Preventing ListBox scrolling to top when updated

Question

I\'m trying to build a simple music player with a ListBox playlist. When adding audio files to the playlist, it first fills the ListBox with the filenames and then (on a sep

Answer 1

Yes, .BeginUpdate() is a good solution:

Public Class Form1

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
    Timer1.Start()

End Sub
Dim ix As Integer
Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick

    ix = ListBox1.TopIndex
    Label1.Text = ListBox1.TopIndex     'get most top displayed in the listbox
    ListBox1.BeginUpdate()              'do not refresh during update
    ListBox1.Items.Clear()              'do updates
    For i = 1 To 100
        ListBox1.Items.Add(i.ToString & "." & Int((101) * Rnd()).ToString)
    Next
    ListBox1.TopIndex = ix              'set the top item to be displayed
    ListBox1.EndUpdate()                'refresh the listbox

End Sub

Private Sub VScrollBar1_Scroll(ByVal sender As System.Object, ByVal e As System.Windows.Forms.ScrollEventArgs) _
Handles VScrollBar1.Scroll
    VScrollBar1.Maximum = ListBox1.Items.Count
    ListBox1.TopIndex = VScrollBar1.Value       ' link another scrollbar if you want
    Label2.Text = VScrollBar1.Value

End Sub

End Class

The code speaks by himself. A timer is generating random number. The numbers are populated in the List Box. Before the update just read the current Top Index of the List Box. During the update switch off the rendering by Begin Update. Then restore the Top Index and call End Update.

I put an extra Scroll Bar, linked to the List Box.