1/*
2 * Copyright 2017 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 androidx.recyclerview.selection;
18
19import androidx.annotation.NonNull;
20import androidx.recyclerview.selection.ItemDetailsLookup.ItemDetails;
21import androidx.recyclerview.widget.RecyclerView;
22
23/**
24 * Override methods in this class to provide application specific behaviors
25 * related to focusing item.
26 *
27 * @param <K> Selection key type. @see {@link StorageStrategy} for supported types.
28 */
29public abstract class FocusDelegate<K> {
30
31    static <K> FocusDelegate<K> dummy() {
32        return new FocusDelegate<K>() {
33            @Override
34            public void focusItem(@NonNull ItemDetails<K> item) {
35            }
36
37            @Override
38            public boolean hasFocusedItem() {
39                return false;
40            }
41
42            @Override
43            public int getFocusedPosition() {
44                return RecyclerView.NO_POSITION;
45            }
46
47            @Override
48            public void clearFocus() {
49            }
50        };
51    }
52
53    /**
54     * If environment supports focus, focus {@code item}.
55     */
56    public abstract void focusItem(@NonNull ItemDetails<K> item);
57
58    /**
59     * @return true if there is a focused item.
60     */
61    public abstract boolean hasFocusedItem();
62
63    /**
64     * @return the position of the currently focused item, if any.
65     */
66    public abstract int getFocusedPosition();
67
68    /**
69     * If the environment supports focus and something is focused, unfocus it.
70     */
71    public abstract void clearFocus();
72}
73