Allow interpolation of background-size values with keywords in CSS Animations

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

+// Copyright 2016 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/CSSSizeListInterpolationType.h"
+
+#include "core/animation/ListInterpolationFunctions.h"
+#include "core/animation/SizeInterpolationFunctions.h"
+#include "core/animation/SizeListPropertyFunctions.h"
+#include "core/css/CSSValueList.h"
+#include "core/css/resolver/StyleResolverState.h"
+
+namespace blink {
+
+class UnderlyingSizeListChecker : public InterpolationType::ConversionChecker {
+public:
+    ~UnderlyingSizeListChecker() final {}
+
+    static std::unique_ptr<UnderlyingSizeListChecker> create(const NonInterpolableList& underlyingList)
+    {
+        return wrapUnique(new UnderlyingSizeListChecker(underlyingList));
+    }
+
+private:
+    UnderlyingSizeListChecker(const NonInterpolableList& underlyingList)
+        : m_underlyingList(&underlyingList)
+    { }
+
+    bool isValid(const InterpolationEnvironment&, const InterpolationValue& underlying) const final
+    {
+        const auto& underlyingList = toNonInterpolableList(*underlying.nonInterpolableValue);
+        size_t underlyingLength = underlyingList.length();
+        if (underlyingLength != m_underlyingList->length())
+            return false;
+        for (size_t i = 0; i < underlyingLength; i++) {
+            bool compatible = SizeInterpolationFunctions::nonInterpolableValuesAreCompatible(
+                underlyingList.get(i), m_underlyingList->get(i));
+            if (!compatible)
+                return false;
+        }
+        return true;
+    }
+
+    RefPtr<const NonInterpolableList> m_underlyingList;
+};
+
+class InheritedSizeListChecker : public InterpolationType::ConversionChecker {
+public:
+    ~InheritedSizeListChecker() final {}
+
+    static std::unique_ptr<InheritedSizeListChecker> create(CSSPropertyID property, const SizeList& inheritedSizeList)
+    {
+        return wrapUnique(new InheritedSizeListChecker(property, inheritedSizeList));
+    }
+
+private:
+    InheritedSizeListChecker(CSSPropertyID property, const SizeList& inheritedSizeList)
+        : m_property(property)
+        , m_inheritedSizeList(inheritedSizeList)
+    { }
+
+    bool isValid(const InterpolationEnvironment& environment, const InterpolationValue&) const final
+    {
+        return m_inheritedSizeList == SizeListPropertyFunctions::getSizeList(m_property, *environment.state().parentStyle());
+    }
+
+    CSSPropertyID m_property;
+    SizeList m_inheritedSizeList;
+};
+
+InterpolationValue convertSizeList(const SizeList& sizeList, float zoom)
+{
+    // Flatten pairs of width/height into individual items, even for contain and cover keywords.
+    return ListInterpolationFunctions::createList(sizeList.size() * 2, [&sizeList, zoom](size_t index) -> InterpolationValue {
+        bool convertWidth = index % 2 == 0;
+        return SizeInterpolationFunctions::convertFillSizeSide(sizeList[index / 2], zoom, convertWidth);
+    });
+}
+
+InterpolationValue maybeConvertCSSSizeList(const CSSValue& value)
+{
+    // CSSPropertyParser doesn't put single values in lists so wrap it up in a temporary list.
+    const CSSValueList* list = nullptr;
+    if (!value.isBaseValueList()) {
+        CSSValueList* tempList = CSSValueList::createCommaSeparated();
+        tempList->append(value);
+        list = tempList;
+    } else {
+        list = toCSSValueList(&value);
+    }
+
+    // Flatten pairs of width/height into individual items, even for contain and cover keywords.
