startDate method

@override DateTime startDate(DateTime date)

Returns the next date that fits the dayInYear.

• If the current date - DayInYear.dayInYear is equal to zero, date is returned.
• If the current date - DayInYear.dayInYear is less than the dayInYear, it's returned the same year with the DayInYear.dayInYear being the dayInYear.
• If the current date - DayInYear.dayInYear is greater than the dayInYear, it's returned the next year with the DayInYear.dayInYear being the dayInYear.

Implementation

@override
DateTime startDate(DateTime date) {
  if (valid(date)) return date;
  final thisYearDay = date.firstDayOfYear
      .add(Duration(days: dayInYear - 1))
      .clamp(max: date.lastDayOfYear);
  if (date.dayInYear <= dayInYear) return thisYearDay;
  return next(date);
}