form1.vb

Mastering VBNet Include Source Code

    Private Sub bttnDelNode_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles bttnDelNode.Click
        GlobeTree.SelectedNode.Remove() ' Removes the selected node
        txtContinent.Text = ""
        txtCountry.Text = ""
        txtCity.Text = ""
    End Sub

    Private Sub bttnExpandNode_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles bttnExpandNode.Click
        GlobeTree.SelectedNode.Expand()
    End Sub

    Private Sub GlobeTree_AfterSelect(ByVal sender As System.Object, ByVal e As System.Windows.Forms.TreeViewEventArgs) Handles GlobeTree.AfterSelect
        If GlobeTree.SelectedNode Is Nothing Then Exit Sub
        ' every time a node is selected with the mouse, we display its parts (continent/country/city) 
        ' on the three TextBox controls on the form
        Dim components() As String
        txtContinent.Text = ""
        txtCountry.Text = ""
        txtCity.Text = ""
        components = Split(GlobeTree.SelectedNode.FullPath.ToString, GlobeTree.PathSeparator)
        Console.WriteLine(GlobeTree.SelectedNode.FullPath.ToString)
        If components.Length > 1 Then txtContinent.Text = components(1)
        If components.Length > 2 Then txtCountry.Text = components(2)
        If components.Length > 3 Then txtCity.Text = components(3)
    End Sub

    Private Sub bttnAddNode_Click_1(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles bttnAddNode.Click
        Dim nd As TreeNode
        Dim Continents As TreeNode
        ' Add continent, if it's not on the control already
        ' If no continent name was specified, none of the following statements will be executed
        If txtContinent.Text.Trim <> "" Then
            Continents = GlobeTree.Nodes(0)
            Dim ContinentFound, CountryFound, CityFound As Boolean
            Dim ContinentNode, CountryNode, CityNode As TreeNode
            For Each nd In Continents.Nodes
                If nd.Text.ToUpper = txtContinent.Text.ToUpper Then
                    ContinentFound = True
                    Exit For
                End If
            Next
            If Not ContinentFound Then
                nd = Continents.Nodes.Add(txtContinent.Text)
            End If
            ContinentNode = nd
            ' Add country, if it's no on the control already
            ' If no country was specified, none of the following statements will be executed
            If txtCountry.Text.Trim <> "" Then
                Dim Countries As TreeNode
                Countries = ContinentNode
                If Not Countries Is Nothing Then
                    For Each nd In Countries.Nodes
                        If nd.Text.ToUpper = txtCountry.Text.ToUpper Then
                            CountryFound = True
                            Exit For
                        End If
                    Next
                End If
                If Not CountryFound Then
                    nd = ContinentNode.Nodes.Add(txtCountry.Text)
                End If
                CountryNode = nd
                ' Add city, if it's not on the control already 
                If txtCity.Text.Trim <> "" Then
                    Dim Cities As TreeNode
                    Cities = CountryNode
                    If Not Cities Is Nothing Then
                        For Each nd In Cities.Nodes
                            If nd.Text.ToUpper = txtCity.Text.ToUpper Then
                                CityFound = True
                                Exit For
                            End If
                        Next
                    End If
                    If Not CityFound Then
                        nd = CountryNode.Nodes.Add(txtCity.Text)
                    End If
                    CityNode = nd
                End If
            End If
        End If

    End Sub

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim continent, country, city As TreeNode
        Dim Continents, Countries, Cities As TreeNodeCollection

        ListBox1.Items.Clear()
        Continents = GlobeTree.Nodes(0).Nodes
        For Each continent In Continents
            If continent.Checked Then ListBox1.Items.Add(continent.FullPath)
            Countries = continent.Nodes
            For Each country In Countries
                If country.Checked Or country.Parent.Checked Then _
                          ListBox1.Items.Add("     " & country.FullPath)
                Cities = country.Nodes
                For Each city In Cities
                    If city.Checked Or city.Parent.Checked Or _
                            city.Parent.Parent.Checked Then _
                            ListBox1.Items.Add("          " & _
                            city.FullPath)
                Next
            Next
        Next
    End Sub


    Private Sub FileLoad_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles FileLoad.Click
        OpenFileDialog1.DefaultExt = "XML"
        If OpenFileDialog1.ShowDialog = DialogResult.OK Then
            '        LoadNodes(GlobeTree, OpenFileDialog1.FileName)
            ' The following statements persists the globe structure using
            ' the NodeSerializer class's methods. Unocomment the following two statements
            ' to test the functionality of the NodeSerializer class
            Dim NS As New NodeSerializer()
            NS.LoadNodes(GlobeTree, OpenFileDialog1.FileName)
        End If
    End Sub

