diff --git a/res/drawable/accessibility_button_navigation.xml b/res/drawable/accessibility_button_navigation.xml
new file mode 100644
index 00000000000..30273fb4e1f
--- /dev/null
+++ b/res/drawable/accessibility_button_navigation.xml
@@ -0,0 +1,70 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright (C) 2021 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.
+-->
+
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="125dp"
+    android:height="153dp"
+    android:viewportWidth="125"
+    android:viewportHeight="153">
+    <group>
+        <clip-path
+            android:pathData="M0,0h125v153h-125z"/>
+        <path
+            android:pathData="M0,0h125v153h-125z"
+            android:fillColor="#ffffff"/>
+        <path
+            android:pathData="M7.4,-62.9L117.6,-62.9A6.3,6.3 0,0 1,123.9 -56.6L123.9,145.6A6.3,6.3 0,0 1,117.6 151.9L7.4,151.9A6.3,6.3 0,0 1,1.1 145.6L1.1,-56.6A6.3,6.3 0,0 1,7.4 -62.9z"
+            android:strokeWidth="1.8"
+            android:fillColor="#DADCE0"
+            android:strokeColor="#BDC1C6"/>
+        <group>
+            <clip-path
+                android:pathData="M7.4,-62.9L116.6,-62.9A6.3,6.3 0,0 1,122.9 -56.6L122.9,145.6A6.3,6.3 0,0 1,116.6 151.9L7.4,151.9A6.3,6.3 0,0 1,1.1 145.6L1.1,-56.6A6.3,6.3 0,0 1,7.4 -62.9z"/>
+            <path
+                android:pathData="M12.4,-61L112.6,-61A5.4,5.4 0,0 1,118 -55.6L118,140.6A5.4,5.4 0,0 1,112.6 146L12.4,146A5.4,5.4 0,0 1,7 140.6L7,-55.6A5.4,5.4 0,0 1,12.4 -61z"
+                android:fillColor="#F8F9FA"/>
+            <group>
+                <clip-path
+                    android:pathData="M12.4,-61L112.6,-61A5.4,5.4 0,0 1,118 -55.6L118,140.6A5.4,5.4 0,0 1,112.6 146L12.4,146A5.4,5.4 0,0 1,7 140.6L7,-55.6A5.4,5.4 0,0 1,12.4 -61z"/>
+            </group>
+        </group>
+        <path
+            android:pathData="M7,126H118V140.6C118,143.582 115.582,146 112.6,146H12.4C9.418,146 7,143.582 7,140.6V126Z"
+            android:fillColor="#000000"
+            android:fillAlpha="0.87"/>
+        <path
+            android:strokeWidth="1"
+            android:pathData="M63.5,138.688C64.713,138.688 65.697,137.708 65.697,136.5C65.697,135.292 64.713,134.312 63.5,134.312C62.286,134.312 61.303,135.292 61.303,136.5C61.303,137.708 62.286,138.688 63.5,138.688Z"
+            android:fillColor="#00000000"
+            android:fillType="evenOdd"
+            android:strokeColor="#9AA0A6"/>
+        <path
+            android:strokeWidth="1"
+            android:pathData="M33.694,133.953C33.827,133.876 33.994,133.972 33.994,134.126V138.874C33.994,139.028 33.827,139.125 33.694,139.047L29.604,136.673C29.471,136.596 29.471,136.404 29.604,136.327L33.694,133.953Z"
+            android:fillColor="#00000000"
+            android:fillType="evenOdd"
+            android:strokeColor="#9AA0A6"/>
+        <path
+            android:pathData="M96.111,131.2C96.111,131.86 95.611,132.4 95,132.4C94.389,132.4 93.889,131.86 93.889,131.2C93.889,130.54 94.389,130 95,130C95.611,130 96.111,130.54 96.111,131.2ZM95,133C96.572,133 98.272,132.82 99.722,132.4L100,133.6C98.967,133.9 97.778,134.098 96.667,134.2V142H95.556V138.4H94.444V142H93.333V134.2C92.222,134.098 91.033,133.9 90,133.6L90.278,132.4C91.728,132.82 93.428,133 95,133Z"
+            android:fillColor="#ffffff"
+            android:fillType="evenOdd"/>
+        <path
+            android:pathData="M94.5,135.5m-15.5,0a15.5,15.5 0,1 1,31 0a15.5,15.5 0,1 1,-31 0"
+            android:strokeWidth="4"
+            android:fillColor="#00000000"
+            android:strokeColor="#4285F4"/>
+    </group>
+</vector>
\ No newline at end of file
diff --git a/res/drawable/accessibility_button_preview_base.xml b/res/drawable/accessibility_button_preview_base.xml
new file mode 100644
index 00000000000..0712b9508b1
--- /dev/null
+++ b/res/drawable/accessibility_button_preview_base.xml
@@ -0,0 +1,45 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright (C) 2021 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.
