Adding upstream version 124.0.1.upstream/124.0.1

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

1 files changed, 700 insertions, 0 deletions

diff --git a/dom/smil/SMILAnimationController.cpp b/dom/smil/SMILAnimationController.cpp
new file mode 100644
index 0000000000..2c103b0f16
--- /dev/null
+++ b/dom/smil/SMILAnimationController.cpp
@@ -0,0 +1,700 @@
+/* -*- 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 "SMILAnimationController.h"
+
+#include <algorithm>
+
+#include "mozilla/AutoRestore.h"
+#include "mozilla/PresShell.h"
+#include "mozilla/PresShellInlines.h"
+#include "mozilla/RestyleManager.h"
+#include "mozilla/SMILTimedElement.h"
+#include "mozilla/dom/DocumentInlines.h"
+#include "mozilla/dom/Element.h"
+#include "mozilla/dom/SVGAnimationElement.h"
+#include "nsContentUtils.h"
+#include "nsCSSProps.h"
+#include "nsRefreshDriver.h"
+#include "mozilla/dom/Document.h"
+#include "SMILCompositor.h"
+#include "SMILCSSProperty.h"
+
+using namespace mozilla::dom;
+
+namespace mozilla {
+
+//----------------------------------------------------------------------
+// SMILAnimationController implementation
+
+//----------------------------------------------------------------------
+// ctors, dtors, factory methods
+
+SMILAnimationController::SMILAnimationController(Document* aDoc)
+    : mDocument(aDoc) {
+  MOZ_ASSERT(aDoc, "need a non-null document");
+
+  if (nsRefreshDriver* refreshDriver = GetRefreshDriver()) {
+    mStartTime = refreshDriver->MostRecentRefresh();
+  } else {
+    mStartTime = mozilla::TimeStamp::Now();
+  }
+  mCurrentSampleTime = mStartTime;
+
+  Begin();
+}
+
+SMILAnimationController::~SMILAnimationController() {
+  NS_ASSERTION(mAnimationElementTable.IsEmpty(),
+               "Animation controller shouldn't be tracking any animation"
+               " elements when it dies");
+  NS_ASSERTION(!mRegisteredWithRefreshDriver,
+               "Leaving stale entry in refresh driver's observer list");
+}
+
+void SMILAnimationController::Disconnect() {
+  MOZ_ASSERT(mDocument, "disconnecting when we weren't connected...?");
+  MOZ_ASSERT(mRefCnt.get() == 1,
+             "Expecting to disconnect when doc is sole remaining owner");
+  NS_ASSERTION(mPauseState & SMILTimeContainer::PAUSE_PAGEHIDE,
+               "Expecting to be paused for pagehide before disconnect");
+
+  StopSampling(GetRefreshDriver());
+
+  mDocument = nullptr;  // (raw pointer)
+}
+
+//----------------------------------------------------------------------
+// SMILTimeContainer methods:
+
+void SMILAnimationController::Pause(uint32_t aType) {
+  SMILTimeContainer::Pause(aType);
+  UpdateSampling();
+}
+
+void SMILAnimationController::Resume(uint32_t aType) {
+  bool wasPaused = !!mPauseState;
+  // Update mCurrentSampleTime so that calls to GetParentTime--used for
+  // calculating parent offsets--are accurate
+  mCurrentSampleTime = mozilla::TimeStamp::Now();
+
+  SMILTimeContainer::Resume(aType);
+
+  if (wasPaused && !mPauseState) {
+    UpdateSampling();
+  }
+}
+
+SMILTime SMILAnimationController::GetParentTime() const {
+  return (SMILTime)(mCurrentSampleTime - mStartTime).ToMilliseconds();
+}
+
+//----------------------------------------------------------------------
+// nsARefreshObserver methods:
+NS_IMPL_ADDREF(SMILAnimationController)
+NS_IMPL_RELEASE(SMILAnimationController)
+
+// nsRefreshDriver Callback function
+void SMILAnimationController::WillRefresh(mozilla::TimeStamp aTime) {
+  // Although we never expect aTime to go backwards, when we initialise the
+  // animation controller, if we can't get hold of a refresh driver we
+  // initialise mCurrentSampleTime to Now(). It may be possible that after
+  // doing so we get sampled by a refresh driver whose most recent refresh time
+  // predates when we were initialised, so to be safe we make sure to take the
+  // most recent time here.
