[syncfusion_flutter_datepicker]: cellBuilder cache invalidate

[ziqq]

Summary

When SfDateRangePicker uses cellBuilder, switching the app theme between light and dark does not fully refresh the month cells.

The picker itself receives the new theme, but the custom month cells appear to remain cached. As a result, the cells stay visually stale and only start behaving correctly again after an external rebuild such as:

• parent setState
• hot reload
• any change that forces the picker to recreate month cells

In our case, explicitly changing monthViewSettings.specialDates on theme change works as a workaround, which suggests the issue is related to internal month-cell caching.

Package version

syncfusion_flutter_datepicker: 33.2.7

Question

Is this expected behavior?

If not, could SfDateRangePicker invalidate or rebuild cached month cells when inherited theme dependencies change, or provide an official way to force a rebuild of month cells without using unrelated inputs like specialDates as a cache-busting workaround?

Steps to reproduce

1. Open a screen with SfDateRangePicker using cellBuilder.
2. Switch the app theme from light to dark or back.
3. Observe the month cells.

Expected behavior

The month cells created by cellBuilder should update immediately after a theme change, just like the rest of the widget tree.

Actual behavior

The month cells remain stale after a theme change and only refresh after an external rebuild, for example:

• parent setState
• hot reload
• changing specialDates

Additional notes

In our implementation, the custom cells use CustomPaint and repaint correctly when a theme-related Listenable changes.

However, repaint alone is not enough here, because the month-cell widgets created by cellBuilder appear to remain cached internally. Once we force a cache invalidation by updating specialDates, the picker updates correctly again.

This workaround fixes the issue for us:

@override
void didChangeDependencies() {
  super.didChangeDependencies();

  final nextTheme = Theme.of(context);
  if (identical(_theme.value, nextTheme)) return;

  _theme.value = nextTheme;

  // Forces Syncfusion to recreate cached month cells.
  _cacheRevision += 1;
  _specialDates = _buildSpecialDates();
}

So the issue seems to be that a theme change does not invalidate the internal cache for month cells produced by cellBuilder.

Code sample

Code sample

import 'package:flutter/material.dart';
import 'package:syncfusion_flutter_datepicker/datepicker.dart';

void main() {
  runApp(const MyApp());
}

class MyApp extends StatefulWidget {
  const MyApp({super.key});

  @override
  State<MyApp> createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  ThemeMode _themeMode = ThemeMode.light;

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      themeMode: _themeMode,
      theme: ThemeData.light(),
      darkTheme: ThemeData.dark(),
      home: Scaffold(
        appBar: AppBar(
          title: const Text('DatePicker cache issue'),
          actions: [
            IconButton(
              onPressed: () {
                setState(() {
                  _themeMode = _themeMode == ThemeMode.light
                      ? ThemeMode.dark
                      : ThemeMode.light;
                });
              },
              icon: const Icon(Icons.brightness_6),
            ),
          ],
        ),
        body: const _PickerBody(),
      ),
    );
  }
}

class _PickerBody extends StatefulWidget {
  const _PickerBody();

  @override
  State<_PickerBody> createState() => _PickerBodyState();
}

class _PickerBodyState extends State<_PickerBody> {
  final DateRangePickerController _controller = DateRangePickerController();
  int _cacheRevision = 0;

  List<DateTime> get _specialDates => [
        DateTime(9999, 1, 1).add(Duration(days: _cacheRevision)),
      ];

  @override
  void didChangeDependencies() {
    super.didChangeDependencies();

    // Workaround:
    // Uncommenting this forces the picker to recreate month cells
    // after theme changes.
    //
    // _cacheRevision += 1;
  }

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);

    return SfDateRangePicker(
      controller: _controller,
      navigationMode: DateRangePickerNavigationMode.scroll,
      navigationDirection: DateRangePickerNavigationDirection.vertical,
      enableMultiView: true,
      selectionMode: DateRangePickerSelectionMode.single,
      cellBuilder: (context, details) {
        final isDark = theme.brightness == Brightness.dark;

        return Container(
          alignment: Alignment.center,
          margin: const EdgeInsets.all(4),
          decoration: BoxDecoration(
            shape: BoxShape.circle,
            color: isDark ? Colors.blueGrey.shade700 : Colors.blue.shade50,
            border: Border.all(
              color: isDark ? Colors.white70 : Colors.black54,
            ),
          ),
          child: Text(
            '${details.date.day}',
            style: TextStyle(
              color: isDark ? Colors.white : Colors.black,
            ),
          ),
        );
      },
      monthViewSettings: DateRangePickerMonthViewSettings(
        specialDates: _specialDates,
      ),
    );
  }
}

Screenshots or Video

Screenshots / Video demonstration

On which target platforms have you observed this bug?

iOS, Android

[Mugunthan-Ramalingam]

Hi Ziqq,

As you have already shared a workaround, you may continue using it if it works well for your scenario. Alternatively, you can use the below approach to handle the issue where the month cells are not updated on theme (light/dark) changes when using cellBuilder in SfDateRangePicker.

You can assign a ValueKey to the picker based on the current theme brightness. This approach forces the entire widget to rebuild whenever the theme changes, ensuring that all internally cached month cells are recreated and the cellBuilder is invoked with updated theme values.

Compared to modifying unrelated properties like specialDates, this workaround is more appropriate and cleaner, as it directly triggers a rebuild without relying on indirect cache invalidation methods.

We have shared a sample for your reference, which you can further customize based on your specific requirements.

However, we have reproduced this issue on our end, and a fix has been scheduled for our upcoming weekly release on June 23, 2026.

We will notify you once the release is available. Thank you for your patience.

Sample:

gh_2533.zip

Regards,
Mugunthan.

[Mugunthan-Ramalingam]

Hi Ziqq,

We would like to provide an update regarding the reported issue where SfDateRangePicker month cells are not fully refreshed when switching between light and dark themes while using cellBuilder.

The fix for this issue has already been completed, and we had planned to include it in an earlier weekly release. However, since we were preparing for the main release, we did not proceed with the weekly release as originally scheduled. Unfortunately, the main release has been delayed, which in turn delayed the availability of this fix.

We are now planning to include the fix in our next weekly patch release scheduled for July 09, 2026.

We sincerely apologize for the delay and any inconvenience this may have caused. Thank you for your patience and understanding.

We will notify you as soon as the fix is rolled out.

Regards,
Mugunthan.

[ziqq]

Hi @Mugunthan-Ramalingam, thx my friend

[Mugunthan-Ramalingam]

Hi Ziqq,

You're welcome. Thank you for your understanding and patience.

We will notify you once the fix is rolled out.

Regards,
Mugunthan.

[Mugunthan-Ramalingam]

Hi Ziqq,

The reported issue has been resolved, and the fix is included in the version mentioned below. We kindly request you to upgrade the syncfusion_flutter_datepicker package to the latest version to avoid this issue.

Version: https://pub.dev/packages/syncfusion_flutter_datepicker/versions/34.1.30

Root Cause:
When using cellBuilder, theme changes did not mark the custom cells for repaint.

Thank you for your patience and understanding. Please let us know if you need any assistance with the upgrade or have further questions.

Regards,
Mugunthan.

[ziqq]

Hi @Mugunthan-Ramalingam, thx

[Harsha-SF4223]

Hi @ziqq ,

You're welcome. Please let us know if you need any further assistance, we will be happy to assist.

Regards,
Harsha.

[ziqq]

Hi @Harsha-SF4223,

I checked it and it works. I think you can close this issue.