Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream

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

1 files changed, 995 insertions, 0 deletions

diff --git a/dom/smil/SMILAnimationFunction.cpp b/dom/smil/SMILAnimationFunction.cpp
new file mode 100644
index 0000000000..3fe16f7276
--- /dev/null
+++ b/dom/smil/SMILAnimationFunction.cpp
@@ -0,0 +1,995 @@
+/* -*- 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 "SMILAnimationFunction.h"
+
+#include <math.h>
+
+#include <algorithm>
+#include <utility>
+
+#include "mozilla/DebugOnly.h"
+#include "mozilla/SMILAttr.h"
+#include "mozilla/SMILCSSValueType.h"
+#include "mozilla/SMILNullType.h"
+#include "mozilla/SMILParserUtils.h"
+#include "mozilla/SMILTimedElement.h"
+#include "mozilla/dom/SVGAnimationElement.h"
+#include "nsAttrValueInlines.h"
+#include "nsCOMArray.h"
+#include "nsCOMPtr.h"
+#include "nsContentUtils.h"
+#include "nsGkAtoms.h"
+#include "nsIContent.h"
+#include "nsReadableUtils.h"
+#include "nsString.h"
+
+using namespace mozilla::dom;
+
+namespace mozilla {
+
+//----------------------------------------------------------------------
+// Static members
+
+nsAttrValue::EnumTable SMILAnimationFunction::sAccumulateTable[] = {
+    {"none", false}, {"sum", true}, {nullptr, 0}};
+
+nsAttrValue::EnumTable SMILAnimationFunction::sAdditiveTable[] = {
+    {"replace", false}, {"sum", true}, {nullptr, 0}};
+
+nsAttrValue::EnumTable SMILAnimationFunction::sCalcModeTable[] = {
+    {"linear", CALC_LINEAR},
+    {"discrete", CALC_DISCRETE},
+    {"paced", CALC_PACED},
+    {"spline", CALC_SPLINE},
+    {nullptr, 0}};
+
+// Any negative number should be fine as a sentinel here,
+// because valid distances are non-negative.
+#define COMPUTE_DISTANCE_ERROR (-1)
+
+//----------------------------------------------------------------------
+// Constructors etc.
+
+SMILAnimationFunction::SMILAnimationFunction()
+    : mSampleTime(-1),
+      mRepeatIteration(0),
+      mBeginTime(INT64_MIN),
+      mAnimationElement(nullptr),
+      mErrorFlags(0),
+      mIsActive(false),
+      mIsFrozen(false),
+      mLastValue(false),
+      mHasChanged(true),
+      mValueNeedsReparsingEverySample(false),
+      mPrevSampleWasSingleValueAnimation(false),
+      mWasSkippedInPrevSample(false) {}
+
+void SMILAnimationFunction::SetAnimationElement(
+    SVGAnimationElement* aAnimationElement) {
+  mAnimationElement = aAnimationElement;
+}
+
+bool SMILAnimationFunction::SetAttr(nsAtom* aAttribute, const nsAString& aValue,
+                                    nsAttrValue& aResult,
+                                    nsresult* aParseResult) {
+  // Some elements such as set and discard don't support all possible attributes
+  if (IsDisallowedAttribute(aAttribute)) {
+    aResult.SetTo(aValue);
+    if (aParseResult) {
+      *aParseResult = NS_OK;
+    }
+    return true;
+  }
+
+  bool foundMatch = true;
+  nsresult parseResult = NS_OK;
+
+  // The attributes 'by', 'from', 'to', and 'values' may be parsed differently
+  // depending on the element & attribute we're animating.  So instead of
+  // parsing them now we re-parse them at every sample.
+  if (aAttribute == nsGkAtoms::by || aAttribute == nsGkAtoms::from ||
+      aAttribute == nsGkAtoms::to || aAttribute == nsGkAtoms::values) {
+    // We parse to, from, by, values at sample time.
+    // XXX Need to flag which attribute has changed and then when we parse it at
+    // sample time, report any errors and reset the flag
+    mHasChanged = true;
+    aResult.SetTo(aValue);
+  } else if (aAttribute == nsGkAtoms::accumulate) {
+    parseResult = SetAccumulate(aValue, aResult);
+  } else if (aAttribute == nsGkAtoms::additive) {
+    parseResult = SetAdditive(aValue, aResult);
+  } else if (aAttribute == nsGkAtoms::calcMode) {
+    parseResult = SetCalcMode(aValue, aResult);
+  } else if (aAttribute == nsGkAtoms::keyTimes) {
+    parseResult = SetKeyTimes(aValue, aResult);
+  } else if (aAttribute == nsGkAtoms::keySplines) {
+    parseResult = SetKeySplines(aValue, aResult);
+  } else {
+    foundMatch = false;
+  }
+
+  if (foundMatch && aParseResult) {
+    *aParseResult = parseResult;
+  }
+
+  return foundMatch;
+}
+
+bool SMILAnimationFunction::UnsetAttr(nsAtom* aAttribute) {
+  if (IsDisallowedAttribute(aAttribute)) {
+    return true;
+  }
+
+  bool foundMatch = true;
+
+  if (aAttribute == nsGkAtoms::by || aAttribute == nsGkAtoms::from ||
+      aAttribute == nsGkAtoms::to || aAttribute == nsGkAtoms::values) {
+    mHasChanged = true;
+  } else if (aAttribute == nsGkAtoms::accumulate) {
+    UnsetAccumulate();
+  } else if (aAttribute == nsGkAtoms::additive) {
+    UnsetAdditive();
+  } else if (aAttribute == nsGkAtoms::calcMode) {
+    UnsetCalcMode();
+  } else if (aAttribute == nsGkAtoms::keyTimes) {
+    UnsetKeyTimes();
+  } else if (aAttribute == nsGkAtoms::keySplines) {
+    UnsetKeySplines();
+  } else {
+    foundMatch = false;
+  }
+
+  return foundMatch;
+}
+
+void SMILAnimationFunction::SampleAt(SMILTime aSampleTime,
+                                     const SMILTimeValue& aSimpleDuration,
+                                     uint32_t aRepeatIteration) {
+  // * Update mHasChanged ("Might this sample be different from prev one?")
