### TreeIndentation and IndentGuide Examples (Dart)

Source: https://context7.com/alyssonpp/flutter_tree_view2/llms.txt

Demonstrates how to use TreeIndentation with different IndentGuide styles (connecting lines, scoping lines, blank) for visual tree node structuring. It also shows how to provide a default indent guide to an entire subtree using DefaultIndentGuide.

```dart
import 'package:flutter/material.dart';
import 'package:flutter_fancy_tree_view2/flutter_fancy_tree_view2.dart';

// Basic indentation with connecting lines
Widget buildNodeTile(TreeEntry<MyNode> entry) {
  return TreeIndentation(
    entry: entry,
    guide: const IndentGuide.connectingLines(
      indent: 48,
      color: Colors.grey,
      thickness: 1.0,
      origin: 0.5,
      roundCorners: true,
      connectBranches: true,
    ),
    child: Row(
      children: [
        FolderButton(
          isOpen: entry.hasChildren ? entry.isExpanded : null,
          onPressed: entry.hasChildren ? () => toggleNode(entry.node) : null,
        ),
        Expanded(child: Text(entry.node.title)),
      ],
    ),
  );
}

// Alternative: scoping lines style
Widget buildScopingNode(TreeEntry<MyNode> entry) {
  return TreeIndentation(
    entry: entry,
    guide: const IndentGuide.scopingLines(
      indent: 40,
      color: Colors.blue,
      thickness: 2.0,
    ),
    child: Text(entry.node.title),
  );
}

// Blank indentation (no lines)
Widget buildBlankIndent(TreeEntry<MyNode> entry) {
  return TreeIndentation(
    entry: entry,
    guide: const IndentGuide(indent: 40),
    child: Text(entry.node.title),
  );
}

// Provide default indent guide to entire subtree
Widget buildTreeWithDefaultGuide() {
  return DefaultIndentGuide(
    guide: const IndentGuide.connectingLines(indent: 32),
    child: TreeView<MyNode>(
      treeController: treeController,
      nodeBuilder: (context, entry) {
        // TreeIndentation will use DefaultIndentGuide.of(context)
        return TreeIndentation(
          entry: entry,
          child: Text(entry.node.title),
        );
      },
    ),
  );
}

```

--------------------------------

### Render Tree Node with Indentation and Guides in Flutter

Source: https://github.com/alyssonpp/flutter_tree_view2/blob/main/example/example.md

This Flutter code snippet demonstrates how to render a tree node with indentation and optional connecting lines as an indent guide. It utilizes the `TreeIndentation` widget, which takes an `entry` and a `guide`. The `guide` parameter accepts an `IndentGuide` widget, such as `IndentGuide.connectingLines`, to visually represent the indentation hierarchy. The child of `TreeIndentation` is a `Padding` widget containing a `Row` with a `FolderButton` to indicate expansion state and a `Text` widget to display the node's title.

```dart
child: TreeIndentation(
        entry: entry,
        // Provide an indent guide if desired. Indent guides can be used to
        // add decorations to the indentation of tree nodes.
        // This could also be provided through a DefaultTreeIndentGuide
        // inherited widget placed above the tree view.
        guide: const IndentGuide.connectingLines(indent: 48),
        // The widget to render next to the indentation. TreeIndentation
        // respects the text direction of `Directionality.maybeOf(context)`
        // and defaults to left-to-right.
        child: Padding(
          padding: const EdgeInsets.fromLTRB(4, 8, 8, 8),
          child: Row(
            children: [
              // Add a widget to indicate the expansion state of this node.
              // See also: ExpandIcon.
              FolderButton(
                isOpen: entry.hasChildren ? entry.isExpanded : null,
                onPressed: entry.hasChildren ? onTap : null,
              ),
              Text(entry.node.title),
            ],
          ),
        ),
      ),
    );
  }
}
```

--------------------------------

### Flutter Tree View Basic Implementation

Source: https://github.com/alyssonpp/flutter_tree_view2/blob/main/example/example.md

