/// <summary>
/// Add a feedback adorner to a UI element.
/// This is used to show when a connection can or can't be attached to a particular connector.
/// 'indicator' will be a view-model object that is transformed into a UI element using a data-template.
/// </summary>
private void AddFeedbackAdorner(FrameworkElement adornedElement, object indicator)
{
AdornerLayer adornerLayer = AdornerLayer.GetAdornerLayer(this);
if (feedbackAdorner != null)
{
if (feedbackAdorner.AdornedElement == adornedElement)
{
// No change.
return;
}
adornerLayer.Remove(feedbackAdorner);
feedbackAdorner = null;
}
//
// Create a content control to contain 'indicator'.
// The view-model object 'indicator' is transformed into a UI element using
// normal WPF data-template rules.
//
ContentControl adornerElement = new ContentControl();
adornerElement.HorizontalAlignment = HorizontalAlignment.Left;
adornerElement.VerticalAlignment = VerticalAlignment.Center;
adornerElement.Content = indicator;
//
// Create the adorner and add it to the adorner layer.
//
feedbackAdorner = new FrameworkElementAdorner(adornerElement, adornedElement);
adornerLayer.Add(feedbackAdorner);
}
/// <summary>
/// If there is an existing feedback adorner, remove it.
/// </summary>
private void ClearFeedbackAdorner()
{
if (feedbackAdorner == null)
{
return;
}
AdornerLayer adornerLayer = AdornerLayer.GetAdornerLayer(this);
adornerLayer.Remove(feedbackAdorner);
feedbackAdorner = null;
}
