TreeView class

The TreeView control enables a hierarchical list with expanding and collapsing nodes that contain nested items. It can be used to illustrate a folder structure or nested relationships in your UI.

The tree view uses a combination of indentation and icons to represent the nested relationship between parent nodes and child nodes. Collapsed items use a chevron pointing to the right, and expanded nodes use a chevron pointing down.

You can include an icon in the TreeViewItem template to represent items. For example, if you show a file system hierarchy, you could use folder icons for the parent items and file icons for the leaf items.

See also:

• docs.microsoft.com/en-us/windows/apps/design/controls/tree-view
• TreeViewItem, used to render the tiles
• Checkbox, used on multiple selection mode

Inheritance

• Object
• DiagnosticableTree
• Widget
• StatefulWidget
• TreeView

Available Extensions

• ItemExtension

Constructors

TreeView({Key? key, required List<TreeViewItem> items, TreeViewSelectionMode selectionMode = TreeViewSelectionMode.none, TreeViewSelectionChangedCallback? onSelectionChanged, TreeViewItemInvoked? onItemInvoked, TreeViewItemOnExpandToggle? onItemExpandToggle, TreeViewItemOnSecondaryTap? onSecondaryTap, TreeViewItemGesturesCallback? gesturesBuilder, Widget loadingWidget = kTreeViewLoadingIndicator, bool shrinkWrap = true, bool? scrollPrimary, ScrollController? scrollController, double? cacheExtent, double? itemExtent, bool addRepaintBoundaries = true, bool usePrototypeItem = false, bool narrowSpacing = false, bool includePartiallySelectedItems = false, bool deselectParentWhenChildrenDeselected = true})

Creates a tree view.

const

Properties

addRepaintBoundaries → bool

Whether to wrap each child in a RepaintBoundary.

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

deselectParentWhenChildrenDeselected → bool

If selectionMode is TreeViewSelectionMode.multiple, indicates if a parent will automatically be deselected when all of its children are deselected. If you disable this behavior, also consider if you want to set includePartiallySelectedItems to true.

final

gesturesBuilder → TreeViewItemGesturesCallback?

A callback that receives a notification that the gestures for an item

final

hashCode → int

The hash code for this object.

no setter, inherited

includePartiallySelectedItems → bool

If true, will include items that are in an indeterminute (partially selected) state in the list of selected items in the onSelectionChanged callback.

final

itemExtent → double?

If non-null, forces the children to have the given extent in the scroll direction.

final

items → List<TreeViewItem>

The items of the tree view.

final

key → Key?

Controls how one widget replaces another widget in the tree.

final, inherited

loadingWidget → Widget

A widget to be shown when a node is loading. Only used if TreeViewItem.loadingWidget is null.

final

narrowSpacing → bool

Whether or not to have narrow spacing between the contents of each item.

final

onItemExpandToggle → TreeViewItemOnExpandToggle?

Called when an item's expand state is toggled.

final

onItemInvoked → TreeViewItemInvoked?

Called when an item is invoked

final

onSecondaryTap → TreeViewItemOnSecondaryTap?

A tap with a secondary button has occurred.

final

onSelectionChanged → TreeViewSelectionChangedCallback?

Called when the selection changes. The items that are currently selected will be passed to the callback. This could be empty if nothing is now selected. If TreeView.selectionMode is TreeViewSelectionMode.single then it will contain exactly zero or one items.

final

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

scrollController → ScrollController?

An object that can be used to control the position to which this scroll view is scrolled.

final

scrollPrimary → bool?

Whether this is the primary scroll view associated with the parent PrimaryScrollController.

final

selectionMode → TreeViewSelectionMode

The current selection mode.

final

shrinkWrap → bool

Whether the extent of the scroll view in the scrollDirection should be determined by the contents being viewed.

final

usePrototypeItem → bool

Whether or not to give the internal ListView a prototype item based on the first item in the tree view. Set this to true to allow the ListView to more efficiently calculate the maximum scrolling extent, and it will force the vertical size of each item to be the same size as the first item in the tree view.

final

Methods

createElement() → StatefulElement

Creates a StatefulElement to manage this widget's location in the tree.

inherited

createState() → State<TreeView>

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.

override

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