Web Animations API: Deferred computation of interpolated values

Source/core/animation/LegacyStyleInterpolation.h

+// 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.
+
+#ifndef LegacyStyleInterpolation_h
+#define LegacyStyleInterpolation_h
+
+#include "core/animation/InterpolableValuePromise.h"
+#include "core/animation/Interpolation.h"
+
+namespace WebCore {
+
+class LegacyStyleInterpolation : public StyleInterpolation {
+public:
+    static PassRefPtrWillBeRawPtr<LegacyStyleInterpolation> create(PassRefPtrWillBeRawPtr<InterpolableValuePromise> start, PassRefPtrWillBeRawPtr<InterpolableValuePromise> end, CSSPropertyID);
+
+    static PassRefPtrWillBeRawPtr<LegacyStyleInterpolation> create(PassRefPtrWillBeRawPtr<AnimatableValue> start, PassRefPtrWillBeRawPtr<AnimatableValue> end, CSSPropertyID id)

[shans, 2014/05/08 16:12:58]

Why do we still have this? The point of InterpolableValuePromise was to abstract
away whether AnimatableValues or CSSValues were provided, I thought?

+    {
+        return adoptRefWillBeNoop(new LegacyStyleInterpolation(InterpolableAnimatableValue::create(start), InterpolableAnimatableValue::create(end), id));
+    }
+
+    virtual void apply(StyleResolverState&) const OVERRIDE;
+
+    virtual bool isLegacyStyleInterpolation() const OVERRIDE FINAL { return true; }
+
+    PassRefPtrWillBeRawPtr<AnimatableValue> currentValue() const
+    {
+        InterpolableAnimatableValue* value = static_cast<InterpolableAnimatableValue*>(m_cachedValue.get());
+        return value ? value->value() : 0;
+    }
+
+    virtual void trace(Visitor*) OVERRIDE;
+
+private:
+    LegacyStyleInterpolation(PassRefPtrWillBeRawPtr<InterpolableValuePromise> start, PassRefPtrWillBeRawPtr<InterpolableValuePromise> end, CSSPropertyID id)
+        : StyleInterpolation(nullptr, nullptr, id)
+        , m_startPromise(start)
+        , m_endPromise(end)
+    {
+    }
+
+    LegacyStyleInterpolation(PassOwnPtrWillBeRawPtr<InterpolableValue> startValue, PassOwnPtrWillBeRawPtr<InterpolableValue> endValue, CSSPropertyID id)
+        : StyleInterpolation(startValue, endValue, id)
+        , m_startPromise(nullptr)
+        , m_endPromise(nullptr)
+    {
+    }
+
+    const RefPtrWillBeMember<InterpolableValuePromise> m_startPromise;
+    const RefPtrWillBeMember<InterpolableValuePromise> m_endPromise;
+};
+
+DEFINE_TYPE_CASTS(LegacyStyleInterpolation, Interpolation, value, value->isLegacyStyleInterpolation(), value.isLegacyStyleInterpolation());
+
+}
+
+#endif