This Dart code snippet demonstrates the basic setup for a tree view using the flutter_tree_view2 package. It includes defining a data model, initializing the TreeController with root nodes and a children provider, and building the TreeView widget with a custom node builder.

```dart
import 'package:flutter/material.dart';
import 'package:flutter_fancy_tree_view2/flutter_fancy_tree_view2.dart';

void main() => runApp(const MaterialApp(home: Scaffold(body: MyTreeView())));

// Create a class to hold your hierarchical data (optional, could be a Map or
// any other data structure that's capable of representing hierarchical data).
class MyNode {
  const MyNode({
    required this.title,
    this.children = const <MyNode>[],
  });

  final String title;
  final List<MyNode> children;
}

class MyTreeView extends StatefulWidget {
  const MyTreeView({super.key});

  @override
  State<MyTreeView> createState() => _MyTreeViewState();
}

class _MyTreeViewState extends State<MyTreeView> {
  // In this example a static nested tree is used, but your hierarchical data
  // can be composed and stored in many different ways.
  static const List<MyNode> roots = <MyNode>[
    MyNode(
      title: 'Root 1',
      children: <MyNode>[
        MyNode(
          title: 'Node 1.1',
          children: <MyNode>[
            MyNode(title: 'Node 1.1.1'),
            MyNode(title: 'Node 1.1.2'),
          ],
        ),
        MyNode(title: 'Node 1.2'),
      ],
    ),
    MyNode(
      title: 'Root 2',
      children: <MyNode>[
        MyNode(
          title: 'Node 2.1',
          children: <MyNode>[
            MyNode(title: 'Node 2.1.1'),
          ],
        ),
        MyNode(title: 'Node 2.2')
      ],
    ),
  ];

  // This controller is responsible for both providing your hierarchical data
  // to tree views and also manipulate the states of your tree nodes.
  late final TreeController<MyNode> treeController;

  @override
  void initState() {
    super.initState();
    treeController = TreeController<MyNode>(
      // Provide the root nodes that will be used as a starting point when
      // traversing your hierarchical data.
      roots: roots,
      // Provide a callback for the controller to get the children of a
      // given node when traversing your hierarchical data. Avoid doing
      // heavy computations in this method, it should behave like a getter.
      childrenProvider: (MyNode node) => node.children,
    );
  }

  @override
  void dispose() {
    // Remember to dispose your tree controller to release resources.
    treeController.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    // This package provides some different tree views to customize how 
    // your hierarchical data is incorporated into your app. In this example,
    // a TreeView is used which has no custom behaviors, if you wanted your
    // tree nodes to animate in and out when the parent node is expanded
    // and collapsed, the AnimatedTreeView could be used instead.
    //
    // The tree view widgets also have a Sliver variant to make it easy
    // to incorporate your hierarchical data in sophisticated scrolling
    // experiences.
    return TreeView<MyNode>(
      // This controller is used by tree views to build a flat representation
      // of a tree structure so it can be lazy rendered by a SliverList.
      // It is also used to store and manipulate the different states of the
      // tree nodes.
      treeController: treeController,
      // Provide a widget builder callback to map your tree nodes into widgets.
      nodeBuilder: (BuildContext context, TreeEntry<MyNode> entry) {
        // Provide a widget to display your tree nodes in the tree view.
        //
        // Can be any widget, just make sure to include a [TreeIndentation]
        // within its widget subtree to properly indent your tree nodes.
        return MyTreeTile(
          // Add a key to your tiles to avoid syncing descendant animations.
          key: ValueKey(entry.node),
          // Your tree nodes are wrapped in TreeEntry instances when traversing
          // the tree, these objects hold important details about its node
          // relative to the tree, like: expansion state, level, parent, etc.
          //
          // TreeEntrys are short lived, each time TreeController.rebuild is
          // called, a new TreeEntry is created for each node so its properties
          // are always up to date.
          entry: entry,
          // Add a callback to toggle the expansion state of this node.
          onTap: () => treeController.toggleExpansion(entry.node),
        );
      },
    );
  }
}

// Create a widget to display the data held by your tree nodes.
class MyTreeTile extends StatelessWidget {
  const MyTreeTile({
    super.key,
    required this.entry,
    required this.onTap,
  });

  final TreeEntry<MyNode> entry;
  final VoidCallback onTap;

  @override
  Widget build(BuildContext context) {
    return InkWell(
      onTap: onTap,
      // Wrap your content in a TreeIndentation widget which will properly
      child: Padding(
        padding: EdgeInsets.only(left: entry.level * 20.0), // Indentation based on level
        child: Text(entry.node.title),
      ),
    );
  }
}

