This code demonstrates a problem using a treeview twice

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  • Franky
    #1

    This code demonstrates a problem using a treeview twice

    Been having a problem using a treeview. Work great the first time the form
    containing it is entered but not the second time.

    Took a while to create a small sample that exhibits the problem, but here it
    is.

    Seems to have something to do with doing ShowDialog

    Easy to reproduce this project, simply add two forms.

    One with a Button and one with a TreeView

    The one with a Button, Form2, is the Start Form

    The WriteLine statements make it easy to see what is happening

    Public Class Form2
    'This is the Start Form
    Private mForm1 As Form1
    Private Sub Button1_Click(B yVal sender As Object, ByVal e As
    System.EventArg s) Handles Button1.Click
    Dim zz As DialogResult = mForm1.ShowDial og()
    End Sub
    Private Sub Form2_Load(ByVa l sender As Object, ByVal e As System.EventArg s)
    Handles Me.Load
    mForm1 = New Form1
    End Sub
    End Class

    The Form contains a TreeView
    Imports System.IO
    Imports VB = Microsoft.Visua lBasic
    Public Class Form1
    Public Sub ExpandPath(ByVa l pathToFind As String)
    If Directory.Exist s(pathToFind) Then 'If directory does not exists, don't
    look
    Console.WriteLi ne("SEARCH IN TOPMOST COLLECTION")
    SearchHere(Tree View1.Nodes, pathToFind.ToUp per)
    End If
    End Sub
    Private Sub SearchHere(ByVa l currentTreeColl ection As TreeNodeCollect ion,
    ByVal pathToFind As String)
    Dim tnPath As String
    Static zz As Integer
    zz += 1
    Dim z As Integer = zz
    For Each tn As TreeNode In currentTreeColl ection
    tnPath = tn.Tag.ToUpper
    If tnPath.Length <= pathToFind.Leng th Then
    If pathToFind = tnPath Then
    Dim tp As TreeNode = tn.Nodes.Add("D UMMY")
    tp.Tag = "DUMMY"
    tn.Expand()
    Console.WriteLi ne(z.ToString & "DONE " & tn.Tag)
    TreeView1.Selec tedNode = tn
    Exit For
    ElseIf pathToFind.Subs tring(0, tnPath.Length) = tnPath Then
    Dim tp As TreeNode = tn.Nodes.Add("D UMMY")
    tp.Tag = "DUMMY"
    tn.Expand()
    Console.WriteLi ne(z.ToString & "NOW SEARCH IN " & tn.Tag)
    SearchHere(tn.N odes, pathToFind)
    Exit For
    End If
    End If
    Next
    Console.WriteLi ne(z.ToString & "SEARCH EXITED ")
    End Sub
    Private Sub TreeView1_Befor eExpand(ByVal sender As Object, ByVal e As
    System.Windows. Forms.TreeViewC ancelEventArgs) Handles TreeView1.Befor eExpand
    'Clears out any nodes (especially the dummy) and then adds folder nodes
    Dim SubNode As TreeNode
    Console.WriteLi ne("Entered BeforeExpand " & e.Node.Tag)
    e.Node.Nodes.Cl ear()
    For Each subDir As String In Directory.GetDi rectories(e.Nod e.Tag & "\") 'Now
    add the folder's contents to the tree
    SubNode = e.Node.Nodes.Ad d(IO.Path.GetFi leName(subDir))
    SubNode.Tag = subDir
    If Directory.GetDi rectories(subDi r).Length <0 _
    OrElse ((Directory.Get Files(subDir).L ength 0)) Then
    'If not empty add a dummy node
    Dim tn As TreeNode = SubNode.Nodes.A dd("DUMMY")
    tn.Tag = "DUMMY"
    End If
    Next subDir
    End Sub
    Private Sub Form1_Load(ByVa l sender As Object, ByVal e As System.EventArg s)
    Handles Me.Load
    Static beenHereBefore As Boolean 'Need to initialize the tree
    If Not beenHereBefore Then 'Add C: to the tree the first time
    Dim SubNode As TreeNode = TreeView1.Nodes .Add("C:")
    SubNode.Tag = "C:"
    Dim tn As TreeNode = SubNode.Nodes.A dd("DUMMY")
    tn.Tag = "DUMMY"
    End If
    ExpandPath("C:\ Documents and Settings\All Users\Start Menu")
    End Sub
    End Class


    Tags: None
    • Tom Shelton
      #2
      Re: This code demonstrates a problem using a treeview twice

      On 2006-12-08, Franky <frankieNOSPAM@ a-znet.comwrote:
      Been having a problem using a treeview. Work great the first time the form
      containing it is entered but not the second time.
      >
      Took a while to create a small sample that exhibits the problem, but here it
      is.
      >
      Seems to have something to do with doing ShowDialog
      Franky - the problem has nothing to do with ShowDialog. The problem is that
      you are keeping a reference to the form and showing it over and over again -
      so it never gets it's state reset.

      You can fix it one of two ways...

      1. change the form load of the treeview form like this:


      Private Sub Form1_Load(ByVa l sender As Object, ByVal e As System.EventArg s) Handles Me.Load
      'Static beenHereBefore As Boolean 'Need to initialize the tree
      'If Not beenHereBefore Then 'Add C: to the tree the first time
      TreeView1.Nodes .Clear()
      Dim SubNode As TreeNode = TreeView1.Nodes .Add("C:")
      SubNode.Tag = "C:"
      Dim tn As TreeNode = SubNode.Nodes.A dd("DUMMY")
      tn.Tag = "DUMMY"
      'End If
      ExpandPath("C:\ Program Files")
      End Sub


      Notice, I'm just letting the tree re-init each time.

