// Fires when the property to update is changed
private static void OnTargetPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
ContainsItemBehavior behavior = (ContainsItemBehavior)d;
// Update bindings to reflect the new target property
if (e.OldValue is string)
{
behavior.clearValueBinding((string)e.OldValue);
}
if (e.NewValue is string)
{
behavior.setValueBinding((string)e.NewValue);
}
}
// Fires when a collection is specified
private static void OnCollectionPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
ContainsItemBehavior behavior = (ContainsItemBehavior)d;
if (e.NewValue is INotifyCollectionChanged)
{
// Validate the new collection to ensure that it has a Contains method
// with the expected signature
MethodInfo info = e.NewValue.GetType().GetMethod("Contains");
if (info == null)
{
throw new ArgumentException(Strings.ContainsErrorMessage);
}
if (info.ReturnType != typeof(bool) && info.ReturnType != typeof(bool?))
{
throw new ArgumentException(Strings.ContainsErrorMessage);
}
ParameterInfo[] parameters = info.GetParameters();
if (parameters.Length != 1)
{
throw new ArgumentException(Strings.ContainsErrorMessage);
}
// Store the type of item the Contains method expects
behavior._expectedItemType = parameters[0].ParameterType;
// Hook-up to check whether the collection contains the item when the collection changes
((INotifyCollectionChanged)e.NewValue).CollectionChanged += behavior.OnCollectionChanged;
// Check whether the item is present in the collection
behavior.checkContains();
}
// Unhook from the previous collection
if (e.OldValue is INotifyCollectionChanged)
{
((INotifyCollectionChanged)e.OldValue).CollectionChanged -= behavior.OnCollectionChanged;
}
}