```

--------------------------------

### FolderButton Widget Example (Dart)

Source: https://context7.com/alyssonpp/flutter_tree_view2/llms.txt

Illustrates the usage of the FolderButton widget for creating interactive folder icons in a tree view. It supports automatic animation between open, closed, and leaf states, and allows for custom icons and animation settings.

```dart
import 'package:flutter/material.dart';
import 'package:flutter_fancy_tree_view2/flutter_fancy_tree_view2.dart';

Widget buildFolderButton(TreeEntry<MyNode> entry, TreeController<MyNode> controller) {
  return FolderButton(
    // null = show file icon (leaf node), true = open folder, false = closed folder
    isOpen: entry.hasChildren ? entry.isExpanded : null,
    onPressed: entry.hasChildren
        ? () => controller.toggleExpansion(entry.node)
        : null,

    // Custom icons
    icon: const Icon(Icons.article),           // Shown when isOpen is null
    openedIcon: const Icon(Icons.folder_open), // Shown when isOpen is true
    closedIcon: const Icon(Icons.folder),      // Shown when isOpen is false

    // Animation settings
    duration: const Duration(milliseconds: 200),
    curve: Curves.easeInOut,
    transitionBuilder: (child, animation) {
      return RotationTransition(turns: animation, child: child);
    },

    // IconButton properties
    iconSize: 24,
    color: Colors.blue,
    tooltip: 'Toggle folder',
  );
}

```

--------------------------------

### Render Tree Views with TreeView and AnimatedTreeView in Dart

Source: https://context7.com/alyssonpp/flutter_tree_view2/llms.txt

Illustrates how to use `TreeView` and `AnimatedTreeView` widgets to display hierarchical data managed by a `TreeController`. `TreeView` offers basic rendering, while `AnimatedTreeView` adds smooth animations for expansion and collapse transitions. Customization options for animations and node building are included.

```dart
import 'package:flutter/material.dart';
import 'package:flutter_fancy_tree_view2/flutter_fancy_tree_view2.dart';

class MyTreeView extends StatefulWidget {
  const MyTreeView({super.key});

  @override
  State<MyTreeView> createState() => _MyTreeViewState();
}

class _MyTreeViewState extends State<MyTreeView> {
  late final TreeController<MyNode> treeController;

  @override
  void initState() {
    super.initState();
    treeController = TreeController<MyNode>(
      roots: myRootNodes,
      childrenProvider: (node) => node.children,
    );
  }

  @override
  void dispose() {
    treeController.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    // Basic TreeView without animations
    return TreeView<MyNode>(
      treeController: treeController,
      nodeBuilder: (BuildContext context, TreeEntry<MyNode> entry) {
        return ListTile(
          title: Text(entry.node.title),
          leading: Icon(entry.hasChildren ? Icons.folder : Icons.article),
          onTap: () => treeController.toggleExpansion(entry.node),
        );
      },
    );
  }
}

// AnimatedTreeView with custom animation settings
Widget buildAnimatedTree() {
  return AnimatedTreeView<MyNode>(
    treeController: treeController,
    duration: const Duration(milliseconds: 300),
    curve: Curves.easeInOut,
    maxNodesToShowWhenAnimating: 50,
    transitionBuilder: (context, child, animation) {
      return FadeTransition(
        opacity: animation,
        child: SizeTransition(
          sizeFactor: animation,
          child: child,
        ),
      );
    },
    nodeBuilder: (context, entry) {
      return MyNodeTile(entry: entry);
    },
  );
}
```

