TreeDraggable<T extends Object> class

A widget that wraps either Draggable or LongPressDraggable depending on the value of longPressDelay, with additional tree view capabilities.

It is also responsible for automatically collapsing the node it holds when the drag starts and expanding it back when the drag ends (if it was collapsed). This can be toggled off in collapseOnDragStart.

Usage:

Widget build(BuildContext context) {
  return TreeDraggable<Node>(
    node: entry.node,
    // Usually the child wrapped in [Material] widget (and [IntrinsicWidth] if necessary).
    feedback: MyTreeNodeTileFeedback(),
    // Usually the child widget with some opacity.
    childWhenDragging: MyTreeNodeTileWhenDragging(),
    child: MyTreeNodeTile(),
  );
}

This widget depends on an ancestor TreeViewScope, which is automatically added to the widget tree by SliverTree and SliverAnimatedTree.

Inheritance

Constructors

TreeDraggable({Key? key, required Widget child, required T node, bool collapseOnDragStart = true, bool expandOnDragEnd = false, double autoScrollSensitivity = 100.0, Axis? axis, required Widget feedback, Widget? childWhenDragging, Offset feedbackOffset = Offset.zero, DragAnchorStrategy dragAnchorStrategy = pointerDragAnchorStrategy, VoidCallback? onDragStarted, DragUpdateCallback? onDragUpdate, DraggableCanceledCallback? onDraggableCanceled, DragEndCallback? onDragEnd, VoidCallback? onDragCompleted, Axis? affinity, bool ignoringFeedbackSemantics = true, bool ignoringFeedbackPointer = true, bool rootOverlay = false, HitTestBehavior hitTestBehavior = HitTestBehavior.deferToChild, Duration? longPressDelay, bool longPressHapticFeedbackOnStart = true})
Creates a TreeDraggable.
const

Properties

affinity → Axis?
Controls how this widget competes with other gestures to initiate a drag.
final
autoScrollSensitivity → double
Defines the size of the Rect created around the drag global position when dragging a tree node.
final
axis → Axis?
The Axis to restrict this draggable's movement, if specified.
final
child → Widget
The widget below this widget in the tree.
final
childWhenDragging → Widget?
The widget to display instead of child when one or more drags are under way.
final
collapseOnDragStart → bool
Whether node should be collapsed when the inner Draggable detects the start of a drag gesture.
final
dragAnchorStrategy → DragAnchorStrategy
A strategy that is used by this draggable to get the anchor offset when it is dragged.
final
expandOnDragEnd → bool
Whether node should be expanded when the inner Draggable detects the end of a drag gesture.
final
feedback → Widget
The widget to show under the pointer when a drag is under way.
final
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.
final
hashCode → int
The hash code for this object.
no setterinherited
hitTestBehavior → HitTestBehavior
How to behave during hit test.
final
ignoringFeedbackPointer → bool
Whether the feedback widget is ignored during hit testing.
final
ignoringFeedbackSemantics → bool
Whether the semantics of the feedback widget is ignored when building the semantics tree.
final
key → Key?
Controls how one widget replaces another widget in the tree.
finalinherited
longPressDelay → Duration?
The Duration that the user has to press down before a long press is registered.
final
longPressHapticFeedbackOnStart → bool
Whether haptic feedback should be triggered on drag start when using a LongPressDraggable (i.e., longPressDelay != null).
final
node → T
The tree node that is going to be provided to Draggable.data.
final
onDragCompleted → VoidCallback?
Called when the draggable is dropped and accepted by a DragTarget.
final
onDragEnd → DragEndCallback?
Called when the draggable is dropped.
final
onDraggableCanceled → DraggableCanceledCallback?
Called when the draggable is dropped without being accepted by a DragTarget.
final
onDragStarted → VoidCallback?
Called when the draggable starts being dragged.
final
onDragUpdate → DragUpdateCallback?
Called when the draggable is dragged.
final
rootOverlay → bool
Whether the feedback widget will be put on the root Overlay.
final
runtimeType → Type
A representation of the runtime type of the object.
no setterinherited

Methods

createElement() → StatefulElement
Creates a StatefulElement to manage this widget's location in the tree.
inherited
createState() → State<TreeDraggable<T>>
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