Sort event list if any event time was clamped

third_party/WebKit/Source/modules/webaudio/AudioParamTimeline.cpp

 /*
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 453 matching lines @@
   // range.
   if (!m_events.size() || (endFrame / sampleRate <= m_events[0].time())) {
     for (unsigned i = 0; i < numberOfValues; ++i)
       values[i] = defaultValue;
     return defaultValue;
   }
 
   int numberOfEvents = m_events.size();
 
   if (numberOfEvents > 0) {
+    bool clampedSomeEventTime = false;
     double currentTime = startFrame / sampleRate;
 
     // Look at all the events in the timeline and check to see if any needs
     // to clamp the start time to the current time.
     for (int k = 0; k < numberOfEvents; ++k) {
       ParamEvent& event = m_events[k];
 
       // We're examining the event for the first time and the event time is
       // in the past so clamp the event time to the current time (start of
       // the rendering quantum).
       if (event.needsTimeClampCheck()) {
-        if (event.time() < currentTime)
+        if (event.time() < currentTime) {
           event.setTime(currentTime);
+          clampedSomeEventTime = true;
+        }
 
         // In all cases, we can clear the flag because the event is either
         // in the future, or we've already checked it (just now).
         event.clearTimeClampCheck();
       }
     }
 
+    if (clampedSomeEventTime) {
+      // If we clamped some event time to current time, we need to
+      // sort the event list in time order again, but it must be
+      // stable!
+      std::stable_sort(m_events.begin(), m_events.end(),
+                       ParamEvent::eventPreceeds);
+    }
+
     // Optimize the case where the last event is in the past.
     ParamEvent& lastEvent = m_events[m_events.size() - 1];
     ParamEvent::Type lastEventType = lastEvent.getType();
     double lastEventTime = lastEvent.time();
 
     // If the last event is in the past and the event has ended, then we can
     // just propagate the same value.  Except for SetTarget which lasts
     // "forever".  SetValueCurve also has an explicit SetValue at the end of
     // the curve, so we don't need to worry that SetValueCurve time is a
     // start time, not an end time.
@@ skipping 135 matching lines @@
           ParamEvent::createSetValueEvent(value, currentFrame / sampleRate);
       m_events[i].clearTimeClampCheck();
     }
 
     float value1 = event.value();
     double time1 = event.time();
 
     float value2 = nextEvent ? nextEvent->value() : value1;
     double time2 = nextEvent ? nextEvent->time() : endFrame / sampleRate + 1;
 
+    DCHECK_GE(time2, time1);
     double deltaTime = time2 - time1;
     float k = deltaTime > 0 ? 1 / deltaTime : 0;
 
     // |fillToEndFrame| is the exclusive upper bound of the last frame to be
     // computed for this event.  It's either the last desired frame (|endFrame|)
     // or derived from the end time of the next event (time2). We compute
     // ceil(time2*sampleRate) because fillToEndFrame is the exclusive upper
     // bound.  Consider the case where |startFrame| = 128 and time2 = 128.1
     // (assuming sampleRate = 1).  Since time2 is greater than 128, we want to
     // output a value for frame 128.  This requires that fillToEndFrame be at
@@ skipping 437 matching lines @@
   // propagate the last value to the end of the values buffer.
   for (; writeIndex < numberOfValues; ++writeIndex)
     values[writeIndex] = value;
 
   // This value is used to set the .value attribute of the AudioParam.  it
   // should be the last computed value.
   return values[numberOfValues - 1];
 }
 
 }  // namespace blink