--------------------------------

### Manage Tree State with TreeController in Dart

Source: https://context7.com/alyssonpp/flutter_tree_view2/llms.txt

Demonstrates how to initialize and use `TreeController` to manage the state of a tree view. It covers defining node models, providing data, and performing expansion/collapse operations. This controller is essential for dynamic tree manipulation.

```dart
import 'package:flutter_fancy_tree_view2/flutter_fancy_tree_view2.dart';

// Define your node model
class MyNode {
  MyNode({required this.title, this.children = const []});
  final String title;
  final List<MyNode> children;
  MyNode? parent;
}

// Create hierarchical data
final List<MyNode> roots = [
  MyNode(
    title: 'Root 1',
    children: [
      MyNode(title: 'Child 1.1'),
      MyNode(title: 'Child 1.2'),
    ],
  ),
  MyNode(title: 'Root 2'),
];

// Create the controller
final treeController = TreeController<MyNode>(
  roots: roots,
  childrenProvider: (MyNode node) => node.children,
  parentProvider: (MyNode node) => node.parent, // Required for drag-and-drop
  defaultExpansionState: false, // Nodes collapsed by default
);

// Expansion operations
treeController.expand(roots.first);           // Expand single node
treeController.collapse(roots.first);         // Collapse single node
treeController.toggleExpansion(roots.first);  // Toggle expansion state
treeController.expandAll();                   // Expand all nodes
treeController.collapseAll();                 // Collapse all nodes
treeController.expandCascading([roots.first]); // Expand node and all descendants
treeController.collapseCascading([roots.first]); // Collapse node and all descendants
treeController.expandAncestors(roots.first.children.first); // Expand all ancestors

// Check expansion state
bool isExpanded = treeController.getExpansionState(roots.first);
bool allExpanded = treeController.isTreeExpanded;
bool allCollapsed = treeController.isTreeCollapsed;

// Update the tree view after data changes
treeController.rebuild();

// Cleanup
treeController.dispose();
```

--------------------------------

### Build Tree Node Widget with TreeEntry Context (Dart)

Source: https://context7.com/alyssonpp/flutter_tree_view2/llms.txt

Demonstrates how to build a custom widget for a tree node using the `TreeEntry` object. It accesses node data, level, index, expansion state, and sibling information to render the node with appropriate indentation and UI elements. This function assumes the existence of a `TreeController` and a `MyNode` data class.

```dart
import 'package:flutter_fancy_tree_view2/flutter_fancy_tree_view2.dart';

Widget buildNodeWidget(TreeEntry<MyNode> entry) {
  // Access node data
  MyNode node = entry.node;

  // Tree structure information
  int level = entry.level;              // Depth in tree (0 for roots)
  int index = entry.index;              // Index in flat list
  bool hasChildren = entry.hasChildren; // Has child nodes
  bool isExpanded = entry.isExpanded;   // Current expansion state
  bool hasNextSibling = entry.hasNextSibling; // Has sibling after it

  // Parent access (for traversing up the tree)
  TreeEntry<MyNode>? parent = entry.parent;

  // Skip indentation for root nodes
  bool skipIndent = entry.skipIndentAndPaint; // True if level <= 0

  return Container(
    margin: EdgeInsets.only(left: level * 24.0),
    child: Row(
      children: [
        if (hasChildren)
          IconButton(
            icon: Icon(isExpanded ? Icons.expand_more : Icons.chevron_right),
            onPressed: () => controller.toggleExpansion(node),
          )
        else
          const SizedBox(width: 48),
        Text('${node.title} (Level $level, Index $index)'),
        if (!hasNextSibling) const Text(' [Last child]')
      ],
    ),
  );
}
```

