Private Sub viewer_ScrollViewer(ByVal sender As Object, ByVal e As EventArgs)
   Dim viewer As RasterImageViewer = CType(IIf(TypeOf sender Is RasterImageViewer, sender, Nothing), RasterImageViewer)
   Dim s As String = String.Format("ScrollPosition: {0}", viewer.ScrollPosition)
   Console.WriteLine(s)
End Sub
Public Sub RasterImageViewer_ScrollViewer(ByVal viewer As RasterImageViewer)
   AddHandler viewer.ScrollViewer, AddressOf viewer_ScrollViewer

   MessageBox.Show("Scroll the image and the 'ScrollViewer' event gets fired")
   ' or do something in code to cause a scroll
End Sub

private void viewer_ScrollViewer(object sender, EventArgs e)
{
   RasterImageViewer viewer = sender as RasterImageViewer;
   string s = string.Format("ScrollPosition: {0}", viewer.ScrollPosition);
   Console.WriteLine(s);
}
public void RasterImageViewer_ScrollViewer(RasterImageViewer viewer)
{
   viewer.ScrollViewer += new EventHandler(viewer_ScrollViewer);

   MessageBox.Show("Scroll the image and the 'ScrollViewer' event gets fired");
   // or do something in code to cause a scroll
}