WIP: Implement CSS transitions on top of InterpolationTypes instead of AnimatableValues

third_party/WebKit/Source/core/animation/InvalidatableInterpolation.cpp

-// Copyright 2015 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "core/animation/InvalidatableInterpolation.h"
-
-#include "core/animation/InterpolationEnvironment.h"
-#include "core/animation/StringKeyframe.h"
-#include "core/css/resolver/StyleResolverState.h"
-#include <memory>
-
-namespace blink {
-
-void InvalidatableInterpolation::interpolate(int, double fraction)
-{
-    if (fraction == m_currentFraction)
-        return;
-
-    if (m_currentFraction == 0 || m_currentFraction == 1 || fraction == 0 || fraction == 1)
-        clearCache();
-
-    m_currentFraction = fraction;
-    if (m_isCached && m_cachedPairConversion)
-        m_cachedPairConversion->interpolateValue(fraction, m_cachedValue);
-    // We defer the interpolation to ensureValidInterpolation() if m_cachedPairConversion is null.
-}
-
-std::unique_ptr<PairwisePrimitiveInterpolation> InvalidatableInterpolation::maybeConvertPairwise(const InterpolationEnvironment& environment, const UnderlyingValueOwner& underlyingValueOwner) const
-{
-    ASSERT(m_currentFraction != 0 && m_currentFraction != 1);
-    for (const auto& interpolationType : m_interpolationTypes) {
-        if ((m_startKeyframe->isNeutral() || m_endKeyframe->isNeutral()) && (!underlyingValueOwner || underlyingValueOwner.type() != *interpolationType))
-            continue;
-        ConversionCheckers conversionCheckers;
-        PairwiseInterpolationValue result = interpolationType->maybeConvertPairwise(*m_startKeyframe, *m_endKeyframe, environment, underlyingValueOwner.value(), conversionCheckers);
-        addConversionCheckers(*interpolationType, conversionCheckers);
-        if (result) {
-            return PairwisePrimitiveInterpolation::create(*interpolationType,
-                std::move(result.startInterpolableValue),
-                std::move(result.endInterpolableValue),
-                result.nonInterpolableValue.release());
-        }
-    }
-    return nullptr;
-}
-
-std::unique_ptr<TypedInterpolationValue> InvalidatableInterpolation::convertSingleKeyframe(const PropertySpecificKeyframe& keyframe, const InterpolationEnvironment& environment, const UnderlyingValueOwner& underlyingValueOwner) const
-{
-    if (keyframe.isNeutral() && !underlyingValueOwner)
-        return nullptr;
-    for (const auto& interpolationType : m_interpolationTypes) {
-        if (keyframe.isNeutral() && underlyingValueOwner.type() != *interpolationType)
-            continue;
-        ConversionCheckers conversionCheckers;
-        InterpolationValue result = interpolationType->maybeConvertSingle(keyframe, environment, underlyingValueOwner.value(), conversionCheckers);
-        addConversionCheckers(*interpolationType, conversionCheckers);
-        if (result)
-            return TypedInterpolationValue::create(*interpolationType, std::move(result.interpolableValue), result.nonInterpolableValue.release());
-    }
-    ASSERT(keyframe.isNeutral());
-    return nullptr;
-}
-
-void InvalidatableInterpolation::addConversionCheckers(const InterpolationType& type, ConversionCheckers& conversionCheckers) const
-{
-    for (size_t i = 0; i < conversionCheckers.size(); i++) {
-        conversionCheckers[i]->setType(type);
-        m_conversionCheckers.append(std::move(conversionCheckers[i]));
-    }
-}
-
-std::unique_ptr<TypedInterpolationValue> InvalidatableInterpolation::maybeConvertUnderlyingValue(const InterpolationEnvironment& environment) const
-{
-    for (const auto& interpolationType : m_interpolationTypes) {
-        InterpolationValue result = interpolationType->maybeConvertUnderlyingValue(environment);
-        if (result)
-            return TypedInterpolationValue::create(*interpolationType, std::move(result.interpolableValue), result.nonInterpolableValue.release());
-    }
-    return nullptr;
-}
-
-bool InvalidatableInterpolation::dependsOnUnderlyingValue() const
-{
-    return (m_startKeyframe->underlyingFraction() != 0 && m_currentFraction != 1) || (m_endKeyframe->underlyingFraction() != 0 && m_currentFraction != 0);
-}
-
-bool InvalidatableInterpolation::isNeutralKeyframeActive() const
-{
-    return (m_startKeyframe->isNeutral() && m_currentFraction != 1) || (m_endKeyframe->isNeutral() && m_currentFraction != 0);
-}
-
-void InvalidatableInterpolation::clearCache() const
-{
-    m_isCached = false;
-    m_cachedPairConversion.reset();
-    m_conversionCheckers.clear();
-    m_cachedValue.reset();
-}
-
-bool InvalidatableInterpolation::isCacheValid(const InterpolationEnvironment& environment, const UnderlyingValueOwner& underlyingValueOwner) const
-{
-    if (!m_isCached)
-        return false;
-    if (isNeutralKeyframeActive()) {
-        if (m_cachedPairConversion && m_cachedPairConversion->isFlip())
-            return false;
-        // Pairwise interpolation can never happen between different InterpolationTypes, neutral values always represent the underlying value.