+-->
+
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="125dp"
+    android:height="153dp"
+    android:viewportWidth="125"
+    android:viewportHeight="153">
+    <group>
+        <clip-path
+            android:pathData="M0,0h125v153h-125z"/>
+        <path
+            android:pathData="M0,0h125v153h-125z"
+            android:fillColor="#ffffff"/>
+        <path
+            android:pathData="M7.4,-62.9L117.6,-62.9A6.3,6.3 0,0 1,123.9 -56.6L123.9,145.6A6.3,6.3 0,0 1,117.6 151.9L7.4,151.9A6.3,6.3 0,0 1,1.1 145.6L1.1,-56.6A6.3,6.3 0,0 1,7.4 -62.9z"
+            android:strokeWidth="1.8"
+            android:fillColor="#DADCE0"
+            android:strokeColor="#BDC1C6"/>
+        <group>
+            <clip-path
+                android:pathData="M7.4,-62.9L116.6,-62.9A6.3,6.3 0,0 1,122.9 -56.6L122.9,145.6A6.3,6.3 0,0 1,116.6 151.9L7.4,151.9A6.3,6.3 0,0 1,1.1 145.6L1.1,-56.6A6.3,6.3 0,0 1,7.4 -62.9z"/>
+            <path
+                android:pathData="M12.4,-61L112.6,-61A5.4,5.4 0,0 1,118 -55.6L118,140.6A5.4,5.4 0,0 1,112.6 146L12.4,146A5.4,5.4 0,0 1,7 140.6L7,-55.6A5.4,5.4 0,0 1,12.4 -61z"
+                android:fillColor="#F8F9FA"/>
+            <group>
+                <clip-path
+                    android:pathData="M12.4,-61L112.6,-61A5.4,5.4 0,0 1,118 -55.6L118,140.6A5.4,5.4 0,0 1,112.6 146L12.4,146A5.4,5.4 0,0 1,7 140.6L7,-55.6A5.4,5.4 0,0 1,12.4 -61z"/>
+            </group>
+        </group>
+    </group>
+</vector>
\ No newline at end of file
diff --git a/res/drawable/accessibility_button_preview_large_floating_menu.xml b/res/drawable/accessibility_button_preview_large_floating_menu.xml
new file mode 100644
index 00000000000..e003dc7322c
--- /dev/null
+++ b/res/drawable/accessibility_button_preview_large_floating_menu.xml
@@ -0,0 +1,41 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright (C) 2021 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.