+  // Were we previously sampling a fill="freeze" final val? (We're not anymore.)
+  mHasChanged |= mLastValue;
+
+  // Are we sampling at a new point in simple duration? And does that matter?
+  mHasChanged |=
+      (mSampleTime != aSampleTime || mSimpleDuration != aSimpleDuration) &&
+      !IsValueFixedForSimpleDuration();
+
+  // Are we on a new repeat and accumulating across repeats?
+  if (!mErrorFlags) {  // (can't call GetAccumulate() if we've had parse errors)
+    mHasChanged |= (mRepeatIteration != aRepeatIteration) && GetAccumulate();
+  }
+
+  mSampleTime = aSampleTime;
+  mSimpleDuration = aSimpleDuration;
+  mRepeatIteration = aRepeatIteration;
+  mLastValue = false;
+}
+
+void SMILAnimationFunction::SampleLastValue(uint32_t aRepeatIteration) {
+  if (mHasChanged || !mLastValue || mRepeatIteration != aRepeatIteration) {
+    mHasChanged = true;
+  }
+
+  mRepeatIteration = aRepeatIteration;
+  mLastValue = true;
+}
+
+void SMILAnimationFunction::Activate(SMILTime aBeginTime) {
+  mBeginTime = aBeginTime;
+  mIsActive = true;
+  mIsFrozen = false;
+  mHasChanged = true;
+}
+
+void SMILAnimationFunction::Inactivate(bool aIsFrozen) {
+  mIsActive = false;
+  mIsFrozen = aIsFrozen;
+  mHasChanged = true;
+}
+
+void SMILAnimationFunction::ComposeResult(const SMILAttr& aSMILAttr,
+                                          SMILValue& aResult) {
+  mHasChanged = false;
+  mPrevSampleWasSingleValueAnimation = false;
+  mWasSkippedInPrevSample = false;
+
+  // Skip animations that are inactive or in error
+  if (!IsActiveOrFrozen() || mErrorFlags != 0) return;
+
+  // Get the animation values
+  SMILValueArray values;
+  nsresult rv = GetValues(aSMILAttr, values);
+  if (NS_FAILED(rv)) return;
+
+  // Check that we have the right number of keySplines and keyTimes
+  CheckValueListDependentAttrs(values.Length());
+  if (mErrorFlags != 0) return;
+
+  // If this interval is active, we must have a non-negative mSampleTime
+  MOZ_ASSERT(mSampleTime >= 0 || !mIsActive,
+             "Negative sample time for active animation");
+  MOZ_ASSERT(mSimpleDuration.IsResolved() || mLastValue,
+             "Unresolved simple duration for active or frozen animation");
+
+  // If we want to add but don't have a base value then just fail outright.
+  // This can happen when we skipped getting the base value because there's an
+  // animation function in the sandwich that should replace it but that function
+  // failed unexpectedly.
+  bool isAdditive = IsAdditive();
+  if (isAdditive && aResult.IsNull()) return;
+
+  SMILValue result;
+
+  if (values.Length() == 1 && !IsToAnimation()) {
+    // Single-valued animation
+    result = values[0];
+    mPrevSampleWasSingleValueAnimation = true;
+
+  } else if (mLastValue) {
+    // Sampling last value
+    const SMILValue& last = values[values.Length() - 1];
+    result = last;
+
+    // See comment in AccumulateResult: to-animation does not accumulate
+    if (!IsToAnimation() && GetAccumulate() && mRepeatIteration) {
+      // If the target attribute type doesn't support addition Add will
+      // fail leaving result = last
+      result.Add(last, mRepeatIteration);
+    }
+
+  } else {
+    // Interpolation
+    if (NS_FAILED(InterpolateResult(values, result, aResult))) return;
+
+    if (NS_FAILED(AccumulateResult(values, result))) return;
+  }
+
+  // If additive animation isn't required or isn't supported, set the value.
