1 files changed, 474 insertions, 0 deletions
diff --git a/dom/media/webaudio/AudioEventTimeline.h b/dom/media/webaudio/AudioEventTimeline.h
new file mode 100644
index 000000000..ae06ad4db
--- /dev/null
+++ b/dom/media/webaudio/AudioEventTimeline.h
@@ -0,0 +1,474 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef AudioEventTimeline_h_
+#define AudioEventTimeline_h_
+
+#include <algorithm>
+#include "mozilla/Assertions.h"
+#include "mozilla/FloatingPoint.h"
+#include "mozilla/PodOperations.h"
+
+#include "MainThreadUtils.h"
+#include "nsTArray.h"
+#include "math.h"
+#include "WebAudioUtils.h"
+
+namespace mozilla {
+
+class MediaStream;
+
+namespace dom {
+
+struct AudioTimelineEvent final
+{
+  enum Type : uint32_t
+  {
+    SetValue,
+    SetValueAtTime,
+    LinearRamp,
+    ExponentialRamp,
+    SetTarget,
+    SetValueCurve,
+    Stream,
+    Cancel
+  };
+
+  AudioTimelineEvent(Type aType, double aTime, float aValue, double aTimeConstant = 0.0,
+                     double aDuration = 0.0, const float* aCurve = nullptr,
+                     uint32_t aCurveLength = 0)
+    : mType(aType)
+    , mCurve(nullptr)
+    , mTimeConstant(aTimeConstant)
+    , mDuration(aDuration)
+#ifdef DEBUG
+    , mTimeIsInTicks(false)
+#endif
+  {
+    mTime = aTime;
+    if (aType == AudioTimelineEvent::SetValueCurve) {
+      SetCurveParams(aCurve, aCurveLength);
+    } else {
+      mValue = aValue;
+    }
+  }
+
+  explicit AudioTimelineEvent(MediaStream* aStream)
+    : mType(Stream)
+    , mCurve(nullptr)
+    , mStream(aStream)
+    , mTimeConstant(0.0)
+    , mDuration(0.0)
+#ifdef DEBUG
+    , mTimeIsInTicks(false)
+#endif
+  {
+  }
+
+  AudioTimelineEvent(const AudioTimelineEvent& rhs)
+  {
+    PodCopy(this, &rhs, 1);
+
+    if (rhs.mType == AudioTimelineEvent::SetValueCurve) {
+      SetCurveParams(rhs.mCurve, rhs.mCurveLength);
+    } else if (rhs.mType == AudioTimelineEvent::Stream) {
+      new (&mStream) decltype(mStream)(rhs.mStream);
+    }
+  }
+
+  ~AudioTimelineEvent()
+  {
+    if (mType == AudioTimelineEvent::SetValueCurve) {
+      delete[] mCurve;
+    }
+  }
+
+  template <class TimeType>
+  TimeType Time() const;
+
+  void SetTimeInTicks(int64_t aTimeInTicks)
+  {
+    mTimeInTicks = aTimeInTicks;
+#ifdef DEBUG
+    mTimeIsInTicks = true;
+#endif
+  }
+
+  void SetCurveParams(const float* aCurve, uint32_t aCurveLength) {
+    mCurveLength = aCurveLength;
+    if (aCurveLength) {
+      mCurve = new float[aCurveLength];
+      PodCopy(mCurve, aCurve, aCurveLength);
+    } else {
+      mCurve = nullptr;
+    }
+  }
+
+  Type mType;
+  union {
+    float mValue;
+    uint32_t mCurveLength;
+  };
+  // mCurve contains a buffer of SetValueCurve samples.  We sample the
+  // values in the buffer depending on how far along we are in time.
+  // If we're at time T and the event has started as time T0 and has a
+  // duration of D, we sample the buffer at floor(mCurveLength*(T-T0)/D)
+  // if T<T0+D, and just take the last sample in the buffer otherwise.
+  float* mCurve;
+  RefPtr<MediaStream> mStream;
+  double mTimeConstant;
+  double mDuration;
+#ifdef DEBUG
+  bool mTimeIsInTicks;
+#endif
+
+private:
+  // This member is accessed using the `Time` method, for safety.
+  //
+  // The time for an event can either be in absolute value or in ticks.
