New feature “Text and reading options” for SetupWizard, Wallpaper, and Settings (8/n).

- Extending the LabeledSeekBarPreference
1) Add new attributes, "iconStart", "iconEnd",
"iconStartContentDescription", "iconEndContentDescription"
2) Add new interface setOnSeekBarChangeListener
- It will be integrated with display/font size items in next patches.

Bug: 211503117
Test: make -j64 RunSettingsRoboTests ROBOTEST_FILTER=LabeledSeekBarPreferenceTest
Change-Id: Id8fe4fb68062c0e92ca4c291d2f7c47303e8691e

res/layout/icon_discrete_slider.xml

@@ -0,0 +1,72 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+    Copyright (C) 2022 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.
+-->
+
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:id="@+id/seekbar_frame"
+    android:layout_width="match_parent"
+    android:layout_height="wrap_content"
+    android:background="?android:colorBackground"
+    android:gravity="center_vertical">
+
+    <FrameLayout
+        android:id="@+id/icon_start_frame"
+        android:layout_width="48dp"
+        android:layout_height="48dp"
+        android:background="?android:attr/selectableItemBackgroundBorderless"
+        android:focusable="true"
+        android:visibility="gone">
+
+        <ImageView
+            android:id="@+id/icon_start"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_gravity="start|center_vertical"
+            android:adjustViewBounds="true"
+            android:focusable="false"
+            android:tint="?android:attr/textColorPrimary"
+            android:tintMode="src_in" />
+    </FrameLayout>
+
+    <SeekBar
+        android:id="@*android:id/seekbar"
+        style="@android:style/Widget.Material.SeekBar.Discrete"
+        android:layout_width="0dp"
+        android:layout_height="48dp"
+        android:layout_gravity="center_vertical"
+        android:layout_weight="1"
+        android:paddingEnd="12dp"
+        android:paddingStart="0dp" />
+
+    <FrameLayout
+        android:id="@+id/icon_end_frame"
+        android:layout_width="48dp"
+        android:layout_height="48dp"
+        android:background="?android:attr/selectableItemBackgroundBorderless"
+        android:focusable="true"
+        android:visibility="gone">
+
+        <ImageView
+            android:id="@+id/icon_end"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_gravity="end|center_vertical"
+            android:adjustViewBounds="true"
+            android:focusable="false"
+            android:tint="?android:attr/textColorPrimary"
+            android:tintMode="src_in" />
+    </FrameLayout>
+</LinearLayout>

res/layout/preference_labeled_slider.xml

@@ -46,20 +46,16 @@
         android:textAlignment="viewStart"
         android:textColor="?android:attr/textColorSecondary" />
 
-    <SeekBar
-        android:id="@*android:id/seekbar"
-        android:layout_below="@android:id/summary"
-        android:layout_gravity="center_vertical"
+    <include
+        layout="@layout/icon_discrete_slider"
         android:layout_width="match_parent"
-        android:layout_height="48dp"
-        android:paddingStart="0dp"
-        android:paddingEnd="12dp"
-        style="@android:style/Widget.Material.SeekBar.Discrete" />
+        android:layout_height="wrap_content"
+        android:layout_below="@android:id/summary" />
 
     <LinearLayout
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
-        android:layout_below="@*android:id/seekbar"
+        android:layout_below="@id/seekbar_frame"
         android:orientation="horizontal">
 
         <TextView

res/values/attrs.xml

@@ -169,6 +169,10 @@
         <attr name="textStart" format="reference" />
         <attr name="textEnd" format="reference" />
         <attr name="tickMark" format="reference" />
+        <attr name="iconStart" format="reference" />
+        <attr name="iconEnd" format="reference" />
+        <attr name="iconStartContentDescription" format="reference" />
+        <attr name="iconEndContentDescription" format="reference" />
     </declare-styleable>
 
     <declare-styleable name="TintDrawable">