third_party/WebKit/Source/core/html/forms/StepRange.h

/*
 * Copyright (C) 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public License
 * along with this library; see the file COPYING.LIB.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 *
 */

#ifndef StepRange_h
#define StepRange_h

#include "core/CoreExport.h"
#include "platform/Decimal.h"
#include "wtf/Allocator.h"
#include "wtf/Forward.h"

namespace blink {

enum AnyStepHandling { RejectAny, AnyIsDefaultStep };

class CORE_EXPORT StepRange {
    DISALLOW_NEW();
public:
    enum StepValueShouldBe {
        StepValueShouldBeReal,
        ParsedStepValueShouldBeInteger,
        ScaledStepValueShouldBeInteger,
    };

    struct StepDescription {
        USING_FAST_MALLOC(StepDescription);
    public:
        int defaultStep;
        int defaultStepBase;
        int stepScaleFactor;
        StepValueShouldBe stepValueShouldBe;

        StepDescription(int defaultStep, int defaultStepBase, int stepScaleFactor, StepValueShouldBe stepValueShouldBe = StepValueShouldBeReal)
            : defaultStep(defaultStep)
            , defaultStepBase(defaultStepBase)
            , stepScaleFactor(stepScaleFactor)
            , stepValueShouldBe(stepValueShouldBe)
        {
        }

        StepDescription()
            : defaultStep(1)
            , defaultStepBase(0)
            , stepScaleFactor(1)
            , stepValueShouldBe(StepValueShouldBeReal)
        {
        }

        Decimal defaultValue() const
        {
            return defaultStep * stepScaleFactor;
        }
    };

    StepRange();
    StepRange(const StepRange&);
    StepRange(const Decimal& stepBase, const Decimal& minimum, const Decimal& maximum, bool hasRangeLimitations, const Decimal& step, const StepDescription&);

    Decimal alignValueForStep(const Decimal& currentValue, const Decimal& newValue) const;
    Decimal clampValue(const Decimal& value) const;
    bool hasStep() const { return m_hasStep; }
    Decimal maximum() const { return m_maximum; }
    Decimal minimum() const { return m_minimum; }
    // https://html.spec.whatwg.org/multipage/forms.html#have-range-limitations
    bool hasRangeLimitations() const { return m_hasRangeLimitations; }
    static Decimal parseStep(AnyStepHandling, const StepDescription&, const String&);
    Decimal step() const { return m_step; }
    Decimal stepBase() const { return m_stepBase; }
    bool stepMismatch(const Decimal&) const;

    // Clamp the middle value according to the step
    Decimal defaultValue() const
    {
        return clampValue((m_minimum + m_maximum) / 2);
    }

    // Map value into 0-1 range
    Decimal proportionFromValue(const Decimal& value) const
    {
        if (m_minimum == m_maximum)
            return 0;

        return (value - m_minimum) / (m_maximum - m_minimum);
    }

    // Map from 0-1 range to value
    Decimal valueFromProportion(const Decimal& proportion) const
    {
        return m_minimum + proportion * (m_maximum - m_minimum);
    }

private:
    StepRange& operator=(const StepRange&) = delete;
    Decimal acceptableError() const;
    Decimal roundByStep(const Decimal& value, const Decimal& base) const;

    const Decimal m_maximum; // maximum must be >= minimum.
    const Decimal m_minimum;
    const Decimal m_step;
    const Decimal m_stepBase;
    const StepDescription m_stepDescription;
    const bool m_hasStep;
    const bool m_hasRangeLimitations;
};

} // namespace blink

#endif // StepRange_h