TreeNode Class

Definition

Represents a node of a TreeView.

[System.ComponentModel.TypeConverter(typeof(System.Windows.Forms.TreeNodeConverter))]
public class TreeNode : MarshalByRefObject, ICloneable, System.Runtime.Serialization.ISerializable
Inheritance
Derived
Attributes
Implements

Inherited Members

System.MarshalByRefObject

System.Object

Examples

The following code example displays customer information in a TreeView control. The root tree nodes display customer names, and the child tree nodes display the order numbers assigned to each customer. In this example, 1,000 customers are displayed with 15 orders each. The repainting of the TreeView is suppressed by using the BeginUpdate and EndUpdate methods, and a wait Cursor is displayed while the TreeView creates and paints the TreeNode objects. This example requires that you have a Customer object that can hold a collection of Order objects. It also requires that you have created an instance of a TreeView control on a Form.

// The basic Customer class.
ref class Customer: public System::Object
{
private:
   String^ custName;

protected:
   ArrayList^ custOrders;

public:
   Customer( String^ customername )
   {
      custName = "";
      custOrders = gcnew ArrayList;
      this->custName = customername;
   }


   property String^ CustomerName 
   {
      String^ get()
      {
         return this->custName;
      }

      void set( String^ value )
      {
         this->custName = value;
      }

   }

   property ArrayList^ CustomerOrders 
   {
      ArrayList^ get()
      {
         return this->custOrders;
      }

   }

};


// End Customer class
// The basic customer Order class.
ref class Order: public System::Object
{
private:
   String^ ordID;

public:
   Order( String^ orderid )
   {
      ordID = "";
      this->ordID = orderid;
   }


   property String^ OrderID 
   {
      String^ get()
      {
         return this->ordID;
      }

      void set( String^ value )
      {
         this->ordID = value;
      }

   }

};
// End Order class



void FillMyTreeView()
{
   // Add customers to the ArrayList of Customer objects.
   for ( int x = 0; x < 1000; x++ )
   {
      customerArray->Add( gcnew Customer( "Customer " + x ) );
   }
   
   // Add orders to each Customer object in the ArrayList.
   IEnumerator^ myEnum = customerArray->GetEnumerator();
   while ( myEnum->MoveNext() )
   {
      Customer^ customer1 = safe_cast<Customer^>(myEnum->Current);
      for ( int y = 0; y < 15; y++ )
      {
         customer1->CustomerOrders->Add( gcnew Order( "Order " + y ) );
      }
   }

   // Display a wait cursor while the TreeNodes are being created.
   ::Cursor::Current = gcnew System::Windows::Forms::Cursor( "MyWait.cur" );
   
   // Suppress repainting the TreeView until all the objects have been created.
   treeView1->BeginUpdate();
   
   // Clear the TreeView each time the method is called.
   treeView1->Nodes->Clear();
   
   // Add a root TreeNode for each Customer object in the ArrayList.
   myEnum = customerArray->GetEnumerator();
   while ( myEnum->MoveNext() )
   {
      Customer^ customer2 = safe_cast<Customer^>(myEnum->Current);
      treeView1->Nodes->Add( gcnew TreeNode( customer2->CustomerName ) );
      
      // Add a child treenode for each Order object in the current Customer object.
      IEnumerator^ myEnum = customer2->CustomerOrders->GetEnumerator();
      while ( myEnum->MoveNext() )
      {
         Order^ order1 = safe_cast<Order^>(myEnum->Current);
         treeView1->Nodes[ customerArray->IndexOf( customer2 ) ]->Nodes->Add( gcnew TreeNode( customer2->CustomerName + "." + order1->OrderID ) );
      }
   }
   
   // Reset the cursor to the default for all controls.
   ::Cursor::Current = Cursors::Default;
   
   // Begin repainting the TreeView.
   treeView1->EndUpdate();
}

// The basic Customer class.
public class Customer : System.Object
{
   private string custName = "";
   protected ArrayList custOrders = new ArrayList();

   public Customer(string customername)
   {
      this.custName = customername;
   }

   public string CustomerName
   {      
      get{return this.custName;}
      set{this.custName = value;}
   }

   public ArrayList CustomerOrders 
   {
      get{return this.custOrders;}
   }

} // End Customer class 


// The basic customer Order class.
public class Order : System.Object
{
   private string ordID = "";

   public Order(string orderid)
   {
      this.ordID = orderid;
   }

   public string OrderID
   {      
      get{return this.ordID;}
      set{this.ordID = value;}
   }

} // End Order class

// Create a new ArrayList to hold the Customer objects.
private ArrayList customerArray = new ArrayList(); 

private void FillMyTreeView()
{
   // Add customers to the ArrayList of Customer objects.
   for(int x=0; x<1000; x++)
   {
      customerArray.Add(new Customer("Customer" + x.ToString()));
   }

   // Add orders to each Customer object in the ArrayList.
   foreach(Customer customer1 in customerArray)
   {
      for(int y=0; y<15; y++)
      {
         customer1.CustomerOrders.Add(new Order("Order" + y.ToString()));    
      }
   }

