Add a new setting for QR Code Scanner button on lockscreen

This change adds a new setting to enable/disable the lock screen entry
point for QR Code scanner

Bug: 200536509
Test: make RunSettingsRoboTests -j40

Change-Id: Id200499b62f59fd631d837f9ae8e494532c23e13

res/values/strings.xml

@@ -13309,6 +13309,11 @@
     <!-- Wallet (formerly Cards and passes) summary [CHAR LIMIT=NONE] -->
     <string name="lockscreen_privacy_wallet_summary">Allow access to wallet from lock screen and quick settings</string>
 
+    <!-- QR Code Scanner toggle name [CHAR LIMIT=60] -->
+    <string name="lockscreen_privacy_qr_code_scanner_setting_toggle">Show QR Code Scanner</string>
+    <!-- QR Code Scanner summary [CHAR LIMIT=NONE] -->
+    <string name="lockscreen_privacy_qr_code_scanner_summary">Allow access to QR code scanner from lock screen</string>
+
     <!-- Device controls toggle name [CHAR LIMIT=60] -->
     <string name="lockscreen_privacy_controls_setting_toggle">Show device controls</string>
     <!-- Device controls summary [CHAR LIMIT=NONE] -->

res/xml/security_lockscreen_settings.xml

@@ -51,6 +51,12 @@
             android:summary="@string/lockscreen_privacy_wallet_summary"
             settings:controller="com.android.settings.display.WalletPrivacyPreferenceController" />
 
+        <SwitchPreference
+            android:key="lock_screen_show_qr_scanner"
+            android:title="@string/lockscreen_privacy_qr_code_scanner_setting_toggle"
+            android:summary="@string/lockscreen_privacy_qr_code_scanner_summary"
+            settings:controller="com.android.settings.display.QRCodeScannerPreferenceController" />
+
         <SwitchPreference
             android:key="lockscreen_privacy_controls_switch"
             android:title="@string/lockscreen_privacy_controls_setting_toggle"

src/com/android/settings/display/QRCodeScannerPreferenceController.java

@@ -0,0 +1,108 @@
+/*
+ * 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.display;
+
+import static android.provider.Settings.Secure.SHOW_QR_CODE_SCANNER_SETTING;
+
+import static androidx.lifecycle.Lifecycle.Event.ON_START;
+import static androidx.lifecycle.Lifecycle.Event.ON_STOP;
+
+import android.content.ContentResolver;
+import android.content.Context;
+import android.database.ContentObserver;
+import android.net.Uri;
+import android.provider.Settings;
+
+import androidx.lifecycle.OnLifecycleEvent;
+import androidx.preference.Preference;
+import androidx.preference.PreferenceScreen;
+
+import com.android.settings.R;
+import com.android.settings.core.TogglePreferenceController;
+
+/**
+ * Preference controller for enabling/disabling QR code scanner button on lock screen.
+ */
+public class QRCodeScannerPreferenceController extends TogglePreferenceController {
+    private static final String SETTING_KEY = Settings.Secure.LOCK_SCREEN_SHOW_QR_CODE_SCANNER;
+    private final ContentObserver mSettingsObserver;
+    private final ContentResolver mContentResolver;
+    private Preference mPreference;
+
+    public QRCodeScannerPreferenceController(Context context, String preferenceKey) {
+        super(context, preferenceKey);
+        mContentResolver = context.getContentResolver();
+        mSettingsObserver = new ContentObserver(null) {
+            @Override
+            public void onChange(boolean selfChange, Uri uri) {
+                updateState(mPreference);
+            }
+        };
+    }
+
+    @Override
+    public void displayPreference(PreferenceScreen screen) {
+        super.displayPreference(screen);
+        mPreference = screen.findPreference(getPreferenceKey());
+    }
+
+    /** Called when activity starts being displayed to user. */
+    @OnLifecycleEvent(ON_START)
+    public void onStart() {
+        mContentResolver.registerContentObserver(
+                Settings.Global.getUriFor(SHOW_QR_CODE_SCANNER_SETTING), false,
+                mSettingsObserver);
+    }
+
+    /** Called when activity stops being displayed to user. */
+    @OnLifecycleEvent(ON_STOP)
+    public void onStop() {
+        mContentResolver.unregisterContentObserver(mSettingsObserver);
+    }
+
+    @Override
+    public boolean isChecked() {
+        return Settings.Secure.getInt(mContext.getContentResolver(), SETTING_KEY, 0) != 0;
+    }
+
+    @Override
+    public boolean setChecked(boolean isChecked) {
+        return Settings.Secure.putInt(mContext.getContentResolver(), SETTING_KEY,
+                isChecked ? 1 : 0);
+    }
+
+    @Override
+    public int getAvailabilityStatus() {
+        return isScannerActivityAvailable() ? AVAILABLE : UNSUPPORTED_ON_DEVICE;
+    }
+
+    @Override
+    public void updateState(Preference preference) {
+        super.updateState(preference);
+        refreshSummary(preference);
+    }
+
+    @Override
+    public int getSliceHighlightMenuRes() {
+        return R.string.menu_key_display;
+    }
+
+    private boolean isScannerActivityAvailable() {
+        return Settings.Secure.getString(mContext.getContentResolver(),
+                SHOW_QR_CODE_SCANNER_SETTING) != null;
+    }
+}