Add foundation for removing AnimatableValues from StyleInterpolation

Source/core/animation/InvalidatableStyleInterpolation.cpp

Index: Source/core/animation/InvalidatableStyleInterpolation.cpp
diff --git a/Source/core/animation/InvalidatableStyleInterpolation.cpp b/Source/core/animation/InvalidatableStyleInterpolation.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..9315b36bf3cd75f5c9158f0dbe99979bd627cb5a
--- /dev/null
+++ b/Source/core/animation/InvalidatableStyleInterpolation.cpp
@@ -0,0 +1,188 @@
+// Copyright 2015 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/InvalidatableStyleInterpolation.h"
+
+#include "core/animation/StringKeyframe.h"
+
+namespace blink {
+
+class PairwiseConversionCache : public InvalidatableStyleInterpolation::CachedConversion {
+public:
+    static PassOwnPtrWillBeRawPtr<PairwiseConversionCache> create(
+        PassRefPtrWillBeRawPtr<InterpolationInvalidators> invalidators,
+        const AnimationType& type,
+        PassOwnPtrWillBeRawPtr<InterpolableValue> startInterpolableValue,
+        PassOwnPtrWillBeRawPtr<InterpolableValue> endInterpolableValue,
+        PassRefPtrWillBeRawPtr<NonInterpolableValue> nonInterpolableValue)
+    {
+        return adoptPtrWillBeNoop(new PairwiseConversionCache(invalidators, type, startInterpolableValue, endInterpolableValue, nonInterpolableValue));
+    }
+
+    virtual void interpolate(double fraction, AnimationValue& result) const
+    {
+        ASSERT_UNUSED(m_type, result.type == &m_type);

[shans, 2015/05/28 05:48:14]

This doesn't need to be ASSERT_UNUSED.

[alancutter (OOO until 2018), 2015/06/01 07:35:29]

This used to be ASSERT but it failed to compile in release.

+        ASSERT(result.nonInterpolableValue == m_nonInterpolableValue);

[shans, 2015/05/28 05:48:14]

These probably aren't needed here. We can assert these properties up-front and
when the values are changed.

[alancutter (OOO until 2018), 2015/06/01 07:35:29]

This assertion is to check that nothing's messed with
InvalidatableStyleInterpolation::m_cachedValue unexpectedly since the pairwise
conversion. Putting the assertion at the conversion isn't semantically
equivalent.
I may be mistaking where you meant for the assertion to be, can you elaborate?

+        m_startInterpolableValue->interpolate(*m_endInterpolableValue, fraction, *result.interpolableValue);
+    }
+
+    DEFINE_INLINE_VIRTUAL_TRACE()
+    {
+        CachedConversion::trace(visitor);
+        visitor->trace(m_startInterpolableValue);
+        visitor->trace(m_endInterpolableValue);
+        visitor->trace(m_nonInterpolableValue);
+    }
+
+private:
+    PairwiseConversionCache(
+        PassRefPtrWillBeRawPtr<InterpolationInvalidators> invalidators,
+        const AnimationType& type,
+        PassOwnPtrWillBeRawPtr<InterpolableValue> startInterpolableValue,
+        PassOwnPtrWillBeRawPtr<InterpolableValue> endInterpolableValue,
+        PassRefPtrWillBeRawPtr<NonInterpolableValue> nonInterpolableValue)
+        : CachedConversion(invalidators)
+        , m_type(type)
+        , m_startInterpolableValue(startInterpolableValue)
+        , m_endInterpolableValue(endInterpolableValue)
+        , m_nonInterpolableValue(nonInterpolableValue)
+    { }
+
+    const AnimationType& m_type;
+    OwnPtrWillBeMember<InterpolableValue> m_startInterpolableValue;
+    OwnPtrWillBeMember<InterpolableValue> m_endInterpolableValue;
+    RefPtrWillBeMember<NonInterpolableValue> m_nonInterpolableValue;
+};
+
+class DefaultConversionCache : public InvalidatableStyleInterpolation::CachedConversion {
+public:
+    static PassOwnPtrWillBeRawPtr<DefaultConversionCache> create(
+        PassRefPtrWillBeRawPtr<InterpolationInvalidators> invalidators,
+        AnimationValue& start,
+        AnimationValue& end)
+    {
+        return adoptPtrWillBeNoop(new DefaultConversionCache(invalidators, start, end));
+    }
+
+    static bool isBeforeFlip(double fraction) { return fraction < 0.5; }
+
+    virtual void interpolate(double fraction, AnimationValue& result) const
+    {
+        if (!std::isnan(m_lastFraction) && isBeforeFlip(fraction) == isBeforeFlip(m_lastFraction))

[shans, 2015/05/28 05:48:14]

isBeforeFlip is a more obscure name than < 0.5...

[alancutter (OOO until 2018), 2015/06/01 07:35:29]

Inlined isBeforeFlip().

