Settings: Add option to scramble pin layout when unlocking (1/2).

Change-Id: I3e2c200a0a31d3c765831bc30280029a50c88051

src/com/android/settings/security/screenlock/PinScramblePreferenceController.java

@@ -0,0 +1,78 @@
+/*
+ * Copyright (C) 2018 The LineageOS 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.security.screenlock;
+
+import android.app.admin.DevicePolicyManager;
+import android.content.Context;
+import androidx.preference.Preference;
+import androidx.preference.TwoStatePreference;
+
+import com.android.internal.widget.LockPatternUtils;
+import com.android.settings.core.PreferenceControllerMixin;
+import com.android.settingslib.core.AbstractPreferenceController;
+
+import lineageos.providers.LineageSettings;
+
+public class PinScramblePreferenceController extends AbstractPreferenceController
+        implements PreferenceControllerMixin, Preference.OnPreferenceChangeListener {
+
+    static final String KEY_LOCKSCREEN_SCRAMBLE_PIN_LAYOUT = "lockscreen_scramble_pin_layout";
+
+    private final int mUserId;
+    private final LockPatternUtils mLockPatternUtils;
+
+    public PinScramblePreferenceController(Context context, int userId,
+            LockPatternUtils lockPatternUtils) {
+        super(context);
+        mUserId = userId;
+        mLockPatternUtils = lockPatternUtils;
+    }
+
+    @Override
+    public boolean isAvailable() {
+        return isPinLock();
+    }
+
+    @Override
+    public String getPreferenceKey() {
+        return KEY_LOCKSCREEN_SCRAMBLE_PIN_LAYOUT;
+    }
+
+    @Override
+    public void updateState(Preference preference) {
+        ((TwoStatePreference) preference).setChecked(LineageSettings.System.getInt(
+                mContext.getContentResolver(),
+                LineageSettings.System.LOCKSCREEN_PIN_SCRAMBLE_LAYOUT,
+                0) == 1);
+    }
+
+    private boolean isPinLock() {
+        int quality = mLockPatternUtils.getKeyguardStoredPasswordQuality(mUserId);
+        boolean hasPin = quality == DevicePolicyManager.PASSWORD_QUALITY_NUMERIC ||
+                quality == DevicePolicyManager.PASSWORD_QUALITY_NUMERIC_COMPLEX;
+        return mLockPatternUtils.isSecure(mUserId) && hasPin;
+    }
+
+    @Override
+    public boolean onPreferenceChange(Preference preference, Object newValue) {
+        LineageSettings.System.putInt(
+                mContext.getContentResolver(),
+                LineageSettings.System.LOCKSCREEN_PIN_SCRAMBLE_LAYOUT,
+                (Boolean) newValue ? 1 : 0);
+        return true;
+    }
+}

src/com/android/settings/security/screenlock/ScreenLockSettings.java

@@ -92,6 +92,8 @@ public class ScreenLockSettings extends DashboardFragment
                 context, MY_USER_ID, lockPatternUtils));
         controllers.add(new AutoPinConfirmPreferenceController(
                 context, MY_USER_ID, lockPatternUtils, parent));
+        controllers.add(new PinScramblePreferenceController(
+                context, MY_USER_ID, lockPatternUtils));
         controllers.add(new OwnerInfoPreferenceController(context, parent));
         return controllers;
     }