+  // Initially the time of the event is always in absolute value.
+  // In order to convert it to ticks, call SetTimeInTicks.  Once this
+  // method has been called for an event, the time cannot be converted
+  // back to absolute value.
+  union {
+    double mTime;
+    int64_t mTimeInTicks;
+  };
+};
+
+template <>
+inline double AudioTimelineEvent::Time<double>() const
+{
+  MOZ_ASSERT(!mTimeIsInTicks);
+  return mTime;
+}
+
+template <>
+inline int64_t AudioTimelineEvent::Time<int64_t>() const
+{
+  MOZ_ASSERT(!NS_IsMainThread());
+  MOZ_ASSERT(mTimeIsInTicks);
+  return mTimeInTicks;
+}
+
+/**
+ * Some methods in this class will be instantiated with different ErrorResult
+ * template arguments for testing and production code.
+ *
+ * ErrorResult is a type which satisfies the following:
+ *  - Implements a Throw() method taking an nsresult argument, representing an error code.
+ */
+class AudioEventTimeline
+{
+public:
+  explicit AudioEventTimeline(float aDefaultValue)
+    : mValue(aDefaultValue),
+      mComputedValue(aDefaultValue),
+      mLastComputedValue(aDefaultValue)
+  { }
+
+  template <class ErrorResult>
+  bool ValidateEvent(AudioTimelineEvent& aEvent, ErrorResult& aRv)
+  {
+    MOZ_ASSERT(NS_IsMainThread());
+
+    auto TimeOf = [](const AudioTimelineEvent& aEvent) -> double {
+      return aEvent.template Time<double>();
+    };
+
+    // Validate the event itself
+    if (!WebAudioUtils::IsTimeValid(TimeOf(aEvent)) ||
+        !WebAudioUtils::IsTimeValid(aEvent.mTimeConstant)) {
+      aRv.Throw(NS_ERROR_DOM_SYNTAX_ERR);
+      return false;
+    }
+
+    if (aEvent.mType == AudioTimelineEvent::SetValueCurve) {
+      if (!aEvent.mCurve || !aEvent.mCurveLength) {
+        aRv.Throw(NS_ERROR_DOM_SYNTAX_ERR);
+        return false;
+      }
+      for (uint32_t i = 0; i < aEvent.mCurveLength; ++i) {
+        if (!IsValid(aEvent.mCurve[i])) {
+          aRv.Throw(NS_ERROR_DOM_SYNTAX_ERR);
+          return false;
+        }
+      }
+    }
+
+    bool timeAndValueValid = IsValid(aEvent.mValue) &&
+                             IsValid(aEvent.mDuration);
+    if (!timeAndValueValid) {
+      aRv.Throw(NS_ERROR_DOM_SYNTAX_ERR);
+      return false;
+    }
+
+    // Make sure that non-curve events don't fall within the duration of a
+    // curve event.
+    for (unsigned i = 0; i < mEvents.Length(); ++i) {
+      if (mEvents[i].mType == AudioTimelineEvent::SetValueCurve &&
+          !(aEvent.mType == AudioTimelineEvent::SetValueCurve &&
+            TimeOf(aEvent) == TimeOf(mEvents[i])) &&
+          TimeOf(mEvents[i]) <= TimeOf(aEvent) &&
+          TimeOf(mEvents[i]) + mEvents[i].mDuration >= TimeOf(aEvent)) {
+        aRv.Throw(NS_ERROR_DOM_SYNTAX_ERR);
+        return false;
+      }
+    }
+
+    // Make sure that curve events don't fall in a range which includes other
+    // events.
