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 {
convertToString(Cursor cursor)32         CharSequence convertToString(Cursor cursor);
runQueryOnBackgroundThread(CharSequence constraint)33         Cursor runQueryOnBackgroundThread(CharSequence constraint);
getCursor()34         Cursor getCursor();
changeCursor(Cursor cursor)35         void changeCursor(Cursor cursor);
36     }
37 
CursorFilter(CursorFilterClient client)38     CursorFilter(CursorFilterClient client) {
39         mClient = client;
40     }
41 
42     @Override
convertResultToString(Object resultValue)43     public CharSequence convertResultToString(Object resultValue) {
44         return mClient.convertToString((Cursor) resultValue);
45     }
46 
47     @Override
performFiltering(CharSequence constraint)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
publishResults(CharSequence constraint, FilterResults results)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