Splash screens in Android 12

2021-05-05: With dp3 apis and emulator images the splash screens now work as described. I have published a sample app on GitHub.

The Android 12 Developer Preview contains support for splash screens. Even though the api might change until the final release of Android 12, or the feature might even be removed again, it is interesting to see what we know at the moment.

Curious? Come, join me in my investigations...

First of all, there is a new interface android.window.SplashScreen. Currently the docs say:

The interface that apps use to talk to the splash screen.

Each splash screen instance is bound to a particular
Activity. To obtain a SplashScreen for an Activity,
use Activity.getSplashScreen() to get the SplashScreen.

The interface contains one method: setOnExitAnimationListener()

Specifies whether an Activity wants to handle the splash
screen animation on its own. Normally the splash screen
will show on screen before the content of the activity has
been drawn, and disappear when the activity is showing on
the screen. With this listener set, the activity will
receive OnExitAnimationListener#onSplashScreenExit
callback if splash screen is showed, then the activity can
create its own exit animation based on the
SplashScreenView.

Note that this method must be called before splash screen
leave, so it only takes effect during or before
Activity#onResume.

Let's try to see this in action. As SplashScreen is an interface it is interesting to see the actual implementation.

class MainActivity : AppCompatActivity() {
  override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    Log.d(TAG, "--> ${splashScreen::class.java.name}")
    splashScreen.setOnExitAnimationListener {
      Log.d(TAG, it::class.java.name)
    }
    setContentView(R.layout.activity_main)
  }
}

If we run the code, D/MainActivity: --> android.window.SplashScreen$SplashScreenImpl is printed.

SplashScreenImpl is no public api class, still, we can look what it contains during runtime:

One of its properties, mGlobal, references a SplashScreenManagerGlobal. We don't know much about this class, but peeking inside it reveals

so one of its properties holds an ArrayList of SplashScreenImpl objects.

While this is interesting, it doesn't help with a major issue of my code: the second output (Log.d(TAG, it::class.java.name)) is not printed.

This means that the listener we set using setOnExitAnimationListener() is not invoked. Which is a pity, because the docs of SplashScreen.OnExitAnimationListener sound great. This interface defines one method, onSplashScreenExit(SplashScreenView view).

When receiving this callback, the SplashScreenView object
will be drawing on top of the activity. The
SplashScreenView represents the splash screen view
object, developer can make an exit animation based on this
view.

So, what do we do?

Maybe it's a timing issue, maybe the app is too fast.

splashScreen.setOnExitAnimationListener {
  Log.d(TAG, it::class.java.name)
}
Handler(mainLooper).postDelayed({
  setContentView(R.layout.activity_main)
}, 5000)

No, doesn't help. Let's think again.

Hasn't splash screen support been built into Android since api level 26 (Oreo)?

Right.

android.R.attr contains windowSplashscreenContent. The docs say:

Reference to a drawable to be used as the splash screen
content of the window. This drawable will be placed on top
of the windowBackground with its bounds inset by the
system bars. If the drawable should not be inset by the
system bars, use a fullscreen theme.

In your themes.xml file you can add something like

<item name="android:windowSplashscreenContent">@drawable/anim</item>

and will receive a nice splash screen. But my listener still is not invoked (recall that in the last quote the docs refer to window).

What's interesting: android.R.attr has been updated for the Developer Preview, too:

windowSplashScreenAnimatedIcon

Replace an icon in the center of the starting window

windowSplashScreenAnimationDuration

The duration, in milliseconds, of the window splash screen
icon animation duration when playing the splash screen
starting window. The maximum animation duration should be
limited below 1000ms.

windowSplashScreenBackground

The background color for the splash screen, if not specify
then system will calculate from windowBackground.

windowSplashScreenBrandingImage

Place an drawable image in the bottom of the starting
window, it can be used to represent the branding of the
application.

To mee it is not clear if these additions cater for the old or new api. So, it'll be more than interesting to see what happens in the next preview and beta versions.

Summary

So far I have not been able to make use of the new interfaces and classes regarding splash screens. The reason may be

• I am missing something 😂
• I am doing it the wrong way
• Some pieces of the puzzle are still missing

As the docs say the new api is based upon activities, we may need to configure something in the manifest. Still, I have not yet found any evidence backing this assumption.

What are your thoughts about this. Please share your impressions in the comments.