MVP please help - List box horizontal scroll bar

[Valerie Hough]

I have a list box that uses the horizontal scroll bar. I would like to be
able to "scroll" my headings at the top of the list box when the list box is
scrolled.

Spy reveals that this is not a real scroll bar (hwnd always null), so I
can't see how to find out when, and how much, the list box is scrolled.

If I create my own scroll bar, I have trouble keeping the display smooth.
The best I can seem to do is to intercept and ignore the WM_ERASEBGND
message, but the effect is still not nearly as smooth as using the
ListBox.HorizontalScrollBar property. In addition, when I create a
HScrollBar object and try to anchor it to the bottom of the list box, it
moves when I vertically scroll the list box. I am reduced to repositioning
it every time I receive a vertical scroll message.

Obviously I would prefer to use HorizontalScrollBar, but I would settle for
a decent looking scroll effect using HScrollBar.

Can anyone help?

Thanks in advance,
Valerie Hough

 

[Ken Tucker [MVP]]

Hi,

Use the native window class to listen for the scroll messages on
the listbox

' NativeWindow class to listen to operating system messages.

Private Class MyListener

Inherits NativeWindow

Public Event MyScroll(ByVal sender As Object, ByVal e As EventArgs)

Const WM_MOUSEACTIVATE = &H21

Const WM_MOUSEMOVE = &H200



Private ctrl As Control

Public Sub New(ByVal ctrl As Control)

AssignHandle(ctrl.Handle)

End Sub

Protected Overrides Sub WndProc(ByRef m As Message)

' Listen for operating system messages

Const WM_HSCROLL = &H114

Const WM_VSCROLL = &H115





If m.Msg = WM_Hscroll Or m.Msg = wm_vscroll Then

RaiseEvent MyScroll(ctrl, New EventArgs)

End If

MyBase.WndProc(m)

End Sub

Protected Overrides Sub Finalize()

ReleaseHandle()

MyBase.Finalize()

End Sub

End Class

Dim WithEvents sl As MyListener

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

sl = New MyListener(ListBox1)

end sub



Private Sub sl_MyScroll(ByVal sender As Object, ByVal e As System.EventArgs)
Handles sl.MyScroll

Me.Text = "Scroll"

End Sub






Ken