1/*
2 * Copyright (C) 2016 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
5 * in compliance with the License. You may obtain a copy of the License at
6 *
7 * http://www.apache.org/licenses/LICENSE-2.0
8 *
9 * Unless required by applicable law or agreed to in writing, software distributed under the License
10 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
11 * or implied. See the License for the specific language governing permissions and limitations under
12 * the License.
13 */
14package android.support.v17.leanback.widget;
15
16/**
17 * Interface for receiving notification when a row or item becomes selected. The concept of
18 * current selection is different than focus.  A row or item can be selected without having focus;
19 * for example, when a row header view gains focus then the corresponding row view becomes selected.
20 */
21public interface BaseOnItemViewSelectedListener<T> {
22
23    /**
24     * Called when a row or a new item becomes selected.
25     * <p>
26     * For a non {@link ListRow} case, parameter item may be null.  Event is fired when
27     * selection changes between rows, regardless if row view has focus or not.
28     * <p>
29     * For a {@link ListRow} case, parameter item is null if the list row is empty.
30     * </p>
31     * <p>
32     * In the case of a grid, the row parameter is always null.
33     * </p>
34     * <li>
35     * Row has focus: event is fired when focus changes between children of the row.
36     * </li>
37     * <li>
38     * No row has focus: the event is fired with the currently selected row and last
39     * focused item in the row.
40     * </li>
41     *
42     * @param itemViewHolder The view holder of the item that is currently selected.
43     * @param item The item that is currently selected.
44     * @param rowViewHolder The view holder of the row that is currently selected.
45     * @param row The row that is currently selected.
46     */
47    public void onItemSelected(Presenter.ViewHolder itemViewHolder, Object item,
48                               RowPresenter.ViewHolder rowViewHolder, T row);
49}
50