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      1 /*
      2  * Copyright (C) 2007 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 android.widget;
     18 
     19 import android.database.Cursor;
     20 
     21 /**
     22  * <p>The CursorFilter delegates most of the work to the CursorAdapter.
     23  * Subclasses should override these delegate methods to run the queries
     24  * and convert the results into String that can be used by auto-completion
     25  * widgets.</p>
     26  */
     27 class CursorFilter extends Filter {
     28 
     29     CursorFilterClient mClient;
     30 
     31     interface CursorFilterClient {
     32         CharSequence convertToString(Cursor cursor);
     33         Cursor runQueryOnBackgroundThread(CharSequence constraint);
     34         Cursor getCursor();
     35         void changeCursor(Cursor cursor);
     36     }
     37 
     38     CursorFilter(CursorFilterClient client) {
     39         mClient = client;
     40     }
     41 
     42     @Override
     43     public CharSequence convertResultToString(Object resultValue) {
     44         return mClient.convertToString((Cursor) resultValue);
     45     }
     46 
     47     @Override
     48     protected FilterResults performFiltering(CharSequence constraint) {
     49         Cursor cursor = mClient.runQueryOnBackgroundThread(constraint);
     50 
     51         FilterResults results = new FilterResults();
     52         if (cursor != null) {
     53             results.count = cursor.getCount();
     54             results.values = cursor;
     55         } else {
     56             results.count = 0;
     57             results.values = null;
     58         }
     59         return results;
     60     }
     61 
     62     @Override
     63     protected void publishResults(CharSequence constraint, FilterResults results) {
     64         Cursor oldCursor = mClient.getCursor();
     65 
     66         if (results.values != null && results.values != oldCursor) {
     67             mClient.changeCursor((Cursor) results.values);
     68         }
     69     }
     70 }
     71