--------------------------------

### Implement Drag-and-Drop Tree View with Flutter

Source: https://context7.com/alyssonpp/flutter_tree_view2/llms.txt

This Dart code demonstrates how to set up a draggable tree view using TreeDraggable and TreeDragTarget. It includes a custom node model with parent references and a TreeController configured for drag-and-drop operations. The buildDraggableNode function defines the UI for draggable nodes and drop targets, handling node acceptance and visual feedback during drag operations.

```dart
import 'package:flutter/material.dart';
import 'package:flutter_fancy_tree_view2/flutter_fancy_tree_view2.dart';

// Node model with parent reference (required for drag-and-drop)
class DraggableNode {
  DraggableNode({required this.id, Iterable<DraggableNode>? children})
      : _children = <DraggableNode>[] {
    if (children != null) {
      for (final child in children) {
        child._parent = this;
        _children.add(child);
      }
    }
  }

  final int id;
  final List<DraggableNode> _children;
  DraggableNode? _parent;

  List<DraggableNode> get children => _children;
  DraggableNode? get parent => _parent;
  int get index => _parent?._children.indexOf(this) ?? -1;

  void insertChild(int index, DraggableNode node) {
    node._parent?._children.remove(node);
    node._parent = this;
    _children.insert(index, node);
  }
}

// TreeController with parentProvider (required)
final treeController = TreeController<DraggableNode>(
  roots: rootNodes, // Assuming rootNodes is defined elsewhere
  childrenProvider: (node) => node.children,
  parentProvider: (node) => node.parent, // Required for drag-and-drop!
);

// Build draggable tree node
Widget buildDraggableNode(TreeEntry<DraggableNode> entry) {
  return TreeDragTarget<DraggableNode>(
    node: entry.node,
    toggleExpansionOnHover: true,
    toggleExpansionDelay: const Duration(seconds: 1),

    onNodeAccepted: (TreeDragAndDropDetails<DraggableNode> details) {
      // Determine drop position based on where user dropped
      final oneThird = details.targetBounds.height / 3;
      final dropY = details.dropPosition.dy;

      DraggableNode? newParent;
      int newIndex = 0;

      if (dropY < oneThird) {
        // Drop above target - insert as previous sibling
        newParent = details.targetNode.parent;
        newIndex = details.targetNode.index;
      } else if (dropY < oneThird * 2) {
        // Drop inside target - insert as last child
        newParent = details.targetNode;
        newIndex = details.targetNode.children.length;
        treeController.setExpansionState(details.targetNode, true);
      } else {
        // Drop below target - insert as next sibling
        newParent = details.targetNode.parent;
        newIndex = details.targetNode.index + 1;
      }

      newParent?.insertChild(newIndex, details.draggedNode);
      treeController.rebuild();
    },

    builder: (context, TreeDragAndDropDetails<DraggableNode>? details) {
      // Highlight drop zone when dragging over
      BoxDecoration? decoration;
      if (details != null) {
        decoration = BoxDecoration(
          border: Border.all(color: Colors.blue, width: 2),
        );
      }

      return TreeDraggable<DraggableNode>(
        node: entry.node,
        collapseOnDragStart: true,
        expandOnDragEnd: false,
        autoScrollSensitivity: 100.0,
        longPressDelay: const Duration(milliseconds: 500), // For touch devices

        feedback: Material(
          elevation: 4,
          child: Text('Dragging: Node ${entry.node.id}'),
        ),

        childWhenDragging: Opacity(
          opacity: 0.5,
          child: Text('Node ${entry.node.id}'),
        ),

        child: Container(
          decoration: decoration,
          child: TreeIndentation(
            entry: entry,
            child: Text('Node ${entry.node.id}'),
          ),
        ),
      );
    },
  );
}

```

--------------------------------

### Configure TreeController with Parent Provider

Source: https://github.com/alyssonpp/flutter_tree_view2/blob/main/README.md

Configure the TreeController to use a parentProvider callback. This callback is essential for drag and drop operations and methods like expandAncestors, allowing the controller to access the parent of any given node. If not provided, a default callback returning null is used, which may lead to assertion errors in debug mode for dependent methods.

```dart
final treeController = TreeController<MyTreeNode>(
  ...,
  parentProvider: (MyTreeNode node) => node.parent,
);
```

--------------------------------

### Instantiate TreeController in Dart

Source: https://github.com/alyssonpp/flutter_tree_view2/blob/main/README.md

Initializes a TreeController, which manages the state of the tree view. It requires the root nodes and a childrenProvider callback to recursively access child nodes.

```dart
final treeController = TreeController<MyTreeNode>(
  roots: roots,
  childrenProvider: (MyTreeNode node) => node.children,
);
```

--------------------------------

### Create Hierarchical Data in Dart

Source: https://github.com/alyssonpp/flutter_tree_view2/blob/main/README.md

Demonstrates how to create or fetch hierarchical data using the defined TreeNode model. This involves instantiating the model with data and potentially fetching additional root nodes from a source.

```dart
final List<MyTreeNode> roots = [
  const MyTreeNode(title: 'My static root node'),
  ...fetchOtherRootNodes(),
];
```

