TreeView (tvw)

TreeView (tvw) - Allows you to display a hierarchy of nodes with parents and child.

Examples

What is a TreeNode ?

This is the object that represents an node of a TreeView.
Each TreeNode can contain a collection of other TreeNode objects.
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 label is displayed next to the TreeNode image, if one is displayed.

The Nodes collection holds all the child TreeNode objects assigned to the current TreeNode
You can add, remove, or clone a TreeNode; when doing so, all child tree nodes are added, removed, or cloned

Iterating Through a TreeView

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 node collections start at 0.

For inodecount = 0 To objParentNode.Nodes.Count - 1 
   objnode = objParentNode.Nodes(inodecount) 

    If objnode.Text >= sNodeText Then 
        iinsertposition = inodecount 
    Exit For 

Next inodecount 

Adding Nodes Manually

You can use the TreeNode Editor dialog box to add nodes to a treeview at design time.

Adding Nodes Programatically

When adding a large number of nodes you should place your code between the following two lines

TreeView.BeginUpdate 
'add all the nodes
TreeView.EndUpdate 

You can add nodes to a TreeView by adding TreeNode objects.
The constructor for this object can take the Text for the node, the image index and the selected image index.

Dim objnode as System.Windows.Forms.TreeNode 
objnode = objParentNode.Nodes(inodecount) 

Adding Images

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.

Inserting Nodes

This inserts a new node after the first node

TreeView.Nodes.Insert(1, New TreeNode("Another root node") 

Recursive function that stops when there is no parent
Private Function GetParentString(ByVal Node as TreeNode) As String
Dim suffix as string

If (node.Parent Is Nothing) Then
Return Node.Text
Else
If (Node.Nodes.Count = 0) Then
suffix = ""
else
suffix = "\"
end if

Return GetParentString(Node.Parent) + Node.Text + suffix

end if
End Function

Select a Node

Dim objtreenode As System.Windows.Forms.TreeNode 
objtreeview.SelectedNode = objNodeToSelect 

Selecting a Node with the Right Mouse button

A tree node is not selected by default when you select it with the right mouse button.
You can use the following event to explicitely select it when you use the right mouse button.

Private Sub tvwTreeView_MouseDown(ByVal sender As Object, _ 
                                  ByVal e As System.Windows.Forms.MouseEventArgs) _ 
                                  Handles tvwDiagram.MouseDown 

   Dim objtreenode As System.Windows.Forms.TreeNode 

   objtreenode = Me.tvwDiagram.GetNodeAt(e.X, e.Y) 

   tvwTreeView.SelectedNode = objtreenode 
End Sub 

Expanding all the Tree Nodes

trvTreeView.ExpandAll 

Expanding a particular Tree Nodes

You can expand a TreeNode by calling the Expand method
To expand all child tree node levels in the Nodes collection, call the ExpandAll method

Collapsing Tree Nodes

You can collapse the child TreeNode level by calling the Collapse method

You can also call the Toggle method to alternate the TreeNode between the expanded and collapsed states.

Using Images

Add an ImageList to the windows form
Create icons in the resource editor (32x32)
Add those icons to the ImageList
Link the ImageList to the Treeview

icon defaults - node selected - image position 0
icon defaults - node NOT selected - image position 1

include a link to Controls > ImageList (img)

CheckBoxes

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.

Sorting

treeview1.sorted = true; 

Properties - TreeView

Properties - Node

Methods - Node

Methods - TreeView

Events