+-->
+
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="125dp"
+    android:height="153dp"
+    android:viewportWidth="125"
+    android:viewportHeight="153">
+    <path
+        android:pathData="M0,0h125v153h-125z"
+        android:fillColor="#00000000"/>
+    <group>
+        <clip-path
+            android:pathData="M89,95h29v34h-29z"/>
+        <path
+            android:strokeWidth="1"
+            android:pathData="M105,97.5L131,97.5A14.5,14.5 0,0 1,145.5 112L145.5,112A14.5,14.5 0,0 1,131 126.5L105,126.5A14.5,14.5 0,0 1,90.5 112L90.5,112A14.5,14.5 0,0 1,105 97.5z"
+            android:fillColor="#ffffff"
+            android:strokeColor="#DADCE0"/>
+        <path
+            android:pathData="M105.4,112m-11.2,0a11.2,11.2 0,1 1,22.4 0a11.2,11.2 0,1 1,-22.4 0"
+            android:fillColor="#80868B"/>
+        <path
+            android:pathData="M106.467,107.733C106.467,108.32 105.987,108.8 105.4,108.8C104.814,108.8 104.334,108.32 104.334,107.733C104.334,107.147 104.814,106.667 105.4,106.667C105.987,106.667 106.467,107.147 106.467,107.733ZM105.4,109.333C106.91,109.333 108.542,109.173 109.934,108.8L110.2,109.867C109.208,110.133 108.067,110.309 107,110.4V117.333H105.934V114.133H104.867V117.333H103.8V110.4C102.734,110.309 101.592,110.133 100.6,109.867L100.867,108.8C102.259,109.173 103.891,109.333 105.4,109.333Z"
+            android:fillColor="#ffffff"
+            android:fillType="evenOdd"/>
+    </group>
+</vector>
\ No newline at end of file
diff --git a/res/drawable/accessibility_button_preview_small_floating_menu.xml b/res/drawable/accessibility_button_preview_small_floating_menu.xml
new file mode 100644
index 00000000000..3ff8e4b25f4
--- /dev/null
+++ b/res/drawable/accessibility_button_preview_small_floating_menu.xml
@@ -0,0 +1,41 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright (C) 2021 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.
+-->
+
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="125dp"
+    android:height="153dp"
+    android:viewportWidth="125"
+    android:viewportHeight="153">
+    <path
+        android:pathData="M0,0h125v153h-125z"
+        android:fillColor="#00000000"/>
+    <group>
+        <clip-path
+            android:pathData="M89,106h29v22h-29z"/>
+        <path
+            android:strokeWidth="1"
+            android:pathData="M111,107.5L137,107.5A9.5,9.5 0,0 1,146.5 117L146.5,117A9.5,9.5 0,0 1,137 126.5L111,126.5A9.5,9.5 0,0 1,101.5 117L101.5,117A9.5,9.5 0,0 1,111 107.5z"
+            android:fillColor="#ffffff"
+            android:strokeColor="#DADCE0"/>
+        <path
+            android:pathData="M111.168,116.968m-7.168,0a7.168,7.168 0,1 1,14.336 0a7.168,7.168 0,1 1,-14.336 0"
+            android:fillColor="#80868B"/>
+        <path
+            android:pathData="M111.851,114.237C111.851,114.612 111.543,114.92 111.168,114.92C110.792,114.92 110.485,114.612 110.485,114.237C110.485,113.861 110.792,113.554 111.168,113.554C111.543,113.554 111.851,113.861 111.851,114.237ZM111.168,115.261C112.134,115.261 113.178,115.158 114.069,114.92L114.24,115.602C113.605,115.773 112.875,115.886 112.192,115.944V120.381H111.509V118.333H110.827V120.381H110.144V115.944C109.461,115.886 108.731,115.773 108.096,115.602L108.267,114.92C109.157,115.158 110.202,115.261 111.168,115.261Z"
+            android:fillColor="#ffffff"
+            android:fillType="evenOdd"/>
+    </group>
+</vector>
\ No newline at end of file
diff --git a/res/layout/accessibility_button_preview.xml b/res/layout/accessibility_button_preview.xml
new file mode 100644
index 00000000000..07cb0ffb8ab
--- /dev/null
+++ b/res/layout/accessibility_button_preview.xml
@@ -0,0 +1,33 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright (C) 2021 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="match_parent"
