Added samples for chart, gauge and calendar widgets

lib/main.dart

@@ -1,9 +1,12 @@
 import 'package:flutter/material.dart';
+import 'package:flutter_examples/model/model.dart';
 import 'package:flutter_examples/sample_browser.dart';
 import 'package:syncfusion_flutter_core/core.dart';
 
-void main() {
-  // Register your license here 
+Future<void> main() async {
+  WidgetsFlutterBinding.ensureInitialized(); 
+  await updateControl();
+  // Register your license here
   SyncfusionLicense.registerLicense(null);
-  return runApp(SampleBrowser());
+  runApp(SampleBrowser());
 }

lib/samples/calendar/agenda_view/agenda_view.dart

@@ -0,0 +1,229 @@
+import 'dart:math';
+
+import 'package:flutter/material.dart';
+import 'package:flutter/scheduler.dart';
+import 'package:flutter_examples/model/model.dart';
+import 'package:syncfusion_flutter_calendar/calendar.dart';
+
+//ignore: must_be_immutable
+class AgendaViewCalendar extends StatefulWidget {
+  AgendaViewCalendar({this.sample, Key key}) : super(key: key);
+  SubItem sample;
+
+  @override
+  _AgendaViewCalendarState createState() => _AgendaViewCalendarState(sample);
+}
+
+class _AgendaViewCalendarState extends State<AgendaViewCalendar> {
+  _AgendaViewCalendarState(this.sample);
+
+  final SubItem sample;
+  bool panelOpen;
+  final ValueNotifier<bool> frontPanelVisible = ValueNotifier<bool>(true);
+  List<String> subjectCollection;
+  List<Color> colorCollection;
+  List<Meeting> meetings;
+  MeetingDataSource events;
+  DateTime selectedDate;
+
+  @override
+  void initState() {
+    panelOpen = frontPanelVisible.value;
+    frontPanelVisible.addListener(_subscribeToValueNotifier);
+    meetings = <Meeting>[];
+    selectedDate = DateTime.now();
+    addAppointmentDetails();
+    addAppointments();
+    events = MeetingDataSource(meetings);
+    super.initState();
+  }
+
+  void _subscribeToValueNotifier() => panelOpen = frontPanelVisible.value;
+
+  @override
+  void didUpdateWidget(AgendaViewCalendar oldWidget) {
+    super.didUpdateWidget(oldWidget);
+    frontPanelVisible.removeListener(_subscribeToValueNotifier);
+    frontPanelVisible.addListener(_subscribeToValueNotifier);
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return getAgendaViewCalendar(events, onViewChanged, selectedDate);
+  }
+
+  void addAppointmentDetails() {
+    subjectCollection = <String>[];
+    subjectCollection.add('General Meeting');
+    subjectCollection.add('Plan Execution');
+    subjectCollection.add('Project Plan');
+    subjectCollection.add('Consulting');
+    subjectCollection.add('Support');
+    subjectCollection.add('Development Meeting');
+    subjectCollection.add('Scrum');
+    subjectCollection.add('Project Completion');
+    subjectCollection.add('Release updates');
+    subjectCollection.add('Performance Check');
+
+    colorCollection = <Color>[];
+    colorCollection.add(const Color(0xFF0F8644));
+    colorCollection.add(const Color(0xFF8B1FA9));
+    colorCollection.add(const Color(0xFFD20100));
+    colorCollection.add(const Color(0xFFFC571D));
+    colorCollection.add(const Color(0xFF36B37B));
+    colorCollection.add(const Color(0xFF01A1EF));
+    colorCollection.add(const Color(0xFF3D4FB5));
+    colorCollection.add(const Color(0xFFE47C73));
+    colorCollection.add(const Color(0xFF636363));
+    colorCollection.add(const Color(0xFF0A8043));
+  }
+
+  void addAppointments() {
+    final Random random = Random();
+    final DateTime rangeStartDate =
+    DateTime.now().add(const Duration(days: -(365 ~/ 2)));
+    final DateTime rangeEndDate = DateTime.now().add(const Duration(days: 365));
