Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2117 insertions, 0 deletions

diff --git a/dom/animation/KeyframeEffect.cpp b/dom/animation/KeyframeEffect.cpp
new file mode 100644
index 0000000000..2f0d886ac1
--- /dev/null
+++ b/dom/animation/KeyframeEffect.cpp
@@ -0,0 +1,2117 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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/. */
+
+#include "mozilla/dom/KeyframeEffect.h"
+
+#include "mozilla/dom/Animation.h"
+#include "mozilla/dom/KeyframeAnimationOptionsBinding.h"
+// For UnrestrictedDoubleOrKeyframeAnimationOptions;
+#include "mozilla/dom/KeyframeEffectBinding.h"
+#include "mozilla/dom/MutationObservers.h"
+#include "mozilla/layers/AnimationInfo.h"
+#include "mozilla/AnimationUtils.h"
+#include "mozilla/AutoRestore.h"
+#include "mozilla/ComputedStyleInlines.h"
+#include "mozilla/EffectSet.h"
+#include "mozilla/FloatingPoint.h"  // For IsFinite
+#include "mozilla/LayerAnimationInfo.h"
+#include "mozilla/LookAndFeel.h"  // For LookAndFeel::GetInt
+#include "mozilla/KeyframeUtils.h"
+#include "mozilla/PresShell.h"
+#include "mozilla/PresShellInlines.h"
+#include "mozilla/ServoBindings.h"
+#include "mozilla/StaticPrefs_dom.h"
+#include "mozilla/StaticPrefs_gfx.h"
+#include "mozilla/StaticPrefs_layers.h"
+#include "nsComputedDOMStyle.h"  // nsComputedDOMStyle::GetComputedStyle
+#include "nsContentUtils.h"
+#include "nsCSSPropertyIDSet.h"
+#include "nsCSSProps.h"             // For nsCSSProps::PropHasFlags
+#include "nsCSSPseudoElements.h"    // For PseudoStyleType
+#include "nsDOMMutationObserver.h"  // For nsAutoAnimationMutationBatch
+#include "nsIFrame.h"
+#include "nsIFrameInlines.h"
+#include "nsIScrollableFrame.h"
+#include "nsPresContextInlines.h"
+#include "nsRefreshDriver.h"
+#include "js/PropertyAndElement.h"  // JS_DefineProperty
+#include "WindowRenderer.h"
+
+namespace mozilla {
+
+void AnimationProperty::SetPerformanceWarning(
+    const AnimationPerformanceWarning& aWarning, const dom::Element* aElement) {
+  if (mPerformanceWarning && *mPerformanceWarning == aWarning) {
+    return;
+  }
+
+  mPerformanceWarning = Some(aWarning);
+
+  nsAutoString localizedString;
+  if (StaticPrefs::layers_offmainthreadcomposition_log_animations() &&
+      mPerformanceWarning->ToLocalizedString(localizedString)) {
+    nsAutoCString logMessage = NS_ConvertUTF16toUTF8(localizedString);
+    AnimationUtils::LogAsyncAnimationFailure(logMessage, aElement);
+  }
+}
+
+bool PropertyValuePair::operator==(const PropertyValuePair& aOther) const {
+  if (mProperty != aOther.mProperty) {
+    return false;
+  }
+  if (mServoDeclarationBlock == aOther.mServoDeclarationBlock) {
+    return true;
+  }
+  if (!mServoDeclarationBlock || !aOther.mServoDeclarationBlock) {
+    return false;
+  }
+  return Servo_DeclarationBlock_Equals(mServoDeclarationBlock,
+                                       aOther.mServoDeclarationBlock);
+}
+
+namespace dom {
+
+NS_IMPL_CYCLE_COLLECTION_INHERITED(KeyframeEffect, AnimationEffect,
+                                   mTarget.mElement)
+
+NS_IMPL_CYCLE_COLLECTION_TRACE_BEGIN_INHERITED(KeyframeEffect, AnimationEffect)
+NS_IMPL_CYCLE_COLLECTION_TRACE_END
+
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(KeyframeEffect)
+NS_INTERFACE_MAP_END_INHERITING(AnimationEffect)
+
+NS_IMPL_ADDREF_INHERITED(KeyframeEffect, AnimationEffect)
+NS_IMPL_RELEASE_INHERITED(KeyframeEffect, AnimationEffect)
+
+KeyframeEffect::KeyframeEffect(Document* aDocument,
+                               OwningAnimationTarget&& aTarget,
+                               TimingParams&& aTiming,
+                               const KeyframeEffectParams& aOptions)
+    : AnimationEffect(aDocument, std::move(aTiming)),
+      mTarget(std::move(aTarget)),
+      mEffectOptions(aOptions) {}
+
+KeyframeEffect::KeyframeEffect(Document* aDocument,
+                               OwningAnimationTarget&& aTarget,
+                               const KeyframeEffect& aOther)
+    : AnimationEffect(aDocument, TimingParams{aOther.SpecifiedTiming()}),
+      mTarget(std::move(aTarget)),
+      mEffectOptions{aOther.IterationComposite(), aOther.Composite(),
+                     mTarget.mPseudoType},
+      mKeyframes(aOther.mKeyframes.Clone()),
+      mProperties(aOther.mProperties.Clone()),
+      mBaseValues(aOther.mBaseValues.Clone()) {}
+
+JSObject* KeyframeEffect::WrapObject(JSContext* aCx,
+                                     JS::Handle<JSObject*> aGivenProto) {
+  return KeyframeEffect_Binding::Wrap(aCx, this, aGivenProto);
+}
+
+IterationCompositeOperation KeyframeEffect::IterationComposite() const {
+  return mEffectOptions.mIterationComposite;
+}
+
+void KeyframeEffect::SetIterationComposite(
+    const IterationCompositeOperation& aIterationComposite) {
+  if (mEffectOptions.mIterationComposite == aIterationComposite) {
+    return;
+  }
+
+  if (mAnimation && mAnimation->IsRelevant()) {
+    MutationObservers::NotifyAnimationChanged(mAnimation);
+  }
+
+  mEffectOptions.mIterationComposite = aIterationComposite;
+  RequestRestyle(EffectCompositor::RestyleType::Layer);
+}
+
+CompositeOperation KeyframeEffect::Composite() const {
+  return mEffectOptions.mComposite;
+}
+
+void KeyframeEffect::SetComposite(const CompositeOperation& aComposite) {
+  if (mEffectOptions.mComposite == aComposite) {
+    return;
+  }
+
+  mEffectOptions.mComposite = aComposite;
+
+  if (mAnimation && mAnimation->IsRelevant()) {
+    MutationObservers::NotifyAnimationChanged(mAnimation);
+  }
+
+  if (mTarget) {
+    RefPtr<const ComputedStyle> computedStyle =
+        GetTargetComputedStyle(Flush::None);
+    if (computedStyle) {
+      UpdateProperties(computedStyle);
+    }
+  }
+}
+
+void KeyframeEffect::NotifySpecifiedTimingUpdated() {
+  // Use the same document for a pseudo element and its parent element.
+  // Use nullptr if we don't have mTarget, so disable the mutation batch.
+  nsAutoAnimationMutationBatch mb(mTarget ? mTarget.mElement->OwnerDoc()
+                                          : nullptr);
+
+  if (mAnimation) {
+    mAnimation->NotifyEffectTimingUpdated();
+
+    if (mAnimation->IsRelevant()) {
+      MutationObservers::NotifyAnimationChanged(mAnimation);
+    }
+
+    RequestRestyle(EffectCompositor::RestyleType::Layer);
+  }
+}
+
+void KeyframeEffect::NotifyAnimationTimingUpdated(
+    PostRestyleMode aPostRestyle) {
+  UpdateTargetRegistration();
+
+  // If the effect is not relevant it will be removed from the target
+  // element's effect set. However, effects not in the effect set
+  // will not be included in the set of candidate effects for running on
+  // the compositor and hence they won't have their compositor status
+  // updated. As a result, we need to make sure we clear their compositor
+  // status here.
+  bool isRelevant = mAnimation && mAnimation->IsRelevant();
+  if (!isRelevant) {
+    ResetIsRunningOnCompositor();
+  }
+
+  // Request restyle if necessary.
+  if (aPostRestyle == PostRestyleMode::IfNeeded && mAnimation &&
+      !mProperties.IsEmpty() && HasComputedTimingChanged()) {
+    EffectCompositor::RestyleType restyleType =
+        CanThrottle() ? EffectCompositor::RestyleType::Throttled
+                      : EffectCompositor::RestyleType::Standard;
+    RequestRestyle(restyleType);
+  }
+
+  // Detect changes to "in effect" status since we need to recalculate the
+  // animation cascade for this element whenever that changes.
+  // Note that updating mInEffectOnLastAnimationTimingUpdate has to be done
+  // after above CanThrottle() call since the function uses the flag inside it.
+  bool inEffect = IsInEffect();
+  if (inEffect != mInEffectOnLastAnimationTimingUpdate) {
+    MarkCascadeNeedsUpdate();
+    mInEffectOnLastAnimationTimingUpdate = inEffect;
+  }
+
+  // If we're no longer "in effect", our ComposeStyle method will never be
+  // called and we will never have a chance to update mProgressOnLastCompose
+  // and mCurrentIterationOnLastCompose.
+  // We clear them here to ensure that if we later become "in effect" we will
+  // request a restyle (above).
+  if (!inEffect) {
+    mProgressOnLastCompose.SetNull();
+    mCurrentIterationOnLastCompose = 0;
+  }
+}
+
+static bool KeyframesEqualIgnoringComputedOffsets(
+    const nsTArray<Keyframe>& aLhs, const nsTArray<Keyframe>& aRhs) {
+  if (aLhs.Length() != aRhs.Length()) {
+    return false;
+  }
+
+  for (size_t i = 0, len = aLhs.Length(); i < len; ++i) {
+    const Keyframe& a = aLhs[i];
+    const Keyframe& b = aRhs[i];
+    if (a.mOffset != b.mOffset || a.mTimingFunction != b.mTimingFunction ||
+        a.mPropertyValues != b.mPropertyValues) {
+      return false;
+    }
+  }
+  return true;
+}
+
+// https://drafts.csswg.org/web-animations/#dom-keyframeeffect-setkeyframes
+void KeyframeEffect::SetKeyframes(JSContext* aContext,
+                                  JS::Handle<JSObject*> aKeyframes,
+                                  ErrorResult& aRv) {
+  nsTArray<Keyframe> keyframes = KeyframeUtils::GetKeyframesFromObject(
+      aContext, mDocument, aKeyframes, "KeyframeEffect.setKeyframes", aRv);
+  if (aRv.Failed()) {
+    return;
+  }
+
+  RefPtr<const ComputedStyle> style = GetTargetComputedStyle(Flush::None);
+  SetKeyframes(std::move(keyframes), style, nullptr /* AnimationTimeline */);
+}
+
+void KeyframeEffect::SetKeyframes(nsTArray<Keyframe>&& aKeyframes,
+                                  const ComputedStyle* aStyle,
+                                  const AnimationTimeline* aTimeline) {
+  if (KeyframesEqualIgnoringComputedOffsets(aKeyframes, mKeyframes)) {
+    return;
+  }
+
+  mKeyframes = std::move(aKeyframes);
+  KeyframeUtils::DistributeKeyframes(mKeyframes);
+
+  if (mAnimation && mAnimation->IsRelevant()) {
+    MutationObservers::NotifyAnimationChanged(mAnimation);
+  }
+
+  // We need to call UpdateProperties() unless the target element doesn't have
+  // style (e.g. the target element is not associated with any document).
