Add Color class from libscgui

src/Color.cpp

@@ -0,0 +1,124 @@
+#include "Color.hpp"
+#include <algorithm>
+#include <cmath>
+#include <stdexcept>
+#include <sstream>
+#include <iomanip>
+
+Color::Color(const RGB& rgb) : _rgb {rgb} {}
+
+Color::Color(const HSB& hsb) {
+    if (hsb.s <= 0) {
+        _rgb.r = _rgb.g = _rgb.b = hsb.b;
+    } else {
+        double hi = hsb.h / 60;
+        int i = static_cast<int>(hi);
+        double f = hi - i;
+        double p = hsb.b * (1.0 - hsb.s);
+        double q = hsb.b * (1.0 - (hsb.s * f));
+        double t = hsb.b * (1.0 - (hsb.s * (1.0 -f)));
+        switch (i) {
+            case 0:
+                _rgb.r = hsb.b;
+                _rgb.g = t;
+                _rgb.b = p;
+                break;
+            case 1:
+                _rgb.r = q;
+                _rgb.g = hsb.b;
+                _rgb.b = p;
+                break;
+            case 2:
+                _rgb.r = p;
+                _rgb.g = hsb.b;
+                _rgb.b = t;
+                break;
+            case 3:
+                _rgb.r = p;
+                _rgb.g = q;
+                _rgb.b = hsb.b;
+                break;
+            case 4:
+                _rgb.r = t;
+                _rgb.g = p;
+                _rgb.b = hsb.b;
+                break;
+            case 5:
+            default:
+                _rgb.r = hsb.b;
+                _rgb.g = p;
+                _rgb.b = q;
+                break;
+        }
+    }
+}
+
+Color::operator HSB() const {
+    HSB hsb;
+    double rgb_max = std::max<double>({_rgb.r, _rgb.g, _rgb.b});
+    double rgb_min = std::min<double>({_rgb.r, _rgb.g, _rgb.b});
+    double delta = rgb_max - rgb_min;
+    if (delta < 0.00001) {
+        hsb.h = 0;
+        hsb.s = 0;
+        hsb.b = rgb_max;
+        return hsb;
+    }
+    if (_rgb.r >= rgb_max) { // between yellow and magenta
+        hsb.h = (_rgb.g - _rgb.b) / delta;
+    } else if (_rgb.g >= rgb_max) { //  between cyan and yellow
+        hsb.h = 2.0 + (_rgb.b - _rgb.r) / delta;
+    } else { // between magenta and cyan
+        hsb.h = 4.0 + (_rgb.r - _rgb.g) / delta;
+    }
+    hsb.h *= 60;
+    hsb.s = rgb_max > 0.0 ? delta / rgb_max : 0;
+    hsb.b = rgb_max;
+    return hsb;
+}
+
+Color::Color(const std::string& hex) {
+    if (hex[0] != '#') throw std::runtime_error {"invalid hex color - must start with '#'"};
+    if (hex.size() != 7) throw std::runtime_error {"invalid hex color - must be 7 chars"};
+    unsigned int val;
+
+    std::istringstream iss {hex.substr(1, 2)};
+    iss >> std::hex >> val;
+    _rgb.r = val / 255.0;
+
+    iss.str(hex.substr(3, 2));
+    iss.seekg(0);
+    iss >> std::hex >> val;
+    _rgb.g = val / 255.0;
+
+    iss.str(hex.substr(5, 2));
+    iss.seekg(0);
+    iss >> std::hex >> val;
+    _rgb.b = val / 255.0;
+}
+
+Color& Color::operator=(const RGB& rgb) {
+    _rgb = rgb;
+    return *this;
+}
+
+Color& Color::operator=(const HSB& hsb) {
+    Color tmp {hsb};
+    _rgb = tmp._rgb;
+    return *this;
+}
+
+Color& Color::operator=(const std::string& hex) {
+    Color tmp {hex};
+    _rgb = tmp._rgb;
+    return *this;
+}
+
+std::string Color::hex() const {
+    std::ostringstream oss;
+    oss << '#' << std::hex <<
+        static_cast<unsigned int>(round(_rgb.r * 255)) <<
+        static_cast<unsigned int>(round(_rgb.g * 255)) <<
+        static_cast<unsigned int>(round(_rgb.b * 255));
+    return oss.str();
+}

src/Color.hpp

@@ -0,0 +1,36 @@
+#ifndef _Color_H_
+#define _Color_H_
+
+#include <string>
+
+struct RGB {
+    double r; // 0..1
+    double g; // 0..1
+    double b; // 0..1
+};
+
+struct HSB {
+    double h; // 0..360
+    double s; // 0..1
+    double b; // 0..1
+};
+
+class Color {
+    public:
+        Color(const RGB& rgb);
+        Color(const HSB& hsb);
+        Color(const std::string& hex);
+
+        operator RGB() const { return _rgb; }
+        operator HSB() const;
+        std::string hex() const;
+
+        Color& operator=(const RGB& rgb);
+        Color& operator=(const HSB& hsb);
+        Color& operator=(const std::string& hex);
+
+    private:
+        RGB _rgb;
+};
+
+#endif // _Color_H_