+  aTime = std::max(mCurrentSampleTime, aTime);
+
+  // Sleep detection: If the time between samples is a whole lot greater than we
+  // were expecting then we assume the computer went to sleep or someone's
+  // messing with the clock. In that case, fiddle our parent offset and use our
+  // average time between samples to calculate the new sample time. This
+  // prevents us from hanging while trying to catch up on all the missed time.
+
+  // Smoothing of coefficient for the average function. 0.2 should let us track
+  // the sample rate reasonably tightly without being overly affected by
+  // occasional delays.
+  static const double SAMPLE_DUR_WEIGHTING = 0.2;
+  // If the elapsed time exceeds our expectation by this number of times we'll
+  // initiate special behaviour to basically ignore the intervening time.
+  static const double SAMPLE_DEV_THRESHOLD = 200.0;
+
+  SMILTime elapsedTime =
+      (SMILTime)(aTime - mCurrentSampleTime).ToMilliseconds();
+  if (mAvgTimeBetweenSamples == 0) {
+    // First sample.
+    mAvgTimeBetweenSamples = elapsedTime;
+  } else {
+    if (elapsedTime > SAMPLE_DEV_THRESHOLD * mAvgTimeBetweenSamples) {
+      // Unexpectedly long delay between samples.
+      NS_WARNING(
+          "Detected really long delay between samples, continuing from "
+          "previous sample");
+      mParentOffset += elapsedTime - mAvgTimeBetweenSamples;
+    }
+    // Update the moving average. Due to truncation here the average will
+    // normally be a little less than it should be but that's probably ok.
+    mAvgTimeBetweenSamples =
+        (SMILTime)(elapsedTime * SAMPLE_DUR_WEIGHTING +
+                   mAvgTimeBetweenSamples * (1.0 - SAMPLE_DUR_WEIGHTING));
+  }
+  mCurrentSampleTime = aTime;
+
+  Sample();
+}
+
+//----------------------------------------------------------------------
+// Animation element registration methods:
+
+void SMILAnimationController::RegisterAnimationElement(
+    SVGAnimationElement* aAnimationElement) {
+  const bool wasEmpty = mAnimationElementTable.IsEmpty();
+  mAnimationElementTable.PutEntry(aAnimationElement);
+  if (wasEmpty) {
+    UpdateSampling();
+  }
+}
+
+void SMILAnimationController::UnregisterAnimationElement(
+    SVGAnimationElement* aAnimationElement) {
+  mAnimationElementTable.RemoveEntry(aAnimationElement);
+  if (mAnimationElementTable.IsEmpty()) {
+    UpdateSampling();
+  }
+}
+
+//----------------------------------------------------------------------
+// Page show/hide
+
+void SMILAnimationController::OnPageShow() {
+  Resume(SMILTimeContainer::PAUSE_PAGEHIDE);
+}
+
+void SMILAnimationController::OnPageHide() {
+  Pause(SMILTimeContainer::PAUSE_PAGEHIDE);
+}
+
+//----------------------------------------------------------------------
+// Cycle-collection support
+
+void SMILAnimationController::Traverse(
+    nsCycleCollectionTraversalCallback* aCallback) {
+  // Traverse last compositor table
+  if (mLastCompositorTable) {
+    for (SMILCompositor& compositor : *mLastCompositorTable) {
+      compositor.Traverse(aCallback);
+    }
+  }
+}
+
+void SMILAnimationController::Unlink() { mLastCompositorTable = nullptr; }
+
+//----------------------------------------------------------------------
+// Refresh driver lifecycle related methods
+
+void SMILAnimationController::NotifyRefreshDriverCreated(
+    nsRefreshDriver* aRefreshDriver) {
+  UpdateSampling();
+}
+
+void SMILAnimationController::NotifyRefreshDriverDestroying(
+    nsRefreshDriver* aRefreshDriver) {
+  StopSampling(aRefreshDriver);
+}
+
+//----------------------------------------------------------------------
+// Timer-related implementation helpers
+
+bool SMILAnimationController::ShouldSample() const {
+  return !mPauseState && !mAnimationElementTable.IsEmpty() &&
+         !mChildContainerTable.IsEmpty();
+}
+
+void SMILAnimationController::UpdateSampling() {
+  const bool shouldSample = ShouldSample();
+  const bool isSampling = mRegisteredWithRefreshDriver;
+  if (shouldSample == isSampling) {
+    return;
+  }
+
+  nsRefreshDriver* driver = GetRefreshDriver();
+  if (!driver) {
+    return;
+  }
+
+  if (shouldSample) {
+    // We're effectively resuming from a pause so update our current sample time
+    // or else it will confuse our "average time between samples" calculations.