+  if (aStyle) {
+    UpdateProperties(aStyle, aTimeline);
+  }
+}
+
+void KeyframeEffect::ReplaceTransitionStartValue(AnimationValue&& aStartValue) {
+  if (!aStartValue.mServo) {
+    return;
+  }
+
+  // A typical transition should have a single property and a single segment.
+  //
+  // (And for atypical transitions, that is, those updated by script, we don't
+  // apply the replacing behavior.)
+  if (mProperties.Length() != 1 || mProperties[0].mSegments.Length() != 1) {
+    return;
+  }
+
+  // Likewise, check that the keyframes are of the expected shape.
+  if (mKeyframes.Length() != 2 || mKeyframes[0].mPropertyValues.Length() != 1) {
+    return;
+  }
+
+  // Check that the value we are about to substitute in is actually for the
+  // same property.
+  if (Servo_AnimationValue_GetPropertyId(aStartValue.mServo) !=
+      mProperties[0].mProperty) {
+    return;
+  }
+
+  mKeyframes[0].mPropertyValues[0].mServoDeclarationBlock =
+      Servo_AnimationValue_Uncompute(aStartValue.mServo).Consume();
+  mProperties[0].mSegments[0].mFromValue = std::move(aStartValue);
+}
+
+static bool IsEffectiveProperty(const EffectSet& aEffects,
+                                nsCSSPropertyID aProperty) {
+  return !aEffects.PropertiesWithImportantRules().HasProperty(aProperty) ||
+         !aEffects.PropertiesForAnimationsLevel().HasProperty(aProperty);
+}
+
+const AnimationProperty* KeyframeEffect::GetEffectiveAnimationOfProperty(
+    nsCSSPropertyID aProperty, const EffectSet& aEffects) const {
+  MOZ_ASSERT(mTarget && &aEffects == EffectSet::Get(mTarget.mElement,
+                                                    mTarget.mPseudoType));
+
+  for (const AnimationProperty& property : mProperties) {
+    if (aProperty != property.mProperty) {
+      continue;
+    }
+
+    const AnimationProperty* result = nullptr;
+    // Only include the property if it is not overridden by !important rules in
+    // the transitions level.
+    if (IsEffectiveProperty(aEffects, property.mProperty)) {
+      result = &property;
+    }
+    return result;
+  }
+  return nullptr;
+}
+
+bool KeyframeEffect::HasEffectiveAnimationOfPropertySet(
+    const nsCSSPropertyIDSet& aPropertySet, const EffectSet& aEffectSet) const {
+  for (const AnimationProperty& property : mProperties) {
+    if (aPropertySet.HasProperty(property.mProperty) &&
+        IsEffectiveProperty(aEffectSet, property.mProperty)) {
+      return true;
+    }
+  }
+  return false;
+}
+
+nsCSSPropertyIDSet KeyframeEffect::GetPropertiesForCompositor(
+    EffectSet& aEffects, const nsIFrame* aFrame) const {
+  MOZ_ASSERT(&aEffects ==
+             EffectSet::Get(mTarget.mElement, mTarget.mPseudoType));
+
+  nsCSSPropertyIDSet properties;
+
+  if (!mAnimation || !mAnimation->IsRelevant()) {
+    return properties;
+  }
+
+  static constexpr nsCSSPropertyIDSet compositorAnimatables =
+      nsCSSPropertyIDSet::CompositorAnimatables();
+  static constexpr nsCSSPropertyIDSet transformLikeProperties =
+      nsCSSPropertyIDSet::TransformLikeProperties();
+
+  nsCSSPropertyIDSet transformSet;
+  AnimationPerformanceWarning::Type dummyWarning;
+
+  for (const AnimationProperty& property : mProperties) {
+    if (!compositorAnimatables.HasProperty(property.mProperty)) {
+      continue;
+    }
+
+    // Transform-like properties are combined together on the compositor so we
+    // need to evaluate them as a group. We build up a separate set here then
+    // evaluate it as a separate step below.
+    if (transformLikeProperties.HasProperty(property.mProperty)) {
+      transformSet.AddProperty(property.mProperty);
+      continue;
+    }
+
+    KeyframeEffect::MatchForCompositor matchResult = IsMatchForCompositor(
+        nsCSSPropertyIDSet{property.mProperty}, aFrame, aEffects, dummyWarning);
+    if (matchResult ==
+            KeyframeEffect::MatchForCompositor::NoAndBlockThisProperty ||
+        matchResult == KeyframeEffect::MatchForCompositor::No) {
+      continue;
+    }
+    properties.AddProperty(property.mProperty);
+  }
+
+  if (!transformSet.IsEmpty()) {
+    KeyframeEffect::MatchForCompositor matchResult =
+        IsMatchForCompositor(transformSet, aFrame, aEffects, dummyWarning);
+    if (matchResult == KeyframeEffect::MatchForCompositor::Yes ||
+        matchResult == KeyframeEffect::MatchForCompositor::IfNeeded) {
+      properties |= transformSet;
+    }
+  }
+
+  return properties;
+}
+
+nsCSSPropertyIDSet KeyframeEffect::GetPropertySet() const {
+  nsCSSPropertyIDSet result;
+
+  for (const AnimationProperty& property : mProperties) {
+    result.AddProperty(property.mProperty);
+  }
+
+  return result;
+}
+
+#ifdef DEBUG
+bool SpecifiedKeyframeArraysAreEqual(const nsTArray<Keyframe>& aA,
+                                     const nsTArray<Keyframe>& aB) {
+  if (aA.Length() != aB.Length()) {
+    return false;
+  }
+
+  for (size_t i = 0; i < aA.Length(); i++) {
+    const Keyframe& a = aA[i];
+    const Keyframe& b = aB[i];
+    if (a.mOffset != b.mOffset || a.mTimingFunction != b.mTimingFunction ||
+        a.mPropertyValues != b.mPropertyValues) {
+      return false;
+    }
+  }
+
+  return true;
+}
+#endif
+
+static bool HasCurrentColor(
+    const nsTArray<AnimationPropertySegment>& aSegments) {
+  for (const AnimationPropertySegment& segment : aSegments) {
+    if ((!segment.mFromValue.IsNull() && segment.mFromValue.IsCurrentColor()) ||
+        (!segment.mToValue.IsNull() && segment.mToValue.IsCurrentColor())) {
+      return true;
+    }
+  }
+  return false;
+}
+void KeyframeEffect::UpdateProperties(const ComputedStyle* aStyle,
+                                      const AnimationTimeline* aTimeline) {
+  MOZ_ASSERT(aStyle);
+
+  nsTArray<AnimationProperty> properties = BuildProperties(aStyle);
+
+  bool propertiesChanged = mProperties != properties;
+
+  // We need to update base styles even if any properties are not changed at all
+  // since base styles might have been changed due to parent style changes, etc.
+  bool baseStylesChanged = false;
+  EnsureBaseStyles(aStyle, properties, aTimeline,
+                   !propertiesChanged ? &baseStylesChanged : nullptr);
+
+  if (!propertiesChanged) {
+    if (baseStylesChanged) {
+      RequestRestyle(EffectCompositor::RestyleType::Layer);
+    }
+    // Check if we need to update the cumulative change hint because we now have
+    // style data.
+    if (mNeedsStyleData && mTarget && mTarget.mElement->HasServoData()) {
+      CalculateCumulativeChangeHint(aStyle);
+    }
+    return;
+  }
+
+  // Preserve the state of the mIsRunningOnCompositor flag.
+  nsCSSPropertyIDSet runningOnCompositorProperties;
+
+  for (const AnimationProperty& property : mProperties) {
+    if (property.mIsRunningOnCompositor) {
+      runningOnCompositorProperties.AddProperty(property.mProperty);
+    }
+  }
+
+  mProperties = std::move(properties);
+  UpdateEffectSet();
+
+  mHasCurrentColor = false;
+
+  for (AnimationProperty& property : mProperties) {
+    property.mIsRunningOnCompositor =
+        runningOnCompositorProperties.HasProperty(property.mProperty);
+
+    if (property.mProperty == eCSSProperty_background_color &&
+        !mHasCurrentColor) {
+      if (HasCurrentColor(property.mSegments)) {
+        mHasCurrentColor = true;
+        break;
+      }
+    }
+  }
+
+  CalculateCumulativeChangeHint(aStyle);
+
+  MarkCascadeNeedsUpdate();
+
+  if (mAnimation) {
+    mAnimation->NotifyEffectPropertiesUpdated();
+  }
+
+  RequestRestyle(EffectCompositor::RestyleType::Layer);
+}
+
+void KeyframeEffect::EnsureBaseStyles(
+    const ComputedStyle* aComputedValues,
+    const nsTArray<AnimationProperty>& aProperties,
+    const AnimationTimeline* aTimeline, bool* aBaseStylesChanged) {
+  if (aBaseStylesChanged != nullptr) {
+    *aBaseStylesChanged = false;
+  }
+
+  if (!mTarget) {
+    return;
+  }
+
+  BaseValuesHashmap previousBaseStyles;
+  if (aBaseStylesChanged != nullptr) {
+    previousBaseStyles = std::move(mBaseValues);
+  }
+
+  mBaseValues.Clear();
+
+  nsPresContext* presContext =
+      nsContentUtils::GetContextForContent(mTarget.mElement);
+  // If |aProperties| is empty we're not going to dereference |presContext| so
+  // we don't care if it is nullptr.
+  //
+  // We could just return early when |aProperties| is empty and save looking up
+  // the pres context, but that won't save any effort normally since we don't
+  // call this function if we have no keyframes to begin with. Furthermore, the
+  // case where |presContext| is nullptr is so rare (we've only ever seen in
+  // fuzzing, and even then we've never been able to reproduce it reliably)
+  // it's not worth the runtime cost of an extra branch.
+  MOZ_ASSERT(presContext || aProperties.IsEmpty(),
+             "Typically presContext should not be nullptr but if it is"
+             " we should have also failed to calculate the computed values"
+             " passed-in as aProperties");
+
+  if (!aTimeline) {
+    // If we pass a valid timeline, we use it (note: this happens when we create
+    // a new animation or replace the old one, for CSS Animations and CSS
+    // Transitions). Otherwise, we check the timeline from |mAnimation|.