+  if (!isAdditive || NS_FAILED(aResult.SandwichAdd(result))) {
+    aResult = std::move(result);
+  }
+}
+
+int8_t SMILAnimationFunction::CompareTo(
+    const SMILAnimationFunction* aOther) const {
+  NS_ENSURE_TRUE(aOther, 0);
+
+  NS_ASSERTION(aOther != this, "Trying to compare to self");
+
+  // Inactive animations sort first
+  if (!IsActiveOrFrozen() && aOther->IsActiveOrFrozen()) return -1;
+
+  if (IsActiveOrFrozen() && !aOther->IsActiveOrFrozen()) return 1;
+
+  // Sort based on begin time
+  if (mBeginTime != aOther->GetBeginTime())
+    return mBeginTime > aOther->GetBeginTime() ? 1 : -1;
+
+  // Next sort based on syncbase dependencies: the dependent element sorts after
+  // its syncbase
+  const SMILTimedElement& thisTimedElement = mAnimationElement->TimedElement();
+  const SMILTimedElement& otherTimedElement =
+      aOther->mAnimationElement->TimedElement();
+  if (thisTimedElement.IsTimeDependent(otherTimedElement)) return 1;
+  if (otherTimedElement.IsTimeDependent(thisTimedElement)) return -1;
+
+  // Animations that appear later in the document sort after those earlier in
+  // the document
+  MOZ_ASSERT(mAnimationElement != aOther->mAnimationElement,
+             "Two animations cannot have the same animation content element!");
+
+  return (nsContentUtils::PositionIsBefore(mAnimationElement,
+                                           aOther->mAnimationElement))
+             ? -1
+             : 1;
+}
+
+bool SMILAnimationFunction::WillReplace() const {
+  /*
+   * In IsAdditive() we don't consider to-animation to be additive as it is
+   * a special case that is dealt with differently in the compositing method.
+   * Here, however, we return FALSE for to-animation (i.e. it will NOT replace
+   * the underlying value) as it builds on the underlying value.
+   */
+  return !mErrorFlags && !(IsAdditive() || IsToAnimation());
+}
+
+bool SMILAnimationFunction::HasChanged() const {
+  return mHasChanged || mValueNeedsReparsingEverySample;
+}
+
+bool SMILAnimationFunction::UpdateCachedTarget(
+    const SMILTargetIdentifier& aNewTarget) {
+  if (!mLastTarget.Equals(aNewTarget)) {
+    mLastTarget = aNewTarget;
+    return true;
+  }
+  return false;
+}
+
+//----------------------------------------------------------------------
+// Implementation helpers
+
+nsresult SMILAnimationFunction::InterpolateResult(const SMILValueArray& aValues,
+                                                  SMILValue& aResult,
+                                                  SMILValue& aBaseValue) {
+  // Sanity check animation values
+  if ((!IsToAnimation() && aValues.Length() < 2) ||
+      (IsToAnimation() && aValues.Length() != 1)) {
+    NS_ERROR("Unexpected number of values");
+    return NS_ERROR_FAILURE;
+  }
+
+  if (IsToAnimation() && aBaseValue.IsNull()) {
+    return NS_ERROR_FAILURE;
+  }
+
+  // Get the normalised progress through the simple duration.
+  //
+  // If we have an indefinite simple duration, just set the progress to be
+  // 0 which will give us the expected behaviour of the animation being fixed at
+  // its starting point.
+  double simpleProgress = 0.0;
+
+  if (mSimpleDuration.IsDefinite()) {
+    SMILTime dur = mSimpleDuration.GetMillis();
+
+    MOZ_ASSERT(dur >= 0, "Simple duration should not be negative");
+    MOZ_ASSERT(mSampleTime >= 0, "Sample time should not be negative");
+
+    if (mSampleTime >= dur || mSampleTime < 0) {
+      NS_ERROR("Animation sampled outside interval");
+      return NS_ERROR_FAILURE;
+    }
+
+    if (dur > 0) {
+      simpleProgress = (double)mSampleTime / dur;
+    }  // else leave simpleProgress at 0.0 (e.g. if mSampleTime == dur == 0)
+  }
+
+  nsresult rv = NS_OK;
+  SMILCalcMode calcMode = GetCalcMode();
+
+  // Force discrete calcMode for visibility since StyleAnimationValue will
+  // try to interpolate it using the special clamping behavior defined for
+  // CSS.
+  if (SMILCSSValueType::PropertyFromValue(aValues[0]) ==
+      eCSSProperty_visibility) {
+    calcMode = CALC_DISCRETE;
+  }
+
+  if (calcMode != CALC_DISCRETE) {
+    // Get the normalised progress between adjacent values
+    const SMILValue* from = nullptr;
+    const SMILValue* to = nullptr;
+    // Init to -1 to make sure that if we ever forget to set this, the
+    // MOZ_ASSERT that tests that intervalProgress is in range will fail.
