Creating Trees

Learn how to create and populate TeeTree components with nodes

TeeTree provides multiple flexible methods to create tree structures and add nodes. This guide covers the essential techniques for building your tree hierarchies.

Understanding Tree Structure

A TeeTree component maintains a network-hierarchy of nodes, where:

• Root nodes have no parent
• Child nodes belong to a parent node
• Brother nodes share the same parent
• Each node is a full component with properties, methods, and events

Adding Root Nodes

Root nodes are the top-level nodes in your tree without any parent.

Simple Add

// Add a root node with text
MyRoot := Tree1.Add('This is a Root node');

The Add method without a parent parameter automatically creates a root node.

Adding Child Nodes

Child nodes are attached to a parent node and form the tree hierarchy.

1. Using Parent Node

   The most direct way is to call AddChild on the parent node:

   MyRoot := Tree1.Add('Parent Node');
   MyRoot.AddChild('This is a child node');
   
2. Using Tree Component

   Pass the parent as the second parameter:

   Tree1.Add('Child node text', MyRoot);
   
3. Using Shapes Collection

   Use the Shapes collection’s AddChild method:

   Tree1.Shapes.AddChild(MyRoot, 'Child text');
   

Child Node Variations

AddChild

// Standard child addition
ChildNode := ParentNode.AddChild('Child text');

Adding Brother Nodes

Brother nodes (siblings) share the same parent as an existing node.

var Node: TTreeNodeShape;
begin
  // Add a brother to the selected node
  with Tree1.Selected.First do
    if Assigned(Parent) then
      Node := AddBrother('Brother num: ' + IntToStr(Parent.Count + 1))
    else
      Node := Tree1.AddRoot('Root num: ' + IntToStr(Tree1.Roots.Count + 1));
end;

Before calling AddBrother, check if the node has a parent. Root nodes have no parent, so you should create a new root instead.

10 Methods to Add Nodes

Here’s a comprehensive example from the TeeTree demo showing different addition techniques:

procedure TAddMethodsForm.FormCreate(Sender: TObject);
var 
  MyNode: TTreeNodeShape;
  AnotherNode: TTreeNodeShape;
begin
  // 1. Simple way to add a root node
  Tree1.Add('1.Simple');

  // 2. Preserve the resulting node
  MyNode := Tree1.Add('2.MyNode');

  // 3. Add a child node to MyNode
  Tree1.Add('3.Child', MyNode);

  // 4. Specify X and Y positions with no parent
  Tree1.Add(200, 100, '4.At 100,100', nil);

  // 5. Using MyNode's Add method
  MyNode.Add('5.Child');

  // 6. Adding a brother
  MyNode.AddBrother('6.Brother');

  // 7. Using Shapes.AddChild
  Tree1.Shapes.AddChild(MyNode, '7.AddChild');

  // 8. Using default index property
  AnotherNode := Tree1[0].Add('8.Add Child');

  // 9. Using the node Parent property
  AnotherNode.Parent.Add('9.Another Brother');

  // 10. Chain nodes in one line
  Tree1.Add('10.Root').Add('Child').Add('Sub-Child');
end;

Expanding Nodes

After creating child nodes, expand the parent to make them visible:

MyRoot.Expanded := True;

// Or toggle expansion
MyRoot.Toggle;

Interactive Node Addition

Example of adding nodes interactively based on user selection:

procedure ButtonAddChildClick(Sender: TObject);
var Node: TTreeNodeShape;
begin
  // Add child to selected node
  with Tree1.Selected.First do
  begin
    Node := AddChild('Child num: ' + IntToStr(Count + 1));
    Expanded := True;  // Show the new child
  end;
  
  // Select the new node
  Tree1.Selected.Clear;
  Node.Selected := True;
end;

Inserting Nodes at Specific Positions

// Insert at specific index in children list
NewNode := ParentNode.Insert(2, 'Inserted at position 2');

Best Practices

Performance Tips

When adding many nodes, set capacity for better performance:

// Set before adding nodes (in unit initialization)
TreeListCapacity := 1000;
TreeShapeListCapacity := 100;

Memory Management

• Nodes are automatically freed when their parent is destroyed
• Root nodes are freed when the Tree component is destroyed
• Use Clear to remove all nodes: Tree1.Shapes.Clear

Organization

• Group related nodes under common parents
• Use meaningful text for node identification
• Consider using Data or TagObject properties to associate custom data

Common Patterns

Building from Data

// Build tree from array
for i := 0 to High(MyArray) do
  Tree1.Add(MyArray[i].Name);

Building Hierarchical Structure

var Category, Item: TTreeNodeShape;
begin
  Category := Tree1.Add('Electronics');
  Category.AddChild('Computers');
  Category.AddChild('Phones');
  Category.AddChild('Tablets');
  Category.Expanded := True;
end;

Next Steps

• Learn about Working with Nodes to manipulate existing nodes
• Explore Node Formatting to customize appearance
• See Connections to link nodes together