Adding upstream version 124.0.1.upstream/124.0.1

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

1 files changed, 649 insertions, 0 deletions

diff --git a/dom/svg/SVGAnimatedLength.cpp b/dom/svg/SVGAnimatedLength.cpp
new file mode 100644
index 0000000000..081db5704a
--- /dev/null
+++ b/dom/svg/SVGAnimatedLength.cpp
@@ -0,0 +1,649 @@
+/* -*- 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 "SVGAnimatedLength.h"
+
+#include "mozAutoDocUpdate.h"
+#include "mozilla/ArrayUtils.h"
+#include "mozilla/GeckoBindings.h"
+#include "mozilla/Maybe.h"
+#include "mozilla/PresShell.h"
+#include "mozilla/SMILValue.h"
+#include "mozilla/StaticPresData.h"
+#include "mozilla/SVGIntegrationUtils.h"
+#include "mozilla/dom/SVGViewportElement.h"
+#include "DOMSVGAnimatedLength.h"
+#include "DOMSVGLength.h"
+#include "LayoutLogging.h"
+#include "nsContentUtils.h"
+#include "nsIFrame.h"
+#include "nsLayoutUtils.h"
+#include "nsTextFormatter.h"
+#include "SVGLengthSMILType.h"
+#include "SVGAttrTearoffTable.h"
+#include "SVGGeometryProperty.h"
+
+using namespace mozilla::dom;
+
+namespace mozilla {
+
+//----------------------------------------------------------------------
+// Helper class: AutoChangeLengthNotifier
+// Stack-based helper class to pair calls to WillChangeLength and
+// DidChangeLength.
+class MOZ_RAII AutoChangeLengthNotifier {
+ public:
+  AutoChangeLengthNotifier(SVGAnimatedLength* aLength, SVGElement* aSVGElement,
+                           bool aDoSetAttr = true)
+      : mLength(aLength), mSVGElement(aSVGElement), mDoSetAttr(aDoSetAttr) {
+    MOZ_ASSERT(mLength, "Expecting non-null length");
+    MOZ_ASSERT(mSVGElement, "Expecting non-null element");
+
+    if (mDoSetAttr) {
+      mUpdateBatch.emplace(aSVGElement->GetComposedDoc(), true);
+      mEmptyOrOldValue =
+          mSVGElement->WillChangeLength(mLength->mAttrEnum, mUpdateBatch.ref());
+    }
+  }
+
+  ~AutoChangeLengthNotifier() {
+    if (mDoSetAttr) {
+      mSVGElement->DidChangeLength(mLength->mAttrEnum, mEmptyOrOldValue,
+                                   mUpdateBatch.ref());
+    }
+    if (mLength->mIsAnimated) {
+      mSVGElement->AnimationNeedsResample();
+    }
+  }
+
+ private:
+  SVGAnimatedLength* const mLength;
+  SVGElement* const mSVGElement;
+  Maybe<mozAutoDocUpdate> mUpdateBatch;
+  nsAttrValue mEmptyOrOldValue;
+  bool mDoSetAttr;
+};
+
+static SVGAttrTearoffTable<SVGAnimatedLength, DOMSVGAnimatedLength>
+    sSVGAnimatedLengthTearoffTable;
+
+/* Helper functions */
+
+static void GetValueString(nsAString& aValueAsString, float aValue,
+                           uint16_t aUnitType) {
+  nsTextFormatter::ssprintf(aValueAsString, u"%g", (double)aValue);
+
+  nsAutoString unitString;
+  SVGLength::GetUnitString(unitString, aUnitType);
+  aValueAsString.Append(unitString);
+}
+
+static bool GetValueFromString(const nsAString& aString, float& aValue,
+                               uint16_t* aUnitType) {
+  bool success;
+  auto token = SVGContentUtils::GetAndEnsureOneToken(aString, success);
+
+  if (!success) {
+    return false;
+  }
+
+  RangedPtr<const char16_t> iter = SVGContentUtils::GetStartRangedPtr(token);
+  const RangedPtr<const char16_t> end = SVGContentUtils::GetEndRangedPtr(token);
+
+  if (!SVGContentUtils::ParseNumber(iter, end, aValue)) {
+    return false;
+  }
