How can I determine if a VB.NET ListView is displaying vertical scrollbar to user

Question

I feel like this should be something simple, but I can\'t seem to find out how to do this.

I have a list view control, and I would just like to be able to determine if t

Answer 1

Try this code, all .net, and only a 1 line function.

Private Function IsVerticalScrollVisible(ByVal lst As ListView) As Boolean
    If lst.Items.Count > 0 Then _
        If (lst.Items(0).Bounds.Top - lst.TopItem.Bounds.Top < 0) Or _
        (lst.Items(lst.Items.Count - 1).Bounds.Bottom > lst.ClientSize.Height) _
        Then Return True
End Function

Answer 2

This is a NET update of the MSDN answer (if you look, that is VB6 related):

'Pinvokes - these are usually Shared methods in a 
' Win32NativeMethods class you accumulate 
Private Const GWL_STYLE As Integer = -16
Private Const WS_HSCROLL = &H100000
Private Const WS_VSCROLL = &H200000

<DllImport("user32.dll", SetLastError:=True)> _
private Shared Function GetWindowLong(ByVal hWnd As IntPtr, 
                       ByVal nIndex As Integer) As Integer
End Function

' sometimes you use wrappers since many, many, many things could call
' SendMessage and so that your code doesnt need to know all the MSG params
Friend Shared Function IsVScrollVisible(ByVal ctl As Control) As Boolean
    Dim wndStyle As Integer = GetWindowLong(ctl.Handle, GWL_STYLE)
    Return ((wndStyle And WS_VSCROLL) <> 0)

End Function

' to be complete:
Friend Shared Function IsHScrollVisible(ByVal ctl As Control) As Boolean
    Dim wndStyle As Integer = GetWindowLong(ctl.Handle, GWL_STYLE)
    Return ((wndStyle And WS_HSCROLL) <> 0)

End Function

Elsewhere, subscribe to the ClientSizeChanged event:

Private VScrollVis As Boolean = False
Private Sub lv_ClientSizeChanged(sender As Object, e As EventArgs) 
               Handles myListView.ClientSizeChanged

    VScrollVis = IsVScrollVisible(Me)

    MyBase.OnClientSizeChanged(e)
End Sub

You did not indicate what you wanted to do about it. You could raise a new event whenever VScrollVis changes or you can write code to "fix" the control if the HScroll shows up simply because the VScroll is now Visible.

---

I just want to to call a function and have it return true if the scrollbar is visible

' expose PInvoke if needed, convert to non-Shared
Public Function IsVerticalScrollVisible(ctl As Control)
   Return IsVScrollVisible(ctl)
End Function

Public Function IsHorizontalScrollVisible(ctl As Control)
   Return IsHScrollVisible(ctl)
End Function