packages/SystemUI/res/layout/magnifier_controllers.xml

<?xml version="1.0" encoding="utf-8"?>
<!--
  ~ Copyright (C) 2019 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.
  -->

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="@dimen/magnification_controls_size"
    android:layout_alignParentBottom="true"
    android:layout_alignParentEnd="true"
    android:layout_height="@dimen/magnification_controls_size"
    android:gravity="center">

  <RelativeLayout
      android:layout_width="wrap_content"
      android:layout_height="wrap_content">

    <ImageView
        android:focusable="true"
        android:id="@+id/controller"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@drawable/ic_control_magnification_grey" />

    <View
        android:id="@+id/left_control"
        android:layout_width="@dimen/magnifier_left_right_controls_width"
        android:layout_height="@dimen/magnifier_left_right_controls_height"
        android:layout_alignLeft="@+id/controller"
        android:layout_centerVertical="true" />

    <View
        android:id="@+id/up_control"
        android:layout_width="@dimen/magnifier_up_down_controls_width"
        android:layout_height="@dimen/magnifier_up_down_controls_height"
        android:layout_alignTop="@+id/controller"
        android:layout_centerHorizontal="true" />

    <View
        android:id="@+id/right_control"
        android:layout_width="@dimen/magnifier_left_right_controls_width"
        android:layout_height="@dimen/magnifier_left_right_controls_height"
        android:layout_alignRight="@+id/controller"
        android:layout_centerVertical="true" />

    <View
        android:id="@+id/down_control"
        android:layout_width="@dimen/magnifier_up_down_controls_width"
        android:layout_height="@dimen/magnifier_up_down_controls_height"
        android:layout_alignBottom="@+id/controller"
        android:layout_centerHorizontal="true" />
  </RelativeLayout>

</FrameLayout>