   // Display a wait cursor while the TreeNodes are being created.
   Cursor.Current = new Cursor("MyWait.cur");
        
   // Suppress repainting the TreeView until all the objects have been created.
   treeView1.BeginUpdate();

   // Clear the TreeView each time the method is called.
   treeView1.Nodes.Clear();

   // Add a root TreeNode for each Customer object in the ArrayList.
   foreach(Customer customer2 in customerArray)
   {
      treeView1.Nodes.Add(new TreeNode(customer2.CustomerName));
          
      // Add a child treenode for each Order object in the current Customer object.
      foreach(Order order1 in customer2.CustomerOrders)
      {
         treeView1.Nodes[customerArray.IndexOf(customer2)].Nodes.Add(
           new TreeNode(customer2.CustomerName + "." + order1.OrderID));
      }
   }

   // Reset the cursor to the default for all controls.
   Cursor.Current = Cursors.Default;

   // Begin repainting the TreeView.
   treeView1.EndUpdate();
}
Public Class Customer
   Inherits [Object]
   Private custName As String = ""
   Friend custOrders As New ArrayList()

   Public Sub New(ByVal customername As String)
      Me.custName = customername
   End Sub

   Public Property CustomerName() As String
      Get
         Return Me.custName
      End Get
      Set(ByVal Value As String)
         Me.custName = Value
      End Set
   End Property

   Public ReadOnly Property CustomerOrders() As ArrayList
      Get
         Return Me.custOrders
      End Get
   End Property
End Class 'End Customer class


Public Class Order
   Inherits [Object]
   Private ordID As String

   Public Sub New(ByVal orderid As String)
      Me.ordID = orderid
   End Sub 'New

   Public Property OrderID() As String
      Get
         Return Me.ordID
      End Get
      Set(ByVal Value As String)
         Me.ordID = Value
      End Set
   End Property
End Class ' End Order class

' Create a new ArrayList to hold the Customer objects.
Private customerArray As New ArrayList()

Private Sub FillMyTreeView()
   ' Add customers to the ArrayList of Customer objects.
   Dim x As Integer
   For x = 0 To 999
      customerArray.Add(New Customer("Customer" + x.ToString()))
   Next x

   ' Add orders to each Customer object in the ArrayList.
   Dim customer1 As Customer
   For Each customer1 In customerArray
      Dim y As Integer
      For y = 0 To 14
         customer1.CustomerOrders.Add(New Order("Order" + y.ToString()))
      Next y
   Next customer1

   ' Display a wait cursor while the TreeNodes are being created.
   Cursor.Current = New Cursor("MyWait.cur")

   ' Suppress repainting the TreeView until all the objects have been created.
   treeView1.BeginUpdate()

   ' Clear the TreeView each time the method is called.
   treeView1.Nodes.Clear()

   ' Add a root TreeNode for each Customer object in the ArrayList.
   Dim customer2 As Customer
   For Each customer2 In customerArray
      treeView1.Nodes.Add(New TreeNode(customer2.CustomerName))

      ' Add a child TreeNode for each Order object in the current Customer object.
      Dim order1 As Order
      For Each order1 In customer2.CustomerOrders
         treeView1.Nodes(customerArray.IndexOf(customer2)).Nodes.Add( _
    New TreeNode(customer2.CustomerName + "." + order1.OrderID))
      Next order1
   Next customer2

   ' Reset the cursor to the default for all controls.
   Cursor.Current = System.Windows.Forms.Cursors.Default

   ' Begin repainting the TreeView.
   treeView1.EndUpdate()
End Sub 'FillMyTreeView

Remarks

The Nodes collection holds all the child TreeNode objects assigned to the current TreeNode. You can add, remove, or clone a TreeNode; when you do this, all child tree nodes are added, removed, or cloned. Each TreeNode can contain a collection of other TreeNode objects. This can make it difficult to determine where you are in the TreeView when iterating through the collection. To determine your location in a tree structure, use the FullPath property. The FullPath string can be parsed using the PathSeparator string value to determine where a TreeNode label begins and ends.

The TreeNode label is set by setting the Text property explicitly. The alternative is to create the tree node using one of the TreeNode constructors that has a string parameter that represents the Text property. The label is displayed next to the TreeNode image, if one is displayed.

To display images next to the tree nodes, assign an ImageList to the ImageList property of the parent TreeView control and assign an Image by referencing its index value in the ImageList property. Set the ImageIndex property to the index value of the Image you want to display when the TreeNode is in an unselected state. Likewise, set the SelectedImageIndex property to the index value of the Image you want to display when the TreeNode is selected.

Selecting specific tree nodes and iterating through the Nodes collection can be achieved by using the following property values: FirstNode, LastNode, NextNode, PrevNode, NextVisibleNode, PrevVisibleNode. Assign the TreeNode returned by one of aforementioned properties to the TreeView.SelectedNode property to select that tree node in the TreeView control.

