1 /**************************************************************************** 2 ** 3 ** Copyright (C) 2018 The Qt Company Ltd. 4 ** Contact: https://www.qt.io/licensing/ 5 ** 6 ** This file is part of the QtGui module of the Qt Toolkit. 7 ** 8 ** $QT_BEGIN_LICENSE:LGPL$ 9 ** Commercial License Usage 10 ** Licensees holding valid commercial Qt licenses may use this file in 11 ** accordance with the commercial license agreement provided with the 12 ** Software or, alternatively, in accordance with the terms contained in 13 ** a written agreement between you and The Qt Company. For licensing terms 14 ** and conditions see https://www.qt.io/terms-conditions. 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The licenses are as published by the Free Software 30 ** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3 31 ** included in the packaging of this file. Please review the following 32 ** information to ensure the GNU General Public License requirements will 33 ** be met: https://www.gnu.org/licenses/gpl-2.0.html and 34 ** https://www.gnu.org/licenses/gpl-3.0.html. 35 ** 36 ** $QT_END_LICENSE$ 37 ** 38 ****************************************************************************/ 39 40 #ifndef QCOLORTRANSFERFUNCTION_P_H 41 #define QCOLORTRANSFERFUNCTION_P_H 42 43 // 44 // W A R N I N G 45 // ------------- 46 // 47 // This file is not part of the Qt API. It exists purely as an 48 // implementation detail. This header file may change from version to 49 // version without notice, or even be removed. 50 // 51 // We mean it. 52 // 53 54 #include <QtGui/private/qtguiglobal_p.h> 55 56 #include <cmath> 57 58 QT_BEGIN_NAMESPACE 59 60 // Defines a ICC parametric curve type 4 61 class Q_GUI_EXPORT QColorTransferFunction 62 { 63 public: QColorTransferFunction()64 QColorTransferFunction() noexcept 65 : 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) 66 { } QColorTransferFunction(float a,float b,float c,float d,float e,float f,float g)67 QColorTransferFunction(float a, float b, float c, float d, float e, float f, float g) noexcept 68 : m_a(a), m_b(b), m_c(c), m_d(d), m_e(e), m_f(f), m_g(g), m_flags(0) 69 { } 70 isGamma()71 bool isGamma() const 72 { 73 updateHints(); 74 return m_flags & quint32(Hints::IsGamma); 75 } isLinear()76 bool isLinear() const 77 { 78 updateHints(); 79 return m_flags & quint32(Hints::IsLinear); 80 } isSRgb()81 bool isSRgb() const 82 { 83 updateHints(); 84 return m_flags & quint32(Hints::IsSRgb); 85 } 86 apply(float x)87 float apply(float x) const 88 { 89 if (x < m_d) 90 return m_c * x + m_f; 91 else 92 return std::pow(m_a * x + m_b, m_g) + m_e; 93 } 94 inverted()95 QColorTransferFunction inverted() const 96 { 97 float a, b, c, d, e, f, g; 98 99 d = m_c * m_d + m_f; 100 101 if (!qFuzzyIsNull(m_c)) { 102 c = 1.0f / m_c; 103 f = -m_f / m_c; 104 } else { 105 c = 0.0f; 106 f = 0.0f; 107 } 108 109 if (!qFuzzyIsNull(m_a) && !qFuzzyIsNull(m_g)) { 110 a = std::pow(1.0f / m_a, m_g); 111 b = -a * m_e; 112 e = -m_b / m_a; 113 g = 1.0f / m_g; 114 } else { 115 a = 0.0f; 116 b = 0.0f; 117 e = 1.0f; 118 g = 1.0f; 119 } 120 121 return QColorTransferFunction(a, b, c, d, e, f, g); 122 } 123 124 // A few predefined curves: fromGamma(float gamma)125 static QColorTransferFunction fromGamma(float gamma) 126 { 127 return QColorTransferFunction(1.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, gamma); 128 } fromSRgb()129 static QColorTransferFunction fromSRgb() 130 { 131 return QColorTransferFunction(1.0f / 1.055f, 0.055f / 1.055f, 1.0f / 12.92f, 0.04045f, 0.0f, 0.0f, 2.4f); 132 } fromProPhotoRgb()133 static QColorTransferFunction fromProPhotoRgb() 134 { 135 return QColorTransferFunction(1.0f, 0.0f, 1.0f / 16.0f, 16.0f / 512.0f, 0.0f, 0.0f, 1.8f); 136 } matches(const QColorTransferFunction & o)137 bool matches(const QColorTransferFunction &o) const 138 { 139 return paramCompare(m_a, o.m_a) && paramCompare(m_b, o.m_b) 140 && paramCompare(m_c, o.m_c) && paramCompare(m_d, o.m_d) 141 && paramCompare(m_e, o.m_e) && paramCompare(m_f, o.m_f) 142 && paramCompare(m_g, o.m_g); 143 } 144 friend inline bool operator==(const QColorTransferFunction &f1, const QColorTransferFunction &f2); 145 friend inline bool operator!=(const QColorTransferFunction &f1, const QColorTransferFunction &f2); 146 147 float m_a; 148 float m_b; 149 float m_c; 150 float m_d; 151 float m_e; 152 float m_f; 153 float m_g; 154 155 private: paramCompare(float p1,float p2)156 static inline bool paramCompare(float p1, float p2) 157 { 158 // Much fuzzier than fuzzy compare. 159 // It tries match parameters that has been passed through a 8.8 160 // fixed point form. 161 return (qAbs(p1 - p2) <= (1.0f / 512.0f)); 162 } 163 updateHints()164 void updateHints() const 165 { 166 if (m_flags & quint32(Hints::Calculated)) 167 return; 168 // We do not consider the case with m_d = 1.0f linear or simple, 169 // since it wouldn't be linear for applyExtended(). 170 bool simple = paramCompare(m_a, 1.0f) && paramCompare(m_b, 0.0f) 171 && paramCompare(m_d, 0.0f) 172 && paramCompare(m_e, 0.0f); 173 if (simple) { 174 m_flags |= quint32(Hints::IsGamma); 175 if (qFuzzyCompare(m_g, 1.0f)) 176 m_flags |= quint32(Hints::IsLinear); 177 } else { 178 if (*this == fromSRgb()) 179 m_flags |= quint32(Hints::IsSRgb); 180 } 181 m_flags |= quint32(Hints::Calculated); 182 } 183 enum class Hints : quint32 { 184 Calculated = 1, 185 IsGamma = 2, 186 IsLinear = 4, 187 IsSRgb = 8 188 }; 189 mutable quint32 m_flags; 190 }; 191 192 inline bool operator==(const QColorTransferFunction &f1, const QColorTransferFunction &f2) 193 { 194 return f1.matches(f2); 195 } 196 inline bool operator!=(const QColorTransferFunction &f1, const QColorTransferFunction &f2) 197 { 198 return !f1.matches(f2); 199 } 200 201 QT_END_NAMESPACE 202 203 #endif // QCOLORTRANSFERFUNCTION_P_H 204