+  const nsAString& units = Substring(iter.get(), end.get());
+  *aUnitType = SVGLength::GetUnitTypeForString(units);
+  return *aUnitType != SVGLength_Binding::SVG_LENGTHTYPE_UNKNOWN;
+}
+
+static float FixAxisLength(float aLength) {
+  if (aLength == 0.0f) {
+    LAYOUT_WARNING("zero axis length");
+    return 1e-20f;
+  }
+  return aLength;
+}
+
+GeckoFontMetrics UserSpaceMetrics::DefaultFontMetrics() {
+  return {StyleLength::FromPixels(16.0f),
+          StyleLength::FromPixels(-1),
+          StyleLength::FromPixels(-1),
+          StyleLength::FromPixels(-1),
+          StyleLength::FromPixels(-1),
+          StyleLength::FromPixels(16.0f),
+          0.0f,
+          0.0f};
+}
+
+GeckoFontMetrics UserSpaceMetrics::GetFontMetrics(const Element* aElement) {
+  GeckoFontMetrics metrics = DefaultFontMetrics();
+  auto* presContext =
+      aElement ? nsContentUtils::GetContextForContent(aElement) : nullptr;
+  if (presContext) {
+    SVGGeometryProperty::DoForComputedStyle(
+        aElement, [&](const ComputedStyle* style) {
+          metrics = Gecko_GetFontMetrics(
+              presContext, WritingMode(style).IsVertical(), style->StyleFont(),
+              style->StyleFont()->mFont.size,
+              /* aUseUserFontSet = */ true,
+              /* aRetrieveMathScales */ false);
+        });
+  }
+  return metrics;
+}
+
+WritingMode UserSpaceMetrics::GetWritingMode(const Element* aElement) {
+  WritingMode writingMode;
+  SVGGeometryProperty::DoForComputedStyle(
+      aElement,
+      [&](const ComputedStyle* style) { writingMode = WritingMode(style); });
+  return writingMode;
+}
+
+float UserSpaceMetrics::GetExLength(Type aType) const {
+  return GetFontMetricsForType(aType).mXSize.ToCSSPixels();
+}
+
+float UserSpaceMetrics::GetChSize(Type aType) const {
+  auto metrics = GetFontMetricsForType(aType);
+  if (metrics.mChSize.ToCSSPixels() > 0.0) {
+    return metrics.mChSize.ToCSSPixels();
+  }
+  auto emLength = GetEmLength(aType);
+  WritingMode writingMode = GetWritingModeForType(aType);
+  return writingMode.IsVertical() && !writingMode.IsSideways()
+             ? emLength
+             : emLength * 0.5f;
+}
+
+float UserSpaceMetrics::GetIcWidth(Type aType) const {
+  auto metrics = GetFontMetricsForType(aType);
+  if (metrics.mIcWidth.ToCSSPixels() > 0.0) {
+    return metrics.mIcWidth.ToCSSPixels();
+  }
+  return GetEmLength(aType);
+}
+
+float UserSpaceMetrics::GetCapHeight(Type aType) const {
+  auto metrics = GetFontMetricsForType(aType);
+  if (metrics.mCapHeight.ToCSSPixels() > 0.0) {
+    return metrics.mCapHeight.ToCSSPixels();
+  }
+  return GetEmLength(aType);
+}
+
+CSSSize UserSpaceMetrics::GetCSSViewportSizeFromContext(
+    const nsPresContext* aContext) {
+  return CSSPixel::FromAppUnits(aContext->GetSizeForViewportUnits());
+}
+
+SVGElementMetrics::SVGElementMetrics(const SVGElement* aSVGElement,
+                                     const SVGViewportElement* aCtx)
+    : mSVGElement(aSVGElement), mCtx(aCtx) {}
+
+const Element* SVGElementMetrics::GetElementForType(Type aType) const {
+  switch (aType) {
+    case Type::This:
+      return mSVGElement;
+    case Type::Root:
+      return mSVGElement ? mSVGElement->OwnerDoc()->GetRootElement() : nullptr;
+    default:
+      MOZ_ASSERT_UNREACHABLE("Was a new value added to the enumeration?");