+    android:layout_height="wrap_content"
+    android:clipToPadding="false"
+    android:importantForAccessibility="noHideDescendants">
+
+    <ImageView
+        android:id="@+id/preview_image"
+        android:layout_width="match_parent"
+        android:layout_height="@dimen/accessibility_button_preview_height"
+        android:layout_gravity="center"
+        android:scaleType="fitCenter"
+        android:focusable="false"
+        android:clickable="false"
+        android:adjustViewBounds="true"/>
+</FrameLayout>
\ No newline at end of file
diff --git a/res/values/dimens.xml b/res/values/dimens.xml
index 4fef726d599..dbf21fc8626 100755
--- a/res/values/dimens.xml
+++ b/res/values/dimens.xml
@@ -57,6 +57,8 @@
 
     <dimen name="color_mode_preview_height">320dp</dimen>
 
+    <dimen name="accessibility_button_preview_height">200dp</dimen>
+
     <dimen name="ring_progress_bar_thickness">4dp</dimen>
 
     <!-- Weight of the left pane in a multi-pane preference layout. -->
diff --git a/res/xml/accessibility_button_settings.xml b/res/xml/accessibility_button_settings.xml
index 8d4631afbba..fc91dcaeef6 100644
--- a/res/xml/accessibility_button_settings.xml
+++ b/res/xml/accessibility_button_settings.xml
@@ -19,6 +19,15 @@
     xmlns:settings="http://schemas.android.com/apk/res-auto"
     android:title="@string/accessibility_button_title">
 
+    <com.android.settingslib.widget.LayoutPreference
+        android:key="caption_preview"
+        android:title="@string/summary_placeholder"
+        android:layout="@layout/accessibility_button_preview"
+        android:selectable="false"
+        settings:searchable="false"
+        android:persistent="false"
+        settings:controller="com.android.settings.accessibility.AccessibilityButtonPreviewPreferenceController"/>
+
     <ListPreference
         android:entries="@array/accessibility_button_location_selector_titles"
         android:entryValues="@array/accessibility_button_location_selector_values"
diff --git a/src/com/android/settings/accessibility/AccessibilityButtonPreviewPreferenceController.java b/src/com/android/settings/accessibility/AccessibilityButtonPreviewPreferenceController.java
new file mode 100644
index 00000000000..69a7a46f0c3
--- /dev/null
+++ b/src/com/android/settings/accessibility/AccessibilityButtonPreviewPreferenceController.java
@@ -0,0 +1,126 @@
+/*
+ * Copyright (C) 2021 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.
+ */
+
+package com.android.settings.accessibility;
+
+import android.content.ContentResolver;
+import android.content.Context;
+import android.database.ContentObserver;
+import android.graphics.drawable.Drawable;
+import android.os.Handler;
+import android.os.Looper;
+import android.provider.Settings;
+import android.widget.ImageView;
+
+import androidx.annotation.VisibleForTesting;
+import androidx.preference.PreferenceScreen;
+
+import com.android.settings.R;
+import com.android.settings.core.BasePreferenceController;
+import com.android.settingslib.core.lifecycle.LifecycleObserver;
+import com.android.settingslib.core.lifecycle.events.OnPause;
+import com.android.settingslib.core.lifecycle.events.OnResume;
+import com.android.settingslib.widget.LayoutPreference;
+
+/** Preference controller that controls the preview effect in accessibility button page. */
+public class AccessibilityButtonPreviewPreferenceController extends BasePreferenceController
+        implements LifecycleObserver, OnResume, OnPause {
+
+    private static final int SMALL_SIZE = 0;
+    private static final float DEFAULT_OPACITY = 0.55f;
+    private static final int DEFAULT_SIZE = 0;
+
+    private final ContentResolver mContentResolver;
+    @VisibleForTesting
