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  */
14 package 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  */
21 public 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      */
onItemSelected(Presenter.ViewHolder itemViewHolder, Object item, RowPresenter.ViewHolder rowViewHolder, T row)47     public void onItemSelected(Presenter.ViewHolder itemViewHolder, Object item,
48                                RowPresenter.ViewHolder rowViewHolder, T row);
49 }
50