+    mCurrentSampleTime = mozilla::TimeStamp::Now();
+    driver->AddRefreshObserver(this, FlushType::Style, "SMIL animations");
+    mRegisteredWithRefreshDriver = true;
+    Sample();  // Run the first sample manually.
+  } else {
+    StopSampling(driver);
+  }
+}
+
+void SMILAnimationController::StopSampling(nsRefreshDriver* aRefreshDriver) {
+  if (aRefreshDriver && mRegisteredWithRefreshDriver) {
+    // NOTE: The document might already have been detached from its PresContext
+    // (and RefreshDriver), which would make GetRefreshDriver() return null.
+    MOZ_ASSERT(!GetRefreshDriver() || aRefreshDriver == GetRefreshDriver(),
+               "Stopping sampling with wrong refresh driver");
+    aRefreshDriver->RemoveRefreshObserver(this, FlushType::Style);
+    mRegisteredWithRefreshDriver = false;
+  }
+}
+
+//----------------------------------------------------------------------
+// Sample-related methods and callbacks
+
+void SMILAnimationController::DoSample() {
+  DoSample(true);  // Skip unchanged time containers
+}
+
+void SMILAnimationController::DoSample(bool aSkipUnchangedContainers) {
+  if (!mDocument) {
+    NS_ERROR("Shouldn't be sampling after document has disconnected");
+    return;
+  }
+  if (mRunningSample) {
+    NS_ERROR("Shouldn't be recursively sampling");
+    return;
+  }
+
+  bool isStyleFlushNeeded = mResampleNeeded;
+  mResampleNeeded = false;
+
+  nsCOMPtr<Document> document(mDocument);  // keeps 'this' alive too
+
+  // Set running sample flag -- do this before flushing styles so that when we
+  // flush styles we don't end up requesting extra samples
+  AutoRestore<bool> autoRestoreRunningSample(mRunningSample);
+  mRunningSample = true;
+
+  // STEP 1: Bring model up to date
+  // (i)  Rewind elements where necessary
+  // (ii) Run milestone samples
+  RewindElements();
+  DoMilestoneSamples();
+
+  // STEP 2: Sample the child time containers
+  //
+  // When we sample the child time containers they will simply record the sample
+  // time in document time.
+  TimeContainerHashtable activeContainers(mChildContainerTable.Count());
+  for (SMILTimeContainer* container : mChildContainerTable.Keys()) {
+    if (!container) {
+      continue;
+    }
+
+    if (!container->IsPausedByType(SMILTimeContainer::PAUSE_BEGIN) &&
+        (container->NeedsSample() || !aSkipUnchangedContainers)) {
+      container->ClearMilestones();
+      container->Sample();
+      container->MarkSeekFinished();
+      activeContainers.PutEntry(container);
+    }
+  }
+
+  // STEP 3: (i)  Sample the timed elements AND
+  //         (ii) Create a table of compositors
+  //
+  // (i) Here we sample the timed elements (fetched from the
+  // SVGAnimationElements) which determine from the active time if the
+  // element is active and what its simple time etc. is. This information is
+  // then passed to its time client (SMILAnimationFunction).