+    final ContentObserver mContentObserver;
+    private FloatingMenuLayerDrawable mFloatingMenuPreviewDrawable;
+
+    @VisibleForTesting
+    ImageView mPreview;
+
+    public AccessibilityButtonPreviewPreferenceController(Context context, String preferenceKey) {
+        super(context, preferenceKey);
+        mContentResolver = context.getContentResolver();
+        mContentObserver = new ContentObserver(new Handler(Looper.getMainLooper())) {
+            @Override
+            public void onChange(boolean selfChange) {
+                updatePreviewPreference();
+            }
+        };
+    }
+
+    @Override
+    public int getAvailabilityStatus() {
+        return AVAILABLE;
+    }
+
+    @Override
+    public void displayPreference(PreferenceScreen screen) {
+        super.displayPreference(screen);
+        final LayoutPreference preference = screen.findPreference(getPreferenceKey());
+        mPreview = preference.findViewById(R.id.preview_image);
+
+        updatePreviewPreference();
+    }
+
+    @Override
+    public void onResume() {
+        mContentResolver.registerContentObserver(
+                Settings.Secure.getUriFor(Settings.Secure.ACCESSIBILITY_BUTTON_MODE),
+                /* notifyForDescendants= */ false, mContentObserver);
+        mContentResolver.registerContentObserver(
+                Settings.Secure.getUriFor(Settings.Secure.ACCESSIBILITY_FLOATING_MENU_SIZE),
+                /* notifyForDescendants= */ false, mContentObserver);
+        mContentResolver.registerContentObserver(
+                Settings.Secure.getUriFor(Settings.Secure.ACCESSIBILITY_FLOATING_MENU_OPACITY),
+                /* notifyForDescendants= */ false, mContentObserver);
+    }
+
+    @Override
+    public void onPause() {
+        mContentResolver.unregisterContentObserver(mContentObserver);
+    }
+
+    private void updatePreviewPreference() {
+        if (AccessibilityUtil.isFloatingMenuEnabled(mContext)) {
+            final int size = Settings.Secure.getInt(mContentResolver,
+                    Settings.Secure.ACCESSIBILITY_FLOATING_MENU_SIZE, DEFAULT_SIZE);
+            final int opacity = (int) (Settings.Secure.getFloat(mContentResolver,
+                    Settings.Secure.ACCESSIBILITY_FLOATING_MENU_OPACITY, DEFAULT_OPACITY) * 100);
+            final int floatingMenuIconId = (size == SMALL_SIZE)
+                    ? R.drawable.accessibility_button_preview_small_floating_menu
+                    : R.drawable.accessibility_button_preview_large_floating_menu;
+
+            mPreview.setImageDrawable(getFloatingMenuPreviewDrawable(floatingMenuIconId, opacity));
+            // Only change opacity(alpha) would not invoke redraw view, need to invalidate manually.
+            mPreview.invalidate();
+        } else {
+            mPreview.setImageDrawable(
+                    mContext.getDrawable(R.drawable.accessibility_button_navigation));
+        }
+    }
+
+    private Drawable getFloatingMenuPreviewDrawable(int resId, int opacity) {
+        if (mFloatingMenuPreviewDrawable == null) {
+            mFloatingMenuPreviewDrawable = FloatingMenuLayerDrawable.createLayerDrawable(
+                    mContext, resId, opacity);
+        } else {
+            mFloatingMenuPreviewDrawable.updateLayerDrawable(mContext, resId, opacity);
+        }
+
+        return mFloatingMenuPreviewDrawable;
+    }
+}
diff --git a/src/com/android/settings/accessibility/FloatingMenuLayerDrawable.java b/src/com/android/settings/accessibility/FloatingMenuLayerDrawable.java
new file mode 100644
index 00000000000..bfce114ae13
--- /dev/null
+++ b/src/com/android/settings/accessibility/FloatingMenuLayerDrawable.java
@@ -0,0 +1,133 @@
+/*
+ * Copyright (C) 2021 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.