+    double intervalProgress = -1.f;
+    if (IsToAnimation()) {
+      from = &aBaseValue;
+      to = &aValues[0];
+      if (calcMode == CALC_PACED) {
+        // Note: key[Times/Splines/Points] are ignored for calcMode="paced"
+        intervalProgress = simpleProgress;
+      } else {
+        double scaledSimpleProgress =
+            ScaleSimpleProgress(simpleProgress, calcMode);
+        intervalProgress = ScaleIntervalProgress(scaledSimpleProgress, 0);
+      }
+    } else if (calcMode == CALC_PACED) {
+      rv = ComputePacedPosition(aValues, simpleProgress, intervalProgress, from,
+                                to);
+      // Note: If the above call fails, we'll skip the "from->Interpolate"
+      // call below, and we'll drop into the CALC_DISCRETE section
+      // instead. (as the spec says we should, because our failure was
+      // presumably due to the values being non-additive)
+    } else {  // calcMode == CALC_LINEAR or calcMode == CALC_SPLINE
+      double scaledSimpleProgress =
+          ScaleSimpleProgress(simpleProgress, calcMode);
+      uint32_t index =
+          (uint32_t)floor(scaledSimpleProgress * (aValues.Length() - 1));
+      from = &aValues[index];
+      to = &aValues[index + 1];
+      intervalProgress = scaledSimpleProgress * (aValues.Length() - 1) - index;
+      intervalProgress = ScaleIntervalProgress(intervalProgress, index);
+    }
+
+    if (NS_SUCCEEDED(rv)) {
+      MOZ_ASSERT(from, "NULL from-value during interpolation");
+      MOZ_ASSERT(to, "NULL to-value during interpolation");
+      MOZ_ASSERT(0.0f <= intervalProgress && intervalProgress < 1.0f,
+                 "Interval progress should be in the range [0, 1)");
+      rv = from->Interpolate(*to, intervalProgress, aResult);
+    }
+  }
+
+  // Discrete-CalcMode case
+  // Note: If interpolation failed (isn't supported for this type), the SVG
+  // spec says to force discrete mode.
+  if (calcMode == CALC_DISCRETE || NS_FAILED(rv)) {
+    double scaledSimpleProgress =
+        ScaleSimpleProgress(simpleProgress, CALC_DISCRETE);
+
+    // Floating-point errors can mean that, for example, a sample time of 29s in
+    // a 100s duration animation gives us a simple progress of 0.28999999999
+    // instead of the 0.29 we'd expect. Normally this isn't a noticeable
+    // problem, but when we have sudden jumps in animation values (such as is
+    // the case here with discrete animation) we can get unexpected results.
+    //
+    // To counteract this, before we perform a floor() on the animation
+    // progress, we add a tiny fudge factor to push us into the correct interval
+    // in cases where floating-point errors might cause us to fall short.
+    static const double kFloatingPointFudgeFactor = 1.0e-16;
+    if (scaledSimpleProgress + kFloatingPointFudgeFactor <= 1.0) {
+      scaledSimpleProgress += kFloatingPointFudgeFactor;
+    }
+
+    if (IsToAnimation()) {
+      // We don't follow SMIL 3, 12.6.4, where discrete to animations
+      // are the same as <set> animations.  Instead, we treat it as a
+      // discrete animation with two values (the underlying value and
+      // the to="" value), and honor keyTimes="" as well.
+      uint32_t index = (uint32_t)floor(scaledSimpleProgress * 2);
+      aResult = index == 0 ? aBaseValue : aValues[0];
+    } else {
+      uint32_t index = (uint32_t)floor(scaledSimpleProgress * aValues.Length());
+      aResult = aValues[index];
+
+      // For animation of CSS properties, normally when interpolating we perform
+      // a zero-value fixup which means that empty values (values with type
+      // SMILCSSValueType but a null pointer value) are converted into
+      // a suitable zero value based on whatever they're being interpolated
+      // with. For discrete animation, however, since we don't interpolate,
+      // that never happens. In some rare cases, such as discrete non-additive
+      // by-animation, we can arrive here with |aResult| being such an empty
+      // value so we need to manually perform the fixup.
+      //
+      // We could define a generic method for this on SMILValue but its faster
+      // and simpler to just special case SMILCSSValueType.
+      if (aResult.mType == &SMILCSSValueType::sSingleton) {
+        // We have currently only ever encountered this case for the first
+        // value of a by-animation (which has two values) and since we have no
+        // way of testing other cases we just skip them (but assert if we
+        // ever do encounter them so that we can add code to handle them).
+        if (index + 1 >= aValues.Length()) {
+          MOZ_ASSERT(aResult.mU.mPtr, "The last value should not be empty");
+        } else {
+          // Base the type of the zero value on the next element in the series.
+          SMILCSSValueType::FinalizeValue(aResult, aValues[index + 1]);
+        }
+      }
+    }
+    rv = NS_OK;
+  }
+  return rv;
+}
+
+nsresult SMILAnimationFunction::AccumulateResult(const SMILValueArray& aValues,
+                                                 SMILValue& aResult) {
+  if (!IsToAnimation() && GetAccumulate() && mRepeatIteration) {
+    const SMILValue& lastValue = aValues[aValues.Length() - 1];
+
+    // If the target attribute type doesn't support addition, Add will
+    // fail and we leave aResult untouched.