+    aTimeline = mAnimation ? mAnimation->GetTimeline() : nullptr;
+  }
+
+  RefPtr<const ComputedStyle> baseComputedStyle;
+  for (const AnimationProperty& property : aProperties) {
+    EnsureBaseStyle(property, presContext, aComputedValues, aTimeline,
+                    baseComputedStyle);
+  }
+
+  if (aBaseStylesChanged != nullptr &&
+      std::any_of(
+          mBaseValues.cbegin(), mBaseValues.cend(), [&](const auto& entry) {
+            return AnimationValue(entry.GetData()) !=
+                   AnimationValue(previousBaseStyles.Get(entry.GetKey()));
+          })) {
+    *aBaseStylesChanged = true;
+  }
+}
+
+void KeyframeEffect::EnsureBaseStyle(
+    const AnimationProperty& aProperty, nsPresContext* aPresContext,
+    const ComputedStyle* aComputedStyle, const AnimationTimeline* aTimeline,
+    RefPtr<const ComputedStyle>& aBaseComputedStyle) {
+  auto needBaseStyleForScrollTimeline =
+      [this](const AnimationProperty& aProperty,
+             const AnimationTimeline* aTimeline) {
+        static constexpr TimeDuration zeroDuration;
+        const TimingParams& timing = NormalizedTiming();
+        // For scroll-timeline with a positive delay, it's possible to scroll
+        // back and forth between delay phase and active phase, so we need to
+        // keep its base style and maybe use it to override the animations in
+        // delay on the compositor.
+        return aTimeline && aTimeline->IsScrollTimeline() &&
+               nsCSSPropertyIDSet::CompositorAnimatables().HasProperty(
+                   aProperty.mProperty) &&
+               (timing.Delay() > zeroDuration ||
+                timing.EndDelay() > zeroDuration);
+      };
+  auto hasAdditiveValues = [](const AnimationProperty& aProperty) {
+    for (const AnimationPropertySegment& segment : aProperty.mSegments) {
+      if (!segment.HasReplaceableValues()) {
+        return true;
+      }
+    }
+    return false;
+  };
+
+  // Note: Check base style for compositor (i.e. for scroll-driven animations)
+  // first because it is much cleaper.
+  const bool needBaseStyle =
+      needBaseStyleForScrollTimeline(aProperty, aTimeline) ||
+      hasAdditiveValues(aProperty);
+  if (!needBaseStyle) {
+    return;
+  }
+
+  if (!aBaseComputedStyle) {
+    MOZ_ASSERT(mTarget, "Should have a valid target");
+
+    Element* animatingElement = AnimationUtils::GetElementForRestyle(
+        mTarget.mElement, mTarget.mPseudoType);
+    if (!animatingElement) {
+      return;
+    }
+    aBaseComputedStyle = aPresContext->StyleSet()->GetBaseContextForElement(
+        animatingElement, aComputedStyle);
+  }
+  RefPtr<StyleAnimationValue> baseValue =
+      Servo_ComputedValues_ExtractAnimationValue(aBaseComputedStyle,
+                                                 aProperty.mProperty)
+          .Consume();
+  mBaseValues.InsertOrUpdate(aProperty.mProperty, std::move(baseValue));
+}
+
+void KeyframeEffect::WillComposeStyle() {
+  ComputedTiming computedTiming = GetComputedTiming();
+  mProgressOnLastCompose = computedTiming.mProgress;
+  mCurrentIterationOnLastCompose = computedTiming.mCurrentIteration;
+}
+
+void KeyframeEffect::ComposeStyleRule(StyleAnimationValueMap& aAnimationValues,
+                                      const AnimationProperty& aProperty,
+                                      const AnimationPropertySegment& aSegment,
+                                      const ComputedTiming& aComputedTiming) {
+  auto* opaqueTable =
+      reinterpret_cast<RawServoAnimationValueTable*>(&mBaseValues);
+  Servo_AnimationCompose(&aAnimationValues, opaqueTable, aProperty.mProperty,
+                         &aSegment, &aProperty.mSegments.LastElement(),
+                         &aComputedTiming, mEffectOptions.mIterationComposite);
+}
+
+void KeyframeEffect::ComposeStyle(StyleAnimationValueMap& aComposeResult,
+                                  const nsCSSPropertyIDSet& aPropertiesToSkip) {
+  ComputedTiming computedTiming = GetComputedTiming();
+
+  // If the progress is null, we don't have fill data for the current
+  // time so we shouldn't animate.
+  if (computedTiming.mProgress.IsNull()) {
+    return;
+  }
+
+  for (size_t propIdx = 0, propEnd = mProperties.Length(); propIdx != propEnd;
+       ++propIdx) {
+    const AnimationProperty& prop = mProperties[propIdx];
+
+    MOZ_ASSERT(prop.mSegments[0].mFromKey == 0.0, "incorrect first from key");
+    MOZ_ASSERT(prop.mSegments[prop.mSegments.Length() - 1].mToKey == 1.0,
+               "incorrect last to key");
+
+    if (aPropertiesToSkip.HasProperty(prop.mProperty)) {
+      continue;
+    }
+
+    MOZ_ASSERT(prop.mSegments.Length() > 0,
+               "property should not be in animations if it has no segments");
+
+    // FIXME: Maybe cache the current segment?
+    const AnimationPropertySegment *segment = prop.mSegments.Elements(),
+                                   *segmentEnd =
+                                       segment + prop.mSegments.Length();
+    while (segment->mToKey <= computedTiming.mProgress.Value()) {
+      MOZ_ASSERT(segment->mFromKey <= segment->mToKey, "incorrect keys");
+      if ((segment + 1) == segmentEnd) {
+        break;
+      }
+      ++segment;
+      MOZ_ASSERT(segment->mFromKey == (segment - 1)->mToKey, "incorrect keys");
+    }
+    MOZ_ASSERT(segment->mFromKey <= segment->mToKey, "incorrect keys");
+    MOZ_ASSERT(segment >= prop.mSegments.Elements() &&
+                   size_t(segment - prop.mSegments.Elements()) <
+                       prop.mSegments.Length(),
+               "out of array bounds");
+
+    ComposeStyleRule(aComposeResult, prop, *segment, computedTiming);
+  }
+
+  // If the animation produces a change hint that affects the overflow region,
+  // we need to record the current time to unthrottle the animation
+  // periodically when the animation is being throttled because it's scrolled
+  // out of view.
+  if (HasPropertiesThatMightAffectOverflow()) {
+    nsPresContext* presContext =
+        nsContentUtils::GetContextForContent(mTarget.mElement);
+    EffectSet* effectSet =
+        EffectSet::Get(mTarget.mElement, mTarget.mPseudoType);
+    if (presContext && effectSet) {
+      TimeStamp now = presContext->RefreshDriver()->MostRecentRefresh();
+      effectSet->UpdateLastOverflowAnimationSyncTime(now);
+    }
+  }
+}
+
+bool KeyframeEffect::IsRunningOnCompositor() const {
+  // We consider animation is running on compositor if there is at least
+  // one property running on compositor.
+  // Animation.IsRunningOnCompotitor will return more fine grained
+  // information in bug 1196114.
+  for (const AnimationProperty& property : mProperties) {
+    if (property.mIsRunningOnCompositor) {
+      return true;
+    }
+  }
+  return false;
+}
+
+void KeyframeEffect::SetIsRunningOnCompositor(nsCSSPropertyID aProperty,
+                                              bool aIsRunning) {
+  MOZ_ASSERT(
+      nsCSSProps::PropHasFlags(aProperty, CSSPropFlags::CanAnimateOnCompositor),
+      "Property being animated on compositor is a recognized "
+      "compositor-animatable property");
+  for (AnimationProperty& property : mProperties) {
+    if (property.mProperty == aProperty) {
+      property.mIsRunningOnCompositor = aIsRunning;
+      // We currently only set a performance warning message when animations
+      // cannot be run on the compositor, so if this animation is running
+      // on the compositor we don't need a message.
+      if (aIsRunning) {
+        property.mPerformanceWarning.reset();
+      } else if (mAnimation && mAnimation->IsPartialPrerendered()) {
+        ResetPartialPrerendered();
+      }
+      return;
+    }
+  }
+}
+
+void KeyframeEffect::SetIsRunningOnCompositor(
+    const nsCSSPropertyIDSet& aPropertySet, bool aIsRunning) {
+  for (AnimationProperty& property : mProperties) {
+    if (aPropertySet.HasProperty(property.mProperty)) {
+      MOZ_ASSERT(nsCSSProps::PropHasFlags(property.mProperty,
+                                          CSSPropFlags::CanAnimateOnCompositor),
+                 "Property being animated on compositor is a recognized "
+                 "compositor-animatable property");
+      property.mIsRunningOnCompositor = aIsRunning;
+      // We currently only set a performance warning message when animations
+      // cannot be run on the compositor, so if this animation is running
+      // on the compositor we don't need a message.
+      if (aIsRunning) {
+        property.mPerformanceWarning.reset();
+      }
+    }
+  }
+
+  if (!aIsRunning && mAnimation && mAnimation->IsPartialPrerendered()) {
+    ResetPartialPrerendered();
+  }
+}
+
+void KeyframeEffect::ResetIsRunningOnCompositor() {
+  for (AnimationProperty& property : mProperties) {
+    property.mIsRunningOnCompositor = false;
+  }
+
+  if (mAnimation && mAnimation->IsPartialPrerendered()) {
+    ResetPartialPrerendered();
+  }
+}
+
+void KeyframeEffect::ResetPartialPrerendered() {
+  MOZ_ASSERT(mAnimation && mAnimation->IsPartialPrerendered());
+
+  nsIFrame* frame = GetPrimaryFrame();
+  if (!frame) {
+    return;
+  }
+
+  nsIWidget* widget = frame->GetNearestWidget();
+  if (!widget) {
+    return;
+  }
+
+  if (WindowRenderer* windowRenderer = widget->GetWindowRenderer()) {
+    windowRenderer->RemovePartialPrerenderedAnimation(
+        mAnimation->IdOnCompositor(), mAnimation);
+  }
+}
+
+static const KeyframeEffectOptions& KeyframeEffectOptionsFromUnion(
+    const UnrestrictedDoubleOrKeyframeEffectOptions& aOptions) {
+  MOZ_ASSERT(aOptions.IsKeyframeEffectOptions());
+  return aOptions.GetAsKeyframeEffectOptions();
+}
+
+static const KeyframeEffectOptions& KeyframeEffectOptionsFromUnion(
+    const UnrestrictedDoubleOrKeyframeAnimationOptions& aOptions) {
+  MOZ_ASSERT(aOptions.IsKeyframeAnimationOptions());
+  return aOptions.GetAsKeyframeAnimationOptions();
+}
+
+template <class OptionsType>
+static KeyframeEffectParams KeyframeEffectParamsFromUnion(
+    const OptionsType& aOptions, CallerType aCallerType, ErrorResult& aRv) {
+  KeyframeEffectParams result;
+  if (aOptions.IsUnrestrictedDouble()) {
+    return result;
+  }
+
+  const KeyframeEffectOptions& options =
+      KeyframeEffectOptionsFromUnion(aOptions);
+
+  // If dom.animations-api.compositing.enabled is turned off,
+  // iterationComposite and composite are the default value 'replace' in the
+  // dictionary.