+  //
+  // (ii) During the same loop we also build up a table that contains one
+  // compositor for each animated attribute and which maps animated elements to
+  // the corresponding compositor for their target attribute.
+  //
+  // Note that this compositor table needs to be allocated on the heap so we can
+  // store it until the next sample. This lets us find out which elements were
+  // animated in sample 'n-1' but not in sample 'n' (and hence need to have
+  // their animation effects removed in sample 'n').
+  //
+  // Parts (i) and (ii) are not functionally related but we combine them here to
+  // save iterating over the animation elements twice.
+
+  // Create the compositor table
+  UniquePtr<SMILCompositorTable> currentCompositorTable(
+      new SMILCompositorTable(0));
+  nsTArray<RefPtr<SVGAnimationElement>> animElems(
+      mAnimationElementTable.Count());
+
+  for (SVGAnimationElement* animElem : mAnimationElementTable.Keys()) {
+    SampleTimedElement(animElem, &activeContainers);
+    AddAnimationToCompositorTable(animElem, currentCompositorTable.get(),
+                                  isStyleFlushNeeded);
+    animElems.AppendElement(animElem);
+  }
+  activeContainers.Clear();
+
+  // STEP 4: Compare previous sample's compositors against this sample's.
+  // (Transfer cached base values across, & remove animation effects from
+  // no-longer-animated targets.)
+  if (mLastCompositorTable) {
+    // * Transfer over cached base values, from last sample's compositors
+    for (SMILCompositor& compositor : *currentCompositorTable) {
+      SMILCompositor* lastCompositor =
+          mLastCompositorTable->GetEntry(compositor.GetKey());
+
+      if (lastCompositor) {
+        compositor.StealCachedBaseValue(lastCompositor);
+        if (!lastCompositor->HasSameNumberOfAnimationFunctionsAs(compositor)) {
+          // If we have multiple animations on the same element, they share a
+          // compositor. If an active animation ends, it will no longer be in
+          // the compositor table. We need to force compositing to ensure we
+          // render the element with any remaining frozen animations even though
+          // they would not normally trigger compositing.
+          compositor.ToggleForceCompositing();
+        }
+      }
+    }
+
+    // * For each compositor in current sample's hash table, remove entry from
+    // prev sample's hash table -- we don't need to clear animation
+    // effects of those compositors, since they're still being animated.
+    for (const auto& key : currentCompositorTable->Keys()) {
+      mLastCompositorTable->RemoveEntry(key);
+    }
+
+    // * For each entry that remains in prev sample's hash table (i.e. for
+    // every target that's no longer animated), clear animation effects.
+    for (SMILCompositor& compositor : *mLastCompositorTable) {
+      compositor.ClearAnimationEffects();
+    }
+  }
+
+  // return early if there are no active animations to avoid a style flush
+  if (currentCompositorTable->IsEmpty()) {
+    mLastCompositorTable = nullptr;
+    return;
+  }
+
+  if (isStyleFlushNeeded) {
+    document->FlushPendingNotifications(FlushType::Style);
+  }
+
+  // WARNING:
+  // WARNING: the above flush may have destroyed the pres shell and/or
+  // WARNING: frames and other layout related objects.
+  // WARNING:
+
+  // STEP 5: Compose currently-animated attributes.