+      return nullptr;
+  }
+}
+
+GeckoFontMetrics SVGElementMetrics::GetFontMetricsForType(Type aType) const {
+  return GetFontMetrics(GetElementForType(aType));
+}
+
+WritingMode SVGElementMetrics::GetWritingModeForType(Type aType) const {
+  return GetWritingMode(GetElementForType(aType));
+}
+
+float SVGElementMetrics::GetAxisLength(uint8_t aCtxType) const {
+  if (!EnsureCtx()) {
+    return 1.0f;
+  }
+
+  return FixAxisLength(mCtx->GetLength(aCtxType));
+}
+
+CSSSize SVGElementMetrics::GetCSSViewportSize() const {
+  if (!mSVGElement) {
+    return {0.0f, 0.0f};
+  }
+  nsPresContext* context = nsContentUtils::GetContextForContent(mSVGElement);
+  if (!context) {
+    return {0.0f, 0.0f};
+  }
+  return GetCSSViewportSizeFromContext(context);
+}
+
+bool SVGElementMetrics::EnsureCtx() const {
+  if (!mCtx && mSVGElement) {
+    mCtx = mSVGElement->GetCtx();
+    if (!mCtx && mSVGElement->IsSVGElement(nsGkAtoms::svg)) {
+      const auto* e = static_cast<const SVGViewportElement*>(mSVGElement);
+
+      if (!e->IsInner()) {
+        // mSVGElement must be the outer svg element
+        mCtx = e;
+      }
+    }
+  }
+  return mCtx != nullptr;
+}
+
+NonSVGFrameUserSpaceMetrics::NonSVGFrameUserSpaceMetrics(nsIFrame* aFrame)
+    : mFrame(aFrame) {
+  MOZ_ASSERT(mFrame, "Need a frame");
+}
+
+float NonSVGFrameUserSpaceMetrics::GetEmLength(Type aType) const {
+  switch (aType) {
+    case Type::This:
+      return SVGContentUtils::GetFontSize(mFrame);
+    case Type::Root:
+      return SVGContentUtils::GetFontSize(
+          mFrame->PresContext()->Document()->GetRootElement());
+    default:
+      MOZ_ASSERT_UNREACHABLE("Was a new value added to the enumeration?");
+      return 1.0f;
+  }
+}
+
+GeckoFontMetrics NonSVGFrameUserSpaceMetrics::GetFontMetricsForType(
+    Type aType) const {
+  switch (aType) {
+    case Type::This:
+      return Gecko_GetFontMetrics(
+          mFrame->PresContext(), mFrame->GetWritingMode().IsVertical(),
+          mFrame->StyleFont(), mFrame->StyleFont()->mFont.size,
+          /* aUseUserFontSet = */ true,
+          /* aRetrieveMathScales */ false);
+    case Type::Root:
+      return GetFontMetrics(
+          mFrame->PresContext()->Document()->GetRootElement());
+    default:
+      MOZ_ASSERT_UNREACHABLE("Was a new value added to the enumeration?");
+      return DefaultFontMetrics();
+  }
+}
+
+WritingMode NonSVGFrameUserSpaceMetrics::GetWritingModeForType(
+    Type aType) const {
+  switch (aType) {
+    case Type::This:
+      return mFrame->GetWritingMode();
+    case Type::Root:
+      return GetWritingMode(
+          mFrame->PresContext()->Document()->GetRootElement());
+    default:
+      MOZ_ASSERT_UNREACHABLE("Was a new value added to the enumeration?");
+      return WritingMode();
+  }
+}
+
+gfx::Size NonSVGFrameUserSpaceMetrics::GetSize() const {
+  return SVGIntegrationUtils::GetSVGCoordContextForNonSVGFrame(mFrame);
+}
+
+CSSSize NonSVGFrameUserSpaceMetrics::GetCSSViewportSize() const {
+  return GetCSSViewportSizeFromContext(mFrame->PresContext());
+}
+
+float UserSpaceMetricsWithSize::GetAxisLength(uint8_t aCtxType) const {
+  gfx::Size size = GetSize();
+  float length;
+  switch (aCtxType) {
+    case SVGContentUtils::X:
+      length = size.width;
+      break;
+    case SVGContentUtils::Y:
+      length = size.height;
