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      1 /*
      2  * Copyright (C) 2012 Google Inc.
      3  * Licensed to The Android Open Source Project.
      4  *
      5  * Licensed under the Apache License, Version 2.0 (the "License");
      6  * you may not use this file except in compliance with the License.
      7  * You may obtain a copy of the License at
      8  *
      9  *      http://www.apache.org/licenses/LICENSE-2.0
     10  *
     11  * Unless required by applicable law or agreed to in writing, software
     12  * distributed under the License is distributed on an "AS IS" BASIS,
     13  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     14  * See the License for the specific language governing permissions and
     15  * limitations under the License.
     16  */
     17 
     18 package com.android.mail.ui;
     19 
     20 import android.app.Activity;
     21 import android.content.AsyncTaskLoader;
     22 import android.net.Uri;
     23 
     24 import com.android.mail.browse.ConversationCursor;
     25 import com.android.mail.providers.Account;
     26 import com.android.mail.providers.UIProvider.AccountCapabilities;
     27 import com.android.mail.utils.LogUtils;
     28 
     29 import java.util.ArrayList;
     30 
     31 public class ConversationCursorLoader extends AsyncTaskLoader<ConversationCursor> {
     32     private static final String TAG = "ConversationCursorLoader";
     33     private final Uri mUri;
     34     private final ConversationCursor mConversationCursor;
     35     private boolean mInit = false;
     36     private boolean mClosed = false;
     37     private boolean mRetain = false;
     38     private boolean mRetained = false;
     39     private final String mName;
     40 
     41     /** Only used for debugging. Turn {@link #DEBUG} on to make this useful. */
     42     private static final boolean DEBUG = false;
     43     private static final ArrayList<ConversationCursorLoader> sLoaders =
     44             new ArrayList<ConversationCursorLoader>();
     45 
     46     public ConversationCursorLoader(Activity activity, Account account,
     47             Uri uri, String name, boolean ignoreInitialConversationLimit) {
     48         super(activity);
     49         mUri = uri;
     50         mName = name;
     51         final boolean useInitialConversationLimit = ignoreInitialConversationLimit ? false :
     52                 account.supportsCapability(AccountCapabilities.INITIAL_CONVERSATION_LIMIT);
     53         // Initialize the state of the conversation cursor
     54         mConversationCursor = new ConversationCursor(
     55                 activity, mUri, useInitialConversationLimit, name);
     56         addLoader();
     57     }
     58 
     59     private static void dumpLoaders() {
     60         if (DEBUG) {
     61             LogUtils.d(TAG, "Loaders: ");
     62             for (ConversationCursorLoader loader: sLoaders) {
     63                 LogUtils.d(TAG, " >> " + loader.mName + " (" + loader.mUri + ")");
     64             }
     65         }
     66     }
     67 
     68     private void addLoader() {
     69         if (DEBUG) {
     70             LogUtils.d(TAG, "Add loader: " + mUri);
     71             sLoaders.add(this);
     72             if (sLoaders.size() > 1) {
     73                 dumpLoaders();
     74             }
     75         }
     76     }
     77 
     78     /**
     79      * Indicate whether the loader's cursor should be retained after reset
     80      * @param state whether this laoder's cursor should be retained
     81      */
     82     public void retainCursor(boolean state) {
     83         mRetain = state;
     84     }
     85 
     86     @Override
     87     public void onReset() {
     88         if (!mRetain) {
     89             // Mark the cursor as disabled
     90             mConversationCursor.disable();
     91             mClosed = true;
     92             if (DEBUG) {
     93                 LogUtils.d(TAG, "Reset loader/disable cursor: " + mName);
     94                 sLoaders.remove(this);
     95                 if (!sLoaders.isEmpty()) {
     96                     dumpLoaders();
     97                 }
     98             }
     99         } else {
    100             if (DEBUG) {
    101                 LogUtils.d(TAG, "Reset loader/retain cursor: " + mName);
    102                 mRetained = true;
    103             }
    104         }
    105     }
    106 
    107     @Override
    108     public ConversationCursor loadInBackground() {
    109         if (!mInit) {
    110             mConversationCursor.load();
    111             mInit = true;
    112         }
    113         return mConversationCursor;
    114     }
    115 
    116     @Override
    117     protected void onStartLoading() {
    118         if (mClosed) {
    119             mClosed = false;
    120             mConversationCursor.load();
    121             addLoader();
    122             if (DEBUG) {
    123                 LogUtils.d(TAG, "Restarting reset loader: " + mName);
    124             }
    125         } else if (mRetained) {
    126             mRetained = false;
    127             if (DEBUG) {
    128                 LogUtils.d(TAG, "Resuming retained loader: " + mName);
    129             }
    130         }
    131         forceLoad();
    132         mConversationCursor.resume();
    133     }
    134 
    135     @Override
    136     protected void onStopLoading() {
    137         cancelLoad();
    138         mConversationCursor.pause();
    139     }
    140 }
    141