      2. Change the calling form to not keep a reference at all - and then just
      create a new form each time the button is clicked:

      Private Sub Button1_Click(B yVal sender As Object, ByVal e As System.EventArg s) Handles Button1.Click
      Using f As New Form1
      f.ShowDialog(Me )
      End Using
      End Sub


      HTH

      --
      Tom Shelton

        Comment

        • Franky
          #3
          Re: This code demonstrates a problem using a treeview twice

          I know if I reinitialize the treeview it woks OK.
          But I wanted to retain the reference so that it would retain the users last
          expansions.
          When I show it the second time I want it to look like it did when it
          finished the last time.
          Not possible?
          If it stays in memory why does it behave differently if I leave and
          comeback?

          If I do the search twice with the first ShowDialog, it works OK both times.

          Thanks for the reply



          "Tom Shelton" <tom_shelton@co mcastXXXXXXX.ne twrote in message
          news:2JOdnYpQTd wzr-fYnZ2dnUVZ_qunn Z2d@comcast.com ...
          On 2006-12-08, Franky <frankieNOSPAM@ a-znet.comwrote:
          >Been having a problem using a treeview. Work great the first time the
          >form
          >containing it is entered but not the second time.
          >>
          >Took a while to create a small sample that exhibits the problem, but here
          >it
          >is.
          >>
          >Seems to have something to do with doing ShowDialog
          >
          Franky - the problem has nothing to do with ShowDialog. The problem is
          that
          you are keeping a reference to the form and showing it over and over
          again -
          so it never gets it's state reset.
          >
          You can fix it one of two ways...
          >
          1. change the form load of the treeview form like this:
          >
          >
          Private Sub Form1_Load(ByVa l sender As Object, ByVal e As
          System.EventArg s) Handles Me.Load
          'Static beenHereBefore As Boolean 'Need to initialize the tree
          'If Not beenHereBefore Then 'Add C: to the tree the first time
          TreeView1.Nodes .Clear()
          Dim SubNode As TreeNode = TreeView1.Nodes .Add("C:")
          SubNode.Tag = "C:"
          Dim tn As TreeNode = SubNode.Nodes.A dd("DUMMY")
          tn.Tag = "DUMMY"
          'End If
          ExpandPath("C:\ Program Files")
          End Sub
          >
          >
          Notice, I'm just letting the tree re-init each time.
          >
          2. Change the calling form to not keep a reference at all - and then just
          create a new form each time the button is clicked:
          >
          Private Sub Button1_Click(B yVal sender As Object, ByVal e As
          System.EventArg s) Handles Button1.Click
          Using f As New Form1
          f.ShowDialog(Me )
          End Using
          End Sub
          >
          >
          HTH
          >
          --
          Tom Shelton

            Comment

            • Franky
              #4
              Re: This code demonstrates a problem using a treeview twice

              >I know if I reinitialize the treeview it woks OK.
              But I wanted to retain the reference so that it would retain the users
              last expansions.
              When I show it the second time I want it to look like it did when it
              finished the last time.
              Not possible?
              If it stays in memory why does it behave differently if I leave and
              comeback?
              >
              If I do the search twice with the first ShowDialog, it works OK both
              times.
              Do this in Load and notice that there are two folders expanded.

              ExpandPath("C:\ Documents and Settings\All Users\Start Menu")

              ExpandPath("C:\ Documents and Settings\All Users\Documents \My Music")

              However, the equivalent can't be done by putting and clicking a second
              button on Form2 to expand My Music without collapsing StartMenu

              >
              Thanks for the reply
              >
              >
              >
              "Tom Shelton" <tom_shelton@co mcastXXXXXXX.ne twrote in message
              news:2JOdnYpQTd wzr-fYnZ2dnUVZ_qunn Z2d@comcast.com ...
              >On 2006-12-08, Franky <frankieNOSPAM@ a-znet.comwrote:
              >>Been having a problem using a treeview. Work great the first time the
              >>form
              >>containing it is entered but not the second time.
              >>>
              >>Took a while to create a small sample that exhibits the problem, but
              >>here it
              >>is.
              >>>
              >>Seems to have something to do with doing ShowDialog
              >>
              >Franky - the problem has nothing to do with ShowDialog. The problem is
              >that
              >you are keeping a reference to the form and showing it over and over
              >again -
              >so it never gets it's state reset.
              >>
              >You can fix it one of two ways...
              >>
              >1. change the form load of the treeview form like this:
              >>
              >>
              > Private Sub Form1_Load(ByVa l sender As Object, ByVal e As
              >System.EventAr gs) Handles Me.Load
              > 'Static beenHereBefore As Boolean 'Need to initialize the tree
              > 'If Not beenHereBefore Then 'Add C: to the tree the first time
              > TreeView1.Nodes .Clear()
              > Dim SubNode As TreeNode = TreeView1.Nodes .Add("C:")
              > SubNode.Tag = "C:"
              > Dim tn As TreeNode = SubNode.Nodes.A dd("DUMMY")
              > tn.Tag = "DUMMY"
              > 'End If
              > ExpandPath("C:\ Program Files")
              > End Sub
              >>
              >>
              >Notice, I'm just letting the tree re-init each time.
              >>
              >2. Change the calling form to not keep a reference at all - and then
              >just
              >create a new form each time the button is clicked:
              >>
              > Private Sub Button1_Click(B yVal sender As Object, ByVal e As
              >System.EventAr gs) Handles Button1.Click
              > Using f As New Form1
              > f.ShowDialog(Me )
              > End Using
              > End Sub
              >>
              >>
              >HTH
              >>
              >--
              >Tom Shelton
              >
              >


                Comment

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