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      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,
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     24  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     25  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     26  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     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 
     37 namespace {
     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.
     42 const double approximateFrameTime = 1 / 60.0;
     43 
     44 }
     45 
     46 namespace blink {
     47 
     48 unsigned AnimationClock::s_currentTask = 0;
     49 
     50 void AnimationClock::updateTime(double time)
     51 {
     52     if (time > m_time)
     53         m_time = time;
     54     m_currentTask = s_currentTask;
     55 }
     56 
     57 double 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 
     75 void AnimationClock::resetTimeForTesting(double time)
     76 {
     77     m_time = time;
     78     m_currentTask = 0;
     79     s_currentTask = 0;
     80 }
     81 
     82 }
     83