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| |
| #ifndef QCOLORTRANSFERFUNCTION_P_H |
| #define QCOLORTRANSFERFUNCTION_P_H |
| |
| // |
| // W A R N I N G |
| // ------------- |
| // |
| // This file is not part of the Qt API. It exists purely as an |
| // implementation detail. This header file may change from version to |
| // version without notice, or even be removed. |
| // |
| // We mean it. |
| // |
| |
| #include <QtGui/private/qtguiglobal_p.h> |
| |
| #include <cmath> |
| |
| QT_BEGIN_NAMESPACE |
| |
| // Defines a ICC parametric curve type 4 |
| class Q_GUI_EXPORT QColorTransferFunction |
| { |
| public: |
| QColorTransferFunction() noexcept |
| : m_a(1.0f), m_b(0.0f), m_c(1.0f), m_d(0.0f), m_e(0.0f), m_f(0.0f), m_g(1.0f), m_flags(0) |
| { } |
| QColorTransferFunction(float a, float b, float c, float d, float e, float f, float g) noexcept |
| : m_a(a), m_b(b), m_c(c), m_d(d), m_e(e), m_f(f), m_g(g), m_flags(0) |
| { } |
| |
| bool isGamma() const |
| { |
| updateHints(); |
| return m_flags & quint32(Hints::IsGamma); |
| } |
| bool isLinear() const |
| { |
| updateHints(); |
| return m_flags & quint32(Hints::IsLinear); |
| } |
| bool isSRgb() const |
| { |
| updateHints(); |
| return m_flags & quint32(Hints::IsSRgb); |
| } |
| |
| float apply(float x) const |
| { |
| if (x < m_d) |
| return m_c * x + m_f; |
| else |
| return std::pow(m_a * x + m_b, m_g) + m_e; |
| } |
| |
| QColorTransferFunction inverted() const |
| { |
| float a, b, c, d, e, f, g; |
| |
| d = m_c * m_d + m_f; |
| |
| if (!qFuzzyIsNull(m_c)) { |
| c = 1.0f / m_c; |
| f = -m_f / m_c; |
| } else { |
| c = 0.0f; |
| f = 0.0f; |
| } |
| |
| if (!qFuzzyIsNull(m_a) && !qFuzzyIsNull(m_g)) { |
| a = std::pow(1.0f / m_a, m_g); |
| b = -a * m_e; |
| e = -m_b / m_a; |
| g = 1.0f / m_g; |
| } else { |
| a = 0.0f; |
| b = 0.0f; |
| e = 1.0f; |
| g = 1.0f; |
| } |
| |
| return QColorTransferFunction(a, b, c, d, e, f, g); |
| } |
| |
| // A few predefined curves: |
| static QColorTransferFunction fromGamma(float gamma) |
| { |
| return QColorTransferFunction(1.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, gamma); |
| } |
| static QColorTransferFunction fromSRgb() |
| { |
| return QColorTransferFunction(1.0f / 1.055f, 0.055f / 1.055f, 1.0f / 12.92f, 0.04045f, 0.0f, 0.0f, 2.4f); |
| } |
| static QColorTransferFunction fromProPhotoRgb() |
| { |
| return QColorTransferFunction(1.0f, 0.0f, 1.0f / 16.0f, 16.0f / 512.0f, 0.0f, 0.0f, 1.8f); |
| } |
| bool matches(const QColorTransferFunction &o) const |
| { |
| return paramCompare(m_a, o.m_a) && paramCompare(m_b, o.m_b) |
| && paramCompare(m_c, o.m_c) && paramCompare(m_d, o.m_d) |
| && paramCompare(m_e, o.m_e) && paramCompare(m_f, o.m_f) |
| && paramCompare(m_g, o.m_g); |
| } |
| friend inline bool operator==(const QColorTransferFunction &f1, const QColorTransferFunction &f2); |
| friend inline bool operator!=(const QColorTransferFunction &f1, const QColorTransferFunction &f2); |
| |
| float m_a; |
| float m_b; |
| float m_c; |
| float m_d; |
| float m_e; |
| float m_f; |
| float m_g; |
| |
| private: |
| static inline bool paramCompare(float p1, float p2) |
| { |
| // Much fuzzier than fuzzy compare. |
| // It tries match parameters that has been passed through a 8.8 |
| // fixed point form. |
| return (qAbs(p1 - p2) <= (1.0f / 512.0f)); |
| } |
| |
| void updateHints() const |
| { |
| if (m_flags & quint32(Hints::Calculated)) |
| return; |
| // We do not consider the case with m_d = 1.0f linear or simple, |
| // since it wouldn't be linear for applyExtended(). |
| bool simple = paramCompare(m_a, 1.0f) && paramCompare(m_b, 0.0f) |
| && paramCompare(m_d, 0.0f) |
| && paramCompare(m_e, 0.0f); |
| if (simple) { |
| m_flags |= quint32(Hints::IsGamma); |
| if (qFuzzyCompare(m_g, 1.0f)) |
| m_flags |= quint32(Hints::IsLinear); |
| } else { |
| if (*this == fromSRgb()) |
| m_flags |= quint32(Hints::IsSRgb); |
| } |
| m_flags |= quint32(Hints::Calculated); |
| } |
| enum class Hints : quint32 { |
| Calculated = 1, |
| IsGamma = 2, |
| IsLinear = 4, |
| IsSRgb = 8 |
| }; |
| mutable quint32 m_flags; |
| }; |
| |
| inline bool operator==(const QColorTransferFunction &f1, const QColorTransferFunction &f2) |
| { |
| return f1.matches(f2); |
| } |
| inline bool operator!=(const QColorTransferFunction &f1, const QColorTransferFunction &f2) |
| { |
| return !f1.matches(f2); |
| } |
| |
| QT_END_NAMESPACE |
| |
| #endif // QCOLORTRANSFERFUNCTION_P_H |
