1/*
2 * Copyright (C) 2011 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.support.v4.widget;
18
19import android.database.Cursor;
20import android.widget.Filter;
21
22/**
23 * The CursorFilter delegates most of the work to the
24 * {@link android.widget.CursorAdapter}. Subclasses should override these
25 * delegate methods to run the queries and convert the results into String
26 * that can be used by auto-completion widgets.
27 */
28class CursorFilter extends Filter {
29
30    CursorFilterClient mClient;
31
32    interface CursorFilterClient {
33        CharSequence convertToString(Cursor cursor);
34        Cursor runQueryOnBackgroundThread(CharSequence constraint);
35        Cursor getCursor();
36        void changeCursor(Cursor cursor);
37    }
38
39    CursorFilter(CursorFilterClient client) {
40        mClient = client;
41    }
42
43    @Override
44    public CharSequence convertResultToString(Object resultValue) {
45        return mClient.convertToString((Cursor) resultValue);
46    }
47
48    @Override
49    protected FilterResults performFiltering(CharSequence constraint) {
50        Cursor cursor = mClient.runQueryOnBackgroundThread(constraint);
51
52        FilterResults results = new FilterResults();
53        if (cursor != null) {
54            results.count = cursor.getCount();
55            results.values = cursor;
56        } else {
57            results.count = 0;
58            results.values = null;
59        }
60        return results;
61    }
62
63    @Override
64    protected void publishResults(CharSequence constraint, FilterResults results) {
65        Cursor oldCursor = mClient.getCursor();
66
67        if (results.values != null && results.values != oldCursor) {
68            mClient.changeCursor((Cursor) results.values);
69        }
70    }
71}
72