+      break;
+    case SVGContentUtils::XY:
+      length =
+          SVGContentUtils::ComputeNormalizedHypotenuse(size.width, size.height);
+      break;
+    default:
+      MOZ_ASSERT_UNREACHABLE("Unknown axis type");
+      length = 1;
+      break;
+  }
+  return FixAxisLength(length);
+}
+
+float SVGAnimatedLength::GetPixelsPerUnit(const SVGElement* aSVGElement,
+                                          uint8_t aUnitType) const {
+  return SVGLength::GetPixelsPerUnit(SVGElementMetrics(aSVGElement), aUnitType,
+                                     mCtxType);
+}
+
+float SVGAnimatedLength::GetPixelsPerUnit(const SVGViewportElement* aCtx,
+                                          uint8_t aUnitType) const {
+  return SVGLength::GetPixelsPerUnit(SVGElementMetrics(aCtx, aCtx), aUnitType,
+                                     mCtxType);
+}
+
+float SVGAnimatedLength::GetPixelsPerUnit(nsIFrame* aFrame,
+                                          uint8_t aUnitType) const {
+  const nsIContent* content = aFrame->GetContent();
+  MOZ_ASSERT(!content->IsText(), "Not expecting text content");
+  if (content->IsSVGElement()) {
+    return SVGLength::GetPixelsPerUnit(
+        SVGElementMetrics(static_cast<const SVGElement*>(content)), aUnitType,
+        mCtxType);
+  }
+  return SVGLength::GetPixelsPerUnit(NonSVGFrameUserSpaceMetrics(aFrame),
+                                     aUnitType, mCtxType);
+}
+
+float SVGAnimatedLength::GetPixelsPerUnit(const UserSpaceMetrics& aMetrics,
+                                          uint8_t aUnitType) const {
+  return SVGLength::GetPixelsPerUnit(aMetrics, aUnitType, mCtxType);
+}
+
+void SVGAnimatedLength::SetBaseValueInSpecifiedUnits(float aValue,
+                                                     SVGElement* aSVGElement,
+                                                     bool aDoSetAttr) {
+  if (mIsBaseSet && mBaseVal == aValue) {
+    return;
+  }
+
+  AutoChangeLengthNotifier notifier(this, aSVGElement, aDoSetAttr);
+
+  mBaseVal = aValue;
+  mIsBaseSet = true;
+  if (!mIsAnimated) {
+    mAnimVal = mBaseVal;
+  }
+}
+
+nsresult SVGAnimatedLength::ConvertToSpecifiedUnits(uint16_t unitType,
+                                                    SVGElement* aSVGElement) {
+  if (!SVGLength::IsValidUnitType(unitType)) {
+    return NS_ERROR_DOM_NOT_SUPPORTED_ERR;
+  }
+
+  if (mIsBaseSet && mBaseUnitType == uint8_t(unitType)) return NS_OK;
+
+  float valueInSpecifiedUnits;
+
+  if (SVGLength::IsAbsoluteUnit(unitType) &&
+      SVGLength::IsAbsoluteUnit(mBaseUnitType)) {
+    valueInSpecifiedUnits =
+        mBaseVal * SVGLength::GetAbsUnitsPerAbsUnit(unitType, mBaseUnitType);
+  } else {
+    float pixelsPerUnit = GetPixelsPerUnit(aSVGElement, unitType);
+    if (pixelsPerUnit == 0.0f) {
+      return NS_ERROR_ILLEGAL_VALUE;
+    }
+    float valueInPixels =
+        mBaseVal * GetPixelsPerUnit(aSVGElement, mBaseUnitType);
+    valueInSpecifiedUnits = valueInPixels / pixelsPerUnit;
+  }
+
+  if (!std::isfinite(valueInSpecifiedUnits)) {
+    return NS_ERROR_ILLEGAL_VALUE;
+  }
+
+  // Even though we're not changing the visual effect this length will have
+  // on the document, we still need to send out notifications in case we have
+  // mutation listeners, since the actual string value of the attribute will
+  // change.
