Celestia

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// color.cpp
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//
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// Copyright (C) 2001-2008, the Celestia Development Team
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//
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// This program is free software; you can redistribute it and/or
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// modify it under the terms of the GNU General Public License
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// as published by the Free Software Foundation; either version 2
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// of the License, or (at your option) any later version.
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#include <map>
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#include <system_error>
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#include <celcompat/charconv.h>
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#include "color.h"
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using namespace std::string_view_literals;
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namespace
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{
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using ColorMap = std::map<std::string_view, Color>;
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const ColorMap* buildX11ColorMap()
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{
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    return new ColorMap
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    {
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        { "aliceblue"sv,            Color((std::uint8_t)240, (std::uint8_t)248, (std::uint8_t)255) },
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        { "antiquewhite"sv,         Color((std::uint8_t)250, (std::uint8_t)235, (std::uint8_t)215) },
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        { "aqua"sv,                 Color((std::uint8_t)0,   (std::uint8_t)255, (std::uint8_t)255) },
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        { "aquamarine"sv,           Color((std::uint8_t)127, (std::uint8_t)255, (std::uint8_t)212) },
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        { "azure"sv,                Color((std::uint8_t)240, (std::uint8_t)255, (std::uint8_t)255) },
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        { "beige"sv,                Color((std::uint8_t)245, (std::uint8_t)245, (std::uint8_t)220) },
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        { "bisque"sv,               Color((std::uint8_t)255, (std::uint8_t)228, (std::uint8_t)196) },
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        { "black"sv,                Color((std::uint8_t)0,   (std::uint8_t)0,   (std::uint8_t)0)   },
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        { "blanchedalmond"sv,       Color((std::uint8_t)255, (std::uint8_t)235, (std::uint8_t)205) },
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        { "blue"sv,                 Color((std::uint8_t)0,   (std::uint8_t)0,   (std::uint8_t)255) },
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        { "blueviolet"sv,           Color((std::uint8_t)138, (std::uint8_t)43,  (std::uint8_t)226) },
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        { "brown"sv,                Color((std::uint8_t)165, (std::uint8_t)42,  (std::uint8_t)42)  },
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        { "burlywood"sv,            Color((std::uint8_t)222, (std::uint8_t)184, (std::uint8_t)135) },
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        { "cadetblue"sv,            Color((std::uint8_t)95,  (std::uint8_t)158, (std::uint8_t)160) },
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        { "chartreuse"sv,           Color((std::uint8_t)127, (std::uint8_t)255, (std::uint8_t)0)   },
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        { "chocolate"sv,            Color((std::uint8_t)210, (std::uint8_t)105, (std::uint8_t)30)  },
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        { "coral"sv,                Color((std::uint8_t)255, (std::uint8_t)127, (std::uint8_t)80)  },
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        { "cornflowerblue"sv,       Color((std::uint8_t)100, (std::uint8_t)149, (std::uint8_t)237) },
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        { "cornsilk"sv,             Color((std::uint8_t)255, (std::uint8_t)248, (std::uint8_t)220) },
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        { "crimson"sv,              Color((std::uint8_t)220, (std::uint8_t)20,  (std::uint8_t)60)  },
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        { "cyan"sv,                 Color((std::uint8_t)0,   (std::uint8_t)255, (std::uint8_t)255) },
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        { "darkblue"sv,             Color((std::uint8_t)0,   (std::uint8_t)0,   (std::uint8_t)139) },
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        { "darkcyan"sv,             Color((std::uint8_t)0,   (std::uint8_t)139, (std::uint8_t)139) },
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        { "darkgoldenrod"sv,        Color((std::uint8_t)184, (std::uint8_t)134, (std::uint8_t)11)  },
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        { "darkgray"sv,             Color((std::uint8_t)169, (std::uint8_t)169, (std::uint8_t)169) },
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        { "darkgreen"sv,            Color((std::uint8_t)0,   (std::uint8_t)100, (std::uint8_t)0)   },
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        { "darkkhaki"sv,            Color((std::uint8_t)189, (std::uint8_t)183, (std::uint8_t)107) },
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        { "darkmagenta"sv,          Color((std::uint8_t)139, (std::uint8_t)0,   (std::uint8_t)139) },
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        { "darkolivegreen"sv,       Color((std::uint8_t)85,  (std::uint8_t)107, (std::uint8_t)47)  },
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        { "darkorange"sv,           Color((std::uint8_t)255, (std::uint8_t)140, (std::uint8_t)0)   },
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        { "darkorchid"sv,           Color((std::uint8_t)153, (std::uint8_t)50,  (std::uint8_t)204) },
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        { "darkred"sv,              Color((std::uint8_t)139, (std::uint8_t)0,   (std::uint8_t)0)   },
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        { "darksalmon"sv,           Color((std::uint8_t)233, (std::uint8_t)150, (std::uint8_t)122) },
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        { "darkseagreen"sv,         Color((std::uint8_t)143, (std::uint8_t)188, (std::uint8_t)143) },
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        { "darkslateblue"sv,        Color((std::uint8_t)72,  (std::uint8_t)61,  (std::uint8_t)139) },
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        { "darkslategray"sv,        Color((std::uint8_t)47,  (std::uint8_t)79,  (std::uint8_t)79)  },