+    aResult.Add(lastValue, mRepeatIteration);
+  }
+
+  return NS_OK;
+}
+
+/*
+ * Given the simple progress for a paced animation, this method:
+ *  - determines which two elements of the values array we're in between
+ *    (returned as aFrom and aTo)
+ *  - determines where we are between them
+ *    (returned as aIntervalProgress)
+ *
+ * Returns NS_OK, or NS_ERROR_FAILURE if our values don't support distance
+ * computation.
+ */
+nsresult SMILAnimationFunction::ComputePacedPosition(
+    const SMILValueArray& aValues, double aSimpleProgress,
+    double& aIntervalProgress, const SMILValue*& aFrom, const SMILValue*& aTo) {
+  NS_ASSERTION(0.0f <= aSimpleProgress && aSimpleProgress < 1.0f,
+               "aSimpleProgress is out of bounds");
+  NS_ASSERTION(GetCalcMode() == CALC_PACED,
+               "Calling paced-specific function, but not in paced mode");
+  MOZ_ASSERT(aValues.Length() >= 2, "Unexpected number of values");
+
+  // Trivial case: If we have just 2 values, then there's only one interval
+  // for us to traverse, and our progress across that interval is the exact
+  // same as our overall progress.
+  if (aValues.Length() == 2) {
+    aIntervalProgress = aSimpleProgress;
+    aFrom = &aValues[0];
+    aTo = &aValues[1];
+    return NS_OK;
+  }
+
+  double totalDistance = ComputePacedTotalDistance(aValues);
+  if (totalDistance == COMPUTE_DISTANCE_ERROR) return NS_ERROR_FAILURE;
+
+  // If we have 0 total distance, then it's unclear where our "paced" position
+  // should be.  We can just fail, which drops us into discrete animation mode.
+  // (That's fine, since our values are apparently indistinguishable anyway.)
+  if (totalDistance == 0.0) {
+    return NS_ERROR_FAILURE;
+  }
+
+  // total distance we should have moved at this point in time.
+  // (called 'remainingDist' due to how it's used in loop below)
+  double remainingDist = aSimpleProgress * totalDistance;
+
+  // Must be satisfied, because totalDistance is a sum of (non-negative)
+  // distances, and aSimpleProgress is non-negative
+  NS_ASSERTION(remainingDist >= 0, "distance values must be non-negative");
+
+  // Find where remainingDist puts us in the list of values
+  // Note: We could optimize this next loop by caching the
+  // interval-distances in an array, but maybe that's excessive.
+  for (uint32_t i = 0; i < aValues.Length() - 1; i++) {
+    // Note: The following assertion is valid because remainingDist should
+    // start out non-negative, and this loop never shaves off more than its
+    // current value.
+    NS_ASSERTION(remainingDist >= 0, "distance values must be non-negative");
+
+    double curIntervalDist;
+
+    DebugOnly<nsresult> rv =
+        aValues[i].ComputeDistance(aValues[i + 1], curIntervalDist);
+    MOZ_ASSERT(NS_SUCCEEDED(rv),
+               "If we got through ComputePacedTotalDistance, we should "
+               "be able to recompute each sub-distance without errors");
+
+    NS_ASSERTION(curIntervalDist >= 0, "distance values must be non-negative");
+    // Clamp distance value at 0, just in case ComputeDistance is evil.
+    curIntervalDist = std::max(curIntervalDist, 0.0);
+
+    if (remainingDist >= curIntervalDist) {
+      remainingDist -= curIntervalDist;
+    } else {
+      // NOTE: If we get here, then curIntervalDist necessarily is not 0. Why?
+      // Because this clause is only hit when remainingDist < curIntervalDist,
+      // and if curIntervalDist were 0, that would mean remainingDist would
+      // have to be < 0.  But that can't happen, because remainingDist (as
+      // a distance) is non-negative by definition.
+      NS_ASSERTION(curIntervalDist != 0,
+                   "We should never get here with this set to 0...");
+
+      // We found the right spot -- an interpolated position between
+      // values i and i+1.
+      aFrom = &aValues[i];
+      aTo = &aValues[i + 1];
+      aIntervalProgress = remainingDist / curIntervalDist;
+      return NS_OK;
+    }
+  }
+
+  MOZ_ASSERT_UNREACHABLE(
+      "shouldn't complete loop & get here -- if we do, "
+      "then aSimpleProgress was probably out of bounds");
+  return NS_ERROR_FAILURE;
+}
+
+/*
+ * Computes the total distance to be travelled by a paced animation.
+ *
+ * Returns the total distance, or returns COMPUTE_DISTANCE_ERROR if
+ * our values don't support distance computation.