+  result.mIterationComposite = options.mIterationComposite;
+  result.mComposite = options.mComposite;
+
+  result.mPseudoType = PseudoStyleType::NotPseudo;
+  if (DOMStringIsNull(options.mPseudoElement)) {
+    return result;
+  }
+
+  Maybe<PseudoStyleType> pseudoType =
+      nsCSSPseudoElements::GetPseudoType(options.mPseudoElement);
+  if (!pseudoType) {
+    // Per the spec, we throw SyntaxError for syntactically invalid pseudos.
+    aRv.ThrowSyntaxError(
+        nsPrintfCString("'%s' is a syntactically invalid pseudo-element.",
+                        NS_ConvertUTF16toUTF8(options.mPseudoElement).get()));
+    return result;
+  }
+
+  result.mPseudoType = *pseudoType;
+  if (!AnimationUtils::IsSupportedPseudoForAnimations(result.mPseudoType)) {
+    // Per the spec, we throw SyntaxError for unsupported pseudos.
+    aRv.ThrowSyntaxError(
+        nsPrintfCString("'%s' is an unsupported pseudo-element.",
+                        NS_ConvertUTF16toUTF8(options.mPseudoElement).get()));
+  }
+
+  return result;
+}
+
+template <class OptionsType>
+/* static */
+already_AddRefed<KeyframeEffect> KeyframeEffect::ConstructKeyframeEffect(
+    const GlobalObject& aGlobal, Element* aTarget,
+    JS::Handle<JSObject*> aKeyframes, const OptionsType& aOptions,
+    ErrorResult& aRv) {
+  // We should get the document from `aGlobal` instead of the current Realm
+  // to make this works in Xray case.
+  //
+  // In all non-Xray cases, `aGlobal` matches the current Realm, so this
+  // matches the spec behavior.
+  //
+  // In Xray case, the new objects should be created using the document of
+  // the target global, but the KeyframeEffect constructors are called in the
+  // caller's compartment to access `aKeyframes` object.
+  Document* doc = AnimationUtils::GetDocumentFromGlobal(aGlobal.Get());
+  if (!doc) {
+    aRv.Throw(NS_ERROR_FAILURE);
+    return nullptr;
+  }
+
+  KeyframeEffectParams effectOptions =
+      KeyframeEffectParamsFromUnion(aOptions, aGlobal.CallerType(), aRv);
+  // An invalid Pseudo-element aborts all further steps.
+  if (aRv.Failed()) {
+    return nullptr;
+  }
+
+  TimingParams timingParams = TimingParams::FromOptionsUnion(aOptions, aRv);
+  if (aRv.Failed()) {
+    return nullptr;
+  }
+
+  RefPtr<KeyframeEffect> effect = new KeyframeEffect(
+      doc, OwningAnimationTarget(aTarget, effectOptions.mPseudoType),
+      std::move(timingParams), effectOptions);
+
+  effect->SetKeyframes(aGlobal.Context(), aKeyframes, aRv);
+  if (aRv.Failed()) {
+    return nullptr;
+  }
+
+  return effect.forget();
+}
+
+nsTArray<AnimationProperty> KeyframeEffect::BuildProperties(
+    const ComputedStyle* aStyle) {
+  MOZ_ASSERT(aStyle);
+
+  nsTArray<AnimationProperty> result;
+  // If mTarget is false (i.e. mTarget.mElement is null), return an empty
+  // property array.
+  if (!mTarget) {
+    return result;
+  }
+
+  // When GetComputedKeyframeValues or GetAnimationPropertiesFromKeyframes
+  // calculate computed values from |mKeyframes|, they could possibly
+  // trigger a subsequent restyle in which we rebuild animations. If that
+  // happens we could find that |mKeyframes| is overwritten while it is
+  // being iterated over. Normally that shouldn't happen but just in case we
+  // make a copy of |mKeyframes| first and iterate over that instead.
+  auto keyframesCopy(mKeyframes.Clone());
+
+  result = KeyframeUtils::GetAnimationPropertiesFromKeyframes(
+      keyframesCopy, mTarget.mElement, mTarget.mPseudoType, aStyle,
+      mEffectOptions.mComposite);
+
+#ifdef DEBUG
+  MOZ_ASSERT(SpecifiedKeyframeArraysAreEqual(mKeyframes, keyframesCopy),
+             "Apart from the computed offset members, the keyframes array"
+             " should not be modified");
+#endif
+
+  mKeyframes = std::move(keyframesCopy);
+  return result;
+}
+
+template <typename FrameEnumFunc>
+static void EnumerateContinuationsOrIBSplitSiblings(nsIFrame* aFrame,
+                                                    FrameEnumFunc&& aFunc) {
+  while (aFrame) {
+    aFunc(aFrame);
+    aFrame = nsLayoutUtils::GetNextContinuationOrIBSplitSibling(aFrame);
+  }
+}
+
+void KeyframeEffect::UpdateTarget(Element* aElement,
+                                  PseudoStyleType aPseudoType) {
+  OwningAnimationTarget newTarget(aElement, aPseudoType);
+
+  if (mTarget == newTarget) {
+    // Assign the same target, skip it.
+    return;
+  }
+
+  if (mTarget) {
+    // Call ResetIsRunningOnCompositor() prior to UnregisterTarget() since
+    // ResetIsRunningOnCompositor() might try to get the EffectSet associated
+    // with this keyframe effect to remove partial pre-render animation from
+    // the layer manager.
+    ResetIsRunningOnCompositor();
+    UnregisterTarget();
+
+    RequestRestyle(EffectCompositor::RestyleType::Layer);
+
+    nsAutoAnimationMutationBatch mb(mTarget.mElement->OwnerDoc());
+    if (mAnimation) {
+      MutationObservers::NotifyAnimationRemoved(mAnimation);
+    }
+  }
+
+  mTarget = newTarget;
+
+  if (mTarget) {
+    UpdateTargetRegistration();
+    RefPtr<const ComputedStyle> computedStyle =
+        GetTargetComputedStyle(Flush::None);
+    if (computedStyle) {
+      UpdateProperties(computedStyle);
+    }
+
+    RequestRestyle(EffectCompositor::RestyleType::Layer);
+
+    nsAutoAnimationMutationBatch mb(mTarget.mElement->OwnerDoc());
+    if (mAnimation) {
+      MutationObservers::NotifyAnimationAdded(mAnimation);
+      mAnimation->ReschedulePendingTasks();
+    }
+  }
+
+  if (mAnimation) {
+    mAnimation->NotifyEffectTargetUpdated();
+  }
+}
+
+void KeyframeEffect::UpdateTargetRegistration() {
+  if (!mTarget) {
+    return;
+  }
+
+  bool isRelevant = mAnimation && mAnimation->IsRelevant();
+
+  // Animation::IsRelevant() returns a cached value. It only updates when
+  // something calls Animation::UpdateRelevance. Whenever our timing changes,
+  // we should be notifying our Animation before calling this, so
+  // Animation::IsRelevant() should be up-to-date by the time we get here.
+  MOZ_ASSERT(isRelevant ==
+                 ((IsCurrent() || IsInEffect()) && mAnimation &&
+                  mAnimation->ReplaceState() != AnimationReplaceState::Removed),
+             "Out of date Animation::IsRelevant value");
+
+  if (isRelevant && !mInEffectSet) {
+    EffectSet* effectSet =
+        EffectSet::GetOrCreate(mTarget.mElement, mTarget.mPseudoType);
+    effectSet->AddEffect(*this);
+    mInEffectSet = true;
+    UpdateEffectSet(effectSet);
+    nsIFrame* frame = GetPrimaryFrame();
+    EnumerateContinuationsOrIBSplitSiblings(
+        frame, [](nsIFrame* aFrame) { aFrame->MarkNeedsDisplayItemRebuild(); });
+  } else if (!isRelevant && mInEffectSet) {
+    UnregisterTarget();
+  }
+}
+
+void KeyframeEffect::UnregisterTarget() {
+  if (!mInEffectSet) {
+    return;
+  }
+
+  EffectSet* effectSet = EffectSet::Get(mTarget.mElement, mTarget.mPseudoType);
+  MOZ_ASSERT(effectSet,
+             "If mInEffectSet is true, there must be an EffectSet"
+             " on the target element");
+  mInEffectSet = false;
+  if (effectSet) {
+    effectSet->RemoveEffect(*this);
+
+    if (effectSet->IsEmpty()) {
+      EffectSet::DestroyEffectSet(mTarget.mElement, mTarget.mPseudoType);
+    }
+  }
+  nsIFrame* frame = GetPrimaryFrame();
+  EnumerateContinuationsOrIBSplitSiblings(
+      frame, [](nsIFrame* aFrame) { aFrame->MarkNeedsDisplayItemRebuild(); });
+}
+
+void KeyframeEffect::RequestRestyle(
+    EffectCompositor::RestyleType aRestyleType) {
+  if (!mTarget) {
+    return;
+  }
+  nsPresContext* presContext =
+      nsContentUtils::GetContextForContent(mTarget.mElement);
+  if (presContext && mAnimation) {
+    presContext->EffectCompositor()->RequestRestyle(
+        mTarget.mElement, mTarget.mPseudoType, aRestyleType,
+        mAnimation->CascadeLevel());
+  }
+}
+
+already_AddRefed<const ComputedStyle> KeyframeEffect::GetTargetComputedStyle(
+    Flush aFlushType) const {
+  if (!GetRenderedDocument()) {
+    return nullptr;
+  }
+
+  MOZ_ASSERT(mTarget,
+             "Should only have a document when we have a target element");
+
+  OwningAnimationTarget kungfuDeathGrip(mTarget.mElement, mTarget.mPseudoType);
+
+  return aFlushType == Flush::Style
+             ? nsComputedDOMStyle::GetComputedStyle(mTarget.mElement,
+                                                    mTarget.mPseudoType)
+             : nsComputedDOMStyle::GetComputedStyleNoFlush(mTarget.mElement,
+                                                           mTarget.mPseudoType);
+}
+
+#ifdef DEBUG
+void DumpAnimationProperties(
+    const StylePerDocumentStyleData* aRawData,
+    nsTArray<AnimationProperty>& aAnimationProperties) {
+  for (auto& p : aAnimationProperties) {
+    printf("%s\n", nsCString(nsCSSProps::GetStringValue(p.mProperty)).get());
+    for (auto& s : p.mSegments) {
+      nsAutoCString fromValue, toValue;
+      s.mFromValue.SerializeSpecifiedValue(p.mProperty, aRawData, fromValue);
+      s.mToValue.SerializeSpecifiedValue(p.mProperty, aRawData, toValue);
+      printf("  %f..%f: %s..%s\n", s.mFromKey, s.mToKey, fromValue.get(),
+             toValue.get());
+    }
+  }
+}
+#endif
+
+/* static */
+already_AddRefed<KeyframeEffect> KeyframeEffect::Constructor(
+    const GlobalObject& aGlobal, Element* aTarget,
+    JS::Handle<JSObject*> aKeyframes,
+    const UnrestrictedDoubleOrKeyframeEffectOptions& aOptions,
+    ErrorResult& aRv) {
+  return ConstructKeyframeEffect(aGlobal, aTarget, aKeyframes, aOptions, aRv);
+}
+
+/* static */
+already_AddRefed<KeyframeEffect> KeyframeEffect::Constructor(
+    const GlobalObject& aGlobal, Element* aTarget,
+    JS::Handle<JSObject*> aKeyframes,
+    const UnrestrictedDoubleOrKeyframeAnimationOptions& aOptions,
+    ErrorResult& aRv) {
+  return ConstructKeyframeEffect(aGlobal, aTarget, aKeyframes, aOptions, aRv);
+}
+
+/* static */
+already_AddRefed<KeyframeEffect> KeyframeEffect::Constructor(
+    const GlobalObject& aGlobal, KeyframeEffect& aSource, ErrorResult& aRv) {
+  Document* doc = AnimationUtils::GetCurrentRealmDocument(aGlobal.Context());
+  if (!doc) {
+    aRv.Throw(NS_ERROR_FAILURE);
+    return nullptr;
+  }
+
+  // Create a new KeyframeEffect object with aSource's target,
+  // iteration composite operation, composite operation, and spacing mode.
