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Diffstat (limited to 'src/gui/painting/qcolortransferfunction_p.h')
| -rw-r--r-- | src/gui/painting/qcolortransferfunction_p.h | 207 |
1 files changed, 207 insertions, 0 deletions
diff --git a/src/gui/painting/qcolortransferfunction_p.h b/src/gui/painting/qcolortransferfunction_p.h new file mode 100644 index 0000000000..fd7cfa2b2b --- /dev/null +++ b/src/gui/painting/qcolortransferfunction_p.h @@ -0,0 +1,207 @@ +/**************************************************************************** +** +** Copyright (C) 2018 The Qt Company Ltd. +** Contact: https://www.qt.io/licensing/ +** +** This file is part of the QtGui module of the Qt Toolkit. +** +** $QT_BEGIN_LICENSE:LGPL$ +** Commercial License Usage +** Licensees holding valid commercial Qt licenses may use this file in +** accordance with the commercial license agreement provided with the +** Software or, alternatively, in accordance with the terms contained in +** a written agreement between you and The Qt Company. For licensing terms +** and conditions see https://www.qt.io/terms-conditions. For further +** information use the contact form at https://www.qt.io/contact-us. +** +** GNU Lesser General Public License Usage +** Alternatively, this file may be used under the terms of the GNU Lesser +** General Public License version 3 as published by the Free Software +** Foundation and appearing in the file LICENSE.LGPL3 included in the +** packaging of this file. Please review the following information to +** ensure the GNU Lesser General Public License version 3 requirements +** will be met: https://www.gnu.org/licenses/lgpl-3.0.html. +** +** GNU General Public License Usage +** Alternatively, this file may be used under the terms of the GNU +** General Public License version 2.0 or (at your option) the GNU General +** Public license version 3 or any later version approved by the KDE Free +** Qt Foundation. The licenses are as published by the Free Software +** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3 +** included in the packaging of this file. Please review the following +** information to ensure the GNU General Public License requirements will +** be met: https://www.gnu.org/licenses/gpl-2.0.html and +** https://www.gnu.org/licenses/gpl-3.0.html. +** +** $QT_END_LICENSE$ +** +****************************************************************************/ + +#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 fromBt2020() + { + return QColorTransferFunction(1.0f / 1.0993f, 0.0993f / 1.0993f, 1.0f / 4.5f, 0.08145f, 0.0f, 0.0f, 2.2f); + } + 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 |