<activity
    android:name=".MainActivity"
    android:configChanges="screenSize|smallestScreenSize|screenLayout|orientation"
    android:exported="true"
    android:launchMode="singleTask"
    android:resizeableActivity="true"
    android:supportsPictureInPicture="true">
    <meta-data
        android:name="android.app.lib_name"
        android:value="" />
    <intent-filter>
        <action android:name="android.intent.action.MAIN" />
        <category android:name="android.intent.category.LAUNCHER" />
    </intent-filter>
</activity>

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">
    <VideoView
        android:id="@+id/video"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</LinearLayout>

private fun minimize() {
    // 畫中畫builder
    var builder = PictureInPictureParams.Builder()
    // rational設定尺寸大小
    val info = Rational(video.width, video.height)
    builder.setAspectRatio(info).build()
    // 開啟畫中畫
    enterPictureInPictureMode(builder.build())
}

override fun onUserLeaveHint() {
    minimize()
}