How do I make a floating widget on Android?

ByJael Lawler

A floating widget is a small window that floats over other apps on an Android device, allowing users to quickly access information or perform tasks without leaving the current screen (https://www.spaceotechnologies.com/blog/android-floating-widget-tutorial/). Floating widgets provide a convenient way to multitask, as users can toggle between apps without closing screens or navigating away. They are always accessible and visible, even when using other apps.

Users may want to create custom floating widgets for various purposes, such as displaying messages, controlling music playback, monitoring system info, or launching their most-used apps. The key benefit of floating widgets is the ability to improve multitasking and productivity by providing quick access to frequently used features and information.

Prerequisites

Before you can start building a floating widget, you’ll need to have Android Studio installed on your computer. Android Studio is the official integrated development environment (IDE) for Android app development. Here are the basic prerequisites for installing Android Studio:

First, your computer will need to meet the minimum system requirements for Android Studio. The recommended minimum requirements are Windows 8/8.1/10/11 (64-bit), 2nd gen Intel CPU or newer, at least 8 GB RAM, and 2 GB of available disk space (source).

Next, you’ll need to download the latest version of Android Studio from the official website (https://developer.android.com/studio). Follow the installation wizard, selecting all of the default options. Android Studio will download and install any required SDK packages for you.

Once Android Studio is installed, launch it and create a new project to make sure everything is working properly. The default templates will create a simple app that you can run in the emulator. With the prerequisites met, you’ll be ready to start building your floating widget.

Create a New Project

To create a new Android project in Android Studio, first launch Android Studio and click on “Start a new Android Studio project.” In the first screen of the wizard, specify an application name such as “MyWidgetApp” and select “Empty Activity” as the activity type. Make sure the minimum API level is set to API 21 or higher so that the floating widget will be supported.

In the second screen, leave the default values and click “Finish.” Android Studio will now generate the project files and starter code for your app [1]. This sets up the basic structure and dependencies needed to start developing the widget.

Design the Widget Layout

The layout for the floating widget will use a RelativeLayout as the root view. RelativeLayout allows you to position child views relative to each other and the parent layout. This makes it easy to create the overlay effect needed for a floating widget.

According to Tutlane, RelativeLayout is one of the basic layouts in Android that allows positioning of child views relative to each other. Some key properties like alignParentStart, alignParentEnd, alignParentTop, alignParentBottom, etc. can be used to position views relative to the parent layout.

Within the RelativeLayout, we can add the main content view for the widget. This could contain buttons, text, images, etc. By setting properties like layout_alignParentTop, layout_alignParentEnd, we can position it in the corner or edge of the screen.

Additional views like a close button can also be added and positioned accordingly. AbhiAndroid provides examples of relative positioning of views like alignRight to align a button to the right edge.

Using RelativeLayout as the root makes it straightforward to create the floating overlay needed for the widget. The child views can be positioned exactly where needed.

Create the Widget Class

To create the widget, you need to extend the AppWidgetProvider class. This is the base class that provides the required lifecycle and callback methods needed for an App Widget.

Create a new Java class and extend AppWidgetProvider like this:


public class MyWidgetProvider extends AppWidgetProvider {

}

The AppWidgetProvider class allows you to hook into lifecycle events to update and manage the widget. Some key methods include:

  • onUpdate() – Called when the widget is first added and any time the widget configuration changes
  • onDeleted() – Called when a widget instance is deleted from the host
  • onEnabled() – Called when first created and any time the widgets are re-enabled after being disabled
  • onDisabled() – Called when the last widget instance is deleted
  • onAppWidgetOptionsChanged() – Called when widget configuration options change

By overriding these methods you can respond to lifecycle events and update the widget UI accordingly.

Register the Widget

To register the widget in your app, you need to declare it in the AndroidManifest.xml file. This lets the system know that your app contains a widget. Add the following within the <application> tags:

<receiver android:name=".ExampleAppWidgetProvider">
  <intent-filter>
    <action android:name="android.appwidget.action.APPWIDGET_UPDATE" /> 
  </intent-filter>
  <meta-data
    android:name="android.appwidget.provider"
    android:resource="@xml/example_appwidget_info" />
</receiver>

This declares a broadcast receiver for the widget using the class name of your widget provider. The APPWIDGET_UPDATE action handles updates. The android:resource points to the widget configuration file.

For details, see the Android Developers Guide.

Handle Widget Events

The key method to override in your widget class is onUpdate(). This method gets called whenever the widget needs to refresh its UI. According to the Android documentation, onUpdate() gets triggered in the following scenarios:

  • When the widget is first added/installed
  • When the device boots
  • When any widget updatePeriodMillis has elapsed
  • When the widget has been explicitly updated via notifyAppWidgetViewDataChanged()

Therefore, you need to put any logic to refresh your widget UI inside onUpdate(). This includes updating any RemoteViews with new data, restarting background update tasks, etc. You can then call super.onUpdate() so the framework can do any required work.

Add Functionality

The key part of creating a functional widget is implementing the widget behavior in code. This is done in the WidgetProvider Java or Kotlin class that extends the AppWidgetProvider base class.

In the WidgetProvider class, you need to override lifecycle methods like onUpdate() and onReceive() to handle events like the widget being added, removed, or updated. This is where you implement the main logic and functionality.

For example, you can update the widget UI elements in onUpdate() when the widget is added or changed. And handle user interactions like button clicks in onReceive() by creating a PendingIntent to launch an Activity.

To add dynamic content like updating the text or image displayed, you can use a scheduled job with WorkManager to periodically update the widget. This allows creating widgets like clocks, weather displays, news tickers etc.

Overall, the WidgetProvider is where you bring your widget to life by attaching behavior to lifecycle events and user interactions. This is done using the Android SDK and common patterns like PendingIntents, RemoteViews, WorkManager and more. Refer to the Android developer documentation for more details.

Configure Widget Placement

One of the key aspects of creating a widget is allowing the user to place it on their home screen. Android provides a simple way to enable this in your widget code.

When defining your widget information in the AppWidgetProviderInfo metadata, you need to set resizeMode to ResizeMode.HORIZONTAL or ResizeMode.VERTICAL. This allows Android to know that your widget supports resizing, which is required for home screen placement.

Next, you simply need to declare an AppWidgetProviderInfo object in your res/xml/widget_info.xml file and set android:resizeMode="horizontal" or android:resizeMode="vertical". Now when the user adds your widget, they will have the ability to place it on their home screen and resize it.

So by setting that one parameter, you enable full home screen widget placement and control. This provides a much richer experience for the user than just keeping your widget confined to the widget picker screen (Source: Configure app widgets).

Publish the Widget

Once you have finished developing the widget functionality, the final step is to build and deploy the app containing the widget. To publish the widget so it is available for users to add, you need to build and release the app to the Google Play Store or other app store.

Build the app as normal through Android Studio or Gradle. Make sure to increment the version code and version name before building. The compiled APK will now contain the widget code and resources.

Distribute this APK through an app store or directly to users. After installing the app, users will be able to add the widget through the widgets picker on their home screen. No separate installation is needed for the widget itself. Once added, the widget will function as per the code in your app.

See How to make a floating widget for more details on building and releasing an app with widgets.

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