Jean-Luc Makiola
6a2f490b1a
Glance identifies a widget by its GlanceAppWidget subclass's canonical name: GlanceAppWidgetManager stores a providerName -> receivers map under that string, and updateAll resolves a widget's app-widget ids through it. R8 full mode horizontally merged MonthWidget into AgendaWidget — same supertype, same overrides, nothing to tell them apart — so both receivers registered under one provider name and AgendaWidget().updateAll() also matched the month widget's id, redrawing it as the agenda widget on the next PROVIDER_CHANGED. 2.16.0 is where it started because that release gave AgendaWidget the SizeMode.Exact override MonthWidget already had, which is what made the two classes mergeable. Verified in the releaseTest mapping: before, only AgendaWidget survived, carrying an $r8$classId field and MonthWidget's constructor frames; after, both classes are there under their own names. Keeping the real names also survives app updates, which would otherwise renumber the obfuscated name and orphan the stored mapping.
Calendula
A modern Material 3 Expressive calendar for Android.
Reads, writes, and reminds — on top of the system calendar, with zero network access.
Calendula is named after the flower whose name — like the word calendar —
comes from the Latin kalendae, the first day of the month. It lives
entirely on top of Android's CalendarContract: any calendar synced to your
device (CalDAV via DAVx5, Google, local, WebCal subscriptions, …) simply
appears, and everything you create or edit syncs back the same way. No own
database, no sync stack reinvented.
✨ Features
Calendar
- Month, week, and day views with a one-tap view switcher
- Full event details — attendees and their responses, reminders, recurrence (humanized), availability, visibility, foreign time zones
- Per-calendar visibility toggle, grouped by account
Editing
- Create, edit, and delete events — including recurring events with scoped writes: only this event, this and all following, or the whole series
- Recurrence picker with one-tap presets and custom rules (interval, weekday toggles, end conditions); rules it can't express are preserved verbatim
- Conflict-safe saves: if an event changed elsewhere while you were editing, Calendula asks instead of silently overwriting
- Read-only calendars (WebCal, birthdays) are detected and respected
Reminders
- Event reminders delivered by Calendula itself as notifications — essential when it's your only calendar app, since Android delegates reminder delivery to calendar apps
- Tap a reminder to land on the event
Design & privacy
- Real Material 3 Expressive throughout — dynamic color (Android 12+), expressive motion and shapes, light/dark theme
- German and English UI, per-app language setting — and open to community translations
- Zero telemetry, zero analytics, no internet permission — your data never leaves the device
📦 Install
F-Droid (recommended)
Calendula is on the official F-Droid repository — just search for Calendula in any F-Droid client, or install it from f-droid.org.
Self-hosted repo (latest builds)
New versions are built, signed, and published to a self-hosted repository the moment each tag lands — usually a few days ahead of the official repo, which rebuilds on F-Droid's own schedule. Add it for the freshest builds:
-
In your F-Droid client, open Settings → Repositories → Add (or open the link below on your phone):
https://apps.dev.jeanlucmakiola.de/dev/fdroid/repo?fingerprint=C2C0640402BF458FC0ED957AF0B37AA4C14022E72F89CE90B5965B458CF73425Repo:
https://apps.dev.jeanlucmakiola.de/dev/fdroid/repo· fingerprint (SHA-256):C2C0 6404 02BF 458F C0ED 957A F0B3 7AA4 C140 22E7 2F89 CE90 B596 5B45 8CF7 3425 -
Refresh, search for Calendula, install.
Both channels share the same signing key, so you can switch between them without reinstalling. Or build from source — see below.
📚 Documentation
- Building from source — requirements and Gradle tasks
- Architecture — the layered design and key pipelines
- Roadmap — what's shipped and what's next
🌍 Translations
Calendula ships in German and English, and you're warmly invited to add your language. Translations are managed on a self-hosted Weblate:
No coding needed — register on the Weblate server, pick (or request) a language, and translate the strings in your browser. You can also reach this link in the app from the top of Settings → App language.
📜 License
MIT — Jean-Luc Makiola, 2026