+  AutoChangeLengthNotifier notifier(this, aSVGElement);
+
+  mBaseUnitType = uint8_t(unitType);
+  if (!mIsAnimated) {
+    mAnimUnitType = mBaseUnitType;
+  }
+  // Setting aDoSetAttr to false here will ensure we don't call
+  // Will/DidChangeAngle a second time (and dispatch duplicate notifications).
+  SetBaseValueInSpecifiedUnits(valueInSpecifiedUnits, aSVGElement, false);
+
+  return NS_OK;
+}
+
+nsresult SVGAnimatedLength::NewValueSpecifiedUnits(uint16_t aUnitType,
+                                                   float aValueInSpecifiedUnits,
+                                                   SVGElement* aSVGElement) {
+  NS_ENSURE_FINITE(aValueInSpecifiedUnits, NS_ERROR_ILLEGAL_VALUE);
+
+  if (!SVGLength::IsValidUnitType(aUnitType)) {
+    return NS_ERROR_DOM_NOT_SUPPORTED_ERR;
+  }
+
+  if (mIsBaseSet && mBaseVal == aValueInSpecifiedUnits &&
+      mBaseUnitType == uint8_t(aUnitType)) {
+    return NS_OK;
+  }
+
+  AutoChangeLengthNotifier notifier(this, aSVGElement);
+
+  mBaseVal = aValueInSpecifiedUnits;
+  mIsBaseSet = true;
+  mBaseUnitType = uint8_t(aUnitType);
+  if (!mIsAnimated) {
+    mAnimVal = mBaseVal;
+    mAnimUnitType = mBaseUnitType;
+  }
+  return NS_OK;
+}
+
+already_AddRefed<DOMSVGLength> SVGAnimatedLength::ToDOMBaseVal(
+    SVGElement* aSVGElement) {
+  return DOMSVGLength::GetTearOff(this, aSVGElement, false);
+}
+
+already_AddRefed<DOMSVGLength> SVGAnimatedLength::ToDOMAnimVal(
+    SVGElement* aSVGElement) {
+  return DOMSVGLength::GetTearOff(this, aSVGElement, true);
+}
+
+/* Implementation */
+
+nsresult SVGAnimatedLength::SetBaseValueString(const nsAString& aValueAsString,
+                                               SVGElement* aSVGElement,
+                                               bool aDoSetAttr) {
+  float value;
+  uint16_t unitType;
+
+  if (!GetValueFromString(aValueAsString, value, &unitType)) {
+    return NS_ERROR_DOM_SYNTAX_ERR;
+  }
+
+  if (mIsBaseSet && mBaseVal == float(value) &&
+      mBaseUnitType == uint8_t(unitType)) {
+    return NS_OK;
+  }
+
+  AutoChangeLengthNotifier notifier(this, aSVGElement, aDoSetAttr);
+
+  mBaseVal = value;
+  mIsBaseSet = true;
+  mBaseUnitType = uint8_t(unitType);
+  if (!mIsAnimated) {
+    mAnimVal = mBaseVal;
+    mAnimUnitType = mBaseUnitType;
+  }
+
+  return NS_OK;
+}
+
+void SVGAnimatedLength::GetBaseValueString(nsAString& aValueAsString) const {
+  GetValueString(aValueAsString, mBaseVal, mBaseUnitType);
+}
+
+void SVGAnimatedLength::GetAnimValueString(nsAString& aValueAsString) const {
+  GetValueString(aValueAsString, mAnimVal, mAnimUnitType);
+}
+
+nsresult SVGAnimatedLength::SetBaseValue(float aValue, SVGElement* aSVGElement,
+                                         bool aDoSetAttr) {
