.
final
Methods
-
createElement(
) → StatefulElement -
Creates a StatefulElement to manage this widget's location in the tree.
inherited
-
createState(
) → _ReorderableListViewState -
Creates the mutable state for this widget at a given location in the tree.
override
-
debugDescribeChildren(
) → List< DiagnosticsNode> -
Returns a list of
DiagnosticsNode
objects describing this node's children.inherited -
debugFillProperties(
DiagnosticPropertiesBuilder properties) → void -
Add additional properties associated with the node.
inherited
-
noSuchMethod(
Invocation invocation) → dynamic -
Invoked when a nonexistent method or property is accessed.
inherited
-
toDiagnosticsNode(
{String? name, DiagnosticsTreeStyle? style}) → DiagnosticsNode -
Returns a debug representation of the object that is used by debugging
tools and by DiagnosticsNode.toStringDeep.
inherited
-
toString(
{DiagnosticLevel minLevel = DiagnosticLevel.info}) → String -
A string representation of this object.
inherited
-
toStringDeep(
{String prefixLineOne = '', String? prefixOtherLines, DiagnosticLevel minLevel = DiagnosticLevel.debug}) → String -
Returns a string representation of this node and its descendants.
inherited
-
toStringShallow(
{String joiner = ', ', DiagnosticLevel minLevel = DiagnosticLevel.debug}) → String -
Returns a one-line detailed description of the object.
inherited
-
toStringShort(
) → String -
A short, textual description of this widget.
inherited
Operators
-
operator ==(
Object other) → bool -
The equality operator.
inherited