Tree nodes can be expanded to display the next level of child tree nodes. The user can expand the TreeNode by pressing the plus (+) button next to the TreeNode, if one is displayed, or you can expand the TreeNode by calling the Expand method. To expand all child tree node levels in the Nodes collection, call the ExpandAll method. You can collapse the child TreeNode level by calling the Collapse method, or the user can press the minus (-) button next to the TreeNode, if one is displayed. You can also call the Toggle method to alternate the TreeNode between the expanded and collapsed states.

Tree nodes can optionally display a check box. To display the check boxes, set the CheckBoxes property of the TreeView to true. The Checked property is set to true for tree nodes that are in a checked state.

Constructors

TreeNode()

Initializes a new instance of the TreeNode class.

TreeNode(String)

Initializes a new instance of the TreeNode class with the specified label text.

TreeNode(SerializationInfo, StreamingContext)

Initializes a new instance of the TreeNode class using the specified serialization information and context.

TreeNode(String, TreeNode[])

Initializes a new instance of the TreeNode class with the specified label text and child tree nodes.

TreeNode(String, Int32, Int32)

Initializes a new instance of the TreeNode class with the specified label text and images to display when the tree node is in a selected and unselected state.

TreeNode(String, Int32, Int32, TreeNode[])

Initializes a new instance of the TreeNode class with the specified label text, child tree nodes, and images to display when the tree node is in a selected and unselected state.

Properties

BackColor

Gets or sets the background color of the tree node.

Bounds

Gets the bounds of the tree node.

Checked

Gets or sets a value indicating whether the tree node is in a checked state.

ContextMenu

Gets the shortcut menu that is associated with this tree node.

ContextMenuStrip

Gets or sets the shortcut menu associated with this tree node.

FirstNode

Gets the first child tree node in the tree node collection.

ForeColor

Gets or sets the foreground color of the tree node.

FullPath

Gets the path from the root tree node to the current tree node.

Handle

Gets the handle of the tree node.

ImageIndex

Gets or sets the image list index value of the image displayed when the tree node is in the unselected state.

ImageKey

Gets or sets the key for the image associated with this tree node when the node is in an unselected state.

Index

Gets the position of the tree node in the tree node collection.

IsEditing

Gets a value indicating whether the tree node is in an editable state.

IsExpanded

Gets a value indicating whether the tree node is in the expanded state.

IsSelected

Gets a value indicating whether the tree node is in the selected state.

IsVisible

Gets a value indicating whether the tree node is visible or partially visible.

LastNode

Gets the last child tree node.

Level

Gets the zero-based depth of the tree node in the TreeView control.

Name

Gets or sets the name of the tree node.

NextNode

Gets the next sibling tree node.

NextVisibleNode

Gets the next visible tree node.

NodeFont

Gets or sets the font that is used to display the text on the tree node label.

Nodes

Gets the collection of TreeNode objects assigned to the current tree node.

Parent

Gets the parent tree node of the current tree node.

PrevNode

Gets the previous sibling tree node.

PrevVisibleNode

Gets the previous visible tree node.

SelectedImageIndex

Gets or sets the image list index value of the image that is displayed when the tree node is in the selected state.

SelectedImageKey

Gets or sets the key of the image displayed in the tree node when it is in a selected state.

StateImageIndex

Gets or sets the index of the image that is used to indicate the state of the TreeNode when the parent TreeView has its CheckBoxes property set to false.

StateImageKey

Gets or sets the key of the image that is used to indicate the state of the TreeNode when the parent TreeView has its CheckBoxes property set to false.

Tag

Gets or sets the object that contains data about the tree node.

Text

Gets or sets the text displayed in the label of the tree node.

ToolTipText

Gets or sets the text that appears when the mouse pointer hovers over a TreeNode.

TreeView

Gets the parent tree view that the tree node is assigned to.

Methods

BeginEdit()

Initiates the editing of the tree node label.

Clone()

Copies the tree node and the entire subtree rooted at this tree node.

Collapse()

Collapses the tree node.

Collapse(Boolean)

Collapses the TreeNode and optionally collapses its children.

Deserialize(SerializationInfo, StreamingContext)

Loads the state of the TreeNode from the specified SerializationInfo.

EndEdit(Boolean)

Ends the editing of the tree node label.

EnsureVisible()

Ensures that the tree node is visible, expanding tree nodes and scrolling the tree view control as necessary.

Expand()

Expands the tree node.

ExpandAll()

Expands all the child tree nodes.

FromHandle(TreeView, IntPtr)

Returns the tree node with the specified handle and assigned to the specified tree view control.

GetNodeCount(Boolean)

Returns the number of child tree nodes.

Remove()

Removes the current tree node from the tree view control.

Serialize(SerializationInfo, StreamingContext)

Saves the state of the TreeNode to the specified SerializationInfo.

Toggle()

Toggles the tree node to either the expanded or collapsed state.

ToString()

Returns a string that represents the current object.

Explicit Interface Implementations

ISerializable.GetObjectData(SerializationInfo, StreamingContext)

Populates a serialization information object with the data needed to serialize the TreeNode.