How do I add/remove density colors on the Windows Universal App CalendarView control after loading? - xaml

Question

CalendarViewDayItemChanging seems to be the way to add 'density colors' (coloured bars in a DayItem box) to a Windows Universal App CalendarView.
However CalendarViewDayItemChanging is only fired when the DayItem box is loaded i.e. on initial loading and possibly when navigating to a far enough date and back again such that the virtualisation re-loads the DayItem.
However when I create an appointment on the selected date I need to add a density color bar immediately, similarly if I remove an appointment, I need to remove that bar.
How do I get the control to reload or re-render that particular DayItem?
Notes:
There is only the SelectedDates available as a property
There is no obvious way to ge the DayItem collection
Setting the Visibility to Collapsed then Visible instantaneously does not trigger a reload.

Answer 1

There was a similar issue on the MSDN blogs here: https://social.msdn.microsoft.com/Forums/en-US/54c81ada-4147-474b-8425-524ec69bc749/uwp-calendarview?forum=wpdevelop
I think your best bet currently is to have your Appointment creation on a separate page and store a List of Appointments locally or in a db. That way when you navigate back to the Page with your calendar view you can reload the Calendar using the updated Appointment list.

Answer 2

I used the MyCalendarView.UpdateLayout method to force the control to hit the CalendarViewDayItemChanging event again.
I called the method from the DataContextChanged event on my UserControl. This way anytime I change the DataContext the density colors get updated. This is sufficient for my needs. It sounds like you want to do it on a different event.
private void UserControl_DataContextChanged(Windows.UI.Xaml.FrameworkElement sender, Windows.UI.Xaml.DataContextChangedEventArgs args)
{
if (this.DataContext is ObservableCollection<Event>)
{
eventCalendar.UpdateLayout();
}
}