/// <summary>
/// Return a <see cref="ManagedWeakReference"/> to the pool.
/// </summary>
/// <param name="owner">The instance returning the reference to the pool.</param>
/// <param name="managedWeakReference">A <see cref="ManagedWeakReference"/> to return</param>
/// <remarks>
/// The returned <see cref="ManagedWeakReference"/> may not be owner by the <paramref name="owner"/>,
/// in which case, the <paramref name="managedWeakReference"/> will not be returned to the pool. If the reference
/// if an <see cref="IWeakReferenceProvider"/> it is not returned as well.
/// A null <paramref name="managedWeakReference"/> is ignored.
/// </remarks>
public static void ReturnWeakReference(object owner, ManagedWeakReference managedWeakReference)
{
if (Enabled &&
managedWeakReference != null &&
managedWeakReference.Owner == owner &&
!managedWeakReference.IsSelfReference
)
{
lock (_gate)
{
if (_weakReferencePool.Count < MaxReferences)
{
ReturnUnsafeWeakReference(managedWeakReference.GetUnsafeTargetHandle());
if (!(managedWeakReference.Owner is IWeakReferenceProvider))
{
// The owner's weak reference may have been borrowed from an IWeakReferenceProvider instance
// We're not release it if it's the case.
ReturnUnsafeWeakReference(managedWeakReference.GetUnsafeOwnerHandle());
}
managedWeakReference.Dispose();
}
}
}
}
internal void SetWeakDataContext(ManagedWeakReference weakDataContext)
{
if (!_disposed)
{
var previousStorage = _dataContextWeakStorage;
_dataContextWeakStorage = weakDataContext;
OnDataContextChanged();
// Return the reference to the pool after it's been released from the underlying BindingItem instances.
// Failing to do so makes the reference change without the bindings knowing about it,
// making the reference comparison always equal.
Uno.UI.DataBinding.WeakReferencePool.ReturnWeakReference(this, previousStorage);
}
}
internal void SetWeakDataContext(ManagedWeakReference weakDataContext, bool transferReferenceOwnership = false)
{
if (!_disposed && DependencyObjectStore.AreDifferent(DataContext, weakDataContext?.Target))
{
var previousStorage = _dataContextWeakStorage;
_dataContextWeakStorage = weakDataContext;
OnDataContextChanged();
// Return the reference to the pool after it's been released from the next BindingItem instances.
// Failing to do so makes the reference change without the bindings knowing about it,
// making the reference comparison always equal.
Uno.UI.DataBinding.WeakReferencePool.ReturnWeakReference(this, previousStorage);
}
}
/// <summary>
/// Subscibes for updates to the INotifyPropertyChanged interface.
/// </summary>
private static IDisposable SubscribeToNotifyPropertyChanged(ManagedWeakReference dataContextReference, string propertyName, Action newValueAction)
{
// Attach to the Notify property changed events
var notify = dataContextReference.Target as INotifyPropertyChanged;
if (notify != null)
{
if (propertyName.Length != 0 && propertyName[0] == '[')
{
propertyName = "Item" + propertyName;
}
var newValueActionWeak = Uno.UI.DataBinding.WeakReferencePool.RentWeakReference(null, newValueAction);
PropertyChangedEventHandler handler = (s, args) =>
{
if (args.PropertyName == propertyName)
{
if (typeof(BindingPath).Log().IsEnabled(Microsoft.Extensions.Logging.LogLevel.Debug))
{
typeof(BindingPath).Log().Debug("Property changed for {0} on [{1}]".InvariantCultureFormat(propertyName, dataContextReference.Target?.GetType()));
}
(newValueActionWeak.Target as Action)?.Invoke();
}
};
notify.PropertyChanged += handler;
return(Disposable.Create(() =>
{
// This weak reference ensure that the closure will not link
// the caller and the callee, in the same way "newValueActionWeak"
// does not link the callee to the caller.
var that = dataContextReference.Target as INotifyPropertyChanged;
if (that != null)
{
that.PropertyChanged -= handler;
}
Uno.UI.DataBinding.WeakReferencePool.ReturnWeakReference(null, newValueActionWeak);
}));
}
return(null);
}