Source/core/animation/AnimatableLength.h

/*
 * Copyright (C) 2013 Google Inc. All rights reserved.
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 * modification, are permitted provided that the following conditions are
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 *
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 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
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 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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#ifndef AnimatableLength_h
#define AnimatableLength_h

#include "core/animation/AnimatableValue.h"
#include "core/css/CSSCalculationValue.h"
#include "core/css/CSSPrimitiveValue.h"
#include "platform/Length.h"

namespace WebCore {

enum NumberRange {
    AllValues,
    NonNegativeValues,
};

// Handles animation of CSS length and percentage values including CSS calc.
// See primitiveUnitToNumberType() for the list of supported units.
// If created from a CSSPrimitiveValue this class will cache it to be returned in toCSSValue().
class AnimatableLength : public AnimatableValue {
public:
    enum NumberUnitType {
        UnitTypeCalc,
        UnitTypePixels,
        UnitTypePercentage,
        UnitTypeFontSize,
        UnitTypeFontXSize,
        UnitTypeRootFontSize,
        UnitTypeViewportWidth,
        UnitTypeViewportHeight,
        UnitTypeViewportMin,
        UnitTypeViewportMax,
    };

    virtual ~AnimatableLength() { }
    static bool canCreateFrom(const CSSValue*);
    static PassRefPtr<AnimatableLength> create(CSSValue*);
    static PassRefPtr<AnimatableLength> create(double number, NumberUnitType unitType, CSSPrimitiveValue* cssPrimitiveValue = 0)
    {
        return adoptRef(new AnimatableLength(number, unitType, cssPrimitiveValue));
    }
    static PassRefPtr<AnimatableLength> create(PassRefPtr<CSSCalcExpressionNode> calcExpression, CSSPrimitiveValue* cssPrimitiveValue = 0)
    {
        return adoptRef(new AnimatableLength(calcExpression, cssPrimitiveValue));
    }
    PassRefPtr<CSSValue> toCSSValue(NumberRange = AllValues) const;
    Length toLength(const CSSToLengthConversionData&, NumberRange = AllValues) const;

protected:
    virtual PassRefPtr<AnimatableValue> interpolateTo(const AnimatableValue*, double fraction) const OVERRIDE;
    virtual PassRefPtr<AnimatableValue> addWith(const AnimatableValue*) const OVERRIDE;

private:
    AnimatableLength(double number, NumberUnitType unitType, CSSPrimitiveValue* cssPrimitiveValue)
        : m_number(number)
        , m_unitType(unitType)
        , m_cachedCSSPrimitiveValue(cssPrimitiveValue)
    {
        ASSERT(m_unitType != UnitTypeCalc);
    }
    AnimatableLength(PassRefPtr<CSSCalcExpressionNode> calcExpression, CSSPrimitiveValue* cssPrimitiveValue)
        : m_unitType(UnitTypeCalc)
        , m_calcExpression(calcExpression)
        , m_cachedCSSPrimitiveValue(cssPrimitiveValue)
    {
        ASSERT(m_calcExpression);
    }
    virtual AnimatableType type() const OVERRIDE { return TypeLength; }
    virtual bool equalTo(const AnimatableValue*) const OVERRIDE;

    bool isCalc() const
    {
        return m_unitType == UnitTypeCalc;
    }

    bool isViewportUnit() const
    {
        return m_unitType == UnitTypeViewportWidth || m_unitType == UnitTypeViewportHeight || m_unitType == UnitTypeViewportMin || m_unitType == UnitTypeViewportMax;
    }

    static PassRefPtr<AnimatableLength> create(const AnimatableLength* leftAddend, const AnimatableLength* rightAddend)
    {
        ASSERT(leftAddend && rightAddend);
        return create(CSSCalcValue::createExpressionNode(leftAddend->toCSSCalcExpressionNode(), rightAddend->toCSSCalcExpressionNode(), CalcAdd));
    }

    PassRefPtr<CSSPrimitiveValue> toCSSPrimitiveValue(NumberRange) const;
    PassRefPtr<CSSCalcExpressionNode> toCSSCalcExpressionNode() const;

    PassRefPtr<AnimatableLength> scale(double) const;
    double clampedNumber(NumberRange range) const
    {
        ASSERT(!isCalc());
        return (range == NonNegativeValues && m_number <= 0) ? 0 : m_number;
    }

    // Returns true and populates numberType, if primitiveUnit is a primitive length unit. Otherwise, returns false.
    static bool primitiveUnitToNumberType(unsigned short primitiveUnit, NumberUnitType& numberType);

    static unsigned short numberTypeToPrimitiveUnit(NumberUnitType numberType);

    // Zero is effectively unitless, except in the case of percentage.
    // http://www.w3.org/TR/css3-values/#calc-computed-value
    // e.g. calc(100% - 100% + 1em) resolves to calc(0% + 1em), not to calc(1em)
    bool isUnitlessZero() const
    {
        return !isCalc() && !m_number && m_unitType != UnitTypePercentage;
    }

    NumberUnitType commonUnitType(const AnimatableLength* length) const
    {
        if (m_unitType == length->m_unitType)
            return m_unitType;

        if (isUnitlessZero())
            return length->m_unitType;
        if (length->isUnitlessZero())
            return m_unitType;

        return UnitTypeCalc;
    }

    double m_number;
    const NumberUnitType m_unitType;

    RefPtr<CSSCalcExpressionNode> m_calcExpression;

    mutable RefPtr<CSSPrimitiveValue> m_cachedCSSPrimitiveValue;

    friend class AnimationAnimatableLengthTest;
};

DEFINE_ANIMATABLE_VALUE_TYPE_CASTS(AnimatableLength, isLength());

} // namespace WebCore

#endif // AnimatableLength_h