Enable interpolation of CSS property font-variation-settings

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

Index: third_party/WebKit/Source/core/animation/CSSFontVariationSettingsInterpolationType.cpp
diff --git a/third_party/WebKit/Source/core/animation/CSSFontVariationSettingsInterpolationType.cpp b/third_party/WebKit/Source/core/animation/CSSFontVariationSettingsInterpolationType.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..e7b258b0559703265c4a9569dfda8711e1d2b707
--- /dev/null
+++ b/third_party/WebKit/Source/core/animation/CSSFontVariationSettingsInterpolationType.cpp
@@ -0,0 +1,213 @@
+// Copyright 2017 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/CSSFontVariationSettingsInterpolationType.h"
+
+#include "core/css/CSSFontVariationValue.h"
+#include "core/css/CSSValueList.h"
+
+namespace blink {
+
+class CSSFontVariationSettingsNonInterpolableValue
+    : public NonInterpolableValue {
+ public:
+  ~CSSFontVariationSettingsNonInterpolableValue() final {}
+
+  static PassRefPtr<CSSFontVariationSettingsNonInterpolableValue> Create(
+      Vector<AtomicString> tags) {
+    return AdoptRef(
+        new CSSFontVariationSettingsNonInterpolableValue(std::move(tags)));
+  }
+
+  const Vector<AtomicString> Tags() const { return tags_; }
+
+  DECLARE_NON_INTERPOLABLE_VALUE_TYPE();
+
+ private:
+  CSSFontVariationSettingsNonInterpolableValue(Vector<AtomicString> tags)
+      : tags_(std::move(tags)) {
+    DCHECK_GT(tags_.size(), 0u);
+  }
+
+  const Vector<AtomicString> tags_;
+};
+
+DEFINE_NON_INTERPOLABLE_VALUE_TYPE(
+    CSSFontVariationSettingsNonInterpolableValue);
+DEFINE_NON_INTERPOLABLE_VALUE_TYPE_CASTS(
+    CSSFontVariationSettingsNonInterpolableValue);
+
+static const Vector<AtomicString> GetTags(
+    const NonInterpolableValue& non_interpolable_value) {
+  return ToCSSFontVariationSettingsNonInterpolableValue(non_interpolable_value)
+      .Tags();
+}
+
+static bool TagsMatch(const NonInterpolableValue& a,
+                      const NonInterpolableValue& b) {
+  return GetTags(a) == GetTags(b);
+}
+
+class UnderlyingTagsChecker : public InterpolationType::ConversionChecker {
+ public:
+  ~UnderlyingTagsChecker() final {}
+
+  static std::unique_ptr<UnderlyingTagsChecker> Create(
+      const Vector<AtomicString>& tags) {
+    return WTF::WrapUnique(new UnderlyingTagsChecker(tags));
+  }
+
+ private:
+  UnderlyingTagsChecker(const Vector<AtomicString>& tags) : tags_(tags) {}
+
+  bool IsValid(const InterpolationEnvironment&,
+               const InterpolationValue& underlying) const final {
+    return tags_ == GetTags(*underlying.non_interpolable_value);
+  }
+
+  const Vector<AtomicString> tags_;
+};
+
+class InheritedFontVariationSettingsChecker
+    : public InterpolationType::ConversionChecker {
+ public:
+  ~InheritedFontVariationSettingsChecker() final {}
+
+  static std::unique_ptr<InheritedFontVariationSettingsChecker> Create(
+      const FontVariationSettings* settings) {
+    return WTF::WrapUnique(new InheritedFontVariationSettingsChecker(settings));
+  }
+
+ private:
+  InheritedFontVariationSettingsChecker(const FontVariationSettings* settings)
+      : settings_(settings) {}
+
+  bool IsValid(const InterpolationEnvironment& environment,
+               const InterpolationValue&) const final {
+    return DataEquivalent(settings_.Get(), environment.GetState()
+                                               .ParentStyle()
+                                               ->GetFontDescription()
+                                               .VariationSettings());
+  }
+
+  RefPtr<const FontVariationSettings> settings_;
+};
+
+static InterpolationValue ConvertFontVariationSettings(
+    const FontVariationSettings* settings) {
+  if (!settings || settings->size() == 0) {
+    return nullptr;
+  }
+  size_t length = settings->size();
+  std::unique_ptr<InterpolableList> numbers = InterpolableList::Create(length);
+  Vector<AtomicString> tags;
+  for (size_t i = 0; i < length; ++i) {
+    numbers->Set(i, InterpolableNumber::Create(settings->at(i).Value()));
+    tags.push_back(settings->at(i).Tag());
+  }
