feat: add timezone support for current time display

example/lib/main.dart

@@ -7,13 +7,19 @@ import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 import 'package:time/time.dart';
 import 'package:timetable/timetable.dart';
+// import 'package:timezone/data/latest.dart' as tz;
 
 // ignore: unused_import
 import 'positioning_demo.dart';
 import 'utils.dart';
 
 Future<void> main() async {
   initDebugOverlay();
+  // Please ensure the time zone database is initialized
+  // when you need to display current time indicator with specific time zone.
+  //
+  // More information: [https://pub.dev/packages/timezone]
+  // tz.initializeTimeZones();
   runApp(const ExampleApp(child: TimetableExample()));
 }
 
@@ -49,6 +55,7 @@ class _TimetableExampleState extends State<TimetableExample>
     // maxDuration: 10.hours,
     // initialRange: TimeRange(8.hours, 20.hours),
     maxRange: TimeRange(0.hours, 24.hours),
+    // tzIdentifier: 'Europe/Berlin',
   );
 
   final _draggedEvents = <BasicEvent>[];

example/pubspec.lock

@@ -82,26 +82,26 @@ packages:
     dependency: transitive
     description:
       name: characters
-      sha256: "04a925763edad70e8443c99234dc3328f442e811f1d8fd1a72f1c8ad0f69a605"
+      sha256: f71061c654a3380576a52b451dd5532377954cf9dbd272a78fc8479606670803
       url: "https://pub.dev"
     source: hosted
-    version: "1.3.0"
+    version: "1.4.0"
   clock:
     dependency: transitive
     description:
       name: clock
-      sha256: cb6d7f03e1de671e34607e909a7213e31d7752be4fb66a86d29fe1eb14bfb5cf
+      sha256: fddb70d9b5277016c77a80201021d40a2247104d9f4aa7bab7157b7e3f05b84b
       url: "https://pub.dev"
     source: hosted
-    version: "1.1.1"
+    version: "1.1.2"
   collection:
     dependency: "direct main"
     description:
       name: collection
-      sha256: a1ace0a119f20aabc852d165077c036cd864315bd99b7eaa10a60100341941bf
+      sha256: "2f5709ae4d3d59dd8f7cd309b4e023046b57d8a6c82130785d2b0e5868084e76"
       url: "https://pub.dev"
     source: hosted
-    version: "1.19.0"
+    version: "1.19.1"
   color:
     dependency: transitive
     description:
@@ -386,10 +386,10 @@ packages:
     dependency: transitive
     description:
       name: meta
-      sha256: bdb68674043280c3428e9ec998512fb681678676b3c54e773629ffe74419f8c7
+      sha256: e3641ec5d63ebf0d9b41bd43201a66e3fc79a65db5f61fc181f04cd27aab950c
       url: "https://pub.dev"
     source: hosted
-    version: "1.15.0"
+    version: "1.16.0"
   oxidized:
     dependency: transitive
     description:
@@ -426,10 +426,10 @@ packages:
     dependency: transitive
     description:
       name: path
-      sha256: "087ce49c3f0dc39180befefc60fdb4acd8f8620e5682fe2476afd0b3688bb4af"
+      sha256: "75cca69d1490965be98c73ceaea117e8a04dd21217b37b292c9ddbec0d955bc5"
       url: "https://pub.dev"
     source: hosted
-    version: "1.9.0"
+    version: "1.9.1"
   petitparser:
     dependency: transitive
     description:
@@ -604,6 +604,14 @@ packages:
       relative: true
     source: path
     version: "1.0.0-alpha.15"
+  timezone:
+    dependency: "direct main"
+    description:
+      name: timezone
+      sha256: ffc9d5f4d1193534ef051f9254063fa53d588609418c84299956c3db9383587d
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.10.0"
   todo:
     dependency: transitive
     description:
@@ -685,5 +693,5 @@ packages:
     source: hosted
     version: "3.1.3"
 sdks:
-  dart: ">=3.5.0 <4.0.0"
+  dart: ">=3.7.0-0 <4.0.0"
   flutter: ">=3.27.0-0"

example/pubspec.yaml

@@ -17,6 +17,8 @@ dependencies:
   time: ^2.1.4
   timetable:
     path: ../
+  # Optional: it is only required for displaying current time indicator with specific time zone
+  timezone: ^0.10.0
 
 dev_dependencies:
   supernova:

lib/src/components/now_indicator.dart

@@ -8,6 +8,7 @@ import 'package:flutter/material.dart';
 import '../config.dart';
 import '../date/controller.dart';
 import '../theme.dart';
+import '../time/controller.dart';
 import '../utils.dart';
 