+ */
+double SMILAnimationFunction::ComputePacedTotalDistance(
+    const SMILValueArray& aValues) const {
+  NS_ASSERTION(GetCalcMode() == CALC_PACED,
+               "Calling paced-specific function, but not in paced mode");
+
+  double totalDistance = 0.0;
+  for (uint32_t i = 0; i < aValues.Length() - 1; i++) {
+    double tmpDist;
+    nsresult rv = aValues[i].ComputeDistance(aValues[i + 1], tmpDist);
+    if (NS_FAILED(rv)) {
+      return COMPUTE_DISTANCE_ERROR;
+    }
+
+    // Clamp distance value to 0, just in case we have an evil ComputeDistance
+    // implementation somewhere
+    MOZ_ASSERT(tmpDist >= 0.0f, "distance values must be non-negative");
+    tmpDist = std::max(tmpDist, 0.0);
+
+    totalDistance += tmpDist;
+  }
+
+  return totalDistance;
+}
+
+double SMILAnimationFunction::ScaleSimpleProgress(double aProgress,
+                                                  SMILCalcMode aCalcMode) {
+  if (!HasAttr(nsGkAtoms::keyTimes)) return aProgress;
+
+  uint32_t numTimes = mKeyTimes.Length();
+
+  if (numTimes < 2) return aProgress;
+
+  uint32_t i = 0;
+  for (; i < numTimes - 2 && aProgress >= mKeyTimes[i + 1]; ++i) {
+  }
+
+  if (aCalcMode == CALC_DISCRETE) {
+    // discrete calcMode behaviour differs in that each keyTime defines the time
+    // from when the corresponding value is set, and therefore the last value
+    // needn't be 1. So check if we're in the last 'interval', that is, the
+    // space between the final value and 1.0.
+    if (aProgress >= mKeyTimes[i + 1]) {
+      MOZ_ASSERT(i == numTimes - 2,
+                 "aProgress is not in range of the current interval, yet the "
+                 "current interval is not the last bounded interval either.");
+      ++i;
+    }
+    return (double)i / numTimes;
+  }
+
+  double& intervalStart = mKeyTimes[i];
+  double& intervalEnd = mKeyTimes[i + 1];
+
+  double intervalLength = intervalEnd - intervalStart;
+  if (intervalLength <= 0.0) return intervalStart;
+
+  return (i + (aProgress - intervalStart) / intervalLength) /
+         double(numTimes - 1);
+}
+
+double SMILAnimationFunction::ScaleIntervalProgress(double aProgress,
+                                                    uint32_t aIntervalIndex) {
+  if (GetCalcMode() != CALC_SPLINE) return aProgress;
+
+  if (!HasAttr(nsGkAtoms::keySplines)) return aProgress;
+
+  MOZ_ASSERT(aIntervalIndex < mKeySplines.Length(), "Invalid interval index");
+
+  SMILKeySpline const& spline = mKeySplines[aIntervalIndex];
+  return spline.GetSplineValue(aProgress);
+}
+
+bool SMILAnimationFunction::HasAttr(nsAtom* aAttName) const {
+  if (IsDisallowedAttribute(aAttName)) {
+    return false;
+  }
+  return mAnimationElement->HasAttr(aAttName);
+}
+
+const nsAttrValue* SMILAnimationFunction::GetAttr(nsAtom* aAttName) const {
+  if (IsDisallowedAttribute(aAttName)) {
+    return nullptr;
+  }
+  return mAnimationElement->GetParsedAttr(aAttName);
+}
+
+bool SMILAnimationFunction::GetAttr(nsAtom* aAttName,
+                                    nsAString& aResult) const {
+  if (IsDisallowedAttribute(aAttName)) {
+    return false;
+  }
+  return mAnimationElement->GetAttr(aAttName, aResult);
+}
+
+/*
+ * A utility function to make querying an attribute that corresponds to an
+ * SMILValue a little neater.
+ *
+ * @param aAttName    The attribute name (in the global namespace).
+ * @param aSMILAttr   The SMIL attribute to perform the parsing.
+ * @param[out] aResult        The resulting SMILValue.
+ * @param[out] aPreventCachingOfSandwich
+ *                    If |aResult| contains dependencies on its context that
+ *                    should prevent the result of the animation sandwich from
+ *                    being cached and reused in future samples (as reported
+ *                    by SMILAttr::ValueFromString), then this outparam
+ *                    will be set to true. Otherwise it is left unmodified.
+ *
+ * Returns false if a parse error occurred, otherwise returns true.
+ */
+bool SMILAnimationFunction::ParseAttr(nsAtom* aAttName,
+                                      const SMILAttr& aSMILAttr,
+                                      SMILValue& aResult,
+                                      bool& aPreventCachingOfSandwich) const {
+  nsAutoString attValue;
+  if (GetAttr(aAttName, attValue)) {
+    nsresult rv = aSMILAttr.ValueFromString(attValue, mAnimationElement,
+                                            aResult, aPreventCachingOfSandwich);
+    if (NS_FAILED(rv)) return false;
+  }
+  return true;
+}
+
+/*
+ * SMILANIM specifies the following rules for animation function values:
+ *
+ * (1) if values is set, it overrides everything
+ * (2) for from/to/by animation at least to or by must be specified, from on its
+ *     own (or nothing) is an error--which we will ignore
+ * (3) if both by and to are specified only to will be used, by will be ignored
+ * (4) if by is specified without from (by animation), forces additive behaviour
+ * (5) if to is specified without from (to animation), special care needs to be
+ *     taken when compositing animation as such animations are composited last.
+ *
+ * This helper method applies these rules to fill in the values list and to set
+ * some internal state.
