Scheduler: Provide the SnapToCellsMode option

apps/react-storybook/stories/scheduler/SchedulerSnapToCellsMode.stories.tsx

@@ -0,0 +1,88 @@
+import type { Meta, StoryObj } from "@storybook/react-webpack5";
+import dxScheduler from "devextreme/ui/scheduler";
+import { wrapDxWithReact } from "../utils";
+import { resources } from "./data";
+
+const Scheduler = wrapDxWithReact(dxScheduler);
+
+const data = [
+  {
+    text: '1 minute',
+    roomId: 1,
+    assigneeId: [1],
+    priorityId: 1,
+    startDate: new Date(2026, 2, 15, 10, 0),
+    endDate: new Date(2026, 2, 15, 10, 1)
+  },
+  {
+    text: '5 minutes',
+    roomId: 1,
+    assigneeId: [2],
+    priorityId: 1,
+    startDate: new Date(2026, 2, 16, 10, 0),
+    endDate: new Date(2026, 2, 16, 10, 5)
+  },
+  {
+    text: '15 minutes',
+    roomId: 2,
+    assigneeId: [3],
+    priorityId: 2,
+    startDate: new Date(2026, 2, 17, 10, 0),
+    endDate: new Date(2026, 2, 17, 10, 15)
+  },
+  {
+    text: '30 minutes',
+    roomId: 2,
+    assigneeId: [1],
+    priorityId: 2,
+    startDate: new Date(2026, 2, 18, 10, 0),
+    endDate: new Date(2026, 2, 18, 10, 30)
+  },
+  {
+    text: '46 minutes',
+    roomId: 3,
+    assigneeId: [2],
+    priorityId: 1,
+    startDate: new Date(2026, 2, 19, 10, 0),
+    endDate: new Date(2026, 2, 19, 10, 46)
+  },
+  {
+    text: '1 hour',
+    roomId: 2,
+    assigneeId: [4],
+    priorityId: 1,
+    startDate: new Date(2026, 2, 20, 10, 0),
+    endDate: new Date(2026, 2, 20, 11, 0)
+  },
+];
+
+const viewNames = ['day', 'week', 'workWeek', 'month', 'agenda', 'timelineDay', 'timelineWeek', 'timelineWorkWeek', 'timelineMonth'];
+
+const meta: Meta<typeof Scheduler> = {
+  title: 'Components/Scheduler/SnapToCellsMode',
+  component: Scheduler,
+  parameters: { layout: 'padded' },
+};
+export default meta;
+
+type Story = StoryObj<typeof Scheduler>;
+
+export const Overview: Story = {
+  args: {
+    height: 600,
+    views: viewNames,
+    currentView: 'week',
+    currentDate: new Date(2026, 2, 15),
+    startDayHour: 9,
+    endDayHour: 22,
+    dataSource: data,
+    resources,
+    snapToCellsMode: 'auto',
+  },
+  argTypes: {
+    height: { control: 'number' },
+    views: { control: 'object' },
+    snapToCellsMode: { control: 'select', options: ['always', 'auto', 'never'] },
+    currentView: { control: 'select', options: viewNames },
+  },
+};

