Web Animations API: Deferred computation of interpolated values

Source/core/animation/Interpolation.cpp

 // Copyright 2014 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 "config.h"
 #include "core/animation/Interpolation.h"
 
 #include "core/css/CSSCalculationValue.h"
-#include "core/css/resolver/AnimatedStyleBuilder.h"
+#include "core/css/CSSPrimitiveValue.h"
 #include "core/css/resolver/StyleBuilder.h"
-#include "core/css/resolver/StyleResolverState.h"
 
 namespace WebCore {
 
 DEFINE_EMPTY_DESTRUCTOR_WILL_BE_REMOVED(Interpolation);
 
 namespace {
 
 bool typesMatch(const InterpolableValue* start, const InterpolableValue* end)
 {
     if (start->isNumber())
@@ skipping 15 matching lines @@
     return true;
 }
 
 }
 
 Interpolation::Interpolation(PassOwnPtrWillBeRawPtr<InterpolableValue> start, PassOwnPtrWillBeRawPtr<InterpolableValue> end)
     : m_start(start)
     , m_end(end)
     , m_cachedFraction(0)
     , m_cachedIteration(0)
-    , m_cachedValue(m_start->clone())
 {
-    RELEASE_ASSERT(typesMatch(m_start.get(), m_end.get()));
+    if (m_start) {
+        m_cachedValue = m_start->clone();
+        RELEASE_ASSERT(typesMatch(m_start.get(), m_end.get()));
+    }
 }
 
 void Interpolation::interpolate(int iteration, double fraction) const
 {
     if (m_cachedFraction != fraction || m_cachedIteration != iteration) {
-        m_cachedValue = m_start->interpolate(*m_end, fraction);
+        if (m_start)
+            m_cachedValue = m_start->interpolate(*m_end, fraction);
         m_cachedIteration = iteration;
         m_cachedFraction = fraction;
     }
 }
 
 void Interpolation::trace(Visitor* visitor)
 {
     visitor->trace(m_start);
     visitor->trace(m_end);
     visitor->trace(m_cachedValue);
 }
 
 void StyleInterpolation::trace(Visitor* visitor)
 {
     Interpolation::trace(visitor);
 }
 
-void LegacyStyleInterpolation::apply(StyleResolverState& state) const
-{
-    AnimatedStyleBuilder::applyProperty(m_id, state, currentValue().get());
-}
-
-void LegacyStyleInterpolation::trace(Visitor* visitor)
-{
-    StyleInterpolation::trace(visitor);
-}
-
 bool LengthStyleInterpolation::canCreateFrom(const CSSValue& value)
 {
     if (value.isPrimitiveValue()) {
         const CSSPrimitiveValue& primitiveValue = WebCore::toCSSPrimitiveValue(value);
         if (primitiveValue.cssCalcValue())
             return true;
 
         CSSPrimitiveValue::LengthUnitType type;
         // Only returns true if the type is a primitive length unit.
         return CSSPrimitiveValue::unitTypeToLengthUnitType(primitiveValue.primitiveType(), type);
@@ skipping 85 matching lines @@
 }
 
 void DefaultStyleInterpolation::trace(Visitor* visitor)
 {
     StyleInterpolation::trace(visitor);
     visitor->trace(m_startCSSValue);
     visitor->trace(m_endCSSValue);
 }
 
 }