+  // XXXdholbert: This step traverses our animation targets in an effectively
+  // random order. For animation from/to 'inherit' values to work correctly
+  // when the inherited value is *also* being animated, we really should be
+  // traversing our animated nodes in an ancestors-first order (bug 501183)
+  bool mightHavePendingStyleUpdates = false;
+  for (auto& compositor : *currentCompositorTable) {
+    compositor.ComposeAttribute(mightHavePendingStyleUpdates);
+  }
+
+  // Update last compositor table
+  mLastCompositorTable = std::move(currentCompositorTable);
+  mMightHavePendingStyleUpdates = mightHavePendingStyleUpdates;
+
+  NS_ASSERTION(!mResampleNeeded, "Resample dirty flag set during sample!");
+}
+
+void SMILAnimationController::RewindElements() {
+  const bool rewindNeeded = std::any_of(
+      mChildContainerTable.Keys().cbegin(), mChildContainerTable.Keys().cend(),
+      [](SMILTimeContainer* container) { return container->NeedsRewind(); });
+
+  if (!rewindNeeded) return;
+
+  for (SVGAnimationElement* animElem : mAnimationElementTable.Keys()) {
+    SMILTimeContainer* timeContainer = animElem->GetTimeContainer();
+    if (timeContainer && timeContainer->NeedsRewind()) {
+      animElem->TimedElement().Rewind();
+    }
+  }
+
+  for (SMILTimeContainer* container : mChildContainerTable.Keys()) {
+    container->ClearNeedsRewind();
+  }
+}
+
+void SMILAnimationController::DoMilestoneSamples() {
+  // We need to sample the timing model but because SMIL operates independently
+  // of the frame-rate, we can get one sample at t=0s and the next at t=10min.
+  //
+  // In between those two sample times a whole string of significant events
+  // might be expected to take place: events firing, new interdependencies
+  // between animations resolved and dissolved, etc.
+  //
+  // Furthermore, at any given time, we want to sample all the intervals that
+  // end at that time BEFORE any that begin. This behaviour is implied by SMIL's
+  // endpoint-exclusive timing model.
+  //
+  // So we have the animations (specifically the timed elements) register the
+  // next significant moment (called a milestone) in their lifetime and then we
+  // step through the model at each of these moments and sample those animations
+  // registered for those times. This way events can fire in the correct order,
+  // dependencies can be resolved etc.
+
+  SMILTime sampleTime = INT64_MIN;
+
+  while (true) {
+    // We want to find any milestones AT OR BEFORE the current sample time so we
+    // initialise the next milestone to the moment after (1ms after, to be
+    // precise) the current sample time and see if there are any milestones
+    // before that. Any other milestones will be dealt with in a subsequent
+    // sample.
+    SMILMilestone nextMilestone(GetCurrentTimeAsSMILTime() + 1, true);
+    for (SMILTimeContainer* container : mChildContainerTable.Keys()) {
+      if (container->IsPausedByType(SMILTimeContainer::PAUSE_BEGIN)) {
+        continue;
+      }
+      SMILMilestone thisMilestone;
+      bool didGetMilestone =
+          container->GetNextMilestoneInParentTime(thisMilestone);
+      if (didGetMilestone && thisMilestone < nextMilestone) {
+        nextMilestone = thisMilestone;
+      }
+    }
+
+    if (nextMilestone.mTime > GetCurrentTimeAsSMILTime()) {
+      break;
+    }
+
+    nsTArray<RefPtr<dom::SVGAnimationElement>> elements;
+    for (SMILTimeContainer* container : mChildContainerTable.Keys()) {
+      if (container->IsPausedByType(SMILTimeContainer::PAUSE_BEGIN)) {
+        continue;
+      }
+      container->PopMilestoneElementsAtMilestone(nextMilestone, elements);
+    }
+
+    // During the course of a sampling we don't want to actually go backwards.
+    // Due to negative offsets, early ends and the like, a timed element might
+    // register a milestone that is actually in the past. That's fine, but it's
+    // still only going to get *sampled* with whatever time we're up to and no
+    // earlier.
+    //
+    // Because we're only performing this clamping at the last moment, the
+    // animations will still all get sampled in the correct order and
+    // dependencies will be appropriately resolved.
+    sampleTime = std::max(nextMilestone.mTime, sampleTime);
+
+    for (RefPtr<dom::SVGAnimationElement>& elem : elements) {
+      MOZ_ASSERT(elem, "nullptr animation element in list");
+      SMILTimeContainer* container = elem->GetTimeContainer();
+      if (!container)
+        // The container may be nullptr if the element has been detached from
+        // its parent since registering a milestone.
+        continue;
+
+      SMILTimeValue containerTimeValue =
+          container->ParentToContainerTime(sampleTime);
+      if (!containerTimeValue.IsDefinite()) continue;
+
+      // Clamp the converted container time to non-negative values.
