packages/SystemUI/res/layout/udfps_view.xml

<?xml version="1.0" encoding="utf-8"?>
<!--
  ~ Copyright (C) 2020 The Android Open Source Project
  ~
  ~ Licensed under the Apache License, Version 2.0 (the "License");
  ~ you may not use this file except in compliance with the License.
  ~ You may obtain a copy of the License at
  ~
  ~      http://www.apache.org/licenses/LICENSE-2.0
  ~
  ~ Unless required by applicable law or agreed to in writing, software
  ~ distributed under the License is distributed on an "AS IS" BASIS,
  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  ~ See the License for the specific language governing permissions and
  ~ limitations under the License.
  -->
<com.android.systemui.biometrics.UdfpsView
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:systemui="http://schemas.android.com/apk/res-auto"
    android:id="@+id/udfps_view"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    systemui:sensorTouchAreaCoefficient="1.0"
    android:contentDescription="@string/accessibility_fingerprint_label">

    <ViewStub
        android:id="@+id/animation_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>

    <com.android.systemui.biometrics.UdfpsSurfaceView
        android:id="@+id/hbm_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:visibility="invisible"/>

</com.android.systemui.biometrics.UdfpsView>