TreeWidget<T> class

An interactive, scrollable tree widget that displays hierarchical node trees.

It supports custom styles for selected, unselected, and branch connector guide lines.

Keyboard Navigation

  • Up Arrow / Down Arrow: Swaps the selected active node upward or downward in the flattened tree list.
  • Right Arrow:
    • If the active node is a folder and is collapsed, expands it.
    • If the active node is already expanded, moves selection down to its first child.
  • Left Arrow:
    • If the active node is an expanded folder, collapses it.
    • If the active node is collapsed or a leaf node, shifts selection back to its parent folder.
  • Space / Enter: Triggers the onSelect callback with the active node.

Example Usage

final rootNode = TreeNode(
  label: 'Root',
  value: 'root_val',
  children: [
    TreeNode(label: 'Child A', value: 'a_val'),
    TreeNode(
      label: 'Child B (Folder)',
      value: 'b_val',
      children: [
        TreeNode(label: 'Leaf B1', value: 'b1_val'),
      ],
    ),
  ],
);

TreeWidget(
  root: rootNode,
  onSelect: (node) {
    print('Node chosen: ${node.value}');
  },
);

Properties and Settings

Property Type Description
root TreeNode The top-level root node of the tree hierarchy.
onSelect Function(TreeNode) Callback executed when a node is activated.
selectedStyle Style Style applied to the active selected node line.
unselectedStyle Style Style applied to unselected node labels.
lineStyle Style Style applied to vertical/horizontal guide lines.
showRoot bool Whether to display the root node in the tree list.
focused bool Whether this widget currently has focus.
Inheritance
Implemented types

Constructors

TreeWidget({required TreeNode<T> root, void onSelect(TreeNode<T>)?, Style selectedStyle = const Style(foreground: CharmColors.pepper, background: CharmColors.charple, modifiers: Modifier.bold), Style unselectedStyle = const Style(foreground: CharmColors.soda), Style lineStyle = const Style(foreground: CharmColors.bbq), bool showRoot = true, bool focused = true})
Creates a TreeWidget with the specified root node.

Properties

flatNodes → List<FlatNode<T>>
The list of visible flattened nodes in the tree.
no setter
focused ↔ bool
Whether the tree currently has keyboard focus.
getter/setter pairoverride-getter
hashCode → int
The hash code for this object.
no setterinherited
key → Key?
The optional key for this widget.
finalinherited
lineStyle ↔ Style
The style applied to the horizontal and vertical guide lines.
getter/setter pair
onSelect → void Function(TreeNode<T>)?
Callback executed when a node is selected.
final
root → TreeNode<T>
The root node of the tree.
final
runtimeType → Type
A representation of the runtime type of the object.
no setterinherited
selectedIndex ↔ int
The index of the currently selected node in the flattened tree.
getter/setter pair
selectedStyle ↔ Style
The style applied to the selected active node.
getter/setter pair
showRoot ↔ bool
Whether to show the root node in the tree.
getter/setter pair
unselectedStyle ↔ Style
The style applied to unselected nodes.
getter/setter pair

Methods

adjustScroll(int viewportHeight) → void
Adjusts the scroll offset to keep the selected item visible within the viewportHeight.
createElement() → Element
Creates an Element to manage this widget's location in the tree.
inherited
getIntrinsicHeight(int width) → int
Computes the intrinsic height of this widget under the given width constraint.
inherited
handleKeyEvent(KeyEvent event) → bool
Handles incoming key events for navigation and selection.
override
noSuchMethod(Invocation invocation) → dynamic
Invoked when a nonexistent method or property is accessed.
inherited
render(Buffer buffer, Rect area) → void
Renders the widget onto the provided buffer within the specified area.
override
toString() → String
A string representation of this object.
inherited

Operators

operator ==(Object other) → bool
The equality operator.
inherited