private void UpdateContextInternal()
{
if (!_isParentContext)
{
return;
}
ClearOldContext();
object target = _targetReference.Target;
if (target == null)
{
return;
}
var context = GetParentBindingContext(target);
if (context == null)
{
_dataContext = null;
}
else
{
var source = context.Source;
if (source != null)
{
WeakEventManager.GetBindingContextListener(source).Add(this);
}
_dataContext = context;
}
}
private void Update(object source)
{
if (_parentContext != null)
{
var src = _parentContext.Source;
if (src != null)
{
WeakEventManager.GetBindingContextListener(src).Remove(this);
}
}
if (source == null)
{
_parentContext = null;
}
else
{
_parentContext = GetParentBindingContext(source);
if (_parentContext != null)
{
var src = _parentContext.Source;
if (src != null)
{
WeakEventManager.GetBindingContextListener(src).Add(this);
}
}
}
}
/// <summary>
/// Attempts to track the value change.
/// </summary>
public IDisposable TryObserve(object source, IEventListener listener)
{
if (_isDataContext)
{
return(WeakEventManager.GetBindingContextListener(source).AddWithUnsubscriber(listener));
}
if (_memberEvent == null)
{
return(null);
}
return(_memberEvent.SetValue(source, new object[] { listener }) as IDisposable);
}
private void ClearOldContext()
{
var bindingContext = _dataContext as IBindingContext;
if (bindingContext != null)
{
var source = bindingContext.Source;
if (source != null)
{
WeakEventManager.GetBindingContextListener(source).Remove(this);
}
}
}