I'm sure you've felt like you're missing that at some point. quick functionality on your phone's home screen without having to open the entire app. Widgets have been around since Android was in its infancy, but with the arrival of Android 12 they've become fashionable again, forcing us to rethink how we present information at a glance.
To make life easier for developers, Google has launched Jetpack GlanceA library that allows us to leave behind tedious traditional XML and harness the power of Compose. Basically, it's a way to create those small interactive windows using a modern and declarative approachHowever, it's important to understand that it still operates under the rules of RemoteViews, which implies some technical restrictions that we need to be aware of.
Let's get started: Initial setup
To start building your widget, the first thing to do is prepare the ground. You need to extend the class GlanceAppWidgetReceiverThis receiver is the heart that connects the operating system to your Glance interface. In the code, you'll need to define which widget class you want to use by assigning it to the property. glanceAppWidget.
Do not forget that the AndroidManifest.xml This is where the magic of registration happens. You must declare the receiver and add an intent filter for the action. APPWIDGET_UPDATEFurthermore, it is essential to link it to an XML metadata file using the element meta-data, which is where we will define the physical characteristics of the widget.
Defining appearance and size
The resource archive my_app_widget_info.xml This is where you decide how much space your creation will take up. This is where we configure the AppWidgetProviderInfoOne interesting point is that, unlike older widgets, Glance doesn't require an initial design XML file, although using one is highly recommended. predefined load design from the library so that the user does not see an empty space while the interface is being rendered.
Regarding dimensions, Android 12 introduced the concepts of targetCellWidth y targetCellHeightwhich define the size based on grid cells. For your app to be backward compatible, the ideal approach is to take two steps and also define minWidth y minHeight in dp. This way, if the device is old, the system will perform the calculation by rounding up according to the nearest cell.
- ResizeMode: It allows you to decide whether the user can stretch the widget horizontally, vertically, or in both directions.
- Min/Max Resize: They set absolute limits so that the interface does not become illegible or too gigantic.
- UpdatePeriodMillis: Control how often the content refreshes; be careful not to overuse this. will destroy the battery from the user, so it's best not to update more than once an hour.
Building the interface with Compose
The most fun part is creating the UI. To do this, we create a class that inherits from GlanceAppWidget and we overwrote the method provideGlanceThis is where we load the necessary data. One vital technical detail: this method runs on the main thread, so if you need to perform a heavy database query, use withContext to move to a secondary thread and not block the app.
Within provideContentWe started using Glance components. Although they resemble those in Compose, they are specific elements. For example, we can use a Column to stack items vertically or a Row to place buttons side by side. To add interactivity, we use actions like actionStartActivity, which allows the widget to launch a specific activity when clicked.
Finishing and optimization details
If you want your widget to look professional, you need to pay attention to the rounded cornersAndroid 12 allows the use of the system radio by system_app_widget_background_radiusIn Glance, this is easily applied with the modifier. cornerRadiusTo ensure everything works perfectly on older versions of Android, the best approach is to implement custom theme resources that serve as an alternative.
Regarding event management, the GlanceAppWidgetReceiver It's responsible for translating system notifications into Compose lifecycles. You have methods like onUpdate to refresh the eyes or onDeleted to clear data when the user deletes the widget. However, be very careful with the time: receivers have a strict 10-second limitIf your task is lengthy, don't take risks and delegate the work to someone else. Work Manager.
The implementation of these interactive thumbnails allows for the creation of fluid and adaptable experiences thanks to the integration of Jet Pack Compose, optimizing everything from manifest registration and XML dimension management to dynamic component rendering and corner radius adaptation according to the Android version of the device. Share this information so that other users know about the topic.