+    if (aEvent.mType == AudioTimelineEvent::SetValueCurve) {
+      for (unsigned i = 0; i < mEvents.Length(); ++i) {
+        // In case we have two curve at the same time
+        if (mEvents[i].mType == AudioTimelineEvent::SetValueCurve &&
+            TimeOf(mEvents[i]) == TimeOf(aEvent)) {
+          continue;
+        }
+        if (TimeOf(mEvents[i]) > TimeOf(aEvent) &&
+            TimeOf(mEvents[i]) < TimeOf(aEvent) + aEvent.mDuration) {
+          aRv.Throw(NS_ERROR_DOM_SYNTAX_ERR);
+          return false;
+        }
+      }
+    }
+
+    // Make sure that invalid values are not used for exponential curves
+    if (aEvent.mType == AudioTimelineEvent::ExponentialRamp) {
+      if (aEvent.mValue <= 0.f) {
+        aRv.Throw(NS_ERROR_DOM_SYNTAX_ERR);
+        return false;
+      }
+      const AudioTimelineEvent* previousEvent = GetPreviousEvent(TimeOf(aEvent));
+      if (previousEvent) {
+        if (previousEvent->mValue <= 0.f) {
+          aRv.Throw(NS_ERROR_DOM_SYNTAX_ERR);
+          return false;
+        }
+      } else {
+        if (mValue <= 0.f) {
+          aRv.Throw(NS_ERROR_DOM_SYNTAX_ERR);
+          return false;
+        }
+      }
+    }
+    return true;
+  }
+
+  template<typename TimeType>
+  void InsertEvent(const AudioTimelineEvent& aEvent)
+  {
+    for (unsigned i = 0; i < mEvents.Length(); ++i) {
+      if (aEvent.template Time<TimeType>() == mEvents[i].template Time<TimeType>()) {
+        if (aEvent.mType == mEvents[i].mType) {
+          // If times and types are equal, replace the event
+          mEvents.ReplaceElementAt(i, aEvent);
+        } else {
+          // Otherwise, place the element after the last event of another type
+          do {
+            ++i;
+          } while (i < mEvents.Length() &&
+                   aEvent.mType != mEvents[i].mType &&
+                   aEvent.template Time<TimeType>() == mEvents[i].template Time<TimeType>());
+          mEvents.InsertElementAt(i, aEvent);
+        }
+        return;
+      }
+      // Otherwise, place the event right after the latest existing event
+      if (aEvent.template Time<TimeType>() < mEvents[i].template Time<TimeType>()) {
+        mEvents.InsertElementAt(i, aEvent);
+        return;
+      }
+    }
+
+    // If we couldn't find a place for the event, just append it to the list
+    mEvents.AppendElement(aEvent);
+  }
+
+  bool HasSimpleValue() const
+  {
+    return mEvents.IsEmpty();
+  }
+
+  float GetValue() const
+  {
+    // This method should only be called if HasSimpleValue() returns true
+    MOZ_ASSERT(HasSimpleValue());
+    return mValue;
+  }
+
+  float Value() const
+  {
+    // TODO: Return the current value based on the timeline of the AudioContext
+    return mValue;
+  }
+
+  void SetValue(float aValue)
+  {
+    // Silently don't change anything if there are any events
+    if (mEvents.IsEmpty()) {
+      mLastComputedValue = mComputedValue = mValue = aValue;
+    }
+  }
+
+  template <class ErrorResult>
+  void SetValueAtTime(float aValue, double aStartTime, ErrorResult& aRv)
+  {
+    AudioTimelineEvent event(AudioTimelineEvent::SetValueAtTime, aStartTime, aValue);
+
+    if (ValidateEvent(event, aRv)) {
+      InsertEvent<double>(event);
+    }
+  }
+
+  template <class ErrorResult>
+  void LinearRampToValueAtTime(float aValue, double aEndTime, ErrorResult& aRv)
+  {
+    AudioTimelineEvent event(AudioTimelineEvent::LinearRamp, aEndTime, aValue);
+
+    if (ValidateEvent(event, aRv)) {
+      InsertEvent<double>(event);
+    }
+  }
+
+  template <class ErrorResult>
+  void ExponentialRampToValueAtTime(float aValue, double aEndTime, ErrorResult& aRv)
+  {
+    AudioTimelineEvent event(AudioTimelineEvent::ExponentialRamp, aEndTime, aValue);
+
+    if (ValidateEvent(event, aRv)) {
+      InsertEvent<double>(event);
+    }
+  }
+
+  template <class ErrorResult>
+  void SetTargetAtTime(float aTarget, double aStartTime, double aTimeConstant, ErrorResult& aRv)
+  {
+    AudioTimelineEvent event(AudioTimelineEvent::SetTarget, aStartTime, aTarget, aTimeConstant);
+
+    if (ValidateEvent(event, aRv)) {
+      InsertEvent<double>(event);
+    }
+  }
+
+  template <class ErrorResult>
+  void SetValueCurveAtTime(const float* aValues, uint32_t aValuesLength, double aStartTime, double aDuration, ErrorResult& aRv)
+  {
+    AudioTimelineEvent event(AudioTimelineEvent::SetValueCurve, aStartTime, 0.0f, 0.0f, aDuration, aValues, aValuesLength);
+    if (ValidateEvent(event, aRv)) {
+      InsertEvent<double>(event);
+    }
+  }
+
+  template<typename TimeType>
+  void CancelScheduledValues(TimeType aStartTime)
+  {
+    for (unsigned i = 0; i < mEvents.Length(); ++i) {
+      if (mEvents[i].template Time<TimeType>() >= aStartTime) {
+#ifdef DEBUG
+        // Sanity check: the array should be sorted, so all of the following
+        // events should have a time greater than aStartTime too.