+  // The constructor creates a new AnimationEffect object by
+  // aSource's TimingParams.
+  // Note: we don't need to re-throw exceptions since the value specified on
+  //       aSource's timing object can be assumed valid.
+  RefPtr<KeyframeEffect> effect =
+      new KeyframeEffect(doc, OwningAnimationTarget{aSource.mTarget}, aSource);
+  // Copy cumulative change hint. mCumulativeChangeHint should be the same as
+  // the source one because both of targets are the same.
+  effect->mCumulativeChangeHint = aSource.mCumulativeChangeHint;
+
+  return effect.forget();
+}
+
+void KeyframeEffect::SetPseudoElement(const nsAString& aPseudoElement,
+                                      ErrorResult& aRv) {
+  if (DOMStringIsNull(aPseudoElement)) {
+    UpdateTarget(mTarget.mElement, PseudoStyleType::NotPseudo);
+    return;
+  }
+
+  // Note: GetPseudoType() returns Some(NotPseudo) for the null string,
+  // so we handle null case before this.
+  Maybe<PseudoStyleType> pseudoType =
+      nsCSSPseudoElements::GetPseudoType(aPseudoElement);
+  if (!pseudoType || *pseudoType == PseudoStyleType::NotPseudo) {
+    // Per the spec, we throw SyntaxError for syntactically invalid pseudos.
+    aRv.ThrowSyntaxError(
+        nsPrintfCString("'%s' is a syntactically invalid pseudo-element.",
+                        NS_ConvertUTF16toUTF8(aPseudoElement).get()));
+    return;
+  }
+
+  if (!AnimationUtils::IsSupportedPseudoForAnimations(*pseudoType)) {
+    // Per the spec, we throw SyntaxError for unsupported pseudos.
+    aRv.ThrowSyntaxError(
+        nsPrintfCString("'%s' is an unsupported pseudo-element.",
+                        NS_ConvertUTF16toUTF8(aPseudoElement).get()));
+    return;
+  }
+
+  UpdateTarget(mTarget.mElement, *pseudoType);
+}
+
+static void CreatePropertyValue(
+    nsCSSPropertyID aProperty, float aOffset,
+    const Maybe<StyleComputedTimingFunction>& aTimingFunction,
+    const AnimationValue& aValue, dom::CompositeOperation aComposite,
+    const StylePerDocumentStyleData* aRawData,
+    AnimationPropertyValueDetails& aResult) {
+  aResult.mOffset = aOffset;
+
+  if (!aValue.IsNull()) {
+    nsAutoCString stringValue;
+    aValue.SerializeSpecifiedValue(aProperty, aRawData, stringValue);
+    aResult.mValue.Construct(stringValue);
+  }
+
+  if (aTimingFunction) {
+    aResult.mEasing.Construct();
+    aTimingFunction->AppendToString(aResult.mEasing.Value());
+  } else {
+    aResult.mEasing.Construct("linear"_ns);
+  }
+
+  aResult.mComposite = aComposite;
+}
+
+void KeyframeEffect::GetProperties(
+    nsTArray<AnimationPropertyDetails>& aProperties, ErrorResult& aRv) const {
+  const StylePerDocumentStyleData* rawData =
+      mDocument->StyleSetForPresShellOrMediaQueryEvaluation()->RawData();
+
+  for (const AnimationProperty& property : mProperties) {
+    AnimationPropertyDetails propertyDetails;
+    propertyDetails.mProperty =
+        NS_ConvertASCIItoUTF16(nsCSSProps::GetStringValue(property.mProperty));
+    propertyDetails.mRunningOnCompositor = property.mIsRunningOnCompositor;
+
+    nsAutoString localizedString;
+    if (property.mPerformanceWarning &&
+        property.mPerformanceWarning->ToLocalizedString(localizedString)) {
+      propertyDetails.mWarning.Construct(localizedString);
+    }
+
+    if (!propertyDetails.mValues.SetCapacity(property.mSegments.Length(),
+                                             mozilla::fallible)) {
+      aRv.Throw(NS_ERROR_OUT_OF_MEMORY);
+      return;
+    }
+
+    for (size_t segmentIdx = 0, segmentLen = property.mSegments.Length();
+         segmentIdx < segmentLen; segmentIdx++) {
+      const AnimationPropertySegment& segment = property.mSegments[segmentIdx];
+
+      binding_detail::FastAnimationPropertyValueDetails fromValue;
+      CreatePropertyValue(property.mProperty, segment.mFromKey,
+                          segment.mTimingFunction, segment.mFromValue,
+                          segment.mFromComposite, rawData, fromValue);
+      // We don't apply timing functions for zero-length segments, so
+      // don't return one here.
+      if (segment.mFromKey == segment.mToKey) {
+        fromValue.mEasing.Reset();
+      }
+      // Even though we called SetCapacity before, this could fail, since we
+      // might add multiple elements to propertyDetails.mValues for an element
+      // of property.mSegments in the cases mentioned below.
+      if (!propertyDetails.mValues.AppendElement(fromValue,
+                                                 mozilla::fallible)) {
+        aRv.Throw(NS_ERROR_OUT_OF_MEMORY);
+        return;
+      }
+
+      // Normally we can ignore the to-value for this segment since it is
+      // identical to the from-value from the next segment. However, we need
+      // to add it if either:
+      // a) this is the last segment, or
+      // b) the next segment's from-value differs.
+      if (segmentIdx == segmentLen - 1 ||
+          property.mSegments[segmentIdx + 1].mFromValue != segment.mToValue) {
+        binding_detail::FastAnimationPropertyValueDetails toValue;
+        CreatePropertyValue(property.mProperty, segment.mToKey, Nothing(),
+                            segment.mToValue, segment.mToComposite, rawData,
+                            toValue);
+        // It doesn't really make sense to have a timing function on the
+        // last property value or before a sudden jump so we just drop the
+        // easing property altogether.
+        toValue.mEasing.Reset();
+        if (!propertyDetails.mValues.AppendElement(toValue,
+                                                   mozilla::fallible)) {
+          aRv.Throw(NS_ERROR_OUT_OF_MEMORY);
+          return;
+        }
+      }
+    }
+
+    aProperties.AppendElement(propertyDetails);
+  }
+}
+
+void KeyframeEffect::GetKeyframes(JSContext* aCx, nsTArray<JSObject*>& aResult,
+                                  ErrorResult& aRv) const {
+  MOZ_ASSERT(aResult.IsEmpty());
+  MOZ_ASSERT(!aRv.Failed());
+
+  if (!aResult.SetCapacity(mKeyframes.Length(), mozilla::fallible)) {
+    aRv.Throw(NS_ERROR_OUT_OF_MEMORY);
+    return;
+  }
+
+  bool isCSSAnimation = mAnimation && mAnimation->AsCSSAnimation();
+
+  // For Servo, when we have CSS Animation @keyframes with variables, we convert
+  // shorthands to longhands if needed, and store a reference to the unparsed
+  // value. When it comes time to serialize, however, what do you serialize for
+  // a longhand that comes from a variable reference in a shorthand? Servo says,
+  // "an empty string" which is not particularly helpful.
+  //
+  // We should just store shorthands as-is (bug 1391537) and then return the
+  // variable references, but for now, since we don't do that, and in order to
+  // be consistent with Gecko, we just expand the variables (assuming we have
+  // enough context to do so). For that we need to grab the ComputedStyle so we
+  // know what custom property values to provide.
+  RefPtr<const ComputedStyle> computedStyle;
+  if (isCSSAnimation) {
+    // The following will flush style but that's ok since if you update
+    // a variable's computed value, you expect to see that updated value in the
+    // result of getKeyframes().
+    //
+    // If we don't have a target, the following will return null. In that case
+    // we might end up returning variables as-is or empty string. That should be
+    // acceptable however, since such a case is rare and this is only
+    // short-term (and unshipped) behavior until bug 1391537 is fixed.
+    computedStyle = GetTargetComputedStyle(Flush::Style);
+  }
+
+  const StylePerDocumentStyleData* rawData =
+      mDocument->StyleSetForPresShellOrMediaQueryEvaluation()->RawData();
+
+  for (const Keyframe& keyframe : mKeyframes) {
+    // Set up a dictionary object for the explicit members
+    BaseComputedKeyframe keyframeDict;
+    if (keyframe.mOffset) {
+      keyframeDict.mOffset.SetValue(keyframe.mOffset.value());
+    }
+    MOZ_ASSERT(keyframe.mComputedOffset != Keyframe::kComputedOffsetNotSet,
+               "Invalid computed offset");
+    keyframeDict.mComputedOffset.Construct(keyframe.mComputedOffset);
+    if (keyframe.mTimingFunction) {
+      keyframeDict.mEasing.Truncate();
+      keyframe.mTimingFunction.ref().AppendToString(keyframeDict.mEasing);
+    }  // else if null, leave easing as its default "linear".
+
+    // With the pref off (i.e. dom.animations-api.compositing.enabled:false),
+    // the dictionary-to-JS conversion will skip this member entirely.
+    keyframeDict.mComposite = keyframe.mComposite;
+
+    JS::Rooted<JS::Value> keyframeJSValue(aCx);
+    if (!ToJSValue(aCx, keyframeDict, &keyframeJSValue)) {
+      aRv.Throw(NS_ERROR_FAILURE);
+      return;
+    }
+
+    RefPtr<StyleLockedDeclarationBlock> customProperties;
+    // A workaround for CSS Animations in servo backend, custom properties in
+    // keyframe are stored in a servo's declaration block. Find the declaration
+    // block to resolve CSS variables in the keyframe.
+    // This workaround will be solved by bug 1391537.
