1/*
2 * Copyright (C) 2012 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 com.android.server.power;
18
19/**
20 * Low-level screen on blocker mechanism which is used to keep the screen off
21 * or the contents of the screen hidden until the window manager is ready to show new content.
22 */
23interface ScreenOnBlocker {
24    /**
25     * Acquires the screen on blocker.
26     * Prevents the screen from turning on.
27     *
28     * Calls to acquire() nest and must be matched by the same number
29     * of calls to release().
30     */
31    void acquire();
32
33    /**
34     * Releases the screen on blocker.
35     * Allows the screen to turn on.
36     *
37     * It is an error to call release() if the screen on blocker has not been acquired.
38     * The system may crash.
39     */
40    void release();
41}
42