build method
- @override
Describes the part of the user interface represented by this widget.
The framework calls this method when this widget is inserted into the
tree in a given BuildContext
and when the dependencies of this widget
change (e.g., an InheritedWidget
referenced by this widget changes).
The framework replaces the subtree below this widget with the widget
returned by this method, either by updating the existing subtree or by
removing the subtree and inflating a new subtree, depending on whether the
widget returned by this method can update the root of the existing
subtree, as determined by calling Widget.canUpdate
.
Typically implementations return a newly created constellation of widgets
that are configured with information from this widget's constructor and
from the given BuildContext
.
The given BuildContext
contains information about the location in the
tree at which this widget is being built. For example, the context
provides the set of inherited widgets for this location in the tree. A
given widget might be built with multiple different BuildContext
arguments over time if the widget is moved around the tree or if the
widget is inserted into the tree in multiple places at once.
The implementation of this method must only depend on:
- the fields of the widget, which themselves must not change over time, and
- any ambient state obtained from the
context
usingBuildContext.inheritFromWidgetOfExactType
.
If a widget's build method is to depend on anything else, use a
StatefulWidget
instead.
See also:
StatelessWidget
, which contains the discussion on performance considerations.
Implementation
@override
Widget build(BuildContext context) {
final ThemeData themeData = Theme.of(context);
final MaterialLocalizations localizations =
MaterialLocalizations.of(context);
final int year = displayedMonth.year;
final int month = displayedMonth.month;
final int mDay = displayedMonth.day;
final PersianDate getPearData =
PersianDate.pDate(gregorian: displayedMonth.toString());
final PersianDate selectedPersainDate =
PersianDate.pDate(gregorian: selectedDate.toString());
final PersianDate currentPDate =
PersianDate.pDate(gregorian: currentDate.toString());
final List<Widget> labels = <Widget>[];
var pDay = _digits(mDay, 2);
var gMonth = _digits(month, 2);
var parseP = date.parse("$year-$gMonth-$pDay");
var jtgData = date.jalaliToGregorian(parseP[0], parseP[1], 01);
var pMonth = _digits(jtgData[1], 2);
PersianDate pdate =
PersianDate.pDate(gregorian: "${jtgData[0]}-$pMonth-${jtgData[2]}");
var daysInMonth = getDaysInMonth(pdate.year, pdate.month);
var startday = dayShort.indexOf(pdate.weekdayname);
labels.addAll(_getDayHeaders());
for (int i = 0; true; i += 1) {
final int day = i - startday + 1;
if (day > daysInMonth) break;
if (day < 1) {
labels.add(Container());
} else {
var pDay = _digits(day, 2);
var jtgData = date.jalaliToGregorian(
getPearData.year, getPearData.month, int.parse(pDay));
final DateTime dayToBuild =
DateTime(jtgData[0], jtgData[1], jtgData[2]);
final PersianDate getHolidy =
PersianDate.pDate(gregorian: dayToBuild.toString());
final bool disabled = dayToBuild.isAfter(lastDate) ||
dayToBuild.isBefore(firstDate) ||
(selectableDayPredicate != null &&
!selectableDayPredicate(dayToBuild));
BoxDecoration decoration;
TextStyle itemStyle = themeData.textTheme.body1;
final bool isSelectedDay =
selectedPersainDate.year == getPearData.year &&
selectedPersainDate.month == getPearData.month &&
selectedPersainDate.day == day;
if (isSelectedDay) {
// The selected day gets a circle background highlight, and a contrasting text color.
itemStyle = themeData.accentTextTheme.body2;
decoration = BoxDecoration(
color: themeData.accentColor, shape: BoxShape.circle);
} else if (disabled) {
itemStyle = themeData.textTheme.body1
.copyWith(color: themeData.disabledColor);
} else if (currentPDate.year == getPearData.year &&
currentPDate.month == getPearData.month &&
currentPDate.day == day) {
// The current day gets a different text color.
itemStyle =
themeData.textTheme.body2.copyWith(color: themeData.accentColor);
} else if (getHolidy.isHoliday) {
// The current day gets a different text color.
itemStyle = themeData.textTheme.body2.copyWith(color: Colors.red);
}
Widget dayWidget = Container(
decoration: decoration,
child: Center(
child: Semantics(
// We want the day of month to be spoken first irrespective of the
// locale-specific preferences or TextDirection. This is because
// an accessibility user is more likely to be interested in the
// day of month before the rest of the date, as they are looking
// for the day of month. To do that we prepend day of month to the
// formatted full date.
label:
'${localizations.formatDecimal(day)}, ${localizations.formatFullDate(dayToBuild)}',
selected: isSelectedDay,
child: ExcludeSemantics(
child: Text(localizations.formatDecimal(day), style: itemStyle),
),
),
),
);
if (!disabled) {
dayWidget = GestureDetector(
behavior: HitTestBehavior.opaque,
onTap: () {
onChanged(dayToBuild);
},
child: dayWidget,
);
}
labels.add(dayWidget);
}
}
return Padding(
padding: const EdgeInsets.symmetric(horizontal: 8.0),
child: Directionality(
textDirection: TextDirection.rtl,
child: Column(
children: <Widget>[
Container(
height: _kDayPickerRowHeight,
child: Center(
child: ExcludeSemantics(
child: Text(
"${pdate.monthname} ${pdate.year}",
style: themeData.textTheme.subhead,
),
),
),
),
Flexible(
child: GridView.custom(
gridDelegate: _kDayPickerGridDelegate,
childrenDelegate: SliverChildListDelegate(labels,
addRepaintBoundaries: false),
),
),
],
)),
);
}