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      1 /*
      2  * Copyright (C) 2017 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.settings.widget;
     18 
     19 import android.content.Context;
     20 import android.text.TextUtils;
     21 
     22 /**
     23  * Helper class that listens to settings changes and notifies client when there is update in
     24  * corresponding summary info.
     25  */
     26 public abstract class SummaryUpdater {
     27 
     28     protected final Context mContext;
     29 
     30     private final OnSummaryChangeListener mListener;
     31     private String mSummary;
     32 
     33     /**
     34      * Interface definition for a callback to be invoked when the summary has been changed.
     35      */
     36     public interface OnSummaryChangeListener {
     37         /**
     38          * Called when summary has changed.
     39          *
     40          * @param summary The new summary .
     41          */
     42         void onSummaryChanged(String summary);
     43     }
     44 
     45     /**
     46      * Constructor
     47      *
     48      * @param context The Context the updater is running in, through which it can register broadcast
     49      * receiver etc.
     50      * @param listener The listener that would like to receive summary change notification.
     51      *
     52      */
     53     public SummaryUpdater(Context context, OnSummaryChangeListener listener) {
     54         mContext = context;
     55         mListener = listener;
     56     }
     57 
     58     /**
     59      * Notifies the listener when there is update in summary
     60      */
     61     protected void notifyChangeIfNeeded() {
     62         String summary = getSummary();
     63         if (!TextUtils.equals(mSummary, summary)) {
     64             mSummary = summary;
     65             if (mListener != null) {
     66                 mListener.onSummaryChanged(summary);
     67             }
     68         }
     69     }
     70 
     71     /**
     72      * Starts/stops receiving updates on the summary.
     73      *
     74      * @param register true if we want to receive updates, false otherwise
     75      */
     76     public abstract void register(boolean register);
     77 
     78     /**
     79      * Gets the summary. Subclass should checks latest conditions and update the summary
     80      * accordingly.
     81      *
     82      * @return  the latest summary text
     83      */
     84     protected abstract String getSummary();
     85 
     86 }
     87