+    return ListInterpolationFunctions::createList(list->length() * 2, [list](size_t index) -> InterpolationValue {
+        const CSSValue& cssSize = list->item(index / 2);
+        bool convertWidth = index % 2 == 0;
+        return SizeInterpolationFunctions::maybeConvertCSSSizeSide(cssSize, convertWidth);
+    });
+}
+
+InterpolationValue CSSSizeListInterpolationType::maybeConvertNeutral(const InterpolationValue& underlying, ConversionCheckers& conversionCheckers) const
+{
+    const auto& underlyingList = toNonInterpolableList(*underlying.nonInterpolableValue);
+    conversionCheckers.append(UnderlyingSizeListChecker::create(underlyingList));
+    return ListInterpolationFunctions::createList(underlyingList.length(), [&underlyingList](size_t index) {
+        return SizeInterpolationFunctions::createNeutralValue(underlyingList.get(index));
+    });
+}
+
+InterpolationValue CSSSizeListInterpolationType::maybeConvertInitial(const StyleResolverState&, ConversionCheckers&) const
+{
+    return convertSizeList(SizeListPropertyFunctions::getInitialSizeList(cssProperty()), 1);
+}
+
+InterpolationValue CSSSizeListInterpolationType::maybeConvertInherit(const StyleResolverState& state, ConversionCheckers& conversionCheckers) const
+{
+    SizeList inheritedSizeList = SizeListPropertyFunctions::getSizeList(cssProperty(), *state.parentStyle());
+    conversionCheckers.append(InheritedSizeListChecker::create(cssProperty(), inheritedSizeList));
+    return convertSizeList(inheritedSizeList, state.style()->effectiveZoom());
+}
+
+InterpolationValue CSSSizeListInterpolationType::maybeConvertValue(const CSSValue& value, const StyleResolverState&, ConversionCheckers&) const
+{
+    return maybeConvertCSSSizeList(value);
+}
+
+PairwiseInterpolationValue CSSSizeListInterpolationType::maybeMergeSingles(InterpolationValue&& start, InterpolationValue&& end) const
+{
+    return ListInterpolationFunctions::maybeMergeSingles(std::move(start), std::move(end), SizeInterpolationFunctions::maybeMergeSingles);
+}
+
+InterpolationValue CSSSizeListInterpolationType::maybeConvertUnderlyingValue(const InterpolationEnvironment& environment) const
+{
+    const ComputedStyle& style = *environment.state().style();
+    return convertSizeList(SizeListPropertyFunctions::getSizeList(cssProperty(), style), style.effectiveZoom());
+}
+
+void CSSSizeListInterpolationType::composite(UnderlyingValueOwner& underlyingValueOwner, double underlyingFraction, const InterpolationValue& value, double interpolationFraction) const
+{
+    ListInterpolationFunctions::composite(underlyingValueOwner, underlyingFraction, *this, value,
+        SizeInterpolationFunctions::nonInterpolableValuesAreCompatible,
+        SizeInterpolationFunctions::composite);
+}
+
+void CSSSizeListInterpolationType::apply(const InterpolableValue& interpolableValue, const NonInterpolableValue* nonInterpolableValue, InterpolationEnvironment& environment) const
+{
+    const auto& interpolableList = toInterpolableList(interpolableValue);
+    const auto& nonInterpolableList = toNonInterpolableList(*nonInterpolableValue);
+    size_t length = interpolableList.length();
+    DCHECK_EQ(length, nonInterpolableList.length());
+    DCHECK_EQ(length % 2, 0ul);
+    size_t sizeListLength = length / 2;
+    SizeList sizeList(sizeListLength);
+    for (size_t i = 0; i < sizeListLength; i++) {
+        sizeList[i] = SizeInterpolationFunctions::createFillSize(
+            *interpolableList.get(i * 2),
+            nonInterpolableList.get(i * 2),
+            *interpolableList.get(i * 2 + 1),
+            nonInterpolableList.get(i * 2 + 1),
+            environment.state().cssToLengthConversionData());
+    }
+    SizeListPropertyFunctions::setSizeList(cssProperty(), *environment.state().style(), sizeList);
+}
+
+} // namespace blink