+  float pixelsPerUnit = GetPixelsPerUnit(aSVGElement, mBaseUnitType);
+  if (pixelsPerUnit == 0.0f) {
+    return NS_ERROR_ILLEGAL_VALUE;
+  }
+
+  float valueInSpecifiedUnits = aValue / pixelsPerUnit;
+  if (!std::isfinite(valueInSpecifiedUnits)) {
+    return NS_ERROR_ILLEGAL_VALUE;
+  }
+
+  SetBaseValueInSpecifiedUnits(valueInSpecifiedUnits, aSVGElement, aDoSetAttr);
+  return NS_OK;
+}
+
+void SVGAnimatedLength::SetAnimValueInSpecifiedUnits(float aValue,
+                                                     SVGElement* aSVGElement) {
+  if (mAnimVal == aValue && mIsAnimated) {
+    return;
+  }
+  mAnimVal = aValue;
+  mIsAnimated = true;
+  aSVGElement->DidAnimateLength(mAttrEnum);
+}
+
+void SVGAnimatedLength::SetAnimValue(float aValue, uint16_t aUnitType,
+                                     SVGElement* aSVGElement) {
+  if (mIsAnimated && mAnimVal == aValue && mAnimUnitType == aUnitType) {
+    return;
+  }
+  mAnimVal = aValue;
+  mAnimUnitType = aUnitType;
+  mIsAnimated = true;
+  aSVGElement->DidAnimateLength(mAttrEnum);
+}
+
+already_AddRefed<DOMSVGAnimatedLength> SVGAnimatedLength::ToDOMAnimatedLength(
+    SVGElement* aSVGElement) {
+  RefPtr<DOMSVGAnimatedLength> svgAnimatedLength =
+      sSVGAnimatedLengthTearoffTable.GetTearoff(this);
+  if (!svgAnimatedLength) {
+    svgAnimatedLength = new DOMSVGAnimatedLength(this, aSVGElement);
+    sSVGAnimatedLengthTearoffTable.AddTearoff(this, svgAnimatedLength);
+  }
+
+  return svgAnimatedLength.forget();
+}
+
+DOMSVGAnimatedLength::~DOMSVGAnimatedLength() {
+  sSVGAnimatedLengthTearoffTable.RemoveTearoff(mVal);
+}
+
+UniquePtr<SMILAttr> SVGAnimatedLength::ToSMILAttr(SVGElement* aSVGElement) {
+  return MakeUnique<SMILLength>(this, aSVGElement);
+}
+
+nsresult SVGAnimatedLength::SMILLength::ValueFromString(
+    const nsAString& aStr, const SVGAnimationElement* /*aSrcElement*/,
+    SMILValue& aValue, bool& aPreventCachingOfSandwich) const {
+  float value;
+  uint16_t unitType;
+
+  if (!GetValueFromString(aStr, value, &unitType)) {
+    return NS_ERROR_DOM_SYNTAX_ERR;
+  }
+
+  SMILValue val(SVGLengthSMILType::Singleton());
+  SVGLengthAndInfo* lai = static_cast<SVGLengthAndInfo*>(val.mU.mPtr);
+  lai->Set(value, unitType, mVal->GetCtxType());
+  lai->SetInfo(mSVGElement);
+  aValue = std::move(val);
+  aPreventCachingOfSandwich = !SVGLength::IsAbsoluteUnit(unitType);
+
+  return NS_OK;
+}
+
+SMILValue SVGAnimatedLength::SMILLength::GetBaseValue() const {
+  SMILValue val(SVGLengthSMILType::Singleton());
+  auto* lai = static_cast<SVGLengthAndInfo*>(val.mU.mPtr);
+  lai->CopyBaseFrom(*mVal);
+  lai->SetInfo(mSVGElement);
+  return val;
+}
+
+void SVGAnimatedLength::SMILLength::ClearAnimValue() {
+  if (mVal->mIsAnimated) {
+    mVal->mIsAnimated = false;
+    mVal->mAnimVal = mVal->mBaseVal;
