1/*
2 * Copyright (C) 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 com.android.internal.view;
18
19import android.os.Handler;
20import android.os.Message;
21import android.view.Choreographer;
22import android.view.Display;
23
24/**
25 * Utility class to schedule things at vsync-sf instead of vsync-app
26 * @hide
27 */
28public class SurfaceFlingerVsyncChoreographer {
29
30    private static final long ONE_MS_IN_NS = 1000000;
31    private static final long ONE_S_IN_NS = ONE_MS_IN_NS * 1000;
32
33    private final Handler mHandler;
34    private final Choreographer mChoreographer;
35
36    /**
37     * The offset between vsync-app and vsync-surfaceflinger. See
38     * {@link #calculateAppSurfaceFlingerVsyncOffsetMs} why this is necessary.
39     */
40    private long mSurfaceFlingerOffsetMs;
41
42    public SurfaceFlingerVsyncChoreographer(Handler handler, Display display,
43            Choreographer choreographer) {
44        mHandler = handler;
45        mChoreographer = choreographer;
46        mSurfaceFlingerOffsetMs = calculateAppSurfaceFlingerVsyncOffsetMs(display);
47    }
48
49    public long getSurfaceFlingerOffsetMs() {
50        return mSurfaceFlingerOffsetMs;
51    }
52
53    /**
54     * This method calculates the offset between vsync-surfaceflinger and vsync-app. If vsync-app
55     * is a couple of milliseconds before vsync-sf, a touch or animation event that causes a surface
56     * flinger transaction are sometimes processed before the vsync-sf tick, and sometimes after,
57     * which leads to jank. Figure out this difference here and then post all the touch/animation
58     * events to start being processed at vsync-sf.
59     *
60     * @return The offset between vsync-app and vsync-sf, or 0 if vsync app happens after vsync-sf.
61     */
62    private long calculateAppSurfaceFlingerVsyncOffsetMs(Display display) {
63
64        // Calculate vsync offset from SurfaceFlinger.
65        // See frameworks/native/services/surfaceflinger/SurfaceFlinger.cpp:getDisplayConfigs
66        long vsyncPeriod = (long) (ONE_S_IN_NS / display.getRefreshRate());
67        long sfVsyncOffset = vsyncPeriod - (display.getPresentationDeadlineNanos() - ONE_MS_IN_NS);
68        return Math.max(0, (sfVsyncOffset - display.getAppVsyncOffsetNanos()) / ONE_MS_IN_NS);
69    }
70
71    public void scheduleAtSfVsync(Runnable r) {
72        final long delay = calculateDelay();
73        if (delay <= 0) {
74            r.run();
75        } else {
76            mHandler.postDelayed(r, delay);
77        }
78    }
79
80    public void scheduleAtSfVsync(Handler h, Message m) {
81        final long delay = calculateDelay();
82        if (delay <= 0) {
83            h.handleMessage(m);
84        } else {
85            m.setAsynchronous(true);
86            h.sendMessageDelayed(m, delay);
87        }
88    }
89
90    private long calculateDelay() {
91        final long sinceFrameStart = System.nanoTime() - mChoreographer.getLastFrameTimeNanos();
92        return mSurfaceFlingerOffsetMs - sinceFrameStart / 1000000;
93    }
94}
95