AndroidPictureInPictureMode.doc

activity_main.xml
<TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Click the button to go to pip mode!"
        android:textColor="@color/black"
        android:textSize="20dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.454" />

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Go pip mode"
        android:onClick="goPip"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.498"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/textView"
        app:layout_constraintVertical_bias="0.061" />
        
        
 ->in Manifest.xml
          <activity android:name=".MainActivity"
            android:resizeableActivity="true"
            android:supportsPictureInPicture="true"
            android:configChanges="screenSize|smallestScreenSize|screenLayout|orientation"
            >
            
 ->MainActivity.java
 
public class MainActivity extends AppCompatActivity {
    TextView textView;
    Button button;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        textView=findViewById(R.id.textView);
        button=findViewById(R.id.button);
    }

    public void goPip(View view) {
       enterPictureInPictureMode();
    }

    @Override
    public void onPictureInPictureModeChanged(boolean isInPictureInPictureMode, Configuration newConfig) {
        super.onPictureInPictureModeChanged(isInPictureInPictureMode, newConfig);
        if (isInPictureInPictureMode){
            getSupportActionBar().hide();
            textView.setText("INSIDE PIP");
            button.setVisibility(View.INVISIBLE);
        }
        else{
            getSupportActionBar().show();
            textView.setText("Click the button to go to pip mode!");
            button.setVisibility(View.VISIBLE);
        }
    }
}