--------------------------------

### Search and Filter Tree Nodes with TreeController

Source: https://context7.com/alyssonpp/flutter_tree_view2/llms.txt

Demonstrates how to use the `TreeController.search` method to find nodes in a tree structure. It supports both direct and indirect matches and allows for regex-based queries. The `childrenProvider` needs to be configured to respect the filter for accurate results. Rebuilding the controller is necessary to reflect the filtered view.

```dart
import 'package:flutter_fancy_tree_view2/flutter_fancy_tree_view2.dart';

class FilterableNode {
  FilterableNode({required this.title, this.children = const []});
  final String title;
  final List<FilterableNode> children;
}

TreeSearchResult<FilterableNode>? currentFilter;
Pattern? searchPattern;

// Configure childrenProvider to respect filter
Iterable<FilterableNode> getFilteredChildren(FilterableNode node) {
  if (currentFilter != null) {
    return node.children.where(currentFilter!.hasMatch);
  }
  return node.children;
}

final treeController = TreeController<FilterableNode>(
  roots: rootNodes,
  childrenProvider: getFilteredChildren,
);

// Perform search
void search(String query) {
  // Reset filter first to ensure all nodes are traversed
  currentFilter = null;

  // Create pattern (supports regex)
  Pattern pattern;
  try {
    pattern = RegExp(query, caseSensitive: false);
  } on FormatException {
    pattern = query;
  }
  searchPattern = pattern;

  // Execute search
  currentFilter = treeController.search(
    (FilterableNode node) => node.title.contains(pattern),
  );

  // Rebuild to show filtered results
  treeController.rebuild();

  // Access search statistics
  print('Total nodes: ${currentFilter!.totalNodeCount}');
  print('Matching nodes: ${currentFilter!.totalMatchCount}');
}

// Check if a specific node matches
void checkNodeMatch(FilterableNode node) {
  if (currentFilter == null) return;

  TreeSearchMatch? match = currentFilter!.matchOf(node);
  if (match != null) {
    print('Is direct match: ${match.isDirectMatch}');
    print('Subtree node count: ${match.subtreeNodeCount}');
    print('Subtree match count: ${match.subtreeMatchCount}');
  }

  // Quick check if node has any match (direct or indirect)
  bool hasMatch = currentFilter!.hasMatch(node);
}

// Clear filter
void clearSearch() {
  currentFilter = null;
  searchPattern = null;
  treeController.rebuild();
}

```

--------------------------------

### Integrate Tree Views into Scrollable Layouts with SliverTree

Source: https://context7.com/alyssonpp/flutter_tree_view2/llms.txt

Provides `SliverTree` and `SliverAnimatedTree` widgets for use within Flutter's `CustomScrollView`. These slivers allow seamless integration of tree structures alongside other scrollable elements like `SliverAppBar` and `SliverToBoxAdapter`. `SliverAnimatedTree` adds animation support for expansion and collapse transitions.

```dart
import 'package:flutter/material.dart';
import 'package:flutter_fancy_tree_view2/flutter_fancy_tree_view2.dart';

Widget buildCustomScrollTree() {
  return CustomScrollView(
    slivers: [
      // Header
      const SliverAppBar(
        title: Text('My Tree View'),
        floating: true,
      ),

      // Search bar
      SliverToBoxAdapter(
        child: Padding(
          padding: const EdgeInsets.all(16),
          child: TextField(
            decoration: const InputDecoration(hintText: 'Search...'),
          ),
        ),
      ),

      // Animated tree sliver
      SliverAnimatedTree<MyNode>(
        controller: treeController,
        duration: const Duration(milliseconds: 300),
        curve: Curves.easeOut,
        maxNodesToShowWhenAnimating: 50,
        nodeBuilder: (context, entry) {
          return TreeIndentation(
            entry: entry,
            child: ListTile(
              title: Text(entry.node.title),
              onTap: () => treeController.toggleExpansion(entry.node),
            ),
          );
        },
      ),

      // Footer
      const SliverToBoxAdapter(
        child: Padding(
          padding: EdgeInsets.all(16),
          child: Text('End of tree'),
        ),
      ),
    ],
  );
}

// Basic sliver tree without animations
Widget buildBasicSliverTree() {
  return CustomScrollView(
    slivers: [
      SliverTree<MyNode>(
        controller: treeController,
        nodeBuilder: (context, entry) {
          return TreeIndentation(
            entry: entry,
            child: Text(entry.node.title),
          );
        },
      ),
    ],
  );
}

```

--------------------------------

### Build AnimatedTreeView in Flutter

Source: https://github.com/alyssonpp/flutter_tree_view2/blob/main/README.md

Constructs an AnimatedTreeView widget in Flutter, passing the TreeController and defining a nodeBuilder. The nodeBuilder maps tree data to widgets, including logic for toggling expansion and applying indentation.

```dart
@override
Widget build(BuildContext context) {
  return AnimatedTreeView<MyTreeNode>(
    treeController: treeController,
    nodeBuilder: (BuildContext context, TreeEntry<MyTreeNode> entry) {
      return InkWell(
        onTap: () => treeController.toggleExpansion(entry.node),
        child: TreeIndentation(
          entry: entry,
          child: Text(entry.node.title),
        ),
      );
    },
  );
}
```

