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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.camera.settings;
     18 
     19 import java.util.HashMap;
     20 
     21 /**
     22  * A class for storing default values and possible values of
     23  * SharedPreferences settings.  It is optional to store defaults
     24  * and possible values for a setting.  If a default is not specified,
     25  * the SettingsManager API chooses a default based on the type
     26  * requested:
     27  *
     28  * <ul>getString: default is null</ul>
     29  * <ul>getInteger: default is 0</ul>
     30  * <ul>getBoolean: default is false</ul>
     31  *
     32  * If possible values aren't specified for a
     33  * SharedPreferences key, then calling getIndexOfCurrentValue
     34  * and setValueByIndex will throw an IllegalArgumentException.
     35  */
     36 class DefaultsStore {
     37 
     38     /**
     39      * A class for storing a default value and set of possible
     40      * values.  Since all settings values are saved as Strings in
     41      * SharedPreferences, the default and possible values are
     42      * Strings.  This simplifies default values management.
     43      */
     44     private static class Defaults {
     45         private String mDefaultValue;
     46         private String[] mPossibleValues;
     47 
     48         public Defaults(String defaultValue, String[] possibleValues) {
     49             mDefaultValue = defaultValue;
     50             mPossibleValues = possibleValues;
     51         }
     52 
     53         public String getDefaultValue() {
     54             return mDefaultValue;
     55         }
     56 
     57         public String[] getPossibleValues() {
     58             return mPossibleValues;
     59         }
     60     }
     61 
     62     /** Map of Defaults for SharedPreferences keys. */
     63     private static HashMap<String, Defaults> mDefaultsInternalStore =
     64         new HashMap<String, Defaults>();
     65 
     66     /**
     67      * Store a default value and a set of possible values
     68      * for a SharedPreferences key.
     69      */
     70     public void storeDefaults(String key, String defaultValue, String[] possibleValues) {
     71         Defaults defaults = new Defaults(defaultValue, possibleValues);
     72         mDefaultsInternalStore.put(key, defaults);
     73     }
     74 
     75     /**
     76      * Get the default value for a SharedPreferences key,
     77      * if one has been stored.
     78      */
     79     public String getDefaultValue(String key) {
     80         Defaults defaults = mDefaultsInternalStore.get(key);
     81         if (defaults == null) {
     82             return null;
     83         }
     84         return defaults.getDefaultValue();
     85     }
     86 
     87     /**
     88      * Get the set of possible values for a SharedPreferences key,
     89      * if a set has been stored.
     90      */
     91     public String[] getPossibleValues(String key) {
     92         Defaults defaults = mDefaultsInternalStore.get(key);
     93         if (defaults == null) {
     94             return null;
     95         }
     96         return defaults.getPossibleValues();
     97     }
     98 }