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/* -*- 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
#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 "nsPresContextInlines.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;
};
MOZ_CONSTINIT 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;
}
nsAString::const_iterator iter, end;
token.BeginReading(iter);
token.EndReading(end);
if (!SVGContentUtils::ParseNumber(iter, end, aValue)) {
return false;
}
const nsAString& units = Substring(iter, end);
*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::GetZoom(const Element* aElement) {
float zoom = 1.0f;
SVGGeometryProperty::DoForComputedStyle(
aElement, [&](const ComputedStyle* style) {
zoom = style->EffectiveZoom().ToFloat();
});
return zoom;
}
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::GetZoom() const {
return UserSpaceMetrics::GetZoom(mSVGElement);
}
float SVGElementMetrics::GetRootZoom() const {
return UserSpaceMetrics::GetZoom(
mSVGElement ? mSVGElement->OwnerDoc()->GetRootElement() : nullptr);
}
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);
}
float SVGElementMetrics::GetLineHeight(Type aType) const {
return SVGContentUtils::GetLineHeight(GetElementForType(aType));
}
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();
}
}
float NonSVGFrameUserSpaceMetrics::GetZoom() const {
return mFrame->Style()->EffectiveZoom().ToFloat();
}
float NonSVGFrameUserSpaceMetrics::GetRootZoom() const {
return mFrame->PresContext()
->FrameConstructor()
->GetRootElementStyleFrame()
->Style()
->EffectiveZoom()
.ToFloat();
}
gfx::Size NonSVGFrameUserSpaceMetrics::GetSize() const {
return SVGIntegrationUtils::GetSVGCoordContextForNonSVGFrame(mFrame);
}
CSSSize NonSVGFrameUserSpaceMetrics::GetCSSViewportSize() const {
return GetCSSViewportSizeFromContext(mFrame->PresContext());
}
float NonSVGFrameUserSpaceMetrics::GetLineHeight(Type aType) const {
auto* context = mFrame->PresContext();
switch (aType) {
case Type::This: {
const auto lineHeightAu = ReflowInput::CalcLineHeight(
*mFrame->Style(), context, mFrame->GetContent(), NS_UNCONSTRAINEDSIZE,
1.0f);
return CSSPixel::FromAppUnits(lineHeightAu);
}
case Type::Root:
return SVGContentUtils::GetLineHeight(
context->Document()->GetRootElement());
}
MOZ_ASSERT_UNREACHABLE("Was a new value added to the enumeration?");
return 1.0f;
}
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, false);
}
float SVGAnimatedLength::GetPixelsPerUnitWithZoom(const SVGElement* aSVGElement,
uint8_t aUnitType) const {
return SVGLength::GetPixelsPerUnit(SVGElementMetrics(aSVGElement), aUnitType,
mCtxType, true);
}
float SVGAnimatedLength::GetPixelsPerUnitWithZoom(
const SVGViewportElement* aCtx, uint8_t aUnitType) const {
return SVGLength::GetPixelsPerUnit(SVGElementMetrics(aCtx, aCtx), aUnitType,
mCtxType, true);
}
float SVGAnimatedLength::GetPixelsPerUnitWithZoom(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, true);
}
return SVGLength::GetPixelsPerUnit(NonSVGFrameUserSpaceMetrics(aFrame),
aUnitType, mCtxType, true);
}
float SVGAnimatedLength::GetPixelsPerUnitWithZoom(
const UserSpaceMetrics& aMetrics, uint8_t aUnitType) const {
return SVGLength::GetPixelsPerUnit(aMetrics, aUnitType, mCtxType, true);
}
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, false);
}
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, false);
}
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