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      1 /*
      2  * Copyright (C) 2014 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 #include "TimeLord.h"
     17 
     18 namespace android {
     19 namespace uirenderer {
     20 namespace renderthread {
     21 
     22 TimeLord::TimeLord()
     23         : mFrameIntervalNanos(milliseconds_to_nanoseconds(16))
     24         , mFrameTimeNanos(0) {
     25 }
     26 
     27 bool TimeLord::vsyncReceived(nsecs_t vsync) {
     28     if (vsync > mFrameTimeNanos) {
     29         mFrameTimeNanos = vsync;
     30         return true;
     31     }
     32     return false;
     33 }
     34 
     35 nsecs_t TimeLord::computeFrameTimeNanos() {
     36     // Logic copied from Choreographer.java
     37     nsecs_t now = systemTime(CLOCK_MONOTONIC);
     38     nsecs_t jitterNanos = now - mFrameTimeNanos;
     39     if (jitterNanos >= mFrameIntervalNanos) {
     40         nsecs_t lastFrameOffset = jitterNanos % mFrameIntervalNanos;
     41         mFrameTimeNanos = now - lastFrameOffset;
     42     }
     43     return mFrameTimeNanos;
     44 }
     45 
     46 } /* namespace renderthread */
     47 } /* namespace uirenderer */
     48 } /* namespace android */
     49