 /// A widget that displays an indicator at the current date and time.
@@ -36,7 +37,8 @@ class NowIndicator extends StatelessWidget {
   Widget build(BuildContext context) {
     return CustomPaint(
       foregroundPainter: _NowIndicatorPainter(
-        controller: DefaultDateController.of(context)!,
+        dateController: DefaultDateController.of(context)!,
+        timeController: DefaultTimeController.of(context)!,
         style: style ?? TimetableTheme.orDefaultOf(context).nowIndicatorStyle,
         devicePixelRatio: context.mediaQuery.devicePixelRatio,
       ),
@@ -287,28 +289,36 @@ class TriangleNowIndicatorShape extends NowIndicatorShape {
 
 class _NowIndicatorPainter extends CustomPainter {
   factory _NowIndicatorPainter({
-    required DateController controller,
+    required DateController dateController,
+    required TimeController timeController,
     required NowIndicatorStyle style,
     required double devicePixelRatio,
   }) =>
       _NowIndicatorPainter._(
-        controller: controller,
+        dateController: dateController,
+        timeController: timeController,
         style: style,
         devicePixelRatio: devicePixelRatio,
-        repaintNotifier: ValueNotifier(DateTimeTimetable.now()),
+        repaintNotifier: ValueNotifier(
+          timeController.useTimeZone
+              ? DateTimeTimetable.nowAt(timeController.tzIdentifier!)
+              : DateTimeTimetable.now(),
+        ),
       );
   _NowIndicatorPainter._({
-    required this.controller,
+    required this.dateController,
+    required this.timeController,
     required this.style,
     required this.devicePixelRatio,
     required ValueNotifier<DateTime> repaintNotifier,
   })  : _paint = Paint()
           ..color = style.lineColor
           ..strokeWidth = style.lineWidth,
         _repaintNotifier = repaintNotifier,
-        super(repaint: Listenable.merge([controller, repaintNotifier]));
+        super(repaint: Listenable.merge([dateController, repaintNotifier]));
 
-  final DateController controller;
+  final DateController dateController;
+  final TimeController timeController;
   final Paint _paint;
   final NowIndicatorStyle style;
   final double devicePixelRatio;
@@ -318,9 +328,11 @@ class _NowIndicatorPainter extends CustomPainter {
     unawaited(_repaint?.cancel());
     _repaint = null;
 
-    final pageValue = controller.value;
+    final pageValue = dateController.value;
     final dateWidth = size.width / pageValue.visibleDayCount;
-    final now = DateTimeTimetable.now();
+    final now = timeController.useTimeZone
+        ? DateTimeTimetable.nowAt(timeController.tzIdentifier!)
+        : DateTimeTimetable.now();
     final temporalXOffset =
         now.copyWith(isUtc: true).atStartOfDay.page - pageValue.page;
     final left = temporalXOffset * dateWidth;
@@ -346,7 +358,9 @@ class _NowIndicatorPainter extends CustomPainter {
         () {
           // [ChangeNotifier.notifyListeners] is protected, so we use a
           // [ValueNotifier] and always set a different time.
-          _repaintNotifier.value = DateTimeTimetable.now();
+          _repaintNotifier.value = timeController.useTimeZone
+              ? DateTimeTimetable.nowAt(timeController.tzIdentifier!)
+              : DateTimeTimetable.now();
         },
       ),
     );

lib/src/time/controller.dart

@@ -18,6 +18,7 @@ class TimeController extends ValueNotifier<TimeRange> {
     Duration? maxDuration,
     TimeRange? initialRange,
     TimeRange? maxRange,
+    this.tzIdentifier,
     this.minDayHeight,
   })  : assert(!minDuration.isNegative),
         assert(minDuration <= maxPossibleDuration),
@@ -36,6 +37,7 @@ class TimeController extends ValueNotifier<TimeRange> {
               maxRange == null ||
               maxDuration <= maxRange.duration,
         ),
+        assert(tzIdentifier == null || tzIdentifier.isNotEmpty),
         maxRange = maxRange ?? TimeRange.fullDay,
         assert(minDayHeight == null || minDayHeight > 0),
         assert(minDayHeight == null || minDayHeight.isFinite),
@@ -85,11 +87,22 @@ class TimeController extends ValueNotifier<TimeRange> {
   Duration get actualMaxDuration =>
       maxDuration.coerceAtMost(maxDurationFromMinDayHeightOrDefault);
 
+  /// Whether the specified time zone is used when displaying current time.
+  bool get useTimeZone => tzIdentifier != null;
+
   static const maxPossibleDuration = Duration(days: 1);
 
   /// The maximum range that can be revealed when zooming out.
   final TimeRange maxRange;
 
+  /// The time zone identifier that be used when displaying current time.
+  /// If null, the system time zone is used.
+  ///
+  /// Note: Ensure timezone database is initialized before use
+  ///
+  /// More information: [https://pub.dev/packages/timezone#initialization]
+  final String? tzIdentifier;
+
   @override
   set value(TimeRange value) {
     assert(_isValidRange(value));

lib/src/utils.dart

@@ -1,6 +1,7 @@
 import 'package:dart_date/dart_date.dart' show Interval;
 import 'package:flutter/foundation.dart';
 import 'package:flutter/widgets.dart' hide Interval;
+import 'package:timezone/timezone.dart';
 
 import 'week.dart';
 
@@ -88,6 +89,12 @@ extension DateTimeTimetable on DateTime {
     return date;
   }
 
+  static DateTime nowAt(String timezone) {
+    final date = TZDateTime.now(getLocation(timezone)).copyWith(isUtc: true);
+    assert(date.debugCheckIsValidTimetableDateTime());
+    return date;
+  }
+
   static DateTime today() {
     final date = DateTimeTimetable.now().atStartOfDay;
     assert(date.debugCheckIsValidTimetableDate());

pubspec.yaml

@@ -31,6 +31,7 @@ dependencies:
   flutter_layout_grid: ^2.0.0
   intl: '>=0.17.0 <0.21.0'
   meta: ^1.3.0
+  timezone: ^0.10.0
 
 dev_dependencies:
   flutter_test: