Dim txt As String = e.Form.controls("TextBox1").Text
If txt = "" Then \'如果下拉框没有输入内容,则无需查询
    Return
End If
Dim trv As WinForm.TreeView =  e.Form.Controls("TreeView1")
Dim Start As Integer
Dim idx As Integer = - 1
If trv.SelectedNode IsNot Nothing Then \'获取当前节点位置.
    Dim FullName As String = trv.SelectedNode.FullName
    For i As Integer = 0 To trv.AllNodes.count - 1
        If trv.AllNodes(i).FullName = FullName  Then
            Start = i
            Exit For
        End If
    Next
End If
For i As Integer = Start + 1 To trv.AllNodes.count - 1  \'从当前节点的下一个节点开始查找
    Dim nd As WinForm.TreeNode = trv.AllNodes(i)
    If nd.Text.IndexOf(txt) >= 0 Then
        trv.SelectedNode = nd
        nd.EnsureVisible
        idx = i \'将找到的位置复制给变量idx
        Exit For
    End If
Next
If  idx = -1 Then \'idx的值如果等于初始值-1,表示没有找到下一个符合条件的节点,那么从第一个节点开始重新查找.
    For i As Integer = 0 To Start - 1
        Dim nd As WinForm.TreeNode = trv.AllNodes(i)
        If nd.Text.IndexOf(txt) >= 0 Then
            trv.SelectedNode = nd
            nd.EnsureVisible
            Exit For
        End If
    Next
End If
trv.Select()

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