    Private Sub FileSave_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles FileSave.Click
        SaveFileDialog1.DefaultExt = "XML"
        If SaveFileDialog1.ShowDialog = DialogResult.OK Then
            'CreateList(GlobeTree.Nodes(0), SaveFileDialog1.FileName)
            ' The following statements load the globe structure to the TreeView control
            ' using the NodeSerializer class's methods. Unocomment the following two statements
            ' to test the functionality of the NodeSerializer class
            Dim NS As New NodeSerializer()
            NS.CreateList(GlobeTree.Nodes(0), SaveFileDialog1.FileName)
        End If
    End Sub

    <Serializable()> Structure sNode
        Dim node As String
        Dim level As Integer
    End Structure
    Dim GlobeNodes As New ArrayList()


    ' The LoadNodes() subroutine reads a text file with node values (strings)
    ' into an ArrayList and then calls the showNodes() subroutine to add the nodes
    ' to the TreeView control
    ' The LoadNodes() subroutine reads the nodes saved to the file by calling a
    ' SoapFormatter object's Deserialize method
    Sub LoadNodes(ByVal TV As TreeView, ByVal fName As String)
        TV.Nodes.Clear()
        Dim formatter As SoapFormatter
        Dim openFile As FileStream
        openFile = File.Open(fName, FileMode.Open)
        formatter = New SoapFormatter()
        GlobeNodes = CType(formatter.Deserialize(openFile), ArrayList)
        openFile.Close()
        showNodes(TV)
    End Sub

    ' The showNodes() subroutine reconstructs the original tree from the 
    ' contents of the GlobeNodes ArrayList. Each item contains the node's text a\
    ' and the node's level
    Sub showNodes(ByVal TV As TreeView)
        Dim o As Object
        Dim currNode As TreeNode
        Dim level As Integer = 0
        Dim fromLowerLevel As Integer

        Dim i As Integer
        For i = 0 To GlobeNodes.Count - 1
            o = GlobeNodes(i)
            ' IF THE STRICT OPTION IS OFF, YOU CAN USE THE O OBJECT (AND NOT THE ONODE OBJECT)
            ' IN THE REST OF THE CODE, AS SHOWN IN THE TEXT
            Dim oNode As sNode = CType(o, sNode)
            If CType(oNode, sNode).level = level Then
                If currNode Is Nothing Then
                    currNode = TV.Nodes.Add(oNode.node.ToString)
                Else
                    currNode = currNode.Parent.Nodes.Add(oNode.node.ToString)
                End If
            Else
                If oNode.level > level Then
                    currNode = currNode.Nodes.Add(oNode.node.ToString)
                    level = oNode.level
                Else
                    While oNode.level <= level
                        currNode = currNode.Parent
                        level = level - 1
                    End While
                    currNode = currNode.Nodes.Add(oNode.node.ToString)
                End If
            End If
            TV.ExpandAll()
            Application.DoEvents()
        Next
    End Sub

    ' The CreateList() subroutine reads the nodes of the TreeView control passed as argument
    ' and stores them as sNode objects to an ArrayList
    ' Each sNode object contains the node's text and the node's level
    ' After populating the GlobeNodes ArrayList, it calls the SaveNodes() subroutine
    ' to serialize the ArrayList to a disk file.
    ' The file's name is passed to the SaveNodes() subroutine as argument
    Sub CreateList(ByVal node As TreeNode, ByVal fName As String)
        Static level As Integer
        Dim thisNode As TreeNode
        Dim myNode As sNode
        Application.DoEvents()
        myNode.level = level
        myNode.node = node.Text
        GlobeNodes.Add(myNode)
        If node.Nodes.Count > 0 Then
            level = level + 1
            For Each thisNode In node.Nodes
                CreateList(thisNode, fName)
            Next
            level = level - 1
        End If
        SaveNodes(fName)
    End Sub

    ' The SaveNodes() subroutine saves the GlobeNodes ArrayList to a disk file
    ' by calling a SoapFormatter object's Serialize method
    Sub SaveNodes(ByVal fName As String)
        Dim formatter As SoapFormatter
        Dim saveFile As FileStream
        saveFile = File.Create(fName)
        formatter = New SoapFormatter()
        formatter.Serialize(saveFile, GlobeNodes)
        saveFile.Close()
    End Sub

End Class