+    mVal->mAnimUnitType = mVal->mBaseUnitType;
+    mSVGElement->DidAnimateLength(mVal->mAttrEnum);
+  }
+}
+
+nsresult SVGAnimatedLength::SMILLength::SetAnimValue(const SMILValue& aValue) {
+  NS_ASSERTION(aValue.mType == SVGLengthSMILType::Singleton(),
+               "Unexpected type to assign animated value");
+  if (aValue.mType == SVGLengthSMILType::Singleton()) {
+    SVGLengthAndInfo* lai = static_cast<SVGLengthAndInfo*>(aValue.mU.mPtr);
+    mVal->SetAnimValue(lai->Value(), lai->UnitType(), mSVGElement);
+  }
+  return NS_OK;
+}
+
+float SVGLengthAndInfo::ConvertUnits(const SVGLengthAndInfo& aTo) const {
+  if (aTo.mUnitType == mUnitType) {
+    return mValue;
+  }
+  return SVGLength(mValue, mUnitType)
+      .GetValueInSpecifiedUnit(aTo.mUnitType, aTo.Element(), aTo.mCtxType);
+}
+
+float SVGLengthAndInfo::ValueInPixels(const UserSpaceMetrics& aMetrics) const {
+  return mValue == 0.0f ? 0.0f
+                        : mValue * SVGLength::GetPixelsPerUnit(
+                                       aMetrics, mUnitType, mCtxType);
+}
+
+void SVGLengthAndInfo::Add(const SVGLengthAndInfo& aValueToAdd,
+                           uint32_t aCount) {
+  mElement = aValueToAdd.mElement;
+
+  SVGElementMetrics metrics(Element());
+
+  // We may be dealing with two different length units, so we normalize to
+  // pixels for the add:
+
+  float currentLength = ValueInPixels(metrics);
+  float lengthToAdd = aValueToAdd.ValueInPixels(metrics) * aCount;
+
+  // And then we give the resulting value the same units as the value
+  // that we're animating to/by (i.e. the same as aValueToAdd):
+  mUnitType = aValueToAdd.mUnitType;
+  mCtxType = aValueToAdd.mCtxType;
+  mValue = (currentLength + lengthToAdd) /
+           SVGLength::GetPixelsPerUnit(metrics, mUnitType, mCtxType);
+}
+
+void SVGLengthAndInfo::Interpolate(const SVGLengthAndInfo& aStart,
+                                   const SVGLengthAndInfo& aEnd,
+                                   double aUnitDistance,
+                                   SVGLengthAndInfo& aResult) {
+  MOZ_ASSERT(!aStart.mElement || aStart.mElement == aEnd.mElement,
+             "Should not be interpolating between different elements");
+
+  float startValue, endValue;
+  if (!aStart.mElement || aUnitDistance > 0.5) {
+    aResult.mUnitType = aEnd.mUnitType;
+    aResult.mCtxType = aEnd.mCtxType;
+    startValue = aStart.ConvertUnits(aEnd);
+    endValue = aEnd.mValue;
+  } else {
+    aResult.mUnitType = aStart.mUnitType;
+    aResult.mCtxType = aStart.mCtxType;
+    startValue = aStart.mValue;
+    endValue = aEnd.ConvertUnits(aStart);
+  }
+  aResult.mElement = aEnd.mElement;
+  aResult.mValue = startValue + (endValue - startValue) * aUnitDistance;
+}
+
+}  // namespace mozilla