''' <summary>
''' Starts showing animation in image viewer.
''' </summary>
''' <param name="viewer">An image viewer.</param>
''' <param name="delay">The animation delay in milliseconds.</param>
Private Sub StartAnimation(viewer As Vintasoft.Imaging.Wpf.UI.WpfImageViewer, delay As Integer)
    ' start animation
    System.Threading.ThreadPool.QueueUserWorkItem(New System.Threading.WaitCallback(AddressOf ShowAnimation), New Object() {viewer, delay})
End Sub

''' <summary>
''' Shows animation in image viewer.
''' </summary>
''' <param name="state">Data that the method uses.</param>
Private Sub ShowAnimation(state As Object)
    ' get data
    Dim data As Object() = DirectCast(state, Object())
    ' get image viewer
    Dim viewer As Vintasoft.Imaging.Wpf.UI.WpfImageViewer = DirectCast(data(0), Vintasoft.Imaging.Wpf.UI.WpfImageViewer)
    ' get delay value
    Dim delay As Integer = CInt(data(1))
    ' for each image in image collection of image viewer
    For i As Integer = 0 To viewer.Images.Count - 1
        ' change image in image viewer
        viewer.SetFocusedIndexSync(i)
        ' sleep for a while
        System.Threading.Thread.Sleep(delay)
    Next
End Sub

/// <summary>
/// Starts showing animation in image viewer.
/// </summary>
/// <param name="viewer">An image viewer.</param>
/// <param name="delay">The animation delay in milliseconds.</param>
private void StartAnimation(Vintasoft.Imaging.Wpf.UI.WpfImageViewer viewer, int delay)
{
    // start animation
    System.Threading.ThreadPool.QueueUserWorkItem(
        new System.Threading.WaitCallback(ShowAnimation), new object[] { viewer, delay });
}

/// <summary>
/// Shows animation in image viewer.
/// </summary>
/// <param name="state">Data that the method uses.</param>
private void ShowAnimation(object state)
{
    // get data
    object[] data = (object[])state;
    // get image viewer
    Vintasoft.Imaging.Wpf.UI.WpfImageViewer viewer =
         (Vintasoft.Imaging.Wpf.UI.WpfImageViewer)data[0];
    // get delay value
    int delay = (int)data[1];
    // for each image in image collection of image viewer
    for (int i = 0; i < viewer.Images.Count; i++)
    {
        // change image in image viewer
        viewer.SetFocusedIndexSync(i);
        // sleep for a while
        System.Threading.Thread.Sleep(delay);
    }
}