Source/WebCore/svg/properties/SVGPropertyAnimator.h

/*
 * Copyright (C) 2019 Apple Inc.  All rights reserved.
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 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
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 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
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 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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#pragma once

#include "CSSComputedStyleDeclaration.h"
#include "CSSPropertyParser.h"
#include "SVGAttributeAnimator.h"
#include "SVGElement.h"

namespace WebCore {
    
template<typename AnimationFunction>
class SVGPropertyAnimator : public SVGAttributeAnimator {
public:
    bool isDiscrete() const override { return m_function.isDiscrete(); }

    void setFromAndToValues(SVGElement* targetElement, const String& from, const String& to) override
    {
        m_function.setFromAndToValues(targetElement, adjustForInheritance(targetElement, from), adjustForInheritance(targetElement, to));
    }

    void setFromAndByValues(SVGElement* targetElement, const String& from, const String& by) override
    {
        m_function.setFromAndByValues(targetElement, from, by);
    }

    void setToAtEndOfDurationValue(const String& toAtEndOfDuration) override
    {
        m_function.setToAtEndOfDurationValue(toAtEndOfDuration);
    }

protected:
    template<typename... Arguments>
    SVGPropertyAnimator(const QualifiedName& attributeName, Arguments&&... arguments)
        : SVGAttributeAnimator(attributeName)
        , m_function(std::forward<Arguments>(arguments)...)
    {
    }

    void stop(SVGElement* targetElement) override
    {
        removeAnimatedStyleProperty(targetElement);
    }

    Optional<float> calculateDistance(SVGElement* targetElement, const String& from, const String& to) const override
    {
        return m_function.calculateDistance(targetElement, from, to);
    }

    String adjustForInheritance(SVGElement* targetElement, const String& value) const
    {
        static NeverDestroyed<const AtomString> inherit("inherit", AtomString::ConstructFromLiteral);
        return value == inherit ? computeInheritedCSSPropertyValue(targetElement) : value;
    }

    String computeCSSPropertyValue(SVGElement* targetElement, CSSPropertyID id) const
    {
        ASSERT(targetElement);

        // Don't include any properties resulting from CSS Transitions/Animations or SMIL animations, as we want to retrieve the "base value".
        targetElement->setUseOverrideComputedStyle(true);
        RefPtr<CSSValue> value = ComputedStyleExtractor(targetElement).propertyValue(id);
        targetElement->setUseOverrideComputedStyle(false);
        return value ? value->cssText() : String();
    }

    String computeInheritedCSSPropertyValue(SVGElement* targetElement) const
    {
        ASSERT(targetElement);
        auto parent = makeRefPtr(targetElement->parentElement());
        if (!parent || !parent->isSVGElement())
            return emptyString();
        
        SVGElement& svgParent = downcast<SVGElement>(*parent);
        return computeCSSPropertyValue(&svgParent, cssPropertyID(m_attributeName.localName()));
    }

    AnimationFunction m_function;
};
    
}