+  return InterpolationValue(
+      std::move(numbers),
+      CSSFontVariationSettingsNonInterpolableValue::Create(std::move(tags)));
+}
+
+InterpolationValue
+CSSFontVariationSettingsInterpolationType::MaybeConvertNeutral(
+    const InterpolationValue& underlying,
+    ConversionCheckers& conversion_checkers) const {
+  conversion_checkers.push_back(UnderlyingTagsChecker::Create(
+      GetTags(*underlying.non_interpolable_value)));
+  return InterpolationValue(underlying.interpolable_value->CloneAndZero(),
+                            underlying.non_interpolable_value);
+}
+
+InterpolationValue
+CSSFontVariationSettingsInterpolationType::MaybeConvertInitial(
+    const StyleResolverState&,
+    ConversionCheckers&) const {
+  return ConvertFontVariationSettings(FontBuilder::InitialVariationSettings());
+}
+
+InterpolationValue
+CSSFontVariationSettingsInterpolationType::MaybeConvertInherit(
+    const StyleResolverState& state,
+    ConversionCheckers& conversion_checkers) const {
+  const FontVariationSettings* inherited =
+      state.ParentStyle()->GetFontDescription().VariationSettings();
+  conversion_checkers.push_back(
+      InheritedFontVariationSettingsChecker::Create(inherited));
+  return ConvertFontVariationSettings(inherited);
+}
+
+InterpolationValue CSSFontVariationSettingsInterpolationType::MaybeConvertValue(
+    const CSSValue& value,
+    const StyleResolverState*,
+    ConversionCheckers&) const {
+  if (!value.IsValueList()) {
+    return nullptr;
+  }
+  const CSSValueList& list = ToCSSValueList(value);
+  size_t length = list.length();
+  std::unique_ptr<InterpolableList> numbers = InterpolableList::Create(length);
+  Vector<AtomicString> tags;
+  for (size_t i = 0; i < length; ++i) {
+    const CSSFontVariationValue& item = ToCSSFontVariationValue(list.Item(i));
+    numbers->Set(i, InterpolableNumber::Create(item.Value()));
+    tags.push_back(item.Tag());
+  }
+  return InterpolationValue(
+      std::move(numbers),
+      CSSFontVariationSettingsNonInterpolableValue::Create(std::move(tags)));
+}
+
+InterpolationValue CSSFontVariationSettingsInterpolationType::
+    MaybeConvertStandardPropertyUnderlyingValue(
+        const ComputedStyle& style) const {
+  return ConvertFontVariationSettings(
+      style.GetFontDescription().VariationSettings());
+}
+
+PairwiseInterpolationValue
+CSSFontVariationSettingsInterpolationType::MaybeMergeSingles(
+    InterpolationValue&& start,
+    InterpolationValue&& end) const {
+  if (TagsMatch(*start.non_interpolable_value, *end.non_interpolable_value)) {
+    return PairwiseInterpolationValue(std::move(start.interpolable_value),
+                                      std::move(end.interpolable_value),
+                                      std::move(start.non_interpolable_value));
+  }
+  return nullptr;
+}
+
+void CSSFontVariationSettingsInterpolationType::Composite(
+    UnderlyingValueOwner& underlying_value_owner,
+    double underlying_fraction,
+    const InterpolationValue& value,
+    double interpolation_fraction) const {
+  if (TagsMatch(*underlying_value_owner.Value().non_interpolable_value,
+                *value.non_interpolable_value)) {
+    underlying_value_owner.MutableValue().interpolable_value->ScaleAndAdd(
+        underlying_fraction, *value.interpolable_value);
+  } else {
+    underlying_value_owner.Set(*this, value);
+  }
+}
+
+void CSSFontVariationSettingsInterpolationType::ApplyStandardPropertyValue(
+    const InterpolableValue& interpolable_value,
+    const NonInterpolableValue* non_interpolable_value,
+    StyleResolverState& state) const {
+  const InterpolableList& numbers = ToInterpolableList(interpolable_value);
+  const Vector<AtomicString>& tags = GetTags(*non_interpolable_value);
+  DCHECK_EQ(numbers.length(), tags.size());
+
+  RefPtr<FontVariationSettings> settings = FontVariationSettings::Create();
+  size_t length = numbers.length();
+  for (size_t i = 0; i < length; ++i) {
+    settings->Append(FontVariationAxis(
+        tags[i], ToInterpolableNumber(numbers.Get(i))->Value()));
+  }
+  state.GetFontBuilder().SetVariationSettings(settings);
+}
+
+}  // namespace blink