fix

Author: Ambrozy

packages/devextreme/js/__internal/scheduler/view_model/generate_view_model/add_collector.ts

@@ -82,7 +82,11 @@ export const addCollector = (
     ...item,
     info: {
       sourceAppointment: item.info.sourceAppointment,
-      appointment: item.info.appointment,
+      appointment: {
+        ...item.info.appointment,
+        startDate: item.info.appointment.savedBeforeSplit.startDate,
+        endDate: item.info.appointment.savedBeforeSplit.endDate,
+      },
     },
   })).forEach((item) => {
     switch (true) {

packages/devextreme/js/__internal/scheduler/view_model/generate_view_model/m_settings_generator.ts

@@ -79,26 +79,48 @@ export class DateGeneratorBaseStrategy {
     const { isRecurrent } = appointmentAdapter;
 
     const itemGroupIndices = this._getGroupIndices(this.rawAppointment);
+    let dateSettings;
 
-    let sourceList = this._createAppointments(appointmentAdapter, itemGroupIndices);
-    sourceList = this.excludeLocalDST(sourceList, appointmentAdapter);
-    sourceList = this._getProcessedByAppointmentTimeZone(sourceList, appointmentAdapter); // T983264
+    if (appointmentAdapter.isRecurrent && appointmentAdapter.startDateTimeZone) {
+      let sourceList = this._createAppointments(appointmentAdapter, itemGroupIndices);
+      sourceList = this.excludeLocalDST(sourceList, appointmentAdapter);
+      sourceList = this._getProcessedByAppointmentTimeZone(sourceList, appointmentAdapter); // T983264
 
-    if (appointmentAdapter.isRecurrent && appointmentAdapter.recurrenceException) {
-      const exceptions = new Set(appointmentAdapter.recurrenceException?.split(','));
-      sourceList = sourceList
-        .filter((item) => !exceptions.has(getAsciiStringByDate(item.startDate)));
-    }
+      if (appointmentAdapter.isRecurrent && appointmentAdapter.recurrenceException) {
+        const exceptions = new Set(appointmentAdapter.recurrenceException?.split(','));
+        sourceList = sourceList
+          .filter((item) => !exceptions.has(getAsciiStringByDate(item.startDate)));
+      }
+
+      let appointmentList = sourceList;
+      if (appointmentAdapter.isRecurrent && (
+        !this.timeZone
+        || timeZoneUtils.isEqualLocalTimeZone(this.timeZone)
+      )) {
+        appointmentList = this._getProcessedNativeTimezoneDates(appointmentList, appointmentAdapter);
+      }
+
+      dateSettings = this._createGridAppointmentList(appointmentList, sourceList, appointmentAdapter);
+    } else {
+      let appointmentList = this._createAppointments(appointmentAdapter, itemGroupIndices);
+
+      appointmentList = this._getProcessedByAppointmentTimeZone(appointmentList, appointmentAdapter); // T983264
 
-    let appointmentList = sourceList;
-    if (appointmentAdapter.isRecurrent && (
-      !this.timeZone
-      || timeZoneUtils.isEqualLocalTimeZone(this.timeZone)
-    )) {
-      appointmentList = this._getProcessedNativeTimezoneDates(appointmentList, appointmentAdapter);
+      if (this._canProcessNotNativeTimezoneDates(appointmentAdapter)) {
+        appointmentList = this._getProcessedNotNativeTimezoneDates(appointmentList, appointmentAdapter);
+      }
+
+      appointmentList = this.excludeLocalDST(appointmentList, appointmentAdapter);
+      dateSettings = this._createGridAppointmentList(appointmentList, appointmentList, appointmentAdapter);
     }
 
-    let dateSettings = this._createGridAppointmentList(appointmentList, sourceList, appointmentAdapter);
+    dateSettings = dateSettings.map((item) => ({
+      ...item,
+      savedBeforeSplit: {
+        startDate: new Date(item.startDate),
+        endDate: new Date(item.endDate),
+      },
+    }));
 
     const firstViewDates = this._getAppointmentsFirstViewDate(dateSettings);
 
@@ -161,6 +183,36 @@ export class DateGeneratorBaseStrategy {
     return appointmentList;
   }
 
+  _getProcessedNotNativeTimezoneDates(appointmentList, appointment) {
+    return appointmentList.map((item) => {
+      let diffStartDateOffset = this._getCommonOffset(appointment.startDate) - this._getCommonOffset(item.startDate);
+      let diffEndDateOffset = this._getCommonOffset(appointment.endDate) - this._getCommonOffset(item.endDate);
+
+      if (diffStartDateOffset === 0 && diffEndDateOffset === 0) {
+        return item;
+      }
+
+      diffStartDateOffset = this._getProcessedNotNativeDateIfCrossDST(item.startDate, diffStartDateOffset);
+      diffEndDateOffset = this._getProcessedNotNativeDateIfCrossDST(item.endDate, diffEndDateOffset);
+
+      const newStartDate = new Date(item.startDate.getTime() + diffStartDateOffset * toMs('hour'));
+      let newEndDate = new Date(item.endDate.getTime() + diffEndDateOffset * toMs('hour'));
+
+      const testNewStartDate = this.timeZoneCalculator.createDate(newStartDate, 'toGrid');
+      const testNewEndDate = this.timeZoneCalculator.createDate(newEndDate, 'toGrid');
+
+      if (appointment.duration > testNewEndDate.getTime() - testNewStartDate.getTime()) {
+        newEndDate = new Date(newStartDate.getTime() + appointment.duration);
+      }
+
+      return {
+        ...item,
+        startDate: newStartDate,
+        endDate: newEndDate,
+      };
+    });
+  }
+
   _createAppointments(appointment, groupIndices) {
     let appointments = this._createRecurrenceAppointments(appointment, groupIndices);
 

packages/devextreme/js/__internal/scheduler/view_model/generate_view_model/m_view_model_generator.ts

@@ -108,11 +108,7 @@ export class AppointmentViewModelGenerator {
     for (const model of viewModel) {
       // eslint-disable-next-line no-restricted-syntax
       for (const setting of model.settings ?? []) {
-        const appointment = setting?.info?.appointment as {
-          startDate: Date;
-          endDate: Date;
-          normalizedEndDate: Date;
-        } | undefined;
+        const appointment = setting?.info?.appointment as any | undefined;
 
         if (appointment && !processedAppointments.has(appointment)) {
           appointment.startDate = dateUtilsTs

packages/devextreme/js/__internal/scheduler/view_model/generate_view_model/types.ts

@@ -31,7 +31,12 @@ export interface AppointmentViewModelSettingsInternal extends BaseViewModelSetti
   count: number;
   info: {
     sourceAppointment: SimpleAppointment;
-    appointment: SimpleAppointment;
+    appointment: SimpleAppointment & {
+      savedBeforeSplit: {
+        startDate: Date;
+        endDate: Date;
+      };
+    };
   };
   positionByMap: {
     rowIndex: number;