Private Sub viewer_SizeModeChanged(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("SizeModeChanged Event: {0}", viewer.SizeMode.ToString())
   MessageBox.Show(s)
End Sub
Public Sub RasterImageViewer_SizeModeChanged(ByVal viewer As RasterImageViewer)
   AddHandler viewer.SizeModeChanged, AddressOf viewer_SizeModeChanged

   Select Case viewer.SizeMode
      Case RasterPaintSizeMode.Fit
         viewer.SizeMode = RasterPaintSizeMode.FitAlways

      Case RasterPaintSizeMode.FitAlways
         viewer.SizeMode = RasterPaintSizeMode.FitWidth

      Case RasterPaintSizeMode.FitWidth
         viewer.SizeMode = RasterPaintSizeMode.Normal

      Case RasterPaintSizeMode.Normal
         viewer.SizeMode = RasterPaintSizeMode.Stretch

      Case RasterPaintSizeMode.Stretch
         viewer.SizeMode = RasterPaintSizeMode.Fit
   End Select

   RemoveHandler viewer.SizeModeChanged, AddressOf viewer_SizeModeChanged
End Sub

private void viewer_SizeModeChanged(object sender, EventArgs e)
{
   RasterImageViewer viewer = sender as RasterImageViewer;
   string s = string.Format("SizeModeChanged Event: {0}", viewer.SizeMode.ToString());
   MessageBox.Show(s);
}
public void RasterImageViewer_SizeModeChanged(RasterImageViewer viewer)
{
   viewer.SizeModeChanged += new EventHandler(viewer_SizeModeChanged);

   switch (viewer.SizeMode)
   {
      case RasterPaintSizeMode.Fit:
         viewer.SizeMode = RasterPaintSizeMode.FitAlways;
         break;

      case RasterPaintSizeMode.FitAlways:
         viewer.SizeMode = RasterPaintSizeMode.FitWidth;
         break;

      case RasterPaintSizeMode.FitWidth:
         viewer.SizeMode = RasterPaintSizeMode.Normal;
         break;

      case RasterPaintSizeMode.Normal:
         viewer.SizeMode = RasterPaintSizeMode.Stretch;
         break;

      case RasterPaintSizeMode.Stretch:
         viewer.SizeMode = RasterPaintSizeMode.Fit;
         break;
   }

   viewer.SizeModeChanged -= new EventHandler(viewer_SizeModeChanged);
}