Rethinking Android Widgets: Building with Jetpack Glance 🚀

 Move beyond RemoteViews and build declarative, state-driven home screen widgets using the power of Jetpack Compose.

Rethinking Android Widgets: Building with Jetpack Glance

For years, building Android widgets felt like time travel — and not the fun kind. We were stuck using imperative XML layouts and RemoteViews, a system that hadn't changed much in a decade.

Jetpack Glance changes the game. It brings the modern, declarative principles of Jetpack Compose to the home screen. If you understand Compose UI principles, Glance will feel immediately familiar.

💎 Why Glance is the New Standard

Glance isn’t just a library; it’s a bridge. It allows you to write UI in Kotlin and translates it into optimized RemoteViews that the Android System can render safely in a separate process.

  • Declarative APIs: Use familiar building blocks like Row, Column, and Box.
  • Massive Code Reduction: Logic that once took 100+ lines of XML and boilerplate can now be achieved in 30–40 lines.
  • Clean State Handling: Glance integrates with PreferencesDataStore, making state-driven UI updates predictable.
  • Material-Inspired Theming: While it doesn’t offer the full Material 3 component set, it supports Material You concepts like dynamic colors, ensuring your widget visually aligns with the user’s OS.

🏗️ Building a “Smart Task” Widget

Let’s look at a practical example: a Task Tracker that allows users to mark items as “done” directly from the home screen.

1. The Layout (Kotlin)

We use GlanceModifier instead of the standard Compose Modifier. Note that unlike full Compose, Glance doesn't use remember or LaunchedEffect; it relies on state provided during the provideGlance lifecycle.

class TaskWidget : GlanceAppWidget() {

    // Define where the widget gets its data from
    override val stateDefinition = PreferencesGlanceStateDefinition

    override suspend fun provideGlance(context: Context, id: GlanceId) {
        // Entry point: provideContent bridges Compose code to the widget process
        provideContent {
            GlanceTheme {
                TaskContent()
            }
        }
    }

    @Composable
    private fun TaskContent() {
        // Use Glance-specific versions of Row and Column
        Column(
            modifier = GlanceModifier
                .fillMaxSize()
                .background(GlanceTheme.colors.widgetBackground)
                .padding(16.dp)
        ) {
            Text(
                text = "Priority Tasks",
                style = TextStyle(fontWeight = FontWeight.Bold, fontSize = 18.sp)
            )
            
            Spacer(GlanceModifier.height(12.dp))

            Row(
                modifier = GlanceModifier.fillMaxWidth(),
                verticalAlignment = Alignment.CenterVertically
            ) {
                Text("Update Project Specs", modifier = GlanceModifier.defaultWeight())
                
                // Clicks trigger an ActionCallback in the background
                Button(
                    text = "Done",
                    onClick = actionRunCallback<CompleteTaskAction>()
                )
            }
        }
    }
}

🌐 Handling Complex Logic: Fetching API Data

Because widgets live in the Launcher process, you cannot launch arbitrary coroutines directly from the UI. You must use an ActionCallback for network or disk I/O.

class CompleteTaskAction : ActionCallback {
    override suspend fun onAction(
        context: Context,
        glanceId: GlanceId,
        parameters: ActionParameters
    ) {
        // 1. Fetch data from your API or Repository
        val result = TaskRepository.markAsComplete() 
        
        // 2. Update the state. Glance automatically re-renders when 
        // the state definition changes AND you trigger an update.
        updateAppWidgetState(context, PreferencesGlanceStateDefinition, glanceId) { prefs ->
            prefs.toMutablePreferences().apply {
                this[booleanPreferencesKey("task_complete")] = true
            }
        }

        // 3. Explicitly tell the widget to redraw with the new data
        TaskWidget().update(context, glanceId)
    }
}

⚡ Pro Tip: The “Responsive” Secret

Users resize widgets constantly. Instead of one stretched layout, use SizeMode.Responsive to provide distinct UIs for different sizes—essential for tablets and foldables.

class TaskWidget : GlanceAppWidget() {
    // Automatically switches layouts based on available Dp size
    override val sizeMode = SizeMode.Responsive(
        setOf(DpSize(100.dp, 100.dp), DpSize(250.dp, 200.dp))
    )
}

Frequently Asked Questions (FAQs)

Does Glance support Button ripples or gestures?

Currently, Glance buttons are click-only. Because they are translated to RemoteViews, they do not support complex gestures (like swipes) or standard Material ripples.

How do I handle periodic background updates?

The best practice is using WorkManager. Set up a PeriodicWorkRequest to fetch data and call TaskWidget().updateAll(context) to refresh all active instances of your widget.

Is it really “just Compose”?

Not quite. While the syntax is similar, the underlying engine is different. There is no recomposition in the traditional sense; the widget is entirely recreated when update() is called.

💬 Let’s Discuss!

  • Have you tried migrating a legacy widget to Glance? What was your “lines of code” reduction?
  • Are you using WorkManager to keep your home screen content fresh?
  • What’s the one feature from standard Compose you wish Glance supported today?

🎥 Deep Dive Video

For a full walkthrough on setting up your AndroidManifest and handling complex DataStore states, check out this guide: Modern Android Widgets with Jetpack Glance (YouTube)

📘 Master Your Next Technical Interview

Since Java is the foundation of Android development, mastering DSA is essential. I highly recommend “Mastering Data Structures & Algorithms in Java”. It’s a focused roadmap covering 100+ coding challenges to help you ace your technical rounds.

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