packages/devextreme/js/__internal/scheduler/__tests__/snap_to_cells_mode.test.ts

@@ -0,0 +1,86 @@
+import {
+  afterEach, beforeEach, describe, expect, it,
+} from '@jest/globals';
+
+import { createScheduler } from './__mock__/create_scheduler';
+import {
+  DEFAULT_CELL_HEIGHT,
+  setupSchedulerTestEnvironment,
+} from './__mock__/m_mock_scheduler';
+
+describe('snapToCellsMode', () => {
+  beforeEach(() => {
+    setupSchedulerTestEnvironment();
+  });
+
+  afterEach(() => {
+    document.body.innerHTML = '';
+  });
+
+  it('default snapToCellsMode on day view', async () => {
+    const { POM } = await createScheduler({
+      width: 800,
+      height: 600,
+      views: ['day'],
+      currentView: 'day',
+      currentDate: new Date(2026, 2, 15),
+      cellDuration: 30,
+      startDayHour: 9,
+      endDayHour: 18,
+      dataSource: [{
+        text: 'short',
+        startDate: new Date(2026, 2, 15, 10, 0),
+        endDate: new Date(2026, 2, 15, 10, 10),
+      }],
+    });
+
+    const appH = POM.getAppointment('short').getGeometry().height;
+
+    expect(appH).toBeLessThan(DEFAULT_CELL_HEIGHT * 0.45);
+  });
+
+  it('root snapToCellsMode always overrides default on day view', async () => {
+    const { POM } = await createScheduler({
+      width: 800,
+      height: 600,
+      views: ['day'],
+      currentView: 'day',
+      currentDate: new Date(2026, 2, 15),
+      cellDuration: 30,
+      startDayHour: 9,
+      endDayHour: 18,
+      dataSource: [{
+        text: 'short',
+        startDate: new Date(2026, 2, 15, 10, 0),
+        endDate: new Date(2026, 2, 15, 10, 10),
+      }],
+      snapToCellsMode: 'always',
+    });
+
+    const appH = POM.getAppointment('short').getGeometry().height;
+
+    expect(appH).toBeGreaterThan(DEFAULT_CELL_HEIGHT * 0.85);
+  });
+
+  it('views[].snapToCellsMode always overrides default on day view', async () => {
+    const { POM } = await createScheduler({
+      width: 800,
+      height: 600,
+      views: [{ type: 'day', snapToCellsMode: 'always' }],
+      currentView: 'day',
+      currentDate: new Date(2026, 2, 15),
+      cellDuration: 30,
+      startDayHour: 9,
+      endDayHour: 18,
+      dataSource: [{
+        text: 'short',
+        startDate: new Date(2026, 2, 15, 10, 0),
+        endDate: new Date(2026, 2, 15, 10, 10),
+      }],
+    });
+
+    const appH = POM.getAppointment('short').getGeometry().height;
+
+    expect(appH).toBeGreaterThan(DEFAULT_CELL_HEIGHT * 0.85);
+  });
+});

packages/devextreme/js/__internal/scheduler/utils/options/constants.ts

@@ -88,6 +88,7 @@ export const DEFAULT_SCHEDULER_OPTIONS: Properties = {
     mode: 'standard',
   },
   allDayPanelMode: 'all',
+  snapToCellsMode: undefined,
   toolbar: {
     disabled: false,
     multiline: false,

packages/devextreme/js/__internal/scheduler/utils/options/types.ts

@@ -77,6 +77,7 @@ type RequiredOptions = 'views'
   | 'adaptivityEnabled'
   | 'scrolling'
   | 'allDayPanelMode'
+  | 'snapToCellsMode'
   | 'toolbar';
 export type DateOption = 'currentDate' | 'min' | 'max';
 export type SafeSchedulerOptions = SchedulerInternalOptions

packages/devextreme/js/__internal/scheduler/view_model/__mock__/scheduler.mock.ts

@@ -11,6 +11,7 @@ export const getSchedulerMock = ({
   resourceManager,
   dateRange,
   skippedDays,
+  isVirtualScrolling = false,
 }: {
   type: string;
   startDayHour: number;
@@ -19,6 +20,7 @@ export const getSchedulerMock = ({
   resourceManager?: ResourceManager;
   skippedDays?: number[];
   dateRange?: Date[];
+  isVirtualScrolling?: boolean;
 }): Scheduler => ({
   timeZoneCalculator: mockTimeZoneCalculator,
   currentView: { type, skippedDays: skippedDays ?? [] },
@@ -37,6 +39,7 @@ export const getSchedulerMock = ({
   }[name]),
   option: (name: string) => ({ firstDayOfWeek: 0, showAllDayPanel: true }[name]),
   getViewOffsetMs: () => offsetMinutes * 60_000,
+  isVirtualScrolling: () => isVirtualScrolling,
   resourceManager: resourceManager ?? new ResourceManager([]),
   _dataAccessors: mockAppointmentDataAccessor,
 }) as unknown as Scheduler;

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

@@ -23,6 +23,7 @@ export const sortAppointments = (
   const {
     isMonthView,
     hasAllDayPanel,
+    snapToCellsMode,
     viewOffset,
     compareOptions: { endDayHour },
   } = optionManager.options;
@@ -40,9 +41,11 @@ export const sortAppointments = (
       sortByStartDate(innerStep1);
       sortByGroupIndex(innerStep1);
       const innerStep2 = addPosition(innerStep1, optionManager.getCells(panelName));
-      const innerStep3 = isMonthView || panelName === 'allDayPanel'
-        ? snapToCells(innerStep2, optionManager.getCells(panelName))
-        : innerStep2;
+      const innerStep3 = snapToCells(
+        innerStep2,
+        optionManager.getCells(panelName),
+        panelName === 'allDayPanel' ? 'always' : snapToCellsMode,
+      );
       const innerStep4 = addCollector(innerStep3, optionManager.getCollectorOptions(panelName));
       return innerStep4;
     });

packages/devextreme/js/__internal/scheduler/view_model/generate_view_model/options/get_view_model_options.ts

