Android12以降のSplash画面をパワープレイでカスタマイズする

dependencies {
    implementation("androidx.core:core-splashscreen:1.0.0")
}

<style name="Theme.App.Starting" parent="Theme.SplashScreen">
   <item name="windowSplashScreenBackground">@color/red</item>
   <item name="windowSplashScreenAnimatedIcon">@drawable/icon</item>
   <item name="windowSplashScreenAnimationDuration">200</item>
   <item name="postSplashScreenTheme">@style/Theme.App</item>
</style>

<manifest>
   <application android:theme="@style/Theme.App.Starting">
    <!-- or -->
        <activity android:theme="@style/Theme.App.Starting" />
    </application>
</manifest>

class MainActivity : Activity() {

   override fun onCreate(savedInstanceState: Bundle?) {
       val splashScreen = installSplashScreen()

       super.onCreate(savedInstanceState)
       setContentView(R.layout.main_activity)

<android.window.SplashScreenView
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_height="match_parent"
    android:layout_width="match_parent"
    android:padding="0dp"
    android:orientation="vertical">
    <ImageView android:id="@+id/splashscreen_icon_view"
          android:layout_height="wrap_content"
          android:layout_width="wrap_content"
          android:layout_gravity="center"
          android:padding="0dp"
          android:background="@null"
          android:contentDescription="@string/splash_screen_view_icon_description"/>
    <View android:id="@+id/splashscreen_branding_view"
          android:layout_height="wrap_content"
          android:layout_width="wrap_content"
          android:layout_gravity="center_horizontal|bottom"
          android:layout_marginBottom="60dp"
          android:padding="0dp"
          android:background="@null"
          android:forceHasOverlappingRendering="false"
          android:contentDescription="@string/splash_screen_view_branding_description"/>
</android.window.SplashScreenView>

val splashScreen = installSplashScreen()

// 背景
splashScreenView.view
// アイコン
splashScreenView.iconView

class SplashActivity : AppCompatActivity() {

    companion object {
        private const val SPLASH_DURATION = 800L
    }

    private lateinit var binding: ActivitySplashBinding

    private val screenHeight by lazy { Resources.getSystem().displayMetrics.heightPixels }

    override fun onCreate(savedInstanceState: Bundle?) {
        val splashScreen = installSplashScreen()
        super.onCreate(savedInstanceState)

        splashScreen.setOnExitAnimationListener { splashScreenView ->
            val height = getRealDisplayHeight()

            // Activity自体の背景色
            window.decorView.setBackgroundColor(resources.getColor(R.color.background, null))

            // アイコンのTranslate Animation
            val centerX = splashScreenView.view.width / 2;
            val centerY = 0
            val endRadius = height * 0.4f
            val clipPath = Path().apply {
                addCircle(centerX.toFloat(), centerY.toFloat(), endRadius, Path.Direction.CW)
            }
            val translateAnimation = TranslateAnimation(
                Animation.RELATIVE_TO_SELF, 0f,
                Animation.RELATIVE_TO_SELF, 0f,
                Animation.RELATIVE_TO_SELF, 0f,
                Animation.RELATIVE_TO_SELF, -1.5f
            ).apply {
                duration = SPLASH_DURATION
                repeatCount = 0
                fillAfter = true
            }
            splashScreenView.iconView.startAnimation(translateAnimation)

            // 背景のReveal Animation
            splashScreenView.view.clipToOutline = true
            splashScreenView.view.outlineProvider = object : ViewOutlineProvider() {
                override fun getOutline(view: View?, outline: Outline?) {
                    view?.apply {
                        outline?.setPath(clipPath)
                    }
                }
            }
            ViewAnimationUtils.createCircularReveal(
                splashScreenView.view,
                splashScreenView.view.width / 2,
                0,
                screenHeight.toFloat(),
                screenHeight * 0.4f
            ).apply {
                duration = SPLASH_DURATION
                interpolator = AccelerateInterpolator()

                doOnEnd {
                    startMainActivity()
                }
            }.start()
        }
    }

    private fun startMainActivity() {
        startActivity(MainActivity.createIntent(this@SplashActivity))
        // ActivityのFadeAnimation
        // 34以上は遷移先のMainActivityで指定
        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.UPSIDE_DOWN_CAKE) {
            overridePendingTransition(R.anim.fade_in, R.anim.fade_out)
        }
        finish()
    }
}

window.decorView.setBackgroundColor(resources.getColor(R.color.background, null))

try {
    splashScreenView.iconView
} catch(e: NullPointerException) {
    // handle error
}