+ */
+
+package com.android.settings.accessibility;
+
+import android.content.Context;
+import android.graphics.drawable.Drawable;
+import android.graphics.drawable.LayerDrawable;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.VisibleForTesting;
+
+import com.android.settings.R;
+
+import java.util.Objects;
+
+/** LayerDrawable that contains device icon as background and floating menu icon as foreground. */
+public class FloatingMenuLayerDrawable extends LayerDrawable {
+
+    private FloatingMenuLayerDrawableState mState;
+
+    /**
+     * Creates a new layer drawable with the list of specified layers.
+     *
+     * @param layers a list of drawables to use as layers in this new drawable,
+     *               must be non-null
+     */
+    private FloatingMenuLayerDrawable(@NonNull Drawable[] layers) {
+        super(layers);
+    }
+
+    /**
+     * Create the {@link LayerDrawable} that contains device icon as background and floating menu
+     * icon with given {@code opacity} value as foreground.
+     *
+     * @param context the valid context used to get the icon
+     * @param resId the resource ID of the floating menu icon
+     * @param opacity the opacity to apply to the given icon
+     * @return the drawable that combines the device icon and the floating menu icon
+     */
+    public static FloatingMenuLayerDrawable createLayerDrawable(Context context, int resId,
+            int opacity) {
+        final Drawable bg = context.getDrawable(R.drawable.accessibility_button_preview_base);
+        final FloatingMenuLayerDrawable basicDrawable = new FloatingMenuLayerDrawable(
+                new Drawable[]{bg, null});
+
+        basicDrawable.updateLayerDrawable(context, resId, opacity);
+        return basicDrawable;
+    }
+
+    /**
+     * Update the drawable  with given {@code resId} drawable and {@code opacity}(alpha)
+     * value at index 1 layer.
+     *
+     * @param context the valid context used to get the icon
+     * @param resId the resource ID of the floating menu icon
+     * @param opacity the opacity to apply to the given icon
+     */
+    public void updateLayerDrawable(Context context, int resId, int opacity) {
+        final Drawable icon = context.getDrawable(resId);
+        icon.setAlpha(opacity);
+        this.setDrawable(/* index= */ 1, icon);
+        this.setConstantState(context, resId, opacity);
+    }
+
+    @Override
+    public ConstantState getConstantState() {
+        return mState;
+    }
+
+    /** Stores the constant state and data to the given drawable. */
+    private void setConstantState(Context context, int resId, int opacity) {
+        mState = new FloatingMenuLayerDrawableState(context, resId, opacity);
+    }
+
+    /** {@link ConstantState} to store the data of {@link FloatingMenuLayerDrawable}. */
+    @VisibleForTesting
+    static class FloatingMenuLayerDrawableState extends ConstantState {
+
+        private final Context mContext;
+        private final int mResId;
+        private final int mOpacity;
+
+        FloatingMenuLayerDrawableState(Context context, int resId, int opacity) {
+            mContext = context;
+            mResId = resId;
+            mOpacity = opacity;
+        }
+
+        @NonNull
+        @Override
+        public Drawable newDrawable() {
+            return createLayerDrawable(mContext, mResId, mOpacity);
+        }
+
+        @Override
+        public int getChangingConfigurations() {
+            return 0;
+        }
+
+        @Override
+        public boolean equals(Object o) {
+            if (this == o) {
+                return true;
+            }
+            if (o == null || getClass() != o.getClass()) {
+                return false;
+            }
+            final FloatingMenuLayerDrawableState that = (FloatingMenuLayerDrawableState) o;
+            return mResId == that.mResId
+                    && mOpacity == that.mOpacity
+                    && Objects.equals(mContext, that.mContext);
+        }
+
+        @Override
+        public int hashCode() {
+            return Objects.hash(mContext, mResId, mOpacity);
+        }
+    }
+}
diff --git a/tests/robotests/src/com/android/settings/accessibility/AccessibilityButtonPreviewPreferenceControllerTest.java b/tests/robotests/src/com/android/settings/accessibility/AccessibilityButtonPreviewPreferenceControllerTest.java
new file mode 100644
index 00000000000..eb881757b28
--- /dev/null
+++ b/tests/robotests/src/com/android/settings/accessibility/AccessibilityButtonPreviewPreferenceControllerTest.java
@@ -0,0 +1,120 @@
+/*
+ * Copyright (C) 2021 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.
