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
17package android.widget;
18
19import 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 */
27class 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