+      SMILTime containerTime =
+          std::max<SMILTime>(0, containerTimeValue.GetMillis());
+
+      if (nextMilestone.mIsEnd) {
+        elem->TimedElement().SampleEndAt(containerTime);
+      } else {
+        elem->TimedElement().SampleAt(containerTime);
+      }
+    }
+  }
+}
+
+/*static*/
+void SMILAnimationController::SampleTimedElement(
+    SVGAnimationElement* aElement, TimeContainerHashtable* aActiveContainers) {
+  SMILTimeContainer* timeContainer = aElement->GetTimeContainer();
+  if (!timeContainer) return;
+
+  // We'd like to call timeContainer->NeedsSample() here and skip all timed
+  // elements that belong to paused time containers that don't need a sample,
+  // but that doesn't work because we've already called Sample() on all the time
+  // containers so the paused ones don't need a sample any more and they'll
+  // return false.
+  //
+  // Instead we build up a hashmap of active time containers during the previous
+  // step (SampleTimeContainer) and then test here if the container for this
+  // timed element is in the list.
+  if (!aActiveContainers->GetEntry(timeContainer)) return;
+
+  SMILTime containerTime = timeContainer->GetCurrentTimeAsSMILTime();
+
+  MOZ_ASSERT(!timeContainer->IsSeeking(),
+             "Doing a regular sample but the time container is still seeking");
+  aElement->TimedElement().SampleAt(containerTime);
+}
+
+/*static*/
+void SMILAnimationController::AddAnimationToCompositorTable(
+    SVGAnimationElement* aElement, SMILCompositorTable* aCompositorTable,
+    bool& aStyleFlushNeeded) {
+  // Add a compositor to the hash table if there's not already one there
+  SMILTargetIdentifier key;
+  if (!GetTargetIdentifierForAnimation(aElement, key))
+    // Something's wrong/missing about animation's target; skip this animation
+    return;
+
+  SMILAnimationFunction& func = aElement->AnimationFunction();
+
+  // Only add active animation functions. If there are no active animations
+  // targeting an attribute, no compositor will be created and any previously
+  // applied animations will be cleared.
+  if (func.IsActiveOrFrozen()) {
+    // Look up the compositor for our target, & add our animation function
+    // to its list of animation functions.
+    SMILCompositor* result = aCompositorTable->PutEntry(key);
+    aStyleFlushNeeded |= func.ValueNeedsReparsingEverySample();
+    result->AddAnimationFunction(&func);
+
+  } else if (func.HasChanged()) {
+    // Look up the compositor for our target, and force it to skip the
+    // "nothing's changed so don't bother compositing" optimization for this
+    // sample. |func| is inactive, but it's probably *newly* inactive (since
+    // it's got HasChanged() == true), so we need to make sure to recompose
+    // its target.
+    SMILCompositor* result = aCompositorTable->PutEntry(key);
+    aStyleFlushNeeded |= func.ValueNeedsReparsingEverySample();
+    result->ToggleForceCompositing();
+
+    // We've now made sure that |func|'s inactivity will be reflected as of
+    // this sample. We need to clear its HasChanged() flag so that it won't
+    // trigger this same clause in future samples (until it changes again).
+    func.ClearHasChanged();
+  }
+}
+
+static inline bool IsTransformAttribute(int32_t aNamespaceID,
+                                        nsAtom* aAttributeName) {
+  return aNamespaceID == kNameSpaceID_None &&
+         (aAttributeName == nsGkAtoms::transform ||
+          aAttributeName == nsGkAtoms::patternTransform ||
+          aAttributeName == nsGkAtoms::gradientTransform);
+}
+
+// Helper function that, given a SVGAnimationElement, looks up its target
+// element & target attribute and populates a SMILTargetIdentifier
+// for this target.
+/*static*/
+bool SMILAnimationController::GetTargetIdentifierForAnimation(
+    SVGAnimationElement* aAnimElem, SMILTargetIdentifier& aResult) {
+  // Look up target (animated) element
+  Element* targetElem = aAnimElem->GetTargetElementContent();
+  if (!targetElem)
+    // Animation has no target elem -- skip it.
