Web Animations API: Interpolate into reference rather than returning new value.

This is a re-work of https://codereview.chromium.org/238313003/

Review URL: https://codereview.chromium.org/712143003

git-svn-id: svn://svn.chromium.org/blink/trunk@185088 bbb929c8-8fbe-4397-9dbb-9b2b20218538

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

@@ -9,43 +9,43 @@ namespace blink {
 
 DEFINE_EMPTY_DESTRUCTOR_WILL_BE_REMOVED(InterpolableValue);
 
-PassOwnPtrWillBeRawPtr<InterpolableValue> InterpolableNumber::interpolate(const InterpolableValue &to, const double progress) const
+void InterpolableNumber::interpolate(const InterpolableValue &to, const double progress, InterpolableValue& result) const
 {
     const InterpolableNumber& toNumber = toInterpolableNumber(to);
-    if (!progress)
-        return create(m_value);
-    if (progress == 1)
-        return create(toNumber.m_value);
-    return create(m_value * (1 - progress) + toNumber.m_value * progress);
+    InterpolableNumber& resultNumber = toInterpolableNumber(result);
+
+    if (progress == 0)
+        resultNumber.m_value = m_value;
+    else if (progress == 1)
+        resultNumber.m_value = toNumber.m_value;
+    else
+        resultNumber.m_value = m_value * (1 - progress) + toNumber.m_value * progress;
 }
 
-PassOwnPtrWillBeRawPtr<InterpolableValue> InterpolableBool::interpolate(const InterpolableValue &to, const double progress) const
+void InterpolableBool::interpolate(const InterpolableValue &to, const double progress, InterpolableValue& result) const
 {
-    if (progress < 0.5) {
-        return clone();
-    }
-    return to.clone();
+    const InterpolableBool& toBool = toInterpolableBool(to);
+    InterpolableBool& resultBool = toInterpolableBool(result);
+
+    if (progress < 0.5)
+        resultBool.m_value = m_value;
+    else
+        resultBool.m_value = toBool.m_value;
 }
 
-PassOwnPtrWillBeRawPtr<InterpolableValue> InterpolableList::interpolate(const InterpolableValue &to, const double progress) const
+void InterpolableList::interpolate(const InterpolableValue& to, const double progress, InterpolableValue& result) const
 {
     const InterpolableList& toList = toInterpolableList(to);
-    ASSERT(toList.m_size == m_size);
+    InterpolableList& resultList = toInterpolableList(result);
 
-    if (!progress) {
-        return create(*this);
-    }
-    if (progress == 1) {
-        return InterpolableList::create(toList);
-    }
+    ASSERT(toList.m_size == m_size);
+    ASSERT(resultList.m_size == m_size);
 
-    OwnPtrWillBeRawPtr<InterpolableList> result = create(m_size);
     for (size_t i = 0; i < m_size; i++) {
         ASSERT(m_values[i]);
         ASSERT(toList.m_values[i]);
-        result->set(i, m_values[i]->interpolate(*(toList.m_values[i]), progress));
+        m_values[i]->interpolate(*(toList.m_values[i]), progress, *(resultList.m_values[i]));
     }
-    return result.release();
 }
 
 void InterpolableList::trace(Visitor* visitor)
@@ -56,14 +56,15 @@ void InterpolableList::trace(Visitor* visitor)
     InterpolableValue::trace(visitor);
 }
 
-PassOwnPtrWillBeRawPtr<InterpolableValue> InterpolableAnimatableValue::interpolate(const InterpolableValue &other, const double percentage) const
+void InterpolableAnimatableValue::interpolate(const InterpolableValue& to, const double progress, InterpolableValue& result) const
 {
-    const InterpolableAnimatableValue& otherValue = toInterpolableAnimatableValue(other);
-    if (!percentage)
-        return create(m_value);
-    if (percentage == 1)
-        return create(otherValue.m_value);
-    return create(AnimatableValue::interpolate(m_value.get(), otherValue.m_value.get(), percentage));
+    const InterpolableAnimatableValue& toValue = toInterpolableAnimatableValue(to);
+    InterpolableAnimatableValue& resultValue = toInterpolableAnimatableValue(result);
+    if (progress == 0)
+        resultValue.m_value = m_value;
+    if (progress == 1)
+        resultValue.m_value = toValue.m_value;
+    resultValue.m_value = AnimatableValue::interpolate(m_value.get(), toValue.m_value.get(), progress);
 }
 
 void InterpolableAnimatableValue::trace(Visitor* visitor)

third_party/WebKit/Source/core/animation/InterpolableValue.h

@@ -25,7 +25,7 @@ public:
     virtual void trace(Visitor*) { }
 
 private:
-    virtual PassOwnPtrWillBeRawPtr<InterpolableValue> interpolate(const InterpolableValue &to, const double progress) const = 0;
+    virtual void interpolate(const InterpolableValue& to, const double progress, InterpolableValue& result) const = 0;
 
     friend class Interpolation;
 
@@ -51,7 +51,7 @@ public:
     virtual void trace(Visitor* visitor) override { InterpolableValue::trace(visitor); }
 
 private:
-    virtual PassOwnPtrWillBeRawPtr<InterpolableValue> interpolate(const InterpolableValue &to, const double progress) const override final;
+    virtual void interpolate(const InterpolableValue& to, const double progress, InterpolableValue& result) const override final;
     double m_value;
 
     explicit InterpolableNumber(double value)
@@ -75,7 +75,7 @@ public:
     virtual void trace(Visitor* visitor) override { InterpolableValue::trace(visitor); }
 
 private:
-    virtual PassOwnPtrWillBeRawPtr<InterpolableValue> interpolate(const InterpolableValue &to, const double progress) const override final;
+    virtual void interpolate(const InterpolableValue& to, const double progress, InterpolableValue& result) const override final;
     bool m_value;
 
     explicit InterpolableBool(bool value)
@@ -114,7 +114,7 @@ public:
     virtual void trace(Visitor*) override;
 
 private:
-    virtual PassOwnPtrWillBeRawPtr<InterpolableValue> interpolate(const InterpolableValue &other, const double progress) const override final;
+    virtual void interpolate(const InterpolableValue& to, const double progress, InterpolableValue& result) const override final;
     explicit InterpolableList(size_t size)
         : m_size(size)
         , m_values(m_size)
@@ -148,7 +148,7 @@ public:
     virtual void trace(Visitor*) override;
 
 private:
-    virtual PassOwnPtrWillBeRawPtr<InterpolableValue> interpolate(const InterpolableValue &other, const double progress) const override final;
+    virtual void interpolate(const InterpolableValue &to, const double progress, InterpolableValue& result) const override final;
     RefPtrWillBeMember<AnimatableValue> m_value;
 
     InterpolableAnimatableValue(PassRefPtrWillBeRawPtr<AnimatableValue> value)

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

@@ -47,7 +47,7 @@ Interpolation::Interpolation(PassOwnPtrWillBeRawPtr<InterpolableValue> start, Pa
 void Interpolation::interpolate(int iteration, double fraction) const
 {
     if (m_cachedFraction != fraction || m_cachedIteration != iteration) {
-        m_cachedValue = m_start->interpolate(*m_end, fraction);
+        m_start->interpolate(*m_end, fraction, *m_cachedValue);
         m_cachedIteration = iteration;
         m_cachedFraction = fraction;
     }