DraggableList class

A scrolling container that allows the user to interactively drag the list items.

This widget is similar to one created by ListView.builder, and uses an IndexedWidgetBuilder to create each item.

It is up to the application to wrap each child (or an internal part of the child such as a drag handle) with a drag listener that will recognize the start of an item drag and then start the drag by calling DraggableListState.startItemDrag. This is most easily achieved by wrapping each child in a DraggableDragStartListener or a DraggableDelayedDragStartListener. These will take care of recognizing the start of a drag gesture and call the list state's DraggableListState.startItemDrag method.

This widget's DraggableListState can be used to manually start an item drag, or cancel a current drag. To refer to the DraggableListState either provide a GlobalKey or use the static DraggableList.of method from an item's build method.

See also:

Inheritance

Constructors

DraggableList({Key key, @required IndexedWidgetBuilder itemBuilder, @required int itemCount, @required DragEndCallback onDragEnd, @required DragStartCallback onDragStart, @required DragingCallback onDraging, @required DragCancelCallback onDragCancel, DraggableItemProxyDecorator proxyDecorator, EdgeInsetsGeometry padding, Axis scrollDirection = Axis.vertical, bool reverse = false, ScrollController controller, 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 scrolling container that allows the user to interactively drag the list items.
const

Properties

anchor double
The relative position of the zero scroll offset.
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
controller ScrollController
An object that can be used to control the position to which this scroll view is scrolled.
final
dragStartBehavior DragStartBehavior
Determines the way that drag start behavior is handled.
final
hashCode int
The hash code for this object.
read-onlyinherited
itemBuilder IndexedWidgetBuilder
Called, as needed, to build list item widgets.
final
itemCount int
The number of items in the list.
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
onDragCancel DragCancelCallback
final
onDragEnd DragEndCallback
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
onDraging DragingCallback
final
onDragStart DragStartCallback
final
padding EdgeInsetsGeometry
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 DraggableItemProxyDecorator
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.
read-onlyinherited
scrollDirection Axis
The axis along which the scroll view scrolls.
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() DraggableListState
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 non-existent 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

Static Methods

maybeOf(BuildContext context) DraggableListState
The state from the closest instance of this class that encloses the given context.
of(BuildContext context) DraggableListState
The state from the closest instance of this class that encloses the given context.