+ */
+
+package com.android.settings.accessibility;
+
+import static android.provider.Settings.Secure.ACCESSIBILITY_BUTTON_MODE_FLOATING_MENU;
+import static android.provider.Settings.Secure.ACCESSIBILITY_BUTTON_MODE_NAVIGATION_BAR;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+import android.content.ContentResolver;
+import android.content.Context;
+import android.graphics.drawable.Drawable;
+import android.provider.Settings;
+import android.widget.ImageView;
+
+import androidx.test.core.app.ApplicationProvider;
+
+import com.android.settings.R;
+
+import org.junit.Before;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.Mock;
+import org.mockito.Spy;
+import org.mockito.junit.MockitoJUnit;
+import org.mockito.junit.MockitoRule;
+import org.robolectric.RobolectricTestRunner;
+
+/** Tests for {@link AccessibilityButtonPreviewPreferenceController}. */
+@RunWith(RobolectricTestRunner.class)
+public class AccessibilityButtonPreviewPreferenceControllerTest {
+
+    @Rule
+    public MockitoRule mocks = MockitoJUnit.rule();
+
+    @Spy
+    private final Context mContext = ApplicationProvider.getApplicationContext();
+    @Mock
+    private ContentResolver mContentResolver;
+    private AccessibilityButtonPreviewPreferenceController mController;
+
+    @Before
+    public void setUp() {
+        when(mContext.getContentResolver()).thenReturn(mContentResolver);
+        mController = new AccessibilityButtonPreviewPreferenceController(mContext, "test_key");
+        mController.mPreview = new ImageView(mContext);
+    }
+
+    @Test
+    public void onChange_a11yBtnModeNavigationBar_getNavigationBarDrawable() {
+        Settings.Secure.putInt(mContentResolver, Settings.Secure.ACCESSIBILITY_BUTTON_MODE,
+                ACCESSIBILITY_BUTTON_MODE_NAVIGATION_BAR);
+
+        mController.mContentObserver.onChange(false);
+
+        final Drawable navigationBarDrawable = mContext.getDrawable(
+                R.drawable.accessibility_button_navigation);
+        assertThat(mController.mPreview.getDrawable().getConstantState()).isEqualTo(
+                navigationBarDrawable.getConstantState());
+    }
+
+    @Test
+    public void onChange_updatePreviewPreferenceWithConfig_expectedPreviewDrawable() {
+        Settings.Secure.putInt(mContentResolver,
+                Settings.Secure.ACCESSIBILITY_BUTTON_MODE, ACCESSIBILITY_BUTTON_MODE_FLOATING_MENU);
+        Settings.Secure.putInt(mContentResolver,
+                Settings.Secure.ACCESSIBILITY_FLOATING_MENU_SIZE, /* small size */ 0);
+        Settings.Secure.putFloat(mContentResolver,
+                Settings.Secure.ACCESSIBILITY_FLOATING_MENU_OPACITY, 0.1f);
+
+        mController.mContentObserver.onChange(false);
+
+        final Drawable smallFloatingMenuWithTenOpacityDrawable =
+                FloatingMenuLayerDrawable.createLayerDrawable(mContext,
+                        R.drawable.accessibility_button_preview_small_floating_menu, 10);
+        assertThat(mController.mPreview.getDrawable().getConstantState()).isEqualTo(
+                smallFloatingMenuWithTenOpacityDrawable.getConstantState());
+    }
+
+    @Test
+    public void onResume_registerSpecificContentObserver() {
+        mController.onResume();
+
+        verify(mContentResolver).registerContentObserver(
+                Settings.Secure.getUriFor(Settings.Secure.ACCESSIBILITY_BUTTON_MODE), false,
+                mController.mContentObserver);
+        verify(mContentResolver).registerContentObserver(