+        for (unsigned j = i + 1; j < mEvents.Length(); ++j) {
+          MOZ_ASSERT(mEvents[j].template Time<TimeType>() >= aStartTime);
+        }
+#endif
+        mEvents.TruncateLength(i);
+        break;
+      }
+    }
+  }
+
+  void CancelAllEvents()
+  {
+    mEvents.Clear();
+  }
+
+  static bool TimesEqual(int64_t aLhs, int64_t aRhs)
+  {
+    return aLhs == aRhs;
+  }
+
+  // Since we are going to accumulate error by adding 0.01 multiple time in a
+  // loop, we want to fuzz the equality check in GetValueAtTime.
+  static bool TimesEqual(double aLhs, double aRhs)
+  {
+    const float kEpsilon = 0.0000000001f;
+    return fabs(aLhs - aRhs) < kEpsilon;
+  }
+
+  template<class TimeType>
+  float GetValueAtTime(TimeType aTime)
+  {
+    float result;
+    GetValuesAtTimeHelper(aTime, &result, 1);
+    return result;
+  }
+
+  template<class TimeType>
+  void GetValuesAtTime(TimeType aTime, float* aBuffer, const size_t aSize)
+  {
+    MOZ_ASSERT(aBuffer);
+    GetValuesAtTimeHelper(aTime, aBuffer, aSize);
+  }
+
+  // Return the number of events scheduled
+  uint32_t GetEventCount() const
+  {
+    return mEvents.Length();
+  }
+
+  template<class TimeType>
+  void CleanupEventsOlderThan(TimeType aTime)
+  {
+    while (mEvents.Length() > 1 &&
+        aTime > mEvents[1].template Time<TimeType>()) {
+
+      if (mEvents[1].mType == AudioTimelineEvent::SetTarget) {
+        mLastComputedValue = GetValuesAtTimeHelperInternal(
+                                mEvents[1].template Time<TimeType>(),
+                                &mEvents[0], nullptr);
+      }
+
+      mEvents.RemoveElementAt(0);
+    }
+  }
+
+private:
+  template<class TimeType>
+  void GetValuesAtTimeHelper(TimeType aTime, float* aBuffer, const size_t aSize);
+
+  template<class TimeType>
+  float GetValueAtTimeOfEvent(const AudioTimelineEvent* aNext);
+
+  template<class TimeType>
+  float GetValuesAtTimeHelperInternal(TimeType aTime,
+                                      const AudioTimelineEvent* aPrevious,
+                                      const AudioTimelineEvent* aNext);
+
+  const AudioTimelineEvent* GetPreviousEvent(double aTime) const;
+
+  static bool IsValid(double value)
+  {
+    return mozilla::IsFinite(value);
+  }
+
+  // This is a sorted array of the events in the timeline.  Queries of this
+  // data structure should probably be more frequent than modifications to it,
+  // and that is the reason why we're using a simple array as the data structure.
+  // We can optimize this in the future if the performance of the array ends up
+  // being a bottleneck.
+  nsTArray<AudioTimelineEvent> mEvents;
+  float mValue;
+  // This is the value of this AudioParam we computed at the last tick.
+  float mComputedValue;
+  // This is the value of this AudioParam at the last tick of the previous event.
+  float mLastComputedValue;
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif