DayPicker({Key key, @required DateTime selectedDate, @required DateTime currentDate, @required ValueChanged<DateTime> onChanged, @required DateTime displayedMonth })

Creates a day picker.

Rarely used directly. Instead, typically used as part of a DatePicker.

Source 

DayPicker({
  Key key,
  @required this.selectedDate,
  @required this.currentDate,
  @required this.onChanged,
  @required this.displayedMonth
}) : super(key: key) {
  assert(selectedDate != null);
  assert(currentDate != null);
  assert(onChanged != null);
  assert(displayedMonth != null);
}