--------------------------------

### Import flutter_fancy_tree_view2 in Dart

Source: https://github.com/alyssonpp/flutter_tree_view2/blob/main/README.md

Imports the necessary components from the flutter_fancy_tree_view2 package into your Dart code. This allows you to use the package's widgets and controllers.

```dart
import 'package:flutter_fancy_tree_view2/flutter_fancy_tree_view2.dart';
```

--------------------------------

### Add flutter_fancy_tree_view2 Dependency in YAML

Source: https://github.com/alyssonpp/flutter_tree_view2/blob/main/README.md

Adds the flutter_fancy_tree_view2 package as a dependency to your Flutter project's pubspec.yaml file. This command automatically fetches the package.

```yaml
dependencies:
  flutter_fancy_tree_view2: any
```

--------------------------------

### Integrate TreeDraggable and TreeDragTarget Widgets

Source: https://github.com/alyssonpp/flutter_tree_view2/blob/main/README.md

Integrate TreeDraggable and TreeDragTarget into the nodeBuilder to enable drag and drop functionality. TreeDragTarget handles drop events and provides feedback, while TreeDraggable makes the node draggable. The onNodeAccepted callback in TreeDragTarget is where the tree reordering logic should be implemented, followed by a call to treeController.rebuild().

```dart
@override
Widget build(BuildContext context) {
  return AnimatedTreeView<MyTreeNode>(
    treeController: treeController,
    nodeBuilder: (BuildContext context, TreeEntry<MyTreeNode> entry) {
      return TreeDragTarget<MyTreeNode>(
        node: entry.node,
        onNodeAccepted: (TreeDragAndDropDetails details) {
          // Optionally make sure the target node is expanded so the dragging
          // node is visible in its new vicinity when the tree gets rebuilt.
          treeController.setExpansionState(details.targetNode, true);

          // TODO: implement your tree reorder logic

          // Make sure to rebuild your tree view to show the reordered nodes
          // in their new vicinity.
          treeController.rebuild();
        },
        builder: (BuildContext context, TreeDragAndDropDetails? details) {
          Widget myTreeNodeTile = Padding(
            padding: const EdgeInsets.all(8.0),
            child: Text(entry.node.title),
          );

          // If details is not null, a dragging tree node is hovering this
          // drag target. Add some decoration to give feedback to the user.
          if (details != null) {
            myTreeNodeTile = ColoredBox(
              color: Theme.of(context).colorScheme.primary.withOpacity(0.3),
              child: myTreeNodeTile,
            );
          }

          return TreeDraggable<MyTreeNode>(
            node: entry.node,

            // Show some feedback to the user under the dragging pointer,
            // this can be any widget.
            feedback: IntrinsicWidth(
              child: Material(
                elevation: 4,
                child: myTreeNodeTile,
              ),
            ),

            child: InkWell(
              onTap: () => treeController.toggleExpansion(entry.node),
              child: TreeIndentation(
                entry: entry,
                child: myTreeNodeTile,
              ),
            ),
          );
        },
      );
    },
  );
}
```

--------------------------------

### Define TreeNode Model in Dart

Source: https://github.com/alyssonpp/flutter_tree_view2/blob/main/README.md

Defines a simple Dart class to represent a node in the hierarchical data structure. It includes a title and a list of children, enabling the creation of nested data.

```dart
class MyTreeNode {
  const MyTreeNode({
    required this.title,
    this.children = const <MyTreeNode>[],
  });

  final String title;
  final List<MyTreeNode> children;
}
```

--------------------------------

### Update TreeNode Model for Drag and Drop

Source: https://github.com/alyssonpp/flutter_tree_view2/blob/main/README.md

Modify the TreeNode model to include a parent reference. This is crucial for the drag and drop feature, especially for auto-expanding/collapsing nodes and correctly managing parent-child relationships during reordering. The parent is set when children are added.

```dart
class MyTreeNode {
  MyTreeNode({
    required this.title,
    Iterable<MyTreeNode>? children,
  }) : children = <MyTreeNode>[] {
    if (children == null) return;

    for (final MyTreeNode child in children) {
      this.children.add(child);

      // Make sure to update the parent of your nodes when updating the children
      // of a given node.
      child.parent = this;
    }
  }

  final String title;
  final List<MyTreeNode> children;
  MyTreeNode? parent;
}
```

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