/// <summary>
/// Adds filtering of annotations when annotation collection is loaded.
/// </summary>
public static void AddAnnotationsLoadFilter(Vintasoft.Imaging.Annotation.UI.AnnotationViewer viewer)
{
    // Subscribe to the AnnotationsDataChanged event of viewer.
    SubscribeToViewerEvents(viewer);

    // Subscribe to the CollectionAdded event of annotation data controller.
    SubscribeToControllerEvents(viewer.AnnotationDataController);
}

/// <summary>
/// Subscribe to the AnnotationsDataChanged event of viewer.
/// </summary>
private static void SubscribeToViewerEvents(Vintasoft.Imaging.Annotation.UI.AnnotationViewer viewer)
{
    viewer.AnnotationDataControllerChanged += 
        new System.EventHandler<Vintasoft.Imaging.Annotation.AnnotationDataControllerChangedEventArgs>(viewer_AnnotationsDataChanged);
}

/// <summary>
/// Handler of the AnnotationsDataChanged event.
/// </summary>
private static void viewer_AnnotationsDataChanged(object sender, 
    Vintasoft.Imaging.PropertyChangedEventArgs<Vintasoft.Imaging.Annotation.AnnotationDataController> e)
{
    // Unsubscribe from the events of previous annotation data controller.
    UnsubscribeFromControllerEvents(e.OldValue);

    // Subscribe to the events of new annotation data controller.
    SubscribeToControllerEvents(e.NewValue);
}

/// <summary>
/// Subscribe to the CollectionAdded event of annotation data controller.
/// </summary>
private static void SubscribeToControllerEvents(Vintasoft.Imaging.Annotation.AnnotationDataController dataController)
{
    dataController.CollectionAdded += 
        new System.EventHandler<Vintasoft.Imaging.Annotation.AnnotationDataControllerDataCollectionEventArgs>(dataController_CollectionAdded);
}

/// <summary>
/// Unsubscribe from the CollectionAdded event of annotation data controller.
/// </summary>
private static void UnsubscribeFromControllerEvents(Vintasoft.Imaging.Annotation.AnnotationDataController dataController)
{
    if (dataController != null)
        dataController.CollectionAdded -= 
            new System.EventHandler<Vintasoft.Imaging.Annotation.AnnotationDataControllerDataCollectionEventArgs>(dataController_CollectionAdded);
}

/// <summary>
/// Handler of the CollectionAdded event.
/// </summary>
private static void dataController_CollectionAdded(object sender, 
    Vintasoft.Imaging.Annotation.AnnotationDataControllerDataCollectionEventArgs e)
{
    // Annotation data collection is added to the annotation data controller,
    // at this moment we can filter annotations.

    // Filter the annotations.
    ApplyAnnotationFilter(e.AnnotationDataCollection);
}

/// <summary>
/// Filters the annotations of annotation data collection.
/// </summary>
private static void ApplyAnnotationFilter(Vintasoft.Imaging.Annotation.AnnotationDataCollection dataCollection)
{
    // For each annotation in collection.
    foreach (Vintasoft.Imaging.Annotation.AnnotationData data in dataCollection)
    {
        // If annotation is stamp.
        if (data is Vintasoft.Imaging.Annotation.StampAnnotationData)
            // Make annotation invisible.
            data.IsVisible = false;
    }
}

''' <summary>
''' Adds filtering of annotations when annotation collection is loaded.
''' </summary>
Public Shared Sub AddAnnotationsLoadFilter(viewer As Vintasoft.Imaging.Annotation.UI.AnnotationViewer)
    ' Subscribe to the AnnotationsDataChanged event of viewer.
    SubscribeToViewerEvents(viewer)

    ' Subscribe to the CollectionAdded event of annotation data controller.
    SubscribeToControllerEvents(viewer.AnnotationDataController)
End Sub

''' <summary>
''' Subscribe to the AnnotationsDataChanged event of viewer.
''' </summary>
Private Shared Sub SubscribeToViewerEvents(viewer As Vintasoft.Imaging.Annotation.UI.AnnotationViewer)
    AddHandler viewer.AnnotationDataControllerChanged, New System.EventHandler(Of Vintasoft.Imaging.Annotation.AnnotationDataControllerChangedEventArgs)(AddressOf viewer_AnnotationsDataChanged)
End Sub

''' <summary>
''' Handler of the AnnotationsDataChanged event.
''' </summary>
Private Shared Sub viewer_AnnotationsDataChanged(sender As Object, e As Vintasoft.Imaging.PropertyChangedEventArgs(Of Vintasoft.Imaging.Annotation.AnnotationDataController))
    ' Unsubscribe from the events of previous annotation data controller.
    UnsubscribeFromControllerEvents(e.OldValue)

    ' Subscribe to the events of new annotation data controller.
    SubscribeToControllerEvents(e.NewValue)
End Sub

''' <summary>
''' Subscribe to the CollectionAdded event of annotation data controller.
''' </summary>
Private Shared Sub SubscribeToControllerEvents(dataController As Vintasoft.Imaging.Annotation.AnnotationDataController)
    AddHandler dataController.CollectionAdded, New System.EventHandler(Of Vintasoft.Imaging.Annotation.AnnotationDataControllerDataCollectionEventArgs)(AddressOf dataController_CollectionAdded)
End Sub

''' <summary>
''' Unsubscribe from the CollectionAdded event of annotation data controller.
''' </summary>
Private Shared Sub UnsubscribeFromControllerEvents(dataController As Vintasoft.Imaging.Annotation.AnnotationDataController)
    If dataController IsNot Nothing Then
        RemoveHandler dataController.CollectionAdded, New System.EventHandler(Of Vintasoft.Imaging.Annotation.AnnotationDataControllerDataCollectionEventArgs)(AddressOf dataController_CollectionAdded)
    End If
End Sub

''' <summary>
''' Handler of the CollectionAdded event.
''' </summary>
Private Shared Sub dataController_CollectionAdded(sender As Object, e As Vintasoft.Imaging.Annotation.AnnotationDataControllerDataCollectionEventArgs)
    ' Annotation data collection is added to the annotation data controller,
    ' at this moment we can filter annotations.

    ' Filter the annotations.
    ApplyAnnotationFilter(e.AnnotationDataCollection)
End Sub

''' <summary>
''' Filters the annotations of annotation data collection.
''' </summary>
Private Shared Sub ApplyAnnotationFilter(dataCollection As Vintasoft.Imaging.Annotation.AnnotationDataCollection)
    ' For each annotation in collection.
    For Each data As Vintasoft.Imaging.Annotation.AnnotationData In dataCollection
        ' If annotation is stamp.
        If TypeOf data Is Vintasoft.Imaging.Annotation.StampAnnotationData Then
            ' Make annotation invisible.
            data.IsVisible = False
        End If
    Next
End Sub