Add HSVColour class.

Makefile

@@ -378,6 +378,7 @@ APP_OBJS := \
 	src/FileWriter.$(BUILD_TYPE).o \
 	src/FillRangeDialog.$(BUILD_TYPE).o \
 	src/FixedSizeValueRegion.$(BUILD_TYPE).o \
+	src/HSVColour.$(BUILD_TYPE).o \
 	src/IntelHexExport.$(BUILD_TYPE).o \
 	src/IntelHexImport.$(BUILD_TYPE).o \
 	src/IPC.$(BUILD_TYPE).o \
@@ -469,6 +470,7 @@ TEST_OBJS := \
 	src/FileWriter.$(BUILD_TYPE).o \
 	src/FillRangeDialog.$(BUILD_TYPE).o \
 	src/FixedSizeValueRegion.$(BUILD_TYPE).o \
+	src/HSVColour.$(BUILD_TYPE).o \
 	src/IntelHexExport.$(BUILD_TYPE).o \
 	src/IntelHexImport.$(BUILD_TYPE).o \
 	src/LicenseDialog.$(BUILD_TYPE).o \
@@ -511,6 +513,7 @@ TEST_OBJS := \
 	tests/endian_conv.o \
 	tests/FastRectangleFiller.o \
 	tests/FileWriter.o \
+	tests/HSVColour.o \
 	tests/IntelHexExport.o \
 	tests/IntelHexImport.o \
 	tests/LuaPluginLoader.o \

src/HSVColour.cpp

@@ -0,0 +1,179 @@
+/* Reverse Engineer's Hex Editor
+ * Copyright (C) 2024 Daniel Collins <solemnwarning@solemnwarning.net>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program; if not, write to the Free Software Foundation, Inc., 51
+ * Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+*/
+
+#include <algorithm>
+#include <math.h>
+
+#include "HSVColour.hpp"
+
+float REHex::HSVColour::wrap_h(float h)
+{
+	return h - (360.0f * floorf(h / 360.f));
+}
+
+float REHex::HSVColour::clamp_sv(float sv)
+{
+	return std::max(0.0f, std::min(sv, 1.0f));
+}
+
+REHex::HSVColour::HSVColour(float h, float s, float v):
+	h(wrap_h(h)),
+	s(clamp_sv(s)),
+	v(clamp_sv(v)) {}
+
+REHex::HSVColour::HSVColour(const wxColour &rgb)
+{
+	/* https://www.geeksforgeeks.org/program-change-rgb-color-model-hsv-color-model/ */
+
+	float r = (float)(rgb.Red()) / 255.0f;
+	float g = (float)(rgb.Green()) / 255.0f;
+	float b = (float)(rgb.Blue()) / 255.0f;
+
+	float cmax = std::max({ r, g, b });
+	float cmin = std::min({ r, g, b });
+	float cdiff = cmax - cmin;
+
+	if(cmax == cmin)
+	{
+		h = 0.0f;
+	}
+	else if(cmax == r)
+	{
+		h = wrap_h(60.0f * ((g - b) / cdiff) + 360.0f);
+	}
+	else if(cmax == g)
+	{
+		h = wrap_h(60.0f * ((b - r) / cdiff) + 120.0f);
+	}
+	else{
+		assert(cmax == b);
+		h = wrap_h(60.0f * ((r - g) / cdiff) + 240.0f);
+	}
+
+	if(cmax == 0.0f)
+	{
+		s = 0.0f;
+	}
+	else{
+		s = cdiff / cmax;
+	}
+
+	v = cmax;
+}
+
+wxColour REHex::HSVColour::to_rgb() const
+{
+	/* HSV to RGB conversion Copyright (c) 2014, Jan Winkler <winkler@cs.uni-bremen.de>
+	 * https://gist.github.com/fairlight1337/4935ae72bcbcc1ba5c72
+	*/
+
+	float fR, fG, fB;
+
+	float fH = wrap_h(h);
+	float fS = clamp_sv(s);
+	float fV = clamp_sv(v);
+
+	float fC = fV * fS; // Chroma
+	float fHPrime = fmod(fH / 60.0, 6);
+	float fX = fC * (1 - fabs(fmod(fHPrime, 2) - 1));
+	float fM = fV - fC;
+
+	if(0 <= fHPrime && fHPrime < 1) {
+		fR = fC;
+		fG = fX;
+		fB = 0;
+	} else if(1 <= fHPrime && fHPrime < 2) {
+		fR = fX;
+		fG = fC;
+		fB = 0;
+	} else if(2 <= fHPrime && fHPrime < 3) {
+		fR = 0;
+		fG = fC;
+		fB = fX;
+	} else if(3 <= fHPrime && fHPrime < 4) {
+		fR = 0;
+		fG = fX;
+		fB = fC;
+	} else if(4 <= fHPrime && fHPrime < 5) {
+		fR = fX;
+		fG = 0;
+		fB = fC;
+	} else if(5 <= fHPrime && fHPrime < 6) {
+		fR = fC;
+		fG = 0;
+		fB = fX;
+	} else {
+		fR = 0;
+		fG = 0;
+		fB = 0;
+	}
+
+	fR += fM;
+	fG += fM;
+	fB += fM;
+
+	fR *= 255.0;
+	fG *= 255.0;
+	fB *= 255.0;
+
+	return wxColour(fR, fG, fB);
+}
+
+std::pair<float, float> REHex::HSVColour::pick_contrasting_hue(const std::vector<float> &existing_hues)
+{
+	if(existing_hues.empty())
+	{
+		/* No reference colours. Pick an arbitrary hue. */
+		return std::make_pair(0.0f, 360.0f);
+	}
+
+	/* First, wrap all values into the space of 0.0-359.9 and sort them. */
+
+	std::vector<float> sorted_hues;
+	sorted_hues.reserve(existing_hues.size());
+
+	for(auto i = existing_hues.begin(); i != existing_hues.end(); ++i)
+	{
+		sorted_hues.push_back(wrap_h(*i));
+	}
+
+	std::sort(sorted_hues.begin(), sorted_hues.end());
+
+	/* Then we iterate over each one hue, and pick the mid-point between
+	 * the two most distant points.
+	*/
+
+	float hue = 0.0f;
+	float hue_gap = 0.0f;
+
+	for(size_t i = 0; i < sorted_hues.size(); ++i)
+	{
+		float this_hue = sorted_hues[i];
+		float next_hue = sorted_hues.size() > (i + 1) ? sorted_hues[i + 1] : (360.0f + sorted_hues[0]);
+
+		float this_gap = (next_hue - this_hue) / 2.0f;
+		float this_midpoint = this_hue + this_gap;
+
+		if(this_gap > hue_gap)
+		{
+			hue = wrap_h(this_midpoint);
+			hue_gap = this_gap;
+		}
+	}
+
+	return std::make_pair(hue, hue_gap);
+}