+    if (isCSSAnimation) {
+      for (const PropertyValuePair& propertyValue : keyframe.mPropertyValues) {
+        if (propertyValue.mProperty ==
+            nsCSSPropertyID::eCSSPropertyExtra_variable) {
+          customProperties = propertyValue.mServoDeclarationBlock;
+          break;
+        }
+      }
+    }
+
+    JS::Rooted<JSObject*> keyframeObject(aCx, &keyframeJSValue.toObject());
+    for (const PropertyValuePair& propertyValue : keyframe.mPropertyValues) {
+      nsAutoCString stringValue;
+      // Don't serialize the custom properties for this keyframe.
+      if (propertyValue.mProperty ==
+          nsCSSPropertyID::eCSSPropertyExtra_variable) {
+        continue;
+      }
+      if (propertyValue.mServoDeclarationBlock) {
+        Servo_DeclarationBlock_SerializeOneValue(
+            propertyValue.mServoDeclarationBlock, propertyValue.mProperty,
+            &stringValue, computedStyle, customProperties, rawData);
+      } else {
+        if (auto* value = mBaseValues.GetWeak(propertyValue.mProperty)) {
+          Servo_AnimationValue_Serialize(value, propertyValue.mProperty,
+                                         rawData, &stringValue);
+        }
+      }
+
+      // Basically, we need to do the mapping:
+      // * eCSSProperty_offset => "cssOffset"
+      // * eCSSProperty_float => "cssFloat"
+      // This means if property refers to the CSS "offset"/"float" property,
+      // return the string "cssOffset"/"cssFloat". (So avoid overlapping
+      // "offset" property in BaseKeyframe.)
+      // https://drafts.csswg.org/web-animations/#property-name-conversion
+      const char* name = nullptr;
+      switch (propertyValue.mProperty) {
+        case nsCSSPropertyID::eCSSProperty_offset:
+          name = "cssOffset";
+          break;
+        case nsCSSPropertyID::eCSSProperty_float:
+          // FIXME: Bug 1582314: Should handle cssFloat manually if we remove it
+          // from nsCSSProps::PropertyIDLName().
+        default:
+          name = nsCSSProps::PropertyIDLName(propertyValue.mProperty);
+      }
+
+      JS::Rooted<JS::Value> value(aCx);
+      if (!NonVoidUTF8StringToJsval(aCx, stringValue, &value) ||
+          !JS_DefineProperty(aCx, keyframeObject, name, value,
+                             JSPROP_ENUMERATE)) {
+        aRv.Throw(NS_ERROR_FAILURE);
+        return;
+      }
+    }
+
+    aResult.AppendElement(keyframeObject);
+  }
+}
+
+/* static */ const TimeDuration
+KeyframeEffect::OverflowRegionRefreshInterval() {
+  // The amount of time we can wait between updating throttled animations
+  // on the main thread that influence the overflow region.
+  static const TimeDuration kOverflowRegionRefreshInterval =
+      TimeDuration::FromMilliseconds(200);
+
+  return kOverflowRegionRefreshInterval;
+}
+
+static bool IsDefinitivelyInvisibleDueToOpacity(const nsIFrame& aFrame) {
+  if (!aFrame.Style()->IsInOpacityZeroSubtree()) {
+    return false;
+  }
+
+  // Find the root of the opacity: 0 subtree.
+  const nsIFrame* root = &aFrame;
+  while (true) {
+    auto* parent = root->GetInFlowParent();
+    if (!parent || !parent->Style()->IsInOpacityZeroSubtree()) {
+      break;
+    }
+    root = parent;
+  }
+
+  MOZ_ASSERT(root && root->Style()->IsInOpacityZeroSubtree());
+
+  // If aFrame is the root of the opacity: zero subtree, we can't prove we can
+  // optimize it away, because it may have an opacity animation itself.
+  if (root == &aFrame) {
+    return false;
+  }
+
+  // Even if we're in an opacity: zero subtree, if the root of the subtree may
+  // have an opacity animation, we can't optimize us away, as we may become
+  // visible ourselves.
+  return !root->HasAnimationOfOpacity();
+}
+
+static bool CanOptimizeAwayDueToOpacity(const KeyframeEffect& aEffect,
+                                        const nsIFrame& aFrame) {
+  if (!aFrame.Style()->IsInOpacityZeroSubtree()) {
+    return false;
+  }
+  if (IsDefinitivelyInvisibleDueToOpacity(aFrame)) {
+    return true;
+  }
+  return !aEffect.HasOpacityChange() && !aFrame.HasAnimationOfOpacity();
+}
+
+bool KeyframeEffect::CanThrottleIfNotVisible(nsIFrame& aFrame) const {
+  // Unless we are newly in-effect, we can throttle the animation if the
+  // animation is paint only and the target frame is out of view or the document
+  // is in background tabs.
+  if (!mInEffectOnLastAnimationTimingUpdate || !CanIgnoreIfNotVisible()) {
+    return false;
+  }
+
+  PresShell* presShell = GetPresShell();
+  if (presShell && !presShell->IsActive()) {
+    return true;
+  }
+
+  const bool isVisibilityHidden =
+      !aFrame.IsVisibleOrMayHaveVisibleDescendants();
+  const bool canOptimizeAwayVisibility =
+      isVisibilityHidden && !HasVisibilityChange();
+
+  const bool invisible = canOptimizeAwayVisibility ||
+                         CanOptimizeAwayDueToOpacity(*this, aFrame) ||
+                         aFrame.IsScrolledOutOfView();
+  if (!invisible) {
+    return false;
+  }
+
+  // If there are no overflow change hints, we don't need to worry about
+  // unthrottling the animation periodically to update scrollbar positions for
+  // the overflow region.
+  if (!HasPropertiesThatMightAffectOverflow()) {
+    return true;
+  }
+
+  // Don't throttle finite animations since the animation might suddenly
+  // come into view and if it was throttled it will be out-of-sync.
+  if (HasFiniteActiveDuration()) {
+    return false;
+  }
+
+  return isVisibilityHidden ? CanThrottleOverflowChangesInScrollable(aFrame)
+                            : CanThrottleOverflowChanges(aFrame);
+}
+
+bool KeyframeEffect::CanThrottle() const {
+  // Unthrottle if we are not in effect or current. This will be the case when
+  // our owning animation has finished, is idle, or when we are in the delay
+  // phase (but without a backwards fill). In each case the computed progress
+  // value produced on each tick will be the same so we will skip requesting
+  // unnecessary restyles in NotifyAnimationTimingUpdated. Any calls we *do* get
+  // here will be because of a change in state (e.g. we are newly finished or
+  // newly no longer in effect) in which case we shouldn't throttle the sample.
+  if (!IsInEffect() || !IsCurrent()) {
+    return false;
+  }
+
+  nsIFrame* const frame = GetStyleFrame();
+  if (!frame) {
+    // There are two possible cases here.
+    // a) No target element
+    // b) The target element has no frame, e.g. because it is in a display:none
+    //    subtree.
+    // In either case we can throttle the animation because there is no
+    // need to update on the main thread.
+    return true;
+  }
+
+  // Do not throttle any animations during print preview.
+  if (frame->PresContext()->IsPrintingOrPrintPreview()) {
+    return false;
+  }
+
+  if (CanThrottleIfNotVisible(*frame)) {
+    return true;
+  }
+
+  EffectSet* effectSet = nullptr;
+  for (const AnimationProperty& property : mProperties) {
+    if (!property.mIsRunningOnCompositor) {
+      return false;
+    }
+
+    MOZ_ASSERT(nsCSSPropertyIDSet::CompositorAnimatables().HasProperty(
+                   property.mProperty),
+               "The property should be able to run on the compositor");
+    if (!effectSet) {
+      effectSet = EffectSet::Get(mTarget.mElement, mTarget.mPseudoType);
+      MOZ_ASSERT(effectSet,
+                 "CanThrottle should be called on an effect "
+                 "associated with a target element");
+    }
+    MOZ_ASSERT(HasEffectiveAnimationOfProperty(property.mProperty, *effectSet),
+               "There should be an effective animation of the property while "
+               "it is marked as being run on the compositor");
+
+    DisplayItemType displayItemType =
+        LayerAnimationInfo::GetDisplayItemTypeForProperty(property.mProperty);
+
+    // Note that AnimationInfo::GetGenarationFromFrame() is supposed to work
+    // with the primary frame instead of the style frame.
+    Maybe<uint64_t> generation = layers::AnimationInfo::GetGenerationFromFrame(
+        GetPrimaryFrame(), displayItemType);
+    // Unthrottle if the animation needs to be brought up to date
+    if (!generation || effectSet->GetAnimationGeneration() != *generation) {
+      return false;
+    }
+
+    // If this is a transform animation that affects the overflow region,
+    // we should unthrottle the animation periodically.
+    if (HasPropertiesThatMightAffectOverflow() &&
+        !CanThrottleOverflowChangesInScrollable(*frame)) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+bool KeyframeEffect::CanThrottleOverflowChanges(const nsIFrame& aFrame) const {
+  TimeStamp now = aFrame.PresContext()->RefreshDriver()->MostRecentRefresh();
+
+  EffectSet* effectSet = EffectSet::Get(mTarget.mElement, mTarget.mPseudoType);
+  MOZ_ASSERT(effectSet,
+             "CanOverflowTransformChanges is expected to be called"
+             " on an effect in an effect set");
+  MOZ_ASSERT(mAnimation,
+             "CanOverflowTransformChanges is expected to be called"
+             " on an effect with a parent animation");
+  TimeStamp lastSyncTime = effectSet->LastOverflowAnimationSyncTime();
+  // If this animation can cause overflow, we can throttle some of the ticks.
+  return (!lastSyncTime.IsNull() &&
+          (now - lastSyncTime) < OverflowRegionRefreshInterval());
+}
+
+bool KeyframeEffect::CanThrottleOverflowChangesInScrollable(
+    nsIFrame& aFrame) const {
+  // If the target element is not associated with any documents, we don't care
+  // it.
+  Document* doc = GetRenderedDocument();
+  if (!doc) {
+    return true;
+  }
+
+  // If we know that the animation cannot cause overflow,
+  // we can just disable flushes for this animation.
+
+  // If we have no intersection observers, we don't care about overflow.
+  if (!doc->HasIntersectionObservers()) {
+    return true;
+  }
+
+  if (CanThrottleOverflowChanges(aFrame)) {
+    return true;
+  }
+
+  // If the nearest scrollable ancestor has overflow:hidden,
+  // we don't care about overflow.
