Android App Widget Development with Glance

AppWidget.kt

// https://medium.com/atlas/android-app-widget-development-with-glance-532a5a8d602c

// User Interface
<!-- API 31 (Android 12 and up) --> 
<appwidget-provider xmlns:android="http://schemas.android.com/apk/res/android" 
        android:description="@string/widget_description" 
        android:minWidth="200dp" 
        android:minHeight="200dp" 
        android:resizeMode="horizontal|vertical" 
        android:previewImage="@drawable/calendar_widget_preview_image" 
        android:previewLayout="@layout/calendar_widget_small_layout" 
        android:targetCellWidth="2" 
        android:targetCellHeight="3" 
        android:maxResizeWidth="300dp" 
        android:maxResizeHeight="600dp" 
        android:widgetCategory="home_screen" 
        android:updatePeriodMillis="0" 
        /> 
        
  Column(
    modifier = GlanceModifier.padding(all = 2.dp).fillMaxWidth().background(Color.White),
    horizontalAlignment = Alignment.CenterHorizontally
  ) {
    // UP/Prev button
    Image(
        provider = ImageProvider(com.bottlerocket.android.consolidator.R.drawable.ic_arrow_up_24),
        contentDescription = "Back",
        modifier = GlanceModifier.defaultWeight()
            .background(Color.Transparent)
            .clickable(onClick = actionRunCallback<CalendarActionCallback>(
                actionParametersOf(pairs = arrayOf(ActionParameters.Key<DateArrow>(KEY_DATE_ARROW) to DateArrow.Back)))
            )
    )

    val monthEvents = calendarEventsMap.filter { it.key.year == firstMonthState.year && it.key.month == firstMonthState.month }
    MonthCalendarWidgetUI(firstMonthState, monthEvents)

    if (numMonthsToShow >= 2) {
        val secondMonth = firstMonthState.plusMonths(1)
        val secondMonthEvents = calendarEventsMap.filter { it.key.year == secondMonth.year && it.key.month == secondMonth.month }
        MonthCalendarWidgetUI(secondMonth, secondMonthEvents)
    }
}
  
//  Work Manager
fun startCalendarDataFetch(workManager: WorkManager) {
    calendarWidgetLog("queueCalendarDataRequest")
    val constraints = Constraints.Builder()
        .setRequiredNetworkType(NetworkType.CONNECTED)
        .setRequiresCharging(false)
        .setRequiresBatteryNotLow(true)
        .build()

    // NOTE: min period is 15 minutes.
    val request = PeriodicWorkRequestBuilder<CalendarWorkManager>(
        Duration.ofMinutes(
            CALENDAR_WORK_REQ_PERIOD_MINUTES
        ))
        .setConstraints(constraints)
        .setInitialDelay(Duration.ofSeconds(CALENDAR_WORK_REQ_INITIAL_DELAY_SECONDS))
        .build()

    // MUST: Specifying "unique" and "KEEP" will ensure there is only one worker in the system.
    val operation = workManager.enqueueUniquePeriodicWork(
        CALENDAR_FETCH_WORKER,
        ExistingPeriodicWorkPolicy.KEEP,
        request)
    calendarWidgetLog("WorkManager queue status: ${operation.result}")
}

// 

private suspend fun updateWidgetData(events: List<DayEvent>) {
    GlanceAppWidgetManager(context = context).getGlanceIds(ConsolidatorAppWidget::class.java).forEach { glanceId ->
        updateAppWidgetState(context, glanceId) { prefs ->
            calendarWidgetLog("updateAppWidgetState: glanceId: $glanceId")
            // Each app widget instance stores in a different DataStore file.
            prefs.setCalendarData(events)
        }

        // VERY IMPORTANT: Refreshing App Widget with updated events here.
        calendarWidgetLog("updateWidgetData: Update UI")
        ConsolidatorAppWidget().update(context, glanceId)
    }
}
        
// 
class ConsolidatorAppWidget: GlanceAppWidget() {

    private val isDebugOverride = false     // Set to true to have only one widget size to reduce logging clutter
    
    /**
     * Used to dynamically configure Widget as user is resizing it.
     */
    override val sizeMode: SizeMode = SizeMode.Responsive(
        if (isDebugOverride && isDebug()) setOf(ONE_MONTH_WIDGET) else setOf(ONE_MONTH_WIDGET, TWO_MONTH_WIDGET)
    )

...
}

// Useful Links
General App Widget Documentation (Non-Glance specific)
Glance Overview
Glance Sample Code from Google
StackOverflow topic/tag: glance-appwidget
Glance Bugs List