1/*
2 * Copyright (c) 2014, Google Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions are
6 * met:
7 *
8 *     * Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 *     * Redistributions in binary form must reproduce the above
11 * copyright notice, this list of conditions and the following disclaimer
12 * in the documentation and/or other materials provided with the
13 * distribution.
14 *     * Neither the name of Google Inc. nor the names of its
15 * contributors may be used to endorse or promote products derived from
16 * this software without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
21 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
22 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
23 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
24 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
28 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 */
30
31#include "config.h"
32#include "core/animation/AnimationClock.h"
33
34#include "wtf/CurrentTime.h"
35#include <math.h>
36
37namespace {
38
39// FIXME: This is an approximation of time between frames, used when
40// ticking the animation clock outside of animation frame callbacks.
41// Ideally this would be generated by the compositor.
42const double approximateFrameTime = 1 / 60.0;
43
44}
45
46namespace blink {
47
48unsigned AnimationClock::s_currentTask = 0;
49
50void AnimationClock::updateTime(double time)
51{
52    if (time > m_time)
53        m_time = time;
54    m_currentTask = s_currentTask;
55}
56
57double AnimationClock::currentTime()
58{
59    if (m_currentTask != s_currentTask) {
60        const double currentTime = m_monotonicallyIncreasingTime();
61        if (m_time < currentTime) {
62            // Advance to the first estimated frame after the current time.
63            const double frameShift = fmod(currentTime - m_time, approximateFrameTime);
64            const double newTime = currentTime + (approximateFrameTime - frameShift);
65            ASSERT(newTime >= currentTime);
66            ASSERT(newTime <= currentTime + approximateFrameTime);
67            updateTime(newTime);
68        } else {
69            m_currentTask = s_currentTask;
70        }
71    }
72    return m_time;
73}
74
75void AnimationClock::resetTimeForTesting(double time)
76{
77    m_time = time;
78    m_currentTask = 0;
79    s_currentTask = 0;
80}
81
82}
83