+    return false;
+
+  // Look up target (animated) attribute
+  // SMILANIM section 3.1, attributeName may
+  // have an XMLNS prefix to indicate the XML namespace.
+  RefPtr<nsAtom> attributeName;
+  int32_t attributeNamespaceID;
+  if (!aAnimElem->GetTargetAttributeName(&attributeNamespaceID,
+                                         getter_AddRefs(attributeName)))
+    // Animation has no target attr -- skip it.
+    return false;
+
+  // animateTransform can only animate transforms, conversely transforms
+  // can only be animated by animateTransform
+  if (IsTransformAttribute(attributeNamespaceID, attributeName) !=
+      (aAnimElem->IsSVGElement(nsGkAtoms::animateTransform)))
+    return false;
+
+  // Construct the key
+  aResult.mElement = targetElem;
+  aResult.mAttributeName = attributeName;
+  aResult.mAttributeNamespaceID = attributeNamespaceID;
+
+  return true;
+}
+
+bool SMILAnimationController::PreTraverse() {
+  return PreTraverseInSubtree(nullptr);
+}
+
+bool SMILAnimationController::PreTraverseInSubtree(Element* aRoot) {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  if (!mMightHavePendingStyleUpdates) {
+    return false;
+  }
+
+  nsPresContext* context = mDocument->GetPresContext();
+  if (!context) {
+    return false;
+  }
+
+  bool foundElementsNeedingRestyle = false;
+  for (SVGAnimationElement* animElement : mAnimationElementTable.Keys()) {
+    SMILTargetIdentifier key;
+    if (!GetTargetIdentifierForAnimation(animElement, key)) {
+      // Something's wrong/missing about animation's target; skip this animation
+      continue;
+    }
+
+    // Ignore restyles that aren't in the flattened tree subtree rooted at
+    // aRoot.
+    if (aRoot && !nsContentUtils::ContentIsFlattenedTreeDescendantOf(
+                     key.mElement, aRoot)) {
+      continue;
+    }
+
+    context->RestyleManager()->PostRestyleEventForAnimations(
+        key.mElement, PseudoStyleType::NotPseudo, RestyleHint::RESTYLE_SMIL);
+
+    foundElementsNeedingRestyle = true;
+  }
+
+  // Only clear the mMightHavePendingStyleUpdates flag if we definitely posted
+  // all restyles.
+  if (!aRoot) {
+    mMightHavePendingStyleUpdates = false;
+  }
+
+  return foundElementsNeedingRestyle;
+}
+
+//----------------------------------------------------------------------
+// Add/remove child time containers
+
+nsresult SMILAnimationController::AddChild(SMILTimeContainer& aChild) {
+  const bool wasEmpty = mChildContainerTable.IsEmpty();
+  TimeContainerPtrKey* key = mChildContainerTable.PutEntry(&aChild);
+  NS_ENSURE_TRUE(key, NS_ERROR_OUT_OF_MEMORY);
+  if (wasEmpty) {
+    UpdateSampling();
+  }
+  return NS_OK;
+}
+
+void SMILAnimationController::RemoveChild(SMILTimeContainer& aChild) {
+  mChildContainerTable.RemoveEntry(&aChild);
+  if (mChildContainerTable.IsEmpty()) {
+    UpdateSampling();
+  }
+}
+
+// Helper method
+nsRefreshDriver* SMILAnimationController::GetRefreshDriver() {
+  if (!mDocument) {
+    NS_ERROR("Requesting refresh driver after document has disconnected!");
+    return nullptr;
+  }
+
+  nsPresContext* context = mDocument->GetPresContext();
+  return context ? context->RefreshDriver() : nullptr;
+}
+
+void SMILAnimationController::FlagDocumentNeedsFlush() {
+  if (PresShell* presShell = mDocument->GetPresShell()) {
+    presShell->SetNeedStyleFlush();
+  }
+}
+
+}  // namespace mozilla