CppColorGradient/Gradient.h at master · Eren121/CppColorGradient · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
#ifndef Gradient_H
#define Gradient_H

#define _USE_MATH_DEFINES

#include <valarray>
#include <ostream>
#include <algorithm>
#include <map>
#include <stdexcept>
#include <functional>
#include <cassert>
#include <cmath>

#define GRADIENT_KEY_DEFAULT_PRECISION double
#define GRADIENT_COLOR_PRECISION_TYPE double
#define GRADIENT_VALARRAY_FORMAT_OPEN "("
#define GRADIENT_VALARRAY_FORMAT_CLOSE ")"
#define GRADIENT_VALARRAY_FORMAT_SEPARATOR ", "

/////////////////////////////////////////////////////////////////////////////
// Interpolation method  ////////////////////////////////////////////////////
/////////////////////////////////////////////////////////////////////////////

namespace gradient {

    template<typename T>
    T linear_interpolation(T x) {
        return x;
    }

    template<typename T>
    T cosine_interpolation(T x) {
        return T(1) - (cos(x * T(M_PI)) + T(1)) / T(2);
    }
}

/////////////////////////////////////////////////////////////////////////////
// Gradient  ////////////////////////////////////////////////////////////////
/////////////////////////////////////////////////////////////////////////////

namespace gradient {
    using default_precision = GRADIENT_KEY_DEFAULT_PRECISION;
    template<typename ratio> using Interpolation = std::function<ratio(ratio x)>;

    template<typename T, typename precision>
    class GradientBase {
    public:
        explicit GradientBase(const Interpolation<precision>& interpolation)
            : interpolationMethod(interpolation) {}
        GradientBase()
                : interpolationMethod(linear_interpolation<precision>) {}
        virtual ~GradientBase() = default;

        Interpolation<precision>& interpolation() { return this->interpolationMethod; }
        const Interpolation<precision>& interpolation() const { return this->interpolationMethod; }
        void setInterpolation(const Interpolation<precision>& interp) { this->interpolationMethod = interp;}

        T interpolate(const T& lowerBound, const T& upperBound, precision r) const {
            assert(interpolationMethod);
            r = interpolationMethod(r);
            return upperBound * r + lowerBound * (precision(1) - r);
        }

    private:
        Interpolation<precision> interpolationMethod;
    };

    template<typename T, typename precision = default_precision>
    class LinearGradient : public GradientBase<T, precision> {
    public:
        using GradientBase<T, precision>::GradientBase;
        ~LinearGradient() override = default;
        T& operator[](precision keyPoint);
        const T& operator[](precision keyPoint) const;
        T operator()(precision point) const;

    private:
        std::map<precision, T> keyPoints;
    };
}

/////////////////////////////////////////////////////////////////////////////
// Convenience operators  ///////////////////////////////////////////////////
/////////////////////////////////////////////////////////////////////////////

namespace gradient {

    namespace operators {

        template<typename T, typename value_type = typename T::value_type>
        std::ostream &operator<<(std::ostream &ostream, const T &valarray) {
            ostream << GRADIENT_VALARRAY_FORMAT_OPEN;
            bool firstValue = true;
            std::for_each(begin(valarray), end(valarray), [&firstValue, &ostream](const value_type &element) {
                if (!firstValue) {
                    ostream << GRADIENT_VALARRAY_FORMAT_SEPARATOR;
                } else {
                    firstValue = false;
                }
                ostream << element;
            });
            ostream << GRADIENT_VALARRAY_FORMAT_CLOSE;
            return ostream;
        }
    }
}

/////////////////////////////////////////////////////////////////////////////
// LinearGradient implementation  ///////////////////////////////////////////
/////////////////////////////////////////////////////////////////////////////

namespace gradient {

    template<typename T, typename precision>
    T &LinearGradient<T, precision>::operator[](precision keyPoint) {
        return this->keyPoints[keyPoint];
    }

    template<typename T, typename precision>
    const T& LinearGradient<T, precision>::operator[](precision keyPoint) const {
        return this->keyPoints.at(keyPoint);
    }

    template<typename T, typename precision>
    T LinearGradient<T, precision>::operator()(precision point) const {

        assert(!this->keyPoints.empty());
        T returnValue;

        const auto upper_bound_it = this->keyPoints.upper_bound(point);


        if(upper_bound_it == this->keyPoints.end()) {
            returnValue = this->keyPoints.rbegin()->second;
        }
        else {
            if (upper_bound_it == this->keyPoints.begin()) {
                returnValue = this->keyPoints.begin()->second;
            } else {
                const auto lower_bound_it = prev(upper_bound_it);

                const T &min = lower_bound_it->second;
                const T &max = upper_bound_it->second;
                const precision min_point = lower_bound_it->first;
                const precision max_point = upper_bound_it->first;
                const precision ratio = (point - min_point) / (max_point - min_point);
                returnValue = this->interpolate(min, max, ratio);
            }
        }

        return returnValue;
    }
}

/////////////////////////////////////////////////////////////////////////////
// User-Defined Types  //////////////////////////////////////////////////////
/////////////////////////////////////////////////////////////////////////////

namespace gradient {

    using Color = std::valarray<GRADIENT_COLOR_PRECISION_TYPE>;
    using LinearColorGradient = LinearGradient<Color>;

    template class LinearGradient<Color>;
    template void GradientBase<Color, default_precision >::setInterpolation(const Interpolation<default_precision> &interpolation);
}

#endif