TreeView from a text file with tabs denoting indentation

[nandagopal]

Read the file and count the leading tabs. Give the new node the right parent for its level of indentation.

Code Select Expand

' Load a TreeView control from a file that uses tabs
' to show indentation.
Private Sub LoadTreeViewFromFile(ByVal file_name As String, _
    ByVal trv As TreeView)
    ' Get the file's contents.
    Dim stream_reader As New StreamReader(file_name)
    Dim file_contents As String = stream_reader.ReadToEnd()
    stream_reader.Close()

    ' Remove line feeds.
    file_contents = file_contents.Replace(vbLf, "")

    ' Break the file into lines.
    Const charCR As Char = CChar(vbCr)
    Const charTab As Char = CChar(vbTab)
    Dim lines() As String = file_contents.Split(charCR)

    ' Process the lines.
    Dim text_line As String
    Dim level As Integer
    Dim tree_nodes() As TreeNode
    Dim num_nodes As Integer = 0
    ReDim tree_nodes(num_nodes)

    trv.Nodes.Clear()
    For i As Integer = 0 To lines.GetUpperBound(0)
        text_line = lines(i)
        If text_line.Trim().Length > 0 Then
            ' See how many tabs are at the start of the
            ' line.
            level = text_line.Length - _
                text_line.TrimStart(charTab).Length

            ' Make room for the new node.
            If level > num_nodes Then
                num_nodes = level
                ReDim Preserve tree_nodes(num_nodes)
            End If

            ' Add the new node.
            If level = 0 Then
                tree_nodes(level) = _
                    trv.Nodes.Add(text_line.Trim())
            Else
                tree_nodes(level) = tree_nodes(level - _
                    1).Nodes.Add(text_line.Trim())
            End If
            tree_nodes(level).EnsureVisible()
        End If
    Next i

    If trv.Nodes.Count > 0 Then trv.Nodes(0).EnsureVisible()
End Sub