-        if (!underlyingValueOwner || !m_cachedValue || m_cachedValue->type() != underlyingValueOwner.type())
-            return false;
-    }
-    for (const auto& checker : m_conversionCheckers) {
-        if (!checker->isValid(environment, underlyingValueOwner.value()))
-            return false;
-    }
-    return true;
-}
-
-const TypedInterpolationValue* InvalidatableInterpolation::ensureValidInterpolation(const InterpolationEnvironment& environment, const UnderlyingValueOwner& underlyingValueOwner) const
-{
-    ASSERT(!std::isnan(m_currentFraction));
-    if (isCacheValid(environment, underlyingValueOwner))
-        return m_cachedValue.get();
-    clearCache();
-    if (m_currentFraction == 0) {
-        m_cachedValue = convertSingleKeyframe(*m_startKeyframe, environment, underlyingValueOwner);
-    } else if (m_currentFraction == 1) {
-        m_cachedValue = convertSingleKeyframe(*m_endKeyframe, environment, underlyingValueOwner);
-    } else {
-        std::unique_ptr<PairwisePrimitiveInterpolation> pairwiseConversion = maybeConvertPairwise(environment, underlyingValueOwner);
-        if (pairwiseConversion) {
-            m_cachedValue = pairwiseConversion->initialValue();
-            m_cachedPairConversion = std::move(pairwiseConversion);
-        } else {
-            m_cachedPairConversion = FlipPrimitiveInterpolation::create(
-                convertSingleKeyframe(*m_startKeyframe, environment, underlyingValueOwner),
-                convertSingleKeyframe(*m_endKeyframe, environment, underlyingValueOwner));
-        }
-        m_cachedPairConversion->interpolateValue(m_currentFraction, m_cachedValue);
-    }
-    m_isCached = true;
-    return m_cachedValue.get();
-}
-
-void InvalidatableInterpolation::setFlagIfInheritUsed(InterpolationEnvironment& environment) const
-{
-    if (!m_property.isCSSProperty() && !m_property.isPresentationAttribute())
-        return;
-    if (!environment.state().parentStyle())
-        return;
-    const CSSValue* startValue = toCSSPropertySpecificKeyframe(*m_startKeyframe).value();
-    const CSSValue* endValue = toCSSPropertySpecificKeyframe(*m_endKeyframe).value();
-    if ((startValue && startValue->isInheritedValue())
-        || (endValue && endValue->isInheritedValue())) {
-        environment.state().parentStyle()->setHasExplicitlyInheritedProperties();
-    }
-}
-
-double InvalidatableInterpolation::underlyingFraction() const
-{
-    if (m_currentFraction == 0)
-        return m_startKeyframe->underlyingFraction();
-    if (m_currentFraction == 1)
-        return m_endKeyframe->underlyingFraction();
-    return m_cachedPairConversion->interpolateUnderlyingFraction(m_startKeyframe->underlyingFraction(), m_endKeyframe->underlyingFraction(), m_currentFraction);
-}
-
-void InvalidatableInterpolation::applyStack(const ActiveInterpolations& interpolations, InterpolationEnvironment& environment)
-{
-    ASSERT(!interpolations.isEmpty());
-    size_t startingIndex = 0;
-
-    // Compute the underlying value to composite onto.
-    UnderlyingValueOwner underlyingValueOwner;
-    const InvalidatableInterpolation& firstInterpolation = toInvalidatableInterpolation(*interpolations.at(startingIndex));
-    if (firstInterpolation.dependsOnUnderlyingValue()) {
-        underlyingValueOwner.set(firstInterpolation.maybeConvertUnderlyingValue(environment));
-    } else {
-        const TypedInterpolationValue* firstValue = firstInterpolation.ensureValidInterpolation(environment, underlyingValueOwner);
-        // Fast path for replace interpolations that are the only one to apply.
-        if (interpolations.size() == 1) {
-            if (firstValue) {
-                firstInterpolation.setFlagIfInheritUsed(environment);
-                firstValue->type().apply(firstValue->interpolableValue(), firstValue->getNonInterpolableValue(), environment);
-            }
-            return;
-        }
-        underlyingValueOwner.set(firstValue);
-        startingIndex++;
-    }
-
-    // Composite interpolations onto the underlying value.
-    bool shouldApply = false;
-    for (size_t i = startingIndex; i < interpolations.size(); i++) {
-        const InvalidatableInterpolation& currentInterpolation = toInvalidatableInterpolation(*interpolations.at(i));
-        ASSERT(currentInterpolation.dependsOnUnderlyingValue());
-        const TypedInterpolationValue* currentValue = currentInterpolation.ensureValidInterpolation(environment, underlyingValueOwner);
-        if (!currentValue)
-            continue;
-        shouldApply = true;
-        currentInterpolation.setFlagIfInheritUsed(environment);
-        double underlyingFraction = currentInterpolation.underlyingFraction();
-        if (underlyingFraction == 0 || !underlyingValueOwner || underlyingValueOwner.type() != currentValue->type())
-            underlyingValueOwner.set(currentValue);
-        else
-            currentValue->type().composite(underlyingValueOwner, underlyingFraction, currentValue->value(), currentInterpolation.m_currentFraction);
-    }
-
-    if (shouldApply && underlyingValueOwner)
-        underlyingValueOwner.type().apply(*underlyingValueOwner.value().interpolableValue, underlyingValueOwner.value().nonInterpolableValue.get(), environment);
-}
-
-} // namespace blink