public static void OnControlTemplateChanged(BindableObject bindable, object oldValue, object newValue)
{
var self = (IControlTemplated)bindable;
// First make sure any old ContentPresenters are no longer bound up. This MUST be
// done before we attempt to make the new template.
if (oldValue != null)
{
var queue = new FormsQueue <Element>(16);
queue.Enqueue((Element)self);
while (queue.Count > 0)
{
ReadOnlyCollection <Element> children = queue.Dequeue().LogicalChildrenInternal;
for (var i = 0; i < children.Count; i++)
{
Element child = children[i];
var controlTemplated = child as IControlTemplated;
var presenter = child as ContentPresenter;
if (presenter != null)
{
presenter.Clear();
}
else if (controlTemplated == null || controlTemplated.ControlTemplate == null)
{
queue.Enqueue(child);
}
}
}
}
// Now remove all remnants of any other children just to be sure
while (self.InternalChildren.Count > 0)
{
self.InternalChildren.RemoveAt(self.InternalChildren.Count - 1);
}
ControlTemplate template = self.ControlTemplate;
if (template == null)
{
// do nothing for now
}
else
{
var content = template.CreateContent() as View;
if (content == null)
{
throw new NotSupportedException("ControlTemplate must return a type derived from View.");
}
self.InternalChildren.Add(content);
var controlTemplated = (IControlTemplated)bindable;
controlTemplated.OnControlTemplateChanged((ControlTemplate)oldValue, (ControlTemplate)newValue);
controlTemplated.TemplateRoot = content;
controlTemplated.OnApplyTemplate();
}
}
public Task WaitAsync(CancellationToken token)
{
lock (_waiters)
{
if (_currentCount > 0)
{
--_currentCount;
return(Completed);
}
var waiter = new TaskCompletionSource <bool>();
_waiters.Enqueue(waiter);
token.Register(() => waiter.TrySetCanceled());
return(waiter.Task);
}
}