+  nsIScrollableFrame* scrollable =
+      nsLayoutUtils::GetNearestScrollableFrame(&aFrame);
+  if (!scrollable) {
+    return true;
+  }
+
+  ScrollStyles ss = scrollable->GetScrollStyles();
+  if (ss.mVertical == StyleOverflow::Hidden &&
+      ss.mHorizontal == StyleOverflow::Hidden &&
+      scrollable->GetLogicalScrollPosition() == nsPoint(0, 0)) {
+    return true;
+  }
+
+  return false;
+}
+
+nsIFrame* KeyframeEffect::GetStyleFrame() const {
+  nsIFrame* frame = GetPrimaryFrame();
+  if (!frame) {
+    return nullptr;
+  }
+
+  return nsLayoutUtils::GetStyleFrame(frame);
+}
+
+nsIFrame* KeyframeEffect::GetPrimaryFrame() const {
+  nsIFrame* frame = nullptr;
+  if (!mTarget) {
+    return frame;
+  }
+
+  if (mTarget.mPseudoType == PseudoStyleType::before) {
+    frame = nsLayoutUtils::GetBeforeFrame(mTarget.mElement);
+  } else if (mTarget.mPseudoType == PseudoStyleType::after) {
+    frame = nsLayoutUtils::GetAfterFrame(mTarget.mElement);
+  } else if (mTarget.mPseudoType == PseudoStyleType::marker) {
+    frame = nsLayoutUtils::GetMarkerFrame(mTarget.mElement);
+  } else {
+    frame = mTarget.mElement->GetPrimaryFrame();
+    MOZ_ASSERT(mTarget.mPseudoType == PseudoStyleType::NotPseudo,
+               "unknown mTarget.mPseudoType");
+  }
+
+  return frame;
+}
+
+Document* KeyframeEffect::GetRenderedDocument() const {
+  if (!mTarget) {
+    return nullptr;
+  }
+  return mTarget.mElement->GetComposedDoc();
+}
+
+PresShell* KeyframeEffect::GetPresShell() const {
+  Document* doc = GetRenderedDocument();
+  if (!doc) {
+    return nullptr;
+  }
+  return doc->GetPresShell();
+}
+
+/* static */
+bool KeyframeEffect::IsGeometricProperty(const nsCSSPropertyID aProperty) {
+  MOZ_ASSERT(!nsCSSProps::IsShorthand(aProperty),
+             "Property should be a longhand property");
+
+  switch (aProperty) {
+    case eCSSProperty_bottom:
+    case eCSSProperty_height:
+    case eCSSProperty_left:
+    case eCSSProperty_margin_bottom:
+    case eCSSProperty_margin_left:
+    case eCSSProperty_margin_right:
+    case eCSSProperty_margin_top:
+    case eCSSProperty_padding_bottom:
+    case eCSSProperty_padding_left:
+    case eCSSProperty_padding_right:
+    case eCSSProperty_padding_top:
+    case eCSSProperty_right:
+    case eCSSProperty_top:
+    case eCSSProperty_width:
+      return true;
+    default:
+      return false;
+  }
+}
+
+/* static */
+bool KeyframeEffect::CanAnimateTransformOnCompositor(
+    const nsIFrame* aFrame,
+    AnimationPerformanceWarning::Type& aPerformanceWarning /* out */) {
+  // In some cases, such as when we are simply collecting all the compositor
+  // animations regardless of the frame on which they run in order to calculate
+  // change hints, |aFrame| will be the style frame. However, even in that case
+  // we should look at the primary frame since that is where the transform will
+  // be applied.
+  const nsIFrame* primaryFrame =
+      nsLayoutUtils::GetPrimaryFrameFromStyleFrame(aFrame);
+
+  // Note that testing BackfaceIsHidden() is not a sufficient test for
+  // what we need for animating backface-visibility correctly if we
+  // remove the above test for Extend3DContext(); that would require
+  // looking at backface-visibility on descendants as well. See bug 1186204.
+  if (primaryFrame->BackfaceIsHidden()) {
+    aPerformanceWarning =
+        AnimationPerformanceWarning::Type::TransformBackfaceVisibilityHidden;
+    return false;
+  }
+  // Async 'transform' animations of aFrames with SVG transforms is not
+  // supported.  See bug 779599.
+  if (primaryFrame->IsSVGTransformed()) {
+    aPerformanceWarning = AnimationPerformanceWarning::Type::TransformSVG;
+    return false;
+  }
+
+  return true;
+}
+
+bool KeyframeEffect::ShouldBlockAsyncTransformAnimations(
+    const nsIFrame* aFrame, const nsCSSPropertyIDSet& aPropertySet,
+    AnimationPerformanceWarning::Type& aPerformanceWarning /* out */) const {
+  EffectSet* effectSet = EffectSet::Get(mTarget.mElement, mTarget.mPseudoType);
+  // The various transform properties ('transform', 'scale' etc.) get combined
+  // on the compositor.
+  //
+  // As a result, if we have an animation of 'scale' and 'translate', but the
+  // 'translate' property is covered by an !important rule, we will not be
+  // able to combine the result on the compositor since we won't have the
+  // !important rule to incorporate. In that case we should run all the
+  // transform-related animations on the main thread (where we have the
+  // !important rule).
+  nsCSSPropertyIDSet blockedProperties =
+      effectSet->PropertiesWithImportantRules().Intersect(
+          effectSet->PropertiesForAnimationsLevel());
+  if (blockedProperties.Intersects(aPropertySet)) {
+    aPerformanceWarning =
+        AnimationPerformanceWarning::Type::TransformIsBlockedByImportantRules;
+    return true;
+  }
+
+  MOZ_ASSERT(mAnimation);
+  // Note: If the geometric animations are using scroll-timeline, we don't need
+  // to synchronize transform animations with them.
+  const bool enableMainthreadSynchronizationWithGeometricAnimations =
+      StaticPrefs::
+          dom_animations_mainthread_synchronization_with_geometric_animations() &&
+      !mAnimation->UsingScrollTimeline();
+
+  for (const AnimationProperty& property : mProperties) {
+    // If there is a property for animations level that is overridden by
+    // !important rules, it should not block other animations from running
+    // on the compositor.
+    // NOTE: We don't currently check for !important rules for properties that
+    // don't run on the compositor. As result such properties (e.g. margin-left)
+    // can still block async animations even if they are overridden by
+    // !important rules.
+    if (effectSet &&
+        effectSet->PropertiesWithImportantRules().HasProperty(
+            property.mProperty) &&
+        effectSet->PropertiesForAnimationsLevel().HasProperty(
+            property.mProperty)) {
+      continue;
+    }
+    // Check for geometric properties
+    if (enableMainthreadSynchronizationWithGeometricAnimations &&
+        IsGeometricProperty(property.mProperty)) {
+      aPerformanceWarning =
+          AnimationPerformanceWarning::Type::TransformWithGeometricProperties;
+      return true;
+    }
+
+    // Check for unsupported transform animations
+    if (LayerAnimationInfo::GetCSSPropertiesFor(DisplayItemType::TYPE_TRANSFORM)
+            .HasProperty(property.mProperty)) {
+      if (!CanAnimateTransformOnCompositor(aFrame, aPerformanceWarning)) {
+        return true;
+      }
+    }
+  }
+
+  return false;
+}
+
+bool KeyframeEffect::HasGeometricProperties() const {
+  for (const AnimationProperty& property : mProperties) {
+    if (IsGeometricProperty(property.mProperty)) {
+      return true;
+    }
+  }
+
+  return false;
+}
+
+void KeyframeEffect::SetPerformanceWarning(
+    const nsCSSPropertyIDSet& aPropertySet,
+    const AnimationPerformanceWarning& aWarning) {
+  nsCSSPropertyIDSet curr = aPropertySet;
+  for (AnimationProperty& property : mProperties) {
+    if (!curr.HasProperty(property.mProperty)) {
+      continue;
+    }
+    property.SetPerformanceWarning(aWarning, mTarget.mElement);
+    curr.RemoveProperty(property.mProperty);
+    if (curr.IsEmpty()) {
+      return;
+    }
+  }
+}
+
+already_AddRefed<const ComputedStyle>
+KeyframeEffect::CreateComputedStyleForAnimationValue(
+    nsCSSPropertyID aProperty, const AnimationValue& aValue,
+    nsPresContext* aPresContext, const ComputedStyle* aBaseComputedStyle) {
+  MOZ_ASSERT(aBaseComputedStyle,
+             "CreateComputedStyleForAnimationValue needs to be called "
+             "with a valid ComputedStyle");
+
+  Element* elementForResolve = AnimationUtils::GetElementForRestyle(
+      mTarget.mElement, mTarget.mPseudoType);
+  // The element may be null if, for example, we target a pseudo-element that no
+  // longer exists.
+  if (!elementForResolve) {
+    return nullptr;
+  }
+
+  ServoStyleSet* styleSet = aPresContext->StyleSet();
+  return styleSet->ResolveServoStyleByAddingAnimation(
+      elementForResolve, aBaseComputedStyle, aValue.mServo);
+}
+
+void KeyframeEffect::CalculateCumulativeChangeHint(
+    const ComputedStyle* aComputedStyle) {
+  mCumulativeChangeHint = nsChangeHint(0);
+  mNeedsStyleData = false;
+
+  nsPresContext* presContext =
+      mTarget ? nsContentUtils::GetContextForContent(mTarget.mElement)
+              : nullptr;
+  if (!presContext) {
+    // Change hints make no sense if we're not rendered.
+    //
+    // Actually, we cannot even post them anywhere.
+    mNeedsStyleData = true;
+    return;
+  }
+
+  for (const AnimationProperty& property : mProperties) {
+    // For opacity property we don't produce any change hints that are not
+    // included in nsChangeHint_Hints_CanIgnoreIfNotVisible so we can throttle
+    // opacity animations regardless of the change they produce.  This
+    // optimization is particularly important since it allows us to throttle
+    // opacity animations with missing 0%/100% keyframes.
+    if (property.mProperty == eCSSProperty_opacity) {
+      continue;
+    }
+
+    for (const AnimationPropertySegment& segment : property.mSegments) {
+      // In case composite operation is not 'replace' or value is null,
+      // we can't throttle animations which will not cause any layout changes
+      // on invisible elements because we can't calculate the change hint for
+      // such properties until we compose it.
+      if (!segment.HasReplaceableValues()) {
+        if (!nsCSSPropertyIDSet::TransformLikeProperties().HasProperty(
+                property.mProperty)) {
+          mCumulativeChangeHint = ~nsChangeHint_Hints_CanIgnoreIfNotVisible;
+          return;
+        }
+        // We try a little harder to optimize transform animations simply
+        // because they are so common (the second-most commonly animated
+        // property at the time of writing).  So if we encounter a transform
+        // segment that needs composing with the underlying value, we just add
+        // all the change hints a transform animation is known to be able to
+        // generate.
