Solved

Treeview Nodes not showing - no exceptions being thrown

Posted on 2014-02-06
6
315 Views
Last Modified: 2014-02-08
The Treenode I am using works well in most cases, but there is a method in which the nodes are not being added -- and there are no exceptions being thrown.   The default approach is to search for a node name, and then add the node.

In a Public Module for Declarations: the delegate is defined as:

  Public Delegate Sub AppendTreeviewDelegate(ByVal level, ByVal txtstr, ByVal pathstr, ByVal resimgname)

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The method which adds nodes is in the Form1 Class and is:

 Public Sub appendtreeview(ByVal level, ByVal txtstr, ByVal pathstr, ByVal resimgname)
   
        If level = 0 Then
            TreeView1.BeginUpdate()
            TreeView1.Nodes.Add(RootDataControlName, txtstr, resimgname)
            TreeView1.EndUpdate()
        Else
            TreeView1.BeginUpdate()
            TreeView1.Nodes.Find(RootDataControlName, True)(0).Nodes.Add(CurrentTaskControlName, txtstr, resimgname).tag = pathstr
            TreeView1.EndUpdate()
        End If
        TreeView1.ExpandAll()
        TreeView1.Refresh()
  End Sub

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The code inside the threaded method (inside an instantiated class):

        Dim appendtreeviewdel As AppendTreeviewDelegate = New AppendTreeviewDelegate(AddressOf Form1.appendtreeview)
        Dim main As Form1 = CType(Application.OpenForms(0), Form1)

        level = 1
        txtstr = "test"
        filename = "c:\test.txt"  
        resimgname = "testimage"
        main.BeginInvoke(New AppendTreeviewDelegate(AddressOf Form1.appendtreeview), {level, txtstr, filename, resimgname})
  

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A level=0 does exist, so the new nodes should be added at level=1.   Also, all of the parameter values are correct: filenames ("pathstr"), and "testimage" is a valid image in My.Resources, etc.  I have even tried the code below, which does not search for the name of a parent node, but rather directly forces the creation of the new node, however, no luck, and no exceptions are being thrown:

  TreeView1.Nodes.Add(CurrentTaskControlName, txtstr, resimgname).tag = pathstr

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Any suggestions?
0
Comment
Question by:lep1
  • 3
  • 2
6 Comments
 
LVL 83

Expert Comment

by:CodeCruiser
ID: 39839749
Does it work if you use the Add(NodeText) method?
0
 

Author Comment

by:lep1
ID: 39841129
No.  Treeview1.Nodes.Add(txtstr) did not work.
0
 
LVL 28

Expert Comment

by:Ark
ID: 39841342
Are you sure you need BeginInvoke/EndInvoke to get async result? Why not just use main.invoke(...)?
0
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Author Comment

by:lep1
ID: 39841716
Changed BeginInvoke to Invoke, and nothing doing (didn't work),
0
 
LVL 28

Accepted Solution

by:
Ark earned 500 total points
ID: 39843779
Is your class instance really run in different thread? Try check if invoke required:
If main.InvokeRequired Then
   main.invoke(...)
Else
   main.appendtreeview(...)
End If

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BTW, your call to delegate should points to Form1 instance method, not Form1 type method:
New AppendTreeviewDelegate(AddressOf main.appendtreeview ...
0
 

Author Closing Comment

by:lep1
ID: 39844395
Great recommendation. It was due to changing Form1 to main.   Thx.
0

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