+    for (DateTime i = rangeStartDate;
+    i.isBefore(rangeEndDate);
+    i = i.add(const Duration(days: 1))) {
+      final DateTime date = i;
+      final int count = 1 + random.nextInt(3);
+      for (int j = 0; j < count; j++) {
+        final DateTime startDate = DateTime(
+            date.year, date.month, date.day, 8 + random.nextInt(8), 0, 0);
+        meetings.add(Meeting(
+            subjectCollection[random.nextInt(7)],
+            '',
+            '',
+            null,
+            startDate,
+            startDate.add(Duration(hours: random.nextInt(3))),
+            colorCollection[random.nextInt(9)],
+            false,
+            '',
+            '',
+            ''));
+      }
+    }
+
+    // added recurrence appointment
+    meetings.add(Meeting(
+        'Development status',
+        '',
+        '',
+        null,
+        DateTime.now(),
+        DateTime.now().add(const Duration(hours: 2)),
+        colorCollection[random.nextInt(9)],
+        false,
+        '',
+        '',
+        'FREQ=WEEKLY;BYDAY=FR;INTERVAL=1'));
+  }
+
+  void onViewChanged(ViewChangedDetails visibleDatesChangedDetails) {
+    SchedulerBinding.instance.addPostFrameCallback((_) {
+      final DateTime currentViewDate = visibleDatesChangedDetails
+          .visibleDates[visibleDatesChangedDetails.visibleDates.length ~/ 2];
+      if (currentViewDate.month == DateTime.now().month &&
+          currentViewDate.year == DateTime.now().year) {
+        selectedDate = DateTime.now();
+      } else {
+        selectedDate =
+            DateTime(currentViewDate.year, currentViewDate.month, 01);
+      }
+      setState(() {});
+    });
+  }
+}
+
+SfCalendar getAgendaViewCalendar(
+    [CalendarDataSource _calendarDataSource,
+      ViewChangedCallback onViewChanged,
+      DateTime selectedDate]) {
+  return SfCalendar(
+    view: CalendarView.month,
+    initialSelectedDate: selectedDate,
+    onViewChanged: onViewChanged,
+    dataSource: _calendarDataSource,
+    monthViewSettings: MonthViewSettings(showAgenda: true),
+    timeSlotViewSettings: TimeSlotViewSettings(
+        minimumAppointmentDuration: const Duration(minutes: 60)),
+  );
+}
+
+class MeetingDataSource extends CalendarDataSource {
+  MeetingDataSource(this.source);
+
+  List<Meeting> source;
+
+  @override
+  List<dynamic> get appointments => source;
+
+  @override
+  DateTime getStartTime(int index) {
+    return source[index].from;
+  }
+
+  @override
+  DateTime getEndTime(int index) {
+    return source[index].to;
+  }
+
+  @override
+  bool isAllDay(int index) {
+    return source[index].isAllDay;
+  }
+
+  @override
+  String getSubject(int index) {
+    return source[index].eventName;
+  }
+
+  @override
+  String getStartTimeZone(int index) {
+    return source[index].startTimeZone;
+  }
+
+  @override
+  String getEndTimeZone(int index) {
+    return source[index].endTimeZone;
+  }
+
+  @override
+  Color getColor(int index) {
+    return source[index].background;
+  }
+
+  @override
+  String getRecurrenceRule(int index) {
+    return source[index].recurrenceRule;
+  }
+}
+
+class Meeting {
+  Meeting(
+      this.eventName,
+      this.organizer,
+      this.contactID,
+      this.capacity,
+      this.from,
+      this.to,
+      this.background,
+      this.isAllDay,
+      this.startTimeZone,
+      this.endTimeZone,
+      this.recurrenceRule);
+
+  String eventName;
+  String organizer;
+  String contactID;
+  int capacity;
+  DateTime from;
+  DateTime to;
+  Color background;
+  bool isAllDay;
+  String startTimeZone;
+  String endTimeZone;
+  String recurrenceRule;
+}