build method

Future<DateTime?> build(BuildContext context, DateTime? currentDateTime)

Build the picker.

context is passed BuildContext. currentDateTime is passed the currently selected DateTime.

ピッカーのビルドを行ないます。

contextにBuildContextが渡されます。currentDateTimeに現在選択されているDateTimeが渡されます。

Implementation

Future<DateTime?> build(
  BuildContext context,
  DateTime? currentDateTime,
) async {
  assert(
    begin == null ||
        end == null ||
        (begin != null && end != null && begin!.isBefore(end!)),
    "[begin] must be before [end].",
  );
  final theme = Theme.of(context);
  DateTime? res;
  final now = DateTime.now();
  final startYear = begin?.year ?? (now.year - 10);
  final endYear = end?.year ?? (now.year + 10);
  final selectedYear = ((currentDateTime?.year ??
              defaultDateTime?.year ??
              begin?.year ??
              end?.year ??
              now.year) -
          startYear)
      .limit(0, endYear - startYear);
  var selectedMonth = ((currentDateTime?.month ??
              defaultDateTime?.month ??
              begin?.month ??
              end?.month ??
              now.month) -
          1)
      .limit(0, 12);
  if (selectedYear == 0) {
    selectedMonth = selectedMonth - ((begin?.month ?? 1) - 1);
  }
  await _Picker(
    height: 240,
    backgroundColor: backgroundColor ?? theme.colorScheme.surface,
    containerColor: backgroundColor ?? theme.colorScheme.surface,
    headerColor: backgroundColor ?? theme.colorScheme.surface,
    textStyle: TextStyle(color: color ?? theme.colorScheme.onSurface),
    confirmText: confirmText,
    cancelText: cancelText,
    selecteds: [
      selectedYear,
      selectedMonth,
    ],
    adapter: _PickerDataAdapter<int>(
      data: [
        for (var y = startYear; y < endYear; y++) ...[
          () {
            final year = DateTime(y, 1, 1);
            final startMonth = y == startYear ? begin?.month ?? 1 : 1;
            final endMonth = y == endYear - 1 ? end?.month ?? 12 : 12;
            return _PickerItem(
              text: Text(
                "${year.format(yearFormat)}$yearSuffix",
                style: TextStyle(
                  color: color ?? theme.colorScheme.onSurface,
                ),
              ),
              value: y,
              children: [
                for (var m = startMonth - 1; m < endMonth; m++)
                  _PickerItem(
                    text: Text(
                      "${(m + 1).format("00")}$monthSuffix",
                      style: TextStyle(
                        color: color ?? theme.colorScheme.onSurface,
                      ),
                    ),
                    value: m,
                  ),
              ],
            );
          }(),
        ],
      ],
    ),
    changeToFirst: true,
    hideHeader: false,
    onConfirm: (_Picker picker, List<int> value) {
      var month = value[1] + 1;
      if (value[0] == 0) {
        month = month + ((begin?.month ?? 1) - 1);
      }
      if (lastDayOfMonth == true) {
        res = DateTime(value[0] + startYear, month + 1, 0);
      } else {
        res = DateTime(value[0] + startYear, month, day ?? 1);
      }
    },
  ).showModal(context);
  return res;
}