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      1 /*
      2  * Copyright (C) 2014 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.android.inputmethod.latin.settings;
     18 
     19 import android.app.backup.BackupManager;
     20 import android.content.Context;
     21 import android.content.SharedPreferences;
     22 import android.content.SharedPreferences.OnSharedPreferenceChangeListener;
     23 import android.os.Bundle;
     24 import android.preference.ListPreference;
     25 import android.preference.Preference;
     26 import android.preference.PreferenceFragment;
     27 import android.preference.PreferenceScreen;
     28 import android.util.Log;
     29 
     30 /**
     31  * A base abstract class for a {@link PreferenceFragment} that implements a nested
     32  * {@link PreferenceScreen} of the main preference screen.
     33  */
     34 abstract class SubScreenFragment extends PreferenceFragment
     35         implements OnSharedPreferenceChangeListener {
     36     private OnSharedPreferenceChangeListener mSharedPreferenceChangeListener;
     37 
     38     static void setPreferenceEnabled(final String prefKey, final boolean enabled,
     39             final PreferenceScreen screen) {
     40         final Preference preference = screen.findPreference(prefKey);
     41         if (preference != null) {
     42             preference.setEnabled(enabled);
     43         }
     44     }
     45 
     46     static void removePreference(final String prefKey, final PreferenceScreen screen) {
     47         final Preference preference = screen.findPreference(prefKey);
     48         if (preference != null) {
     49             screen.removePreference(preference);
     50         }
     51     }
     52 
     53     static void updateListPreferenceSummaryToCurrentValue(final String prefKey,
     54             final PreferenceScreen screen) {
     55         // Because the "%s" summary trick of {@link ListPreference} doesn't work properly before
     56         // KitKat, we need to update the summary programmatically.
     57         final ListPreference listPreference = (ListPreference)screen.findPreference(prefKey);
     58         if (listPreference == null) {
     59             return;
     60         }
     61         final CharSequence entries[] = listPreference.getEntries();
     62         final int entryIndex = listPreference.findIndexOfValue(listPreference.getValue());
     63         listPreference.setSummary(entryIndex < 0 ? null : entries[entryIndex]);
     64     }
     65 
     66     final void setPreferenceEnabled(final String prefKey, final boolean enabled) {
     67         setPreferenceEnabled(prefKey, enabled, getPreferenceScreen());
     68     }
     69 
     70     final void removePreference(final String prefKey) {
     71         removePreference(prefKey, getPreferenceScreen());
     72     }
     73 
     74     final void updateListPreferenceSummaryToCurrentValue(final String prefKey) {
     75         updateListPreferenceSummaryToCurrentValue(prefKey, getPreferenceScreen());
     76     }
     77 
     78     final SharedPreferences getSharedPreferences() {
     79         return getPreferenceManager().getSharedPreferences();
     80     }
     81 
     82     @Override
     83     public void addPreferencesFromResource(final int preferencesResId) {
     84         super.addPreferencesFromResource(preferencesResId);
     85         TwoStatePreferenceHelper.replaceCheckBoxPreferencesBySwitchPreferences(
     86                 getPreferenceScreen());
     87     }
     88 
     89     @Override
     90     public void onCreate(final Bundle savedInstanceState) {
     91         super.onCreate(savedInstanceState);
     92         mSharedPreferenceChangeListener = new OnSharedPreferenceChangeListener() {
     93             @Override
     94             public void onSharedPreferenceChanged(final SharedPreferences prefs, final String key) {
     95                 final SubScreenFragment fragment = SubScreenFragment.this;
     96                 final Context context = fragment.getActivity();
     97                 if (context == null || fragment.getPreferenceScreen() == null) {
     98                     final String tag = fragment.getClass().getSimpleName();
     99                     // TODO: Introduce a static function to register this class and ensure that
    100                     // onCreate must be called before "onSharedPreferenceChanged" is called.
    101                     Log.w(tag, "onSharedPreferenceChanged called before activity starts.");
    102                     return;
    103                 }
    104                 new BackupManager(context).dataChanged();
    105                 fragment.onSharedPreferenceChanged(prefs, key);
    106             }
    107         };
    108         getSharedPreferences().registerOnSharedPreferenceChangeListener(
    109                 mSharedPreferenceChangeListener);
    110     }
    111 
    112     @Override
    113     public void onDestroy() {
    114         getSharedPreferences().unregisterOnSharedPreferenceChangeListener(
    115                 mSharedPreferenceChangeListener);
    116         super.onDestroy();
    117     }
    118 
    119     @Override
    120     public void onSharedPreferenceChanged(final SharedPreferences prefs, final String key) {
    121         // This method may be overridden by an extended class.
    122     }
    123 }
    124