Announcing Jetpack Glance Alpha for app widgets

Posted by Marcel Pintó Biescas, Developer Relations Engineer, @marxallski

Android 12 revamps a key feature for many Android users, App Widgets, making them more useful, beautiful, and discoverable (84% use at least 1 widget). Today, we’re making it even easier to build them by releasing the first alpha of Jetpack Glance, a new framework built on top of the Jetpack Compose runtime designed to make it faster and easier to build app widgets for the home screen and other surfaces.

We’d love you to give it a try and share your feedback!

Glance offers similar modern, declarative Kotlin APIs that you are used to with Jetpack Compose, helping you build beautiful, responsive app widgets with way less code.

Glance “Hello World” widget sample

class GreetingsWidget(private val name: String): GlanceAppWidget() {
    @Composable
    override fun Content() {
        Text(text = "Hello $name")
    }
}

class GreetingsWidgetReceiver : GlanceAppWidgetReceiver() {

    override val glanceAppWidget = GreetingsWidget("Glance")
}

How it works

Glance provides a base-set of Composables to help build “glanceable” experiences. Starting today with app widget components but with more coming. Using the Jetpack Compose runtime, Glance can translate Composables into actual RemoteViews, and display them in an app widget.

Diagram: Glance structure

This means that Glance requires Compose to be enabled and depends on Runtime, Graphics, and Unit UI Compose layers, but it’s not directly interoperable with other existing Jetpack Compose UI elements. However, state or any other logic within your app can be shared to create a glanceable UI.

What's in Alpha

This initial release introduces the main APIs to enable you to build app widgets in addition to providing interoperability with existing RemoteViews.

Here’s an overview of what the library offers, at a glance:

• Declare your app widgets with GlanceAppWidget and GlanceAppWidgetReceiver.
• Compose your UI with the initial set of Glance Composables: Box, Row, Column, Text, Button, LazyColumn, Image, Spacer.
• Apply modifiers to the composables using GlanceModifier methods.
• Handle user interaction with predefined Actions.
  • actionStartActivity
  • actionRunCallback
  • actionStartService
  • actionStartBroadcastReceiver
• Provide parameters to Action with ActionParameters.
• Handle different size modes by defining SizeMode.Single, SizeMode.Exact or SizeMode.Responsive.
• Persist GlanceAppWidget state by providing a GlanceStateDefinition.
• Local compositions like LocalContext, LocalState, LocalGlanceId, LocalSize.
• Interop with your existing RemoteViews with the AndroidRemoteViews Composable.

We are working on bringing even more functionality with default theming, further Android Studio support, and more. Stay tuned for new releases.

Note: while the minSDK is 21, we are currently only supporting compatibility till SDK v23.

Get started with Glance

Check out the sample on GitHub for a quick start. Glance works with the latest stable Android Studio, although since Glance relies on Compose Runtime, follow the steps on the Jetpack Compose docs to set it up first.

In addition, for a more advanced showcase, checkout the demos in the AndroidX repository.

ResponsiveAppWidget.kt demo

The Alpha version is your opportunity to influence the APIs, so please share your feedback and let us know your experience!

Happy Composing with Glance!