+            return;
+        result.copy(isBeforeFlip(fraction) ? m_start : m_end);
+        m_lastFraction = fraction;
+    }
+
+    DEFINE_INLINE_VIRTUAL_TRACE()
+    {
+        CachedConversion::trace(visitor);
+        visitor->trace(m_start);
+        visitor->trace(m_end);
+    }
+
+private:
+    DefaultConversionCache(
+        PassRefPtrWillBeRawPtr<InterpolationInvalidators> invalidators,
+        AnimationValue& start,
+        AnimationValue& end)
+        : CachedConversion(invalidators)
+        , m_lastFraction(std::numeric_limits<double>::quiet_NaN())
+    {
+        m_start.consume(start);
+        m_end.consume(end);
+    }
+
+    AnimationValue m_start;
+    AnimationValue m_end;
+    mutable double m_lastFraction;
+};
+
+
+InvalidatableStyleInterpolation::InvalidatableStyleInterpolation(
+    const Vector<const AnimationType*>& applicableTypes,
+    PassRefPtrWillBeRawPtr<CSSPropertySpecificKeyframe> startKeyframe,
+    PassRefPtrWillBeRawPtr<CSSPropertySpecificKeyframe> endKeyframe)
+    : StyleInterpolation(nullptr, nullptr, applicableTypes.first()->property())
+    , m_applicableTypes(applicableTypes)
+    , m_startKeyframe(startKeyframe)
+    , m_endKeyframe(endKeyframe)
+    , m_cachedConversion(nullptr)
+{
+    maybeCachePairwiseConversion(nullptr);
+    interpolate(0, 0);
+}
+
+bool InvalidatableStyleInterpolation::maybeCachePairwiseConversion(const StyleResolverState* state) const
+{
+    for (const auto& animationType : m_applicableTypes) {
+        RefPtrWillBeRawPtr<InterpolationInvalidators> invalidators;
+        OwnPtrWillBeRawPtr<InterpolableValue> startInterpolableValue;
+        OwnPtrWillBeRawPtr<InterpolableValue> endInterpolableValue;
+        RefPtrWillBeRawPtr<NonInterpolableValue> nonInterpolableValue;
+        if (animationType->maybeConvertPairwise(*m_startKeyframe, *m_endKeyframe, state, invalidators, startInterpolableValue, endInterpolableValue, nonInterpolableValue)) {

[shans, 2015/05/28 05:48:13]

This is quite messy, and strongly suggests that maybeConvertPairwise should
return the PairwiseConversionCache directly.

[alancutter (OOO until 2018), 2015/06/01 07:35:29]

Something I decided when making the AnimationType interface is to avoid having
them return a pointer to themselves redundantly. Doing it the suggested way
avoids having so many out parameters but would mean PairwiseConversionCache and
ConversionCache get exposed outside of InvalidatableStyleInterpolation.

I opted for the former for its semantic purity at the cost of messy function
signatures. It doesn't seem right to be required to say "animationType = this"
in every AnimationType subclass (assuming maybeConvertSingle() is updated to
match the convention).

WDYT is better?

[alancutter (OOO until 2018), 2015/06/01 23:47:54]

On second thought I can just define a return struct for these conversion
functions. It'll be a bit ugly at first due to the OwnPtrs but once Oilpan lands
the ugliness will go away.

+            m_cachedConversion = PairwiseConversionCache::create(
+                invalidators.release(),
+                *animationType,
+                startInterpolableValue.release(),
+                endInterpolableValue.release(),
+                nonInterpolableValue.release());
+            return true;
+        }
+    }
+    return false;
+}
+
+void InvalidatableStyleInterpolation::interpolate(int, double fraction)
+{
+    m_currentFraction = fraction;
+    if (m_cachedConversion)
+        m_cachedConversion->interpolate(fraction, m_cachedValue);
+    else
+        m_cachedValue.clear();
+}
+
+void InvalidatableStyleInterpolation::validateCache(const StyleResolverState& state) const
+{
+    if (m_cachedConversion && !m_cachedConversion->isInvalid(state))
+        return;
+    m_cachedConversion = nullptr;
+    if (!maybeCachePairwiseConversion(&state))
+        cacheDefaultConversion(state);
+    m_cachedConversion->interpolate(m_currentFraction, m_cachedValue);
+}
+
+void InvalidatableStyleInterpolation::cacheDefaultConversion(const StyleResolverState& state) const
+{
+    RefPtrWillBeRawPtr<InterpolationInvalidators> startInvalidators;
+    AnimationValue startValue = convertSingleKeyframe(state, *m_startKeyframe, startInvalidators);
+
+    RefPtrWillBeRawPtr<InterpolationInvalidators> endInvalidators;
+    AnimationValue endValue = convertSingleKeyframe(state, *m_endKeyframe, endInvalidators);
+
+    InterpolationInvalidators::chain(startInvalidators, endInvalidators.release());
+    m_cachedConversion = DefaultConversionCache::create(startInvalidators.release(), startValue, endValue);
+}
+
+AnimationValue InvalidatableStyleInterpolation::convertSingleKeyframe(const StyleResolverState& state, const CSSPropertySpecificKeyframe& keyframe, RefPtrWillBeRawPtr<InterpolationInvalidators>& resultInvalidators) const
+{
+    for (const auto& animationType : m_applicableTypes) {
+        OwnPtrWillBeRawPtr<InterpolableValue> interpolableValue;
+        RefPtrWillBeRawPtr<NonInterpolableValue> nonInterpolableValue;
+        if (animationType->maybeConvertSingle(keyframe, &state, resultInvalidators, interpolableValue, nonInterpolableValue))
+            return AnimationValue(animationType, interpolableValue.release(), nonInterpolableValue.release());
+    }
+    ASSERT_NOT_REACHED();
+    return AnimationValue();
+}
+
+void InvalidatableStyleInterpolation::apply(StyleResolverState& state) const
+{
+    validateCache(state);
+    if (m_cachedValue)
+        m_cachedValue.type->apply(*m_cachedValue.interpolableValue, m_cachedValue.nonInterpolableValue.get(), state);
+}
+
+} // namespace blink