Extract footer preference as a widget lib

Currently, developer needs to import SettingsLib to use
footer preference. But the size of SettingsLib is too huge.

We extract the footer preference as a lib so that developer
only needs to import a small lib for using footer.

Test: Rebuilt apk, and see the footer preference
Fix: 173088235
Change-Id: I35ba99a49c7a13542d79f0340eecdbe9844102d0
diff --git a/packages/SettingsLib/FooterPreference/Android.bp b/packages/SettingsLib/FooterPreference/Android.bp
new file mode 100644
index 0000000..30d9bd2
--- /dev/null
+++ b/packages/SettingsLib/FooterPreference/Android.bp
@@ -0,0 +1,13 @@
+android_library {
+    name: "SettingsLibFooterPreference",
+
+    srcs: ["src/**/*.java"],
+    resource_dirs: ["res"],
+
+    static_libs: [
+        "androidx.annotation_annotation",
+        "androidx.preference_preference",
+    ],
+    sdk_version: "system_current",
+    min_sdk_version: "21",
+}
diff --git a/packages/SettingsLib/FooterPreference/AndroidManifest.xml b/packages/SettingsLib/FooterPreference/AndroidManifest.xml
new file mode 100644
index 0000000..96d9e51
--- /dev/null
+++ b/packages/SettingsLib/FooterPreference/AndroidManifest.xml
@@ -0,0 +1,23 @@
+<?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.
+  -->
+
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+          package="com.android.settingslib.widget">
+
+    <uses-sdk android:minSdkVersion="21" />
+
+</manifest>
diff --git a/packages/SettingsLib/FooterPreference/res/drawable/ic_info_outline_24.xml b/packages/SettingsLib/FooterPreference/res/drawable/ic_info_outline_24.xml
new file mode 100644
index 0000000..d9afeb0
--- /dev/null
+++ b/packages/SettingsLib/FooterPreference/res/drawable/ic_info_outline_24.xml
@@ -0,0 +1,27 @@
+<?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.
+  -->
+
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+        android:width="24dp"
+        android:height="24dp"
+        android:viewportWidth="24.0"
+        android:viewportHeight="24.0"
+        android:tint="?android:attr/colorControlNormal">
+    <path
+        android:fillColor="#FF000000"
+        android:pathData="M11,17h2v-6h-2v6zM12,2C6.48,2 2,6.48 2,12s4.48,10 10,10 10,-4.48 10,-10S17.52,2 12,2zM12,20c-4.41,0 -8,-3.59 -8,-8s3.59,-8 8,-8 8,3.59 8,8 -3.59,8 -8,8zM11,9h2L13,7h-2v2z"/>
+</vector>
diff --git a/packages/SettingsLib/FooterPreference/res/values/attrs.xml b/packages/SettingsLib/FooterPreference/res/values/attrs.xml
new file mode 100644
index 0000000..deba3af
--- /dev/null
+++ b/packages/SettingsLib/FooterPreference/res/values/attrs.xml
@@ -0,0 +1,19 @@
+<?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.
+-->
+
+<resources>
+    <attr name="footerPreferenceStyle" format="reference" />
+</resources>
\ No newline at end of file
diff --git a/packages/SettingsLib/FooterPreference/src/com/android/settingslib/widget/FooterPreference.java b/packages/SettingsLib/FooterPreference/src/com/android/settingslib/widget/FooterPreference.java
new file mode 100644
index 0000000..15301f6
--- /dev/null
+++ b/packages/SettingsLib/FooterPreference/src/com/android/settingslib/widget/FooterPreference.java
@@ -0,0 +1,139 @@
+/*
+ * 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.
+ */
+
+package com.android.settingslib.widget;
+
+import android.content.Context;
+import android.text.TextUtils;
+import android.text.method.LinkMovementMethod;
+import android.util.AttributeSet;
+import android.widget.TextView;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.StringRes;
+import androidx.core.content.res.TypedArrayUtils;
+import androidx.preference.Preference;
+import androidx.preference.PreferenceViewHolder;
+
+/**
+ * A custom preference acting as "footer" of a page. It has a field for icon and text. It is added
+ * to screen as the last preference.
+ */
+public class FooterPreference extends Preference {
+
+    public static final String KEY_FOOTER = "footer_preference";
+    static final int ORDER_FOOTER = Integer.MAX_VALUE - 1;
+
+    public FooterPreference(Context context, AttributeSet attrs) {
+        super(context, attrs, TypedArrayUtils.getAttr(
+                context, R.attr.footerPreferenceStyle, android.R.attr.preferenceStyle));
+        init();
+    }
+
+    public FooterPreference(Context context) {
+        this(context, null);
+    }
+
+    @Override
+    public void onBindViewHolder(PreferenceViewHolder holder) {
+        super.onBindViewHolder(holder);
+        TextView title = holder.itemView.findViewById(android.R.id.title);
+        title.setMovementMethod(new LinkMovementMethod());
+        title.setClickable(false);
+        title.setLongClickable(false);
+    }
+
+    @Override
+    public void setSummary(CharSequence summary) {
+        setTitle(summary);
+    }
+
+    @Override
+    public void setSummary(int summaryResId) {
+        setTitle(summaryResId);
+    }
+
+    @Override
+    public CharSequence getSummary() {
+        return getTitle();
+    }
+
+    private void init() {
+        if (getIcon() == null) {
+            setIcon(R.drawable.ic_info_outline_24);
+        }
+        setOrder(ORDER_FOOTER);
+        if (TextUtils.isEmpty(getKey())) {
+            setKey(KEY_FOOTER);
+        }
+    }
+
+    /**
+     * The builder is convenient to creat a dynamic FooterPreference.
+     */
+    public static class Builder {
+        private Context mContext;
+        private String mKey;
+        private CharSequence mTitle;
+
+        public Builder(@NonNull Context context) {
+            mContext = context;
+        }
+
+        /**
+         * To set the key value of the {@link FooterPreference}.
+         * @param key The key value.
+         */
+        public Builder setKey(@NonNull String key) {
+            mKey = key;
+            return this;
+        }
+
+        /**
+         * To set the title of the {@link FooterPreference}.
+         * @param title The title.
+         */
+        public Builder setTitle(CharSequence title) {
+            mTitle = title;
+            return this;
+        }
+
+        /**
+         * To set the title of the {@link FooterPreference}.
+         * @param titleResId The resource id of the title.
+         */
+        public Builder setTitle(@StringRes int titleResId) {
+            mTitle = mContext.getText(titleResId);
+            return this;
+        }
+
+        /**
+         * To generate the {@link FooterPreference}.
+         */
+        public FooterPreference build() {
+            final FooterPreference footerPreference = new FooterPreference(mContext);
+            footerPreference.setSelectable(false);
+            if (TextUtils.isEmpty(mTitle)) {
+                throw new IllegalArgumentException("Footer title cannot be empty!");
+            }
+            footerPreference.setTitle(mTitle);
+            if (!TextUtils.isEmpty(mKey)) {
+                footerPreference.setKey(mKey);
+            }
+            return footerPreference;
+        }
+    }
+}