Draggable<T extends Object> class Null safety

A widget that can be dragged from to a DragTarget.

When a draggable widget recognizes the start of a drag gesture, it displays a feedback widget that tracks the user's finger across the screen. If the user lifts their finger while on top of a DragTarget, that target is given the opportunity to accept the data carried by the draggable.

The ignoringFeedbackPointer defaults to true, which means that the feedback widget ignores the pointer during hit testing. Similarly, ignoringFeedbackSemantics defaults to true, and the feedback also ignores semantics when building the semantics tree.

On multitouch devices, multiple drags can occur simultaneously because there can be multiple pointers in contact with the device at once. To limit the number of simultaneous drags, use the maxSimultaneousDrags property. The default is to allow an unlimited number of simultaneous drags.

This widget displays child when zero drags are under way. If childWhenDragging is non-null, this widget instead displays childWhenDragging when one or more drags are underway. Otherwise, this widget always displays child.

The following example has a Draggable widget along with a DragTarget in a row demonstrating an incremented acceptedData integer value when you drag the element to the target.
To create a local project with this code sample, run:
flutter create --sample=widgets.Draggable.1 mysample

See also:



Draggable({Key? key, required Widget child, required Widget feedback, T? data, Axis? axis, Widget? childWhenDragging, Offset feedbackOffset = Offset.zero, @Deprecated('Use dragAnchorStrategy instead. ' 'Replace "dragAnchor: DragAnchor.child" with "dragAnchorStrategy: childDragAnchorStrategy". ' 'Replace "dragAnchor: DragAnchor.pointer" with "dragAnchorStrategy: pointerDragAnchorStrategy". ' 'This feature was deprecated after v2.1.0-10.0.pre.') DragAnchor dragAnchor = DragAnchor.child, DragAnchorStrategy? dragAnchorStrategy, Axis? affinity, int? maxSimultaneousDrags, VoidCallback? onDragStarted, DragUpdateCallback? onDragUpdate, DraggableCanceledCallback? onDraggableCanceled, DragEndCallback? onDragEnd, VoidCallback? onDragCompleted, bool ignoringFeedbackSemantics = true, bool ignoringFeedbackPointer = true, bool rootOverlay = false, HitTestBehavior hitTestBehavior = HitTestBehavior.deferToChild})
Creates a widget that can be dragged to a DragTarget.


affinity Axis?
Controls how this widget competes with other gestures to initiate a drag.
axis Axis?
The Axis to restrict this draggable's movement, if specified.
child Widget
The widget below this widget in the tree.
childWhenDragging Widget?
The widget to display instead of child when one or more drags are under way.
data → T?
The data that will be dropped by this draggable.
dragAnchor DragAnchor
Where this widget should be anchored during a drag.
@Deprecated('Use dragAnchorStrategy instead. ' 'This feature was deprecated after v2.1.0-10.0.pre.'), final
dragAnchorStrategy DragAnchorStrategy?
A strategy that is used by this draggable to get the anchor offset when it is dragged.
feedback Widget
The widget to show under the pointer when a drag is under way.
feedbackOffset Offset
The feedbackOffset can be used to set the hit test target point for the purposes of finding a drag target. It is especially useful if the feedback is transformed compared to the child.
hashCode int
The hash code for this object.
@nonVirtual, read-only, inherited
hitTestBehavior HitTestBehavior
How to behave during hit test.
ignoringFeedbackPointer bool
Whether the feedback widget is ignored during hit testing.
ignoringFeedbackSemantics bool
Whether the semantics of the feedback widget is ignored when building the semantics tree.
key Key?
Controls how one widget replaces another widget in the tree.
final, inherited
maxSimultaneousDrags int?
How many simultaneous drags to support.
onDragCompleted VoidCallback?
Called when the draggable is dropped and accepted by a DragTarget.
onDragEnd DragEndCallback?
Called when the draggable is dropped.
onDraggableCanceled DraggableCanceledCallback?
Called when the draggable is dropped without being accepted by a DragTarget.
onDragStarted VoidCallback?
Called when the draggable starts being dragged.
onDragUpdate DragUpdateCallback?
Called when the draggable is dragged.
rootOverlay bool
Whether the feedback widget will be put on the root Overlay.
runtimeType Type
A representation of the runtime type of the object.
read-only, inherited


createElement() StatefulElement
Creates a StatefulElement to manage this widget's location in the tree.
createRecognizer(GestureMultiDragStartCallback onStart) MultiDragGestureRecognizer
Creates a gesture recognizer that recognizes the start of the drag.
createState() State<Draggable<T>>
Creates the mutable state for this widget at a given location in the tree.
debugDescribeChildren() List<DiagnosticsNode>
Returns a list of DiagnosticsNode objects describing this node's children.
@protected, inherited
debugFillProperties(DiagnosticPropertiesBuilder properties) → void
Add additional properties associated with the node.
noSuchMethod(Invocation invocation) → dynamic
Invoked when a non-existent method or property is accessed.
toDiagnosticsNode({String? name, DiagnosticsTreeStyle? style}) DiagnosticsNode
Returns a debug representation of the object that is used by debugging tools and by DiagnosticsNode.toStringDeep.
toString({DiagnosticLevel minLevel = DiagnosticLevel.info}) String
A string representation of this object.
toStringDeep({String prefixLineOne = '', String? prefixOtherLines, DiagnosticLevel minLevel = DiagnosticLevel.debug}) String
Returns a string representation of this node and its descendants.
toStringShallow({String joiner = ', ', DiagnosticLevel minLevel = DiagnosticLevel.debug}) String
Returns a one-line detailed description of the object.
toStringShort() String
A short, textual description of this widget.


operator ==(Object other) bool
The equality operator.
@nonVirtual, inherited