Merge pull request #17 from 4ms/hsv

Add HSV color class

Author: danngreen

tests/hsv_tests.cc

@@ -0,0 +1,19 @@
+#include "doctest.h"
+#include "util/hsv.hh"
+
+TEST_CASE("HSV to Color") {
+	// check primary colors
+	CHECK(Color{HSVColor{0, 255, 255}} == Colors::red);
+	CHECK(Color{HSVColor{86, 255, 255}} == Colors::green);
+	CHECK(Color{HSVColor{172, 255, 255}} == Colors::blue);
+
+	// check no saturation
+	const auto ns = Color{HSVColor{172, 0, 255}};
+	CHECK(ns.red() == ns.green());
+	CHECK(ns.red() == ns.blue());
+	CHECK(ns.red() == 255);
+
+	// check value
+	const auto v = Color{HSVColor{0, 255, 0}};
+	CHECK(v == Colors::black);
+}

util/hsv.hh

@@ -0,0 +1,39 @@
+#pragma once
+
+#include "util/colors.hh"
+#include <cstdint>
+
+class HSVColor {
+public:
+	uint8_t h;
+	uint8_t s;
+	uint8_t v;
+
+	constexpr operator Color() const {
+		if (!s) {
+			return Color{v, v, v};
+		}
+
+		const auto region = h / 43u;
+		const auto remainder = (h - (region * 43u)) * 6u;
+
+		const uint8_t p = (v * (255u - s)) >> 8u;
+		const uint8_t q = (v * (255u - ((s * remainder) >> 8u))) >> 8u;
+		const uint8_t t = (v * (255u - ((s * (255u - remainder)) >> 8u))) >> 8u;
+
+		switch (region) {
+			case 0:
+				return Color{v, t, p};
+			case 1:
+				return Color{q, v, p};
+			case 2:
+				return Color{p, v, t};
+			case 3:
+				return Color{p, q, v};
+			case 4:
+				return Color{t, p, v};
+			default:
+				return Color{v, p, q};
+		}
+	}
+};