improved performance and battery usage on older devices

lib/state/app/modules/timetable/bloc/timetable_state.dart

@@ -7,6 +7,7 @@ import '../../../../../api/marianumconnect/queries/timetable_get_subjects/timeta
 import '../../../../../api/marianumconnect/queries/timetable_get_timegrid/timetable_get_timegrid_response.dart';
 import '../../../../../api/marianumconnect/queries/timetable_get_week/timetable_get_week_response.dart';
 import '../../../../../api/mhsl/custom_timetable_event/get/get_custom_timetable_event_response.dart';
+import '../../../../../utils/json_equality.dart';
 import 'week_cache.dart';
 
 part 'timetable_state.freezed.dart';
@@ -58,6 +59,45 @@ abstract class TimetableState with _$TimetableState {
     return copyWith(weekCache: updated, dataVersion: dataVersion + 1);
   }
 
+  /// Applies freshly loaded reference data. Values whose content equals the
+  /// current one keep the old instance, and when nothing changed at all this
+  /// returns `this` — every `dataVersion` bump and new identity makes the
+  /// calendar rebuild all appointments and break regions.
+  TimetableState withReferenceData({
+    TimetableGetRoomsResponse? rooms,
+    TimetableGetSubjectsResponse? subjects,
+    TimetableGetHolidaysResponse? schoolHolidays,
+    TimetableGetSchoolyearResponse? schoolyear,
+    TimetableGetTimegridResponse? timegrid,
+    GetCustomTimetableEventResponse? customEvents,
+  }) {
+    T? changed<T>(T? next, T? current) =>
+        next == null || sameJson(next, current) ? null : next;
+    final newRooms = changed(rooms, this.rooms);
+    final newSubjects = changed(subjects, this.subjects);
+    final newHolidays = changed(schoolHolidays, this.schoolHolidays);
+    final newSchoolyear = changed(schoolyear, this.schoolyear);
+    final newTimegrid = changed(timegrid, this.timegrid);
+    final newCustomEvents = changed(customEvents, this.customEvents);
+    if (newRooms == null &&
+        newSubjects == null &&
+        newHolidays == null &&
+        newSchoolyear == null &&
+        newTimegrid == null &&
+        newCustomEvents == null) {
+      return this;
+    }
+    return copyWith(
+      rooms: newRooms ?? this.rooms,
+      subjects: newSubjects ?? this.subjects,
+      schoolHolidays: newHolidays ?? this.schoolHolidays,
+      schoolyear: newSchoolyear ?? this.schoolyear,
+      timegrid: newTimegrid ?? this.timegrid,
+      customEvents: newCustomEvents ?? this.customEvents,
+      dataVersion: dataVersion + 1,
+    );
+  }
+
   bool get hasReferenceData =>
       rooms != null &&
       subjects != null &&