@@ -1,27 +1,48 @@
 import type { Orientation } from '@js/common';
+import type { SnapToCellsMode } from '@js/ui/scheduler';
 import type Scheduler from '@ts/scheduler/m_scheduler';
 
 import type { ViewType } from '../../../types';
 import { getCompareOptions } from '../../common/get_compare_options';
 import type { CompareOptions } from '../../types';
 
-const configByView: Record<Exclude<ViewType, 'agenda'>, {
+interface ViewConfig {
   isTimelineView: boolean;
   isMonthView: boolean;
   viewOrientation: 'horizontal' | 'vertical';
-}> = {
-  day: { isTimelineView: false, isMonthView: false, viewOrientation: 'vertical' },
-  week: { isTimelineView: false, isMonthView: false, viewOrientation: 'vertical' },
-  workWeek: { isTimelineView: false, isMonthView: false, viewOrientation: 'vertical' },
-  month: { isTimelineView: false, isMonthView: true, viewOrientation: 'horizontal' },
-  timelineDay: { isTimelineView: true, isMonthView: false, viewOrientation: 'horizontal' },
-  timelineWeek: { isTimelineView: true, isMonthView: false, viewOrientation: 'horizontal' },
-  timelineWorkWeek: { isTimelineView: true, isMonthView: false, viewOrientation: 'horizontal' },
-  timelineMonth: { isTimelineView: true, isMonthView: true, viewOrientation: 'horizontal' },
+  snapToCellsMode: SnapToCellsMode;
+}
+
+const configByView: Record<Exclude<ViewType, 'agenda'>, ViewConfig> = {
+  day: {
+    isTimelineView: false, isMonthView: false, viewOrientation: 'vertical', snapToCellsMode: 'never',
+  },
+  week: {
+    isTimelineView: false, isMonthView: false, viewOrientation: 'vertical', snapToCellsMode: 'never',
+  },
+  workWeek: {
+    isTimelineView: false, isMonthView: false, viewOrientation: 'vertical', snapToCellsMode: 'never',
+  },
+  month: {
+    isTimelineView: false, isMonthView: true, viewOrientation: 'horizontal', snapToCellsMode: 'always',
+  },
+  timelineDay: {
+    isTimelineView: true, isMonthView: false, viewOrientation: 'horizontal', snapToCellsMode: 'never',
+  },
+  timelineWeek: {
+    isTimelineView: true, isMonthView: false, viewOrientation: 'horizontal', snapToCellsMode: 'never',
+  },
+  timelineWorkWeek: {
+    isTimelineView: true, isMonthView: false, viewOrientation: 'horizontal', snapToCellsMode: 'never',
+  },
+  timelineMonth: {
+    isTimelineView: true, isMonthView: true, viewOrientation: 'horizontal', snapToCellsMode: 'always',
+  },
 };
 
 export interface ViewModelOptions {
   type: ViewType;
+  snapToCellsMode: SnapToCellsMode;
   viewOffset: number;
   groupOrientation?: Orientation;
   isGroupByDate: boolean;
@@ -47,16 +68,23 @@ export const getViewModelOptions = (schedulerStore: Scheduler): ViewModelOptions
     && schedulerStore.getViewOption('groupByDate'),
   );
   const compareOptions = getCompareOptions(schedulerStore);
-  const { isTimelineView, isMonthView, viewOrientation } = configByView[type];
+  const {
+    isTimelineView,
+    isMonthView,
+    viewOrientation,
+    snapToCellsMode: defaultSnapToCellsMode,
+  } = configByView[type];
   const isRTLEnabled = Boolean(schedulerStore.option('rtlEnabled'));
   const isAdaptivityEnabled = Boolean(schedulerStore.option('adaptivityEnabled'));
   const cellDurationMinutes = schedulerStore.getViewOption('cellDuration');
   const allDayPanelMode = schedulerStore.getViewOption('allDayPanelMode');
+  const snapToCellsMode = schedulerStore.getViewOption('snapToCellsMode');
   const showAllDayPanel = schedulerStore.getViewOption('showAllDayPanel');
   const isVirtualScrolling = schedulerStore.isVirtualScrolling();
 
   return {
     type,
+    snapToCellsMode: snapToCellsMode ?? defaultSnapToCellsMode,
     viewOffset,
     groupOrientation,
     isGroupByDate,