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'Controls - How to add nodes to a Treeview at runtime
'This sample shows How to add nodes to a Treeview at runtime.
'For the sample code to run you will need to do the following things:
'1. Add from the components list Microsoft Windows Common controls 5.0(Vb5) or 6.0(Vb6).
'2. Add an Imagelist, a Treeview Control, 2 command buttons,2 textboxes, 2
'   option buttons, and a frame to your form.
'3. The option buttons should be on the frame.
'4. Name one option button OpParent with a caption of Parent.
'5. Name the other option button OpChild with a caption of Child.
'6. Add 2 pictures to the Imagelist.

Option Explicit
Dim tn As Node
Dim img As ImageList
 
Private Sub Command1_Click()    'This procedure adds nodes
    On Error GoTo errhan:
    'This sets focus to the treeview
    TreeView1.SetFocus
    'This checks if the parent option button is selected so it knows to add a parent node
    If Opparent.Value = True Then
        'this adds the parent node
        Set tn = TreeView1.Nodes.Add(, , Text1.Text, "Parent1" & Text1.Text, 1, 1)
        'This checks if the child option button is selected so it knows to add a child node
    ElseIf Opchild.Value = True Then
        'this adds the child node
        Set tn = TreeView1.Nodes.Add(TreeView1.SelectedItem, tvwChild, Text1.Text, "child" & Text1.Text, 2, 2)
    End If
    Exit Sub
 
ErrHan:
    'This is a procedure that checks for errors
    ErrorH
End Sub
 
Private Sub Command2_Click()
    'This procedure deletes nodes 'This loops thru the nodes collection
    For Each tn In TreeView1.Nodes
        'and checks all the nodes to see if the node selected to be deleted exists first
        If tn.Key = Text2.Text Then
            'Then delete the specified node
            TreeView1.Nodes.Remove tn.Key
            'then exits the loop after it has been deleted
            Exit For
        End If
    Next
End Sub
 
Private Sub Form_Load()
    Opparent.Value = True
    Command1.Caption = "Add Node"
    Command2.Caption = "Remove Node"
    TreeView1.ImageList = ImageList1    'this will initialize the Imagelist
    'this adds the first parent node to the treeview
    Set tn = TreeView1.Nodes.Add(, , "p1", "Parent1", 1, 1)
    'this make the parent node expanded
    TreeView1.Nodes(1).Expanded = True
    'this adds the first child node
    Set tn = TreeView1.Nodes.Add("p1", tvwChild, "c1", "child1", 2, 2)
End Sub
 
Public Sub ErrorH()
    'this is the error handler.
    'this checks for a specific error this error is caused if you try to add a key value that already exist
    If Err.Number = 35602 Then
        'if the above error occurs then a msgbox pops up saying choose another key
        MsgBox "Choose a different key the value you requested already exists"
    Else
        'else it just gives the error number and description
        MsgBox "Error number:" & Err.Number & "Error Description:" & Err.Description
    End If
End Sub