+ */
+nsresult SMILAnimationFunction::GetValues(const SMILAttr& aSMILAttr,
+                                          SMILValueArray& aResult) {
+  if (!mAnimationElement) return NS_ERROR_FAILURE;
+
+  mValueNeedsReparsingEverySample = false;
+  SMILValueArray result;
+
+  // If "values" is set, use it
+  if (HasAttr(nsGkAtoms::values)) {
+    nsAutoString attValue;
+    GetAttr(nsGkAtoms::values, attValue);
+    bool preventCachingOfSandwich = false;
+    if (!SMILParserUtils::ParseValues(attValue, mAnimationElement, aSMILAttr,
+                                      result, preventCachingOfSandwich)) {
+      return NS_ERROR_FAILURE;
+    }
+
+    if (preventCachingOfSandwich) {
+      mValueNeedsReparsingEverySample = true;
+    }
+    // Else try to/from/by
+  } else {
+    bool preventCachingOfSandwich = false;
+    bool parseOk = true;
+    SMILValue to, from, by;
+    parseOk &=
+        ParseAttr(nsGkAtoms::to, aSMILAttr, to, preventCachingOfSandwich);
+    parseOk &=
+        ParseAttr(nsGkAtoms::from, aSMILAttr, from, preventCachingOfSandwich);
+    parseOk &=
+        ParseAttr(nsGkAtoms::by, aSMILAttr, by, preventCachingOfSandwich);
+
+    if (preventCachingOfSandwich) {
+      mValueNeedsReparsingEverySample = true;
+    }
+
+    if (!parseOk || !result.SetCapacity(2, fallible)) {
+      return NS_ERROR_FAILURE;
+    }
+
+    // AppendElement() below must succeed, because SetCapacity() succeeded.
+    if (!to.IsNull()) {
+      if (!from.IsNull()) {
+        MOZ_ALWAYS_TRUE(result.AppendElement(from, fallible));
+        MOZ_ALWAYS_TRUE(result.AppendElement(to, fallible));
+      } else {
+        MOZ_ALWAYS_TRUE(result.AppendElement(to, fallible));
+      }
+    } else if (!by.IsNull()) {
+      SMILValue effectiveFrom(by.mType);
+      if (!from.IsNull()) effectiveFrom = from;
+      // Set values to 'from; from + by'
+      MOZ_ALWAYS_TRUE(result.AppendElement(effectiveFrom, fallible));
+      SMILValue effectiveTo(effectiveFrom);
+      if (!effectiveTo.IsNull() && NS_SUCCEEDED(effectiveTo.Add(by))) {
+        MOZ_ALWAYS_TRUE(result.AppendElement(effectiveTo, fallible));
+      } else {
+        // Using by-animation with non-additive type or bad base-value
+        return NS_ERROR_FAILURE;
+      }
+    } else {
+      // No values, no to, no by -- call it a day
+      return NS_ERROR_FAILURE;
+    }
+  }
+
+  aResult = std::move(result);
+
+  return NS_OK;
+}
+
+void SMILAnimationFunction::CheckValueListDependentAttrs(uint32_t aNumValues) {
+  CheckKeyTimes(aNumValues);
+  CheckKeySplines(aNumValues);
+}
+
+/**
+ * Performs checks for the keyTimes attribute required by the SMIL spec but
+ * which depend on other attributes and therefore needs to be updated as
+ * dependent attributes are set.
+ */
+void SMILAnimationFunction::CheckKeyTimes(uint32_t aNumValues) {
+  if (!HasAttr(nsGkAtoms::keyTimes)) return;
+
+  SMILCalcMode calcMode = GetCalcMode();
+
+  // attribute is ignored for calcMode = paced
+  if (calcMode == CALC_PACED) {
+    SetKeyTimesErrorFlag(false);
+    return;
+  }
+
+  uint32_t numKeyTimes = mKeyTimes.Length();
+  if (numKeyTimes < 1) {
+    // keyTimes isn't set or failed preliminary checks
+    SetKeyTimesErrorFlag(true);
+    return;
+  }
+
+  // no. keyTimes == no. values
+  // For to-animation the number of values is considered to be 2.
