Easing.h

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// SPDX-FileCopyrightText: 2026 fuddlesworth
// SPDX-License-Identifier: LGPL-2.1-or-later
 
#pragma once
 
#include <PhosphorAnimation/Curve.h>
#include <PhosphorAnimation/phosphoranimation_export.h>
 
#include <QString>
#include <QtGlobal>
 
namespace PhosphorAnimation {
 
class PHOSPHORANIMATION_EXPORT Easing final : public Curve
{
public:
    enum class Type {
        CubicBezier,
        ElasticIn,
        ElasticOut,
        ElasticInOut,
        BounceIn,
        BounceOut,
        BounceInOut,
    };
 
    Easing() = default;
 
    Easing(const Easing&) = default;
    Easing& operator=(const Easing&) = default;
    Easing(Easing&&) = default;
    Easing& operator=(Easing&&) = default;
 
    QString typeId() const override;
    qreal evaluate(qreal x) const override;
    QString toString() const override;
    std::unique_ptr<Curve> clone() const override;
    bool overshoots() const override;
    bool equals(const Curve& other) const override;
 
    static Easing fromString(const QString& str);
 
    static constexpr qreal MaxElasticPeak = 2.0;
 
    static constexpr qreal MinElasticPeriod = 0.1;
    static constexpr qreal MaxElasticPeriod = 1.0;
 
    static constexpr int ElasticSolveIterations = 24;
 
    static qreal minElasticPeak(qreal period);
 
    static qreal clampAmplitude(Type t, qreal amp, qreal period);
 
    Type type = Type::CubicBezier;
 
    qreal x1 = 0.33;
    qreal y1 = 1.0;
    qreal x2 = 0.68;
    qreal y2 = 1.0;
 
    qreal amplitude = 1.0;
    qreal period = 0.3;
    int bounces = 3;
 
    bool operator==(const Easing& other) const;
    bool operator!=(const Easing& other) const
    {
        return !(*this == other);
    }
 
private:
    static qreal solveElasticGain(qreal peak, qreal period);
 
    static qreal evaluateElasticOut(qreal t, qreal peak, qreal per);
    static qreal evaluateBounceOut(qreal t, qreal amp, int n);
};
 
} // namespace PhosphorAnimation