flutter_flutter/engine/core/animation/animatable/AnimatableValue.h

/*
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#ifndef SKY_ENGINE_CORE_ANIMATION_ANIMATABLE_ANIMATABLEVALUE_H_
#define SKY_ENGINE_CORE_ANIMATION_ANIMATABLE_ANIMATABLEVALUE_H_

#include "sky/engine/core/css/CSSValue.h"
#include "sky/engine/wtf/RefCounted.h"

namespace blink {

class AnimatableValue : public RefCounted<AnimatableValue> {
public:
    virtual ~AnimatableValue() { }

    static const AnimatableValue* neutralValue();

    static PassRefPtr<AnimatableValue> interpolate(const AnimatableValue*, const AnimatableValue*, double fraction);
    static double distance(const AnimatableValue* from, const AnimatableValue* to);
    static bool usesDefaultInterpolation(const AnimatableValue* from, const AnimatableValue* to)
    {
        return !from->isSameType(to) || from->usesDefaultInterpolationWith(to);
    }

    bool equals(const AnimatableValue* value) const
    {
        return isSameType(value) && equalTo(value);
    }
    bool equals(const AnimatableValue& value) const
    {
        return equals(&value);
    }

    bool isClipPathOperation() const { return type() == TypeClipPathOperation; }
    bool isColor() const { return type() == TypeColor; }
    bool isDouble() const { return type() == TypeDouble; }
    bool isFilterOperations() const { return type() == TypeFilterOperations; }
    bool isImage() const { return type() == TypeImage; }
    bool isLength() const { return type() == TypeLength; }
    bool isLengthBox() const { return type() == TypeLengthBox; }
    bool isLengthBoxAndBool() const { return type() == TypeLengthBoxAndBool; }
    bool isLengthPoint() const { return type() == TypeLengthPoint; }
    bool isLengthPoint3D() const { return type() == TypeLengthPoint3D; }
    bool isLengthSize() const { return type() == TypeLengthSize; }
    bool isNeutral() const { return type() == TypeNeutral; }
    bool isRepeatable() const { return type() == TypeRepeatable; }
    bool isShadow() const { return type() == TypeShadow; }
    bool isShapeValue() const { return type() == TypeShapeValue; }
    bool isStrokeDasharrayList() const { return type() == TypeStrokeDasharrayList; }
    bool isTransform() const { return type() == TypeTransform; }
    bool isUnknown() const { return type() == TypeUnknown; }

    bool isSameType(const AnimatableValue* value) const
    {
        ASSERT(value);
        return value->type() == type();
    }

protected:
    enum AnimatableType {
        TypeClipPathOperation,
        TypeColor,
        TypeDouble,
        TypeFilterOperations,
        TypeImage,
        TypeLength,
        TypeLengthBox,
        TypeLengthBoxAndBool,
        TypeLengthPoint,
        TypeLengthPoint3D,
        TypeLengthSize,
        TypeNeutral,
        TypeRepeatable,
        TypeShadow,
        TypeShapeValue,
        TypeStrokeDasharrayList,
        TypeTransform,
        TypeUnknown,
    };

    virtual bool usesDefaultInterpolationWith(const AnimatableValue* value) const { return false; }
    virtual PassRefPtr<AnimatableValue> interpolateTo(const AnimatableValue*, double fraction) const = 0;
    static PassRefPtr<AnimatableValue> defaultInterpolateTo(const AnimatableValue* left, const AnimatableValue* right, double fraction) { return takeConstRef((fraction < 0.5) ? left : right); }

    template <class T>
    static PassRefPtr<T> takeConstRef(const T* value) { return PassRefPtr<T>(const_cast<T*>(value)); }

private:
    virtual AnimatableType type() const = 0;
    // Implementations can assume that the object being compared has the same type as the object this is called on
    virtual bool equalTo(const AnimatableValue*) const = 0;

    virtual double distanceTo(const AnimatableValue*) const;

    template <class Keyframe> friend class KeyframeEffectModel;
};

#define DEFINE_ANIMATABLE_VALUE_TYPE_CASTS(thisType, predicate) \
    DEFINE_TYPE_CASTS(thisType, AnimatableValue, value, value->predicate, value.predicate)

} // namespace blink

#endif  // SKY_ENGINE_CORE_ANIMATION_ANIMATABLE_ANIMATABLEVALUE_H_