+  bool matchingNumOfValues = numKeyTimes == (IsToAnimation() ? 2 : aNumValues);
+  if (!matchingNumOfValues) {
+    SetKeyTimesErrorFlag(true);
+    return;
+  }
+
+  // first value must be 0
+  if (mKeyTimes[0] != 0.0) {
+    SetKeyTimesErrorFlag(true);
+    return;
+  }
+
+  // last value must be 1 for linear or spline calcModes
+  if (calcMode != CALC_DISCRETE && numKeyTimes > 1 &&
+      mKeyTimes[numKeyTimes - 1] != 1.0) {
+    SetKeyTimesErrorFlag(true);
+    return;
+  }
+
+  SetKeyTimesErrorFlag(false);
+}
+
+void SMILAnimationFunction::CheckKeySplines(uint32_t aNumValues) {
+  // attribute is ignored if calc mode is not spline
+  if (GetCalcMode() != CALC_SPLINE) {
+    SetKeySplinesErrorFlag(false);
+    return;
+  }
+
+  // calc mode is spline but the attribute is not set
+  if (!HasAttr(nsGkAtoms::keySplines)) {
+    SetKeySplinesErrorFlag(false);
+    return;
+  }
+
+  if (mKeySplines.Length() < 1) {
+    // keyTimes isn't set or failed preliminary checks
+    SetKeySplinesErrorFlag(true);
+    return;
+  }
+
+  // ignore splines if there's only one value
+  if (aNumValues == 1 && !IsToAnimation()) {
+    SetKeySplinesErrorFlag(false);
+    return;
+  }
+
+  // no. keySpline specs == no. values - 1
+  uint32_t splineSpecs = mKeySplines.Length();
+  if ((splineSpecs != aNumValues - 1 && !IsToAnimation()) ||
+      (IsToAnimation() && splineSpecs != 1)) {
+    SetKeySplinesErrorFlag(true);
+    return;
+  }
+
+  SetKeySplinesErrorFlag(false);
+}
+
+bool SMILAnimationFunction::IsValueFixedForSimpleDuration() const {
+  return mSimpleDuration.IsIndefinite() ||
+         (!mHasChanged && mPrevSampleWasSingleValueAnimation);
+}
+
+//----------------------------------------------------------------------
+// Property getters
+
+bool SMILAnimationFunction::GetAccumulate() const {
+  const nsAttrValue* value = GetAttr(nsGkAtoms::accumulate);
+  if (!value) return false;
+
+  return value->GetEnumValue();
+}
+
+bool SMILAnimationFunction::GetAdditive() const {
+  const nsAttrValue* value = GetAttr(nsGkAtoms::additive);
+  if (!value) return false;
+
+  return value->GetEnumValue();
+}
+
+SMILAnimationFunction::SMILCalcMode SMILAnimationFunction::GetCalcMode() const {
+  const nsAttrValue* value = GetAttr(nsGkAtoms::calcMode);
+  if (!value) return CALC_LINEAR;
+
+  return SMILCalcMode(value->GetEnumValue());
+}
+
+//----------------------------------------------------------------------
+// Property setters / un-setters:
+
+nsresult SMILAnimationFunction::SetAccumulate(const nsAString& aAccumulate,
+                                              nsAttrValue& aResult) {
+  mHasChanged = true;
+  bool parseResult =
+      aResult.ParseEnumValue(aAccumulate, sAccumulateTable, true);
+  SetAccumulateErrorFlag(!parseResult);
+  return parseResult ? NS_OK : NS_ERROR_FAILURE;
+}
+
+void SMILAnimationFunction::UnsetAccumulate() {
+  SetAccumulateErrorFlag(false);
+  mHasChanged = true;
+}
+
+nsresult SMILAnimationFunction::SetAdditive(const nsAString& aAdditive,
+                                            nsAttrValue& aResult) {
+  mHasChanged = true;
+  bool parseResult = aResult.ParseEnumValue(aAdditive, sAdditiveTable, true);
+  SetAdditiveErrorFlag(!parseResult);
+  return parseResult ? NS_OK : NS_ERROR_FAILURE;
+}
+
+void SMILAnimationFunction::UnsetAdditive() {
+  SetAdditiveErrorFlag(false);
+  mHasChanged = true;
+}
+
+nsresult SMILAnimationFunction::SetCalcMode(const nsAString& aCalcMode,
+                                            nsAttrValue& aResult) {
+  mHasChanged = true;
+  bool parseResult = aResult.ParseEnumValue(aCalcMode, sCalcModeTable, true);
+  SetCalcModeErrorFlag(!parseResult);
+  return parseResult ? NS_OK : NS_ERROR_FAILURE;
+}
+
+void SMILAnimationFunction::UnsetCalcMode() {
+  SetCalcModeErrorFlag(false);
+  mHasChanged = true;
+}
+
+nsresult SMILAnimationFunction::SetKeySplines(const nsAString& aKeySplines,
+                                              nsAttrValue& aResult) {
+  mKeySplines.Clear();
+  aResult.SetTo(aKeySplines);
+
+  mHasChanged = true;
+
+  if (!SMILParserUtils::ParseKeySplines(aKeySplines, mKeySplines)) {
+    mKeySplines.Clear();
+    return NS_ERROR_FAILURE;
+  }
+
+  return NS_OK;
+}
+
+void SMILAnimationFunction::UnsetKeySplines() {
+  mKeySplines.Clear();
+  SetKeySplinesErrorFlag(false);
+  mHasChanged = true;
+}
+
+nsresult SMILAnimationFunction::SetKeyTimes(const nsAString& aKeyTimes,
+                                            nsAttrValue& aResult) {
+  mKeyTimes.Clear();
+  aResult.SetTo(aKeyTimes);
+
+  mHasChanged = true;
+
+  if (!SMILParserUtils::ParseSemicolonDelimitedProgressList(aKeyTimes, true,
+                                                            mKeyTimes)) {
+    mKeyTimes.Clear();
+    return NS_ERROR_FAILURE;
+  }
+
+  return NS_OK;
+}
+
+void SMILAnimationFunction::UnsetKeyTimes() {
+  mKeyTimes.Clear();
+  SetKeyTimesErrorFlag(false);
+  mHasChanged = true;
+}
+
+}  // namespace mozilla