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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: |
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 | { } |
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 | |
71 | bool isGamma() const |
72 | { |
73 | updateHints(); |
74 | return m_flags & quint32(Hints::IsGamma); |
75 | } |
76 | bool isLinear() const |
77 | { |
78 | updateHints(); |
79 | return m_flags & quint32(Hints::IsLinear); |
80 | } |
81 | bool isSRgb() const |
82 | { |
83 | updateHints(); |
84 | return m_flags & quint32(Hints::IsSRgb); |
85 | } |
86 | |
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(x: m_a * x + m_b, y: m_g) + m_e; |
93 | } |
94 | |
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(f: 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(f: m_a) && !qFuzzyIsNull(f: m_g)) { |
110 | a = std::pow(x: 1.0f / m_a, y: 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: |
125 | static QColorTransferFunction fromGamma(float gamma) |
126 | { |
127 | return QColorTransferFunction(1.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, gamma); |
128 | } |
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 | } |
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 | } |
137 | bool matches(const QColorTransferFunction &o) const |
138 | { |
139 | return paramCompare(p1: m_a, p2: o.m_a) && paramCompare(p1: m_b, p2: o.m_b) |
140 | && paramCompare(p1: m_c, p2: o.m_c) && paramCompare(p1: m_d, p2: o.m_d) |
141 | && paramCompare(p1: m_e, p2: o.m_e) && paramCompare(p1: m_f, p2: o.m_f) |
142 | && paramCompare(p1: m_g, p2: 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: |
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(t: p1 - p2) <= (1.0f / 512.0f)); |
162 | } |
163 | |
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(p1: m_a, p2: 1.0f) && paramCompare(p1: m_b, p2: 0.0f) |
171 | && paramCompare(p1: m_d, p2: 0.0f) |
172 | && paramCompare(p1: m_e, p2: 0.0f); |
173 | if (simple) { |
174 | m_flags |= quint32(Hints::IsGamma); |
175 | if (qFuzzyCompare(p1: m_g, p2: 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(o: f2); |
195 | } |
196 | inline bool operator!=(const QColorTransferFunction &f1, const QColorTransferFunction &f2) |
197 | { |
198 | return !f1.matches(o: f2); |
199 | } |
200 | |
201 | QT_END_NAMESPACE |
202 | |
203 | #endif // QCOLORTRANSFERFUNCTION_P_H |
204 | |