+                Settings.Secure.getUriFor(Settings.Secure.ACCESSIBILITY_FLOATING_MENU_SIZE), false,
+                mController.mContentObserver);
+        verify(mContentResolver).registerContentObserver(
+                Settings.Secure.getUriFor(Settings.Secure.ACCESSIBILITY_FLOATING_MENU_OPACITY),
+                false,
+                mController.mContentObserver);
+    }
+
+    @Test
+    public void onPause_unregisterContentObserver() {
+        mController.onPause();
+
+        verify(mContentResolver).unregisterContentObserver(mController.mContentObserver);
+    }
+}
diff --git a/tests/robotests/src/com/android/settings/accessibility/FloatingMenuLayerDrawableTest.java b/tests/robotests/src/com/android/settings/accessibility/FloatingMenuLayerDrawableTest.java
new file mode 100644
index 00000000000..ec449d249b5
--- /dev/null
+++ b/tests/robotests/src/com/android/settings/accessibility/FloatingMenuLayerDrawableTest.java
@@ -0,0 +1,73 @@
+/*
+ * Copyright (C) 2021 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.
+ */
+
+package com.android.settings.accessibility;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import android.content.Context;
+import android.graphics.drawable.Drawable;
+
+import androidx.test.core.app.ApplicationProvider;
+
+import com.android.settings.R;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.robolectric.RobolectricTestRunner;
+
+/** Tests for {@link FloatingMenuLayerDrawable}. */
+@RunWith(RobolectricTestRunner.class)
+public class FloatingMenuLayerDrawableTest {
+
+    private static final int TEST_RES_ID =
+            com.android.internal.R.drawable.ic_accessibility_magnification;
+    private static final int TEST_RES_ID_2 =
+            com.android.internal.R.drawable.ic_accessibility_color_inversion;
+    private final Context mContext = ApplicationProvider.getApplicationContext();
+
+    @Test
+    public void createLayerDrawable_configCorrect() {
+        final Drawable expected1stDrawable = mContext.getDrawable(
+                R.drawable.accessibility_button_preview_base);
+        final Drawable expected2ndDrawable = mContext.getDrawable(TEST_RES_ID);
+
+        final FloatingMenuLayerDrawable actualDrawable =
+                FloatingMenuLayerDrawable.createLayerDrawable(mContext, TEST_RES_ID,
+                        /* opacity= */ 27);
+
+        final Drawable actual1stDrawable = actualDrawable.getDrawable(0);
+        final Drawable actual2ndDrawable = actualDrawable.getDrawable(1);
+        // These are VectorDrawables, so it can use getConstantState() to compare.
+        assertThat(actual1stDrawable.getConstantState()).isEqualTo(
+                expected1stDrawable.getConstantState());
+        assertThat(actual2ndDrawable.getConstantState()).isEqualTo(
+                expected2ndDrawable.getConstantState());
+    }
+
+    @Test
+    public void updateLayerDrawable_expectedFloatingMenuLayerDrawableState() {
+        final FloatingMenuLayerDrawable originalDrawable =
+                FloatingMenuLayerDrawable.createLayerDrawable(mContext, TEST_RES_ID, /* opacity= */
+                        72);
+
+        originalDrawable.updateLayerDrawable(mContext, TEST_RES_ID_2, /* opacity= */ 27);
+
+        assertThat(originalDrawable.getConstantState()).isEqualTo(
+                new FloatingMenuLayerDrawable.FloatingMenuLayerDrawableState(mContext,
+                        TEST_RES_ID_2, /* opacity= */ 27));
+    }
+}