loading treeview dynamically is very slow

[cowznofsky]

Rather than load all my data into the treeview I am loading when a
level-1node gets expanded (for the first time).
To set up the code below, I've added a single child node for each
level-1node, just so that I can get the "+" and the capability to
expand.
So the first time I click on any level-1 node, it loads 30 child nodes.

The problem is how slow this is. To me it should be almost
instantaneous. It takes 2-3 seconds, which doesn't sound like much,
but believe me, it's irritating. The scroll bar rolls down the screen.
Once the nodes are populated, expanding and collapsing the parent node
is suitably quick.

Any ideas on at least making this appear quicker?
----------------
Private Sub myTreeView_AfterExpand(ByVal sender As Object, ByVal e As
System.Windows.Forms.TreeViewEventArgs) Handles myTreeView.AfterExpand

Dim classNode As TreeNode
Dim testCtr As Integer

If e.Node.Nodes.Count = 1 Then
If e.Node.Text = e.Node.Nodes(0).Text Then
e.Node.Nodes.Clear()
For testCtr = 1 To 50
classNode = e.Node.Nodes.Add(testCtr.ToString)
Next
End If
End If
End Sub

[Robinson]

Bracket all adds with this:

myTreeView.BeginUpdate ()

..............
..............

myTreeView.EndUpdate ()

[tommaso.gastaldi]

cowznofsky ha scritto:

Rather than load all my data into the treeview I am loading when a
level-1node gets expanded (for the first time).
To set up the code below, I've added a single child node for each
level-1node, just so that I can get the "+" and the capability to
expand.
So the first time I click on any level-1 node, it loads 30 child nodes.

The problem is how slow this is.

See if this improves (vb2005):

Private Sub myTreeView_AfterExpand(ByVal sender As Object, _
ByVal e As
System.Windows.Forms.TreeViewEventArgs) _
Handles MyTreeView.AfterExpand

Dim testCtr As Integer
Dim SubNodes As New List(Of TreeNode)

If e.Node.Nodes.Count = 1 Then
If e.Node.Text = e.Node.Nodes(0).Text Then
e.Node.Nodes.Clear()
For testCtr = 1 To 50
SubNodes.Add(New TreeNode(testCtr.ToString))
Next
e.Node.Nodes.AddRange(SubNodes.ToArray)
End If
End If

End Sub

[cowznofsky]

Ah, much better. Thanks!

Robinson wrote:

Bracket all adds with this:

myTreeView.BeginUpdate ()

.............
.............

myTreeView.EndUpdate ()