src/HSVColour.hpp

@@ -0,0 +1,78 @@
+/* Reverse Engineer's Hex Editor
+ * Copyright (C) 2024 Daniel Collins <solemnwarning@solemnwarning.net>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program; if not, write to the Free Software Foundation, Inc., 51
+ * Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+*/
+
+#ifndef REHEX_HSVCOLOUR_HPP
+#define REHEX_HSVCOLOUR_HPP
+
+#include <utility>
+#include <vector>
+#include <wx/colour.h>
+
+namespace REHex
+{
+	/**
+	 * @brief A Hue/Saturation/Value colour.
+	*/
+	struct HSVColour
+	{
+		float h; /**< Hue (degrees) */
+		float s; /**< Saturation (0.0-1.0) */
+		float v; /**< Value (0.0-1.0) */
+
+		/**
+		 * @brief Construct from Hue/Saturation/Value values.
+		 *
+		 * @param h  Hue (will be wrapped to >= 0.0 && < 360.0).
+		 * @param s  Saturation (will be clamped to 0.0-1.0).
+		 * @param v  Value (will be clamped to 0.0-1.0).
+		*/
+		HSVColour(float h, float s, float v);
+
+		/**
+		 * @brief Construct from an RGB colour.
+		*/
+		HSVColour(const wxColour &rgb);
+
+		/**
+		 * @brief Convert to an RGB colour.
+		*/
+		wxColour to_rgb() const;
+
+		/**
+		 * @brief Wrap a hue value.
+		*/
+		static float wrap_h(float h);
+
+		/**
+		 * @brief Clamp a saturation/value value.
+		*/
+		static float clamp_sv(float sv);
+
+		/**
+		 * @brief Pick a hue that contrasts with other hues.
+		 *
+		 * This function picks a hue which is (numerically) spaced as
+		 * far from any of the provided hues as possible.
+		 *
+		 * Returns the selected hue and the difference between it and
+		 * the nearest one in existing_hues.
+		*/
+		static std::pair<float, float> pick_contrasting_hue(const std::vector<float> &existing_hues);
+	};
+}
+
+#endif /* !REHEX_HSVCOLOUR_HPP */