Disables any redrawing of the tree view.
Assembly: System.Windows.Forms (in System.Windows.Forms.dll)
The preferred way to add items to a tree view control is to use the AddRange method to add an array of tree node items to a tree view. However, if you want to add items one at a time, use the method to prevent the TreeView control from painting during the add operations. To allow the control to resume painting, call the EndUpdate method when all the tree nodes have been added to the tree view.
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 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 a cursor file that is named MyWait.cur in the application directory and that you have created an instance of a TreeView control on a Form.
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