+        mCumulativeChangeHint |=
+            nsChangeHint_ComprehensiveAddOrRemoveTransform |
+            nsChangeHint_UpdatePostTransformOverflow |
+            nsChangeHint_UpdateTransformLayer;
+        continue;
+      }
+
+      RefPtr<const ComputedStyle> fromContext =
+          CreateComputedStyleForAnimationValue(property.mProperty,
+                                               segment.mFromValue, presContext,
+                                               aComputedStyle);
+      if (!fromContext) {
+        mCumulativeChangeHint = ~nsChangeHint_Hints_CanIgnoreIfNotVisible;
+        mNeedsStyleData = true;
+        return;
+      }
+
+      RefPtr<const ComputedStyle> toContext =
+          CreateComputedStyleForAnimationValue(property.mProperty,
+                                               segment.mToValue, presContext,
+                                               aComputedStyle);
+      if (!toContext) {
+        mCumulativeChangeHint = ~nsChangeHint_Hints_CanIgnoreIfNotVisible;
+        mNeedsStyleData = true;
+        return;
+      }
+
+      uint32_t equalStructs = 0;
+      nsChangeHint changeHint =
+          fromContext->CalcStyleDifference(*toContext, &equalStructs);
+
+      mCumulativeChangeHint |= changeHint;
+    }
+  }
+}
+
+void KeyframeEffect::SetAnimation(Animation* aAnimation) {
+  if (mAnimation == aAnimation) {
+    return;
+  }
+
+  // Restyle for the old animation.
+  RequestRestyle(EffectCompositor::RestyleType::Layer);
+
+  mAnimation = aAnimation;
+
+  UpdateNormalizedTiming();
+
+  // The order of these function calls is important:
+  // NotifyAnimationTimingUpdated() need the updated mIsRelevant flag to check
+  // if it should create the effectSet or not, and MarkCascadeNeedsUpdate()
+  // needs a valid effectSet, so we should call them in this order.
+  if (mAnimation) {
+    mAnimation->UpdateRelevance();
+  }
+  NotifyAnimationTimingUpdated(PostRestyleMode::IfNeeded);
+  if (mAnimation) {
+    MarkCascadeNeedsUpdate();
+  }
+}
+
+bool KeyframeEffect::CanIgnoreIfNotVisible() const {
+  if (!StaticPrefs::dom_animations_offscreen_throttling()) {
+    return false;
+  }
+
+  // FIXME: For further sophisticated optimization we need to check
+  // change hint on the segment corresponding to computedTiming.progress.
+  return NS_IsHintSubset(mCumulativeChangeHint,
+                         nsChangeHint_Hints_CanIgnoreIfNotVisible);
+}
+
+void KeyframeEffect::MarkCascadeNeedsUpdate() {
+  if (!mTarget) {
+    return;
+  }
+
+  EffectSet* effectSet = EffectSet::Get(mTarget.mElement, mTarget.mPseudoType);
+  if (!effectSet) {
+    return;
+  }
+  effectSet->MarkCascadeNeedsUpdate();
+}
+
+/* static */
+bool KeyframeEffect::HasComputedTimingChanged(
+    const ComputedTiming& aComputedTiming,
+    IterationCompositeOperation aIterationComposite,
+    const Nullable<double>& aProgressOnLastCompose,
+    uint64_t aCurrentIterationOnLastCompose) {
+  // Typically we don't need to request a restyle if the progress hasn't
+  // changed since the last call to ComposeStyle. The one exception is if the
+  // iteration composite mode is 'accumulate' and the current iteration has
+  // changed, since that will often produce a different result.
+  return aComputedTiming.mProgress != aProgressOnLastCompose ||
+         (aIterationComposite == IterationCompositeOperation::Accumulate &&
+          aComputedTiming.mCurrentIteration != aCurrentIterationOnLastCompose);
+}
+
+bool KeyframeEffect::HasComputedTimingChanged() const {
+  ComputedTiming computedTiming = GetComputedTiming();
+  return HasComputedTimingChanged(
+      computedTiming, mEffectOptions.mIterationComposite,
+      mProgressOnLastCompose, mCurrentIterationOnLastCompose);
+}
+
+bool KeyframeEffect::ContainsAnimatedScale(const nsIFrame* aFrame) const {
+  // For display:table content, transform animations run on the table wrapper
+  // frame. If we are being passed a frame that doesn't support transforms
+  // (i.e. the inner table frame) we could just return false, but it possibly
+  // means we looked up the wrong EffectSet so for now we just assert instead.
+  MOZ_ASSERT(aFrame && aFrame->IsFrameOfType(nsIFrame::eSupportsCSSTransforms),
+             "We should be passed a frame that supports transforms");
+
+  if (!IsCurrent()) {
+    return false;
+  }
+
+  if (!mAnimation ||
+      mAnimation->ReplaceState() == AnimationReplaceState::Removed) {
+    return false;
+  }
+
+  for (const AnimationProperty& prop : mProperties) {
+    if (prop.mProperty != eCSSProperty_transform &&
+        prop.mProperty != eCSSProperty_scale &&
+        prop.mProperty != eCSSProperty_rotate) {
+      continue;
+    }
+
+    AnimationValue baseStyle = BaseStyle(prop.mProperty);
+    if (!baseStyle.IsNull()) {
+      gfx::MatrixScales size = baseStyle.GetScaleValue(aFrame);
+      if (size != gfx::MatrixScales()) {
+        return true;
+      }
+    }
+
+    // This is actually overestimate because there are some cases that combining
+    // the base value and from/to value produces 1:1 scale. But it doesn't
+    // really matter.
+    for (const AnimationPropertySegment& segment : prop.mSegments) {
+      if (!segment.mFromValue.IsNull()) {
+        gfx::MatrixScales from = segment.mFromValue.GetScaleValue(aFrame);
+        if (from != gfx::MatrixScales()) {
+          return true;
+        }
+      }
+      if (!segment.mToValue.IsNull()) {
+        gfx::MatrixScales to = segment.mToValue.GetScaleValue(aFrame);
+        if (to != gfx::MatrixScales()) {
+          return true;
+        }
+      }
+    }
+  }
+
+  return false;
+}
+
+void KeyframeEffect::UpdateEffectSet(EffectSet* aEffectSet) const {
+  if (!mInEffectSet) {
+    return;
+  }
+
+  EffectSet* effectSet =
+      aEffectSet ? aEffectSet
+                 : EffectSet::Get(mTarget.mElement, mTarget.mPseudoType);
+  if (!effectSet) {
+    return;
+  }
+
+  nsIFrame* styleFrame = GetStyleFrame();
+  if (HasAnimationOfPropertySet(nsCSSPropertyIDSet::OpacityProperties())) {
+    effectSet->SetMayHaveOpacityAnimation();
+    EnumerateContinuationsOrIBSplitSiblings(styleFrame, [](nsIFrame* aFrame) {
+      aFrame->SetMayHaveOpacityAnimation();
+    });
+  }
+
+  nsIFrame* primaryFrame = GetPrimaryFrame();
+  if (HasAnimationOfPropertySet(
+          nsCSSPropertyIDSet::TransformLikeProperties())) {
+    effectSet->SetMayHaveTransformAnimation();
+    // For table frames, it's not clear if we should iterate over the
+    // continuations of the table wrapper or the inner table frame.
+    //
+    // Fortunately, this is not currently an issue because we only split tables
+    // when printing (page breaks) where we don't run animations.
+    EnumerateContinuationsOrIBSplitSiblings(primaryFrame, [](nsIFrame* aFrame) {
+      aFrame->SetMayHaveTransformAnimation();
+    });
+  }
+}
+
+KeyframeEffect::MatchForCompositor KeyframeEffect::IsMatchForCompositor(
+    const nsCSSPropertyIDSet& aPropertySet, const nsIFrame* aFrame,
+    const EffectSet& aEffects,
+    AnimationPerformanceWarning::Type& aPerformanceWarning /* out */) const {
+  MOZ_ASSERT(mAnimation);
+
+  if (!mAnimation->IsRelevant()) {
+    return KeyframeEffect::MatchForCompositor::No;
+  }
+
+  if (mAnimation->ShouldBeSynchronizedWithMainThread(aPropertySet, aFrame,
+                                                     aPerformanceWarning)) {
+    // For a given |aFrame|, we don't want some animations of |aProperty| to
+    // run on the compositor and others to run on the main thread, so if any
+    // need to be synchronized with the main thread, run them all there.
+    return KeyframeEffect::MatchForCompositor::NoAndBlockThisProperty;
+  }
+
+  if (mAnimation->UsingScrollTimeline()) {
+    const ScrollTimeline* scrollTimeline =
+        mAnimation->GetTimeline()->AsScrollTimeline();
+    // We don't send this animation to the compositor if
+    // 1. the APZ is disabled entirely or for the source, or
+    // 2. the associated scroll-timeline is inactive, or
+    // 3. the scrolling direction is not available (i.e. no scroll range).
+    // 4. the scroll style of the scroller is overflow:hidden.
+    if (!scrollTimeline->APZIsActiveForSource() ||
+        !scrollTimeline->IsActive() ||
+        !scrollTimeline->ScrollingDirectionIsAvailable() ||
+        scrollTimeline->SourceScrollStyle() == StyleOverflow::Hidden) {
+      return KeyframeEffect::MatchForCompositor::No;
+    }
+
+    // FIXME: Bug 1818346. Support OMTA for view-timeline. We disable it for now
+    // because we need to make view-timeline-inset animations run on the OMTA as
+    // well before enable this.
+    if (scrollTimeline->IsViewTimeline()) {
+      return KeyframeEffect::MatchForCompositor::No;
+    }
+  }
+
+  if (!HasEffectiveAnimationOfPropertySet(aPropertySet, aEffects)) {
+    return KeyframeEffect::MatchForCompositor::No;
+  }
+
+  // If we know that the animation is not visible, we don't need to send the
+  // animation to the compositor.
+  if (!aFrame->IsVisibleOrMayHaveVisibleDescendants() ||
+      CanOptimizeAwayDueToOpacity(*this, *aFrame) ||
+      aFrame->IsScrolledOutOfView()) {
+    return KeyframeEffect::MatchForCompositor::NoAndBlockThisProperty;
+  }
+
+  if (aPropertySet.HasProperty(eCSSProperty_background_color)) {
+    if (!StaticPrefs::gfx_omta_background_color()) {
+      return KeyframeEffect::MatchForCompositor::No;
+    }
+
+    // We don't yet support off-main-thread background-color animations on
+    // canvas frame or on <html> or <body> which genarate
+    // nsDisplayCanvasBackgroundColor or nsDisplaySolidColor display item.
+    if (aFrame->IsCanvasFrame() ||
+        (aFrame->GetContent() &&
+         (aFrame->GetContent()->IsHTMLElement(nsGkAtoms::body) ||
+          aFrame->GetContent()->IsHTMLElement(nsGkAtoms::html)))) {
+      return KeyframeEffect::MatchForCompositor::No;
+    }
+  }
+
+  // We can't run this background color animation on the compositor if there
+  // is any `current-color` keyframe.
+  if (mHasCurrentColor) {
+    aPerformanceWarning = AnimationPerformanceWarning::Type::HasCurrentColor;
+    return KeyframeEffect::MatchForCompositor::NoAndBlockThisProperty;
+  }
+
+  return mAnimation->IsPlaying() ? KeyframeEffect::MatchForCompositor::Yes
+                                 : KeyframeEffect::MatchForCompositor::IfNeeded;
+}
+
+}  // namespace dom
+}  // namespace mozilla