A minimal Android home-screen widget that displays the current BrightDate value — a single scalar count of SI days since the J2000.0 astronomical epoch.
BRIGHTDATE
9627.47168
app/— single-module Android app, Kotlin, AGP 8.7 / Kotlin 2.0, minSdk 26.brightdate/— symlink to the upstream BrightDate reference repo (read-only; used here only as documentation for the J2000.0 / TAI math).
This project does not commit the Gradle wrapper jar. Generate it once:
gradle wrapper --gradle-version 8.10.2Then open the project in Android Studio (Koala / Ladybug or newer) and run the
app configuration, or from the command line:
./gradlew :app:assembleDebug
./gradlew :app:installDebugAfter install, long-press the home screen → Widgets → BrightDate Widget.
BrightDate is computed exactly as the upstream library defines it
(app/src/main/java/org/brightchain/brightdate/widget/BrightDate.kt):
brightdate = (taiUnixSeconds − 946_727_967.816) / 86_400
taiUnixSeconds = unixSeconds + (TAI − UTC)
The TAI−UTC offset is hard-coded to 37 seconds (the value in force since
2017-01-01). If the IERS announces a future leap second, bump
TAI_MINUS_UTC_SECONDS in BrightDate.kt.
The Android AppWidgetProviderInfo.updatePeriodMillis minimum is 30 minutes,
which is unusably slow for a live time display. We instead run a repeating
inexact AlarmManager tick (default 30 s) while at least one widget
instance exists, re-armed in onUpdate, onEnabled, and BootReceiver.
5 fractional digits = ~0.864 s resolution, so the last digit or two will visibly
jump between updates. Lower the interval in BrightDateWidgetProvider.UPDATE_INTERVAL_MS
if you want smoother ticks at the cost of battery.