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        { "darkturquoise"sv,        Color((std::uint8_t)0,   (std::uint8_t)206, (std::uint8_t)209) },
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        { "darkviolet"sv,           Color((std::uint8_t)148, (std::uint8_t)0,   (std::uint8_t)211) },
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        { "deeppink"sv,             Color((std::uint8_t)255, (std::uint8_t)20,  (std::uint8_t)147) },
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        { "deepskyblue"sv,          Color((std::uint8_t)0,   (std::uint8_t)191, (std::uint8_t)255) },
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        { "dimgray"sv,              Color((std::uint8_t)105, (std::uint8_t)105, (std::uint8_t)105) },
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        { "dodgerblue"sv,           Color((std::uint8_t)30,  (std::uint8_t)144, (std::uint8_t)255) },
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        { "firebrick"sv,            Color((std::uint8_t)178, (std::uint8_t)34,  (std::uint8_t)34)  },
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        { "floralwhite"sv,          Color((std::uint8_t)255, (std::uint8_t)250, (std::uint8_t)240) },
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        { "forestgreen"sv,          Color((std::uint8_t)34,  (std::uint8_t)139, (std::uint8_t)34)  },
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        { "fuchsia"sv,              Color((std::uint8_t)255, (std::uint8_t)0,   (std::uint8_t)255) },
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        { "gainsboro"sv,            Color((std::uint8_t)220, (std::uint8_t)220, (std::uint8_t)220) },
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        { "ghostwhite"sv,           Color((std::uint8_t)248, (std::uint8_t)248, (std::uint8_t)255) },
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        { "gold"sv,                 Color((std::uint8_t)255, (std::uint8_t)215, (std::uint8_t)0)   },
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        { "goldenrod"sv,            Color((std::uint8_t)218, (std::uint8_t)165, (std::uint8_t)32)  },
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        { "gray"sv,                 Color((std::uint8_t)128, (std::uint8_t)128, (std::uint8_t)128) },
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        { "green"sv,                Color((std::uint8_t)0,   (std::uint8_t)128, (std::uint8_t)0)   },
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        { "greenyellow"sv,          Color((std::uint8_t)173, (std::uint8_t)255, (std::uint8_t)47)  },
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        { "honeydew"sv,             Color((std::uint8_t)240, (std::uint8_t)255, (std::uint8_t)240) },
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        { "hotpink"sv,              Color((std::uint8_t)255, (std::uint8_t)105, (std::uint8_t)180) },
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        { "indianred"sv,            Color((std::uint8_t)205, (std::uint8_t)92,  (std::uint8_t)92)  },
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        { "indigo"sv,               Color((std::uint8_t)75,  (std::uint8_t)0,   (std::uint8_t)130) },
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        { "ivory"sv,                Color((std::uint8_t)255, (std::uint8_t)255, (std::uint8_t)240) },
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        { "khaki"sv,                Color((std::uint8_t)240, (std::uint8_t)230, (std::uint8_t)140) },
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        { "lavender"sv,             Color((std::uint8_t)230, (std::uint8_t)230, (std::uint8_t)250) },
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        { "lavenderblush"sv,        Color((std::uint8_t)255, (std::uint8_t)240, (std::uint8_t)245) },
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        { "lawngreen"sv,            Color((std::uint8_t)124, (std::uint8_t)252, (std::uint8_t)0)   },
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        { "lemonchiffon"sv,         Color((std::uint8_t)255, (std::uint8_t)250, (std::uint8_t)205) },
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        { "lightblue"sv,            Color((std::uint8_t)173, (std::uint8_t)216, (std::uint8_t)230) },
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        { "lightcoral"sv,           Color((std::uint8_t)240, (std::uint8_t)128, (std::uint8_t)128) },
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        { "lightcyan"sv,            Color((std::uint8_t)224, (std::uint8_t)255, (std::uint8_t)255) },
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        { "lightgoldenrodyellow"sv, Color((std::uint8_t)250, (std::uint8_t)250, (std::uint8_t)210) },
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        { "lightgreen"sv,           Color((std::uint8_t)144, (std::uint8_t)238, (std::uint8_t)144) },
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        { "lightgrey"sv,            Color((std::uint8_t)211, (std::uint8_t)211, (std::uint8_t)211) },
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        { "lightpink"sv,            Color((std::uint8_t)255, (std::uint8_t)182, (std::uint8_t)193) },
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        { "lightsalmon"sv,          Color((std::uint8_t)255, (std::uint8_t)160, (std::uint8_t)122) },
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        { "lightseagreen"sv,        Color((std::uint8_t)32,  (std::uint8_t)178, (std::uint8_t)170) },
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        { "lightskyblue"sv,         Color((std::uint8_t)135, (std::uint8_t)206, (std::uint8_t)250) },
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        { "lightslategray"sv,       Color((std::uint8_t)119, (std::uint8_t)136, (std::uint8_t)153) },
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        { "lightsteelblue"sv,       Color((std::uint8_t)176, (std::uint8_t)196, (std::uint8_t)222) },
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        { "lightyellow"sv,          Color((std::uint8_t)255, (std::uint8_t)255, (std::uint8_t)224) },
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        { "lime"sv,                 Color((std::uint8_t)0,   (std::uint8_t)255, (std::uint8_t)0)   },
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        { "limegreen"sv,            Color((std::uint8_t)50,  (std::uint8_t)205, (std::uint8_t)50)  },
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        { "linen"sv,                Color((std::uint8_t)250, (std::uint8_t)240, (std::uint8_t)230) },
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        { "magenta"sv,              Color((std::uint8_t)255, (std::uint8_t)0,   (std::uint8_t)255) },
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        { "maroon"sv,               Color((std::uint8_t)128, (std::uint8_t)0,   (std::uint8_t)0)   },
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        { "mediumaquamarine"sv,     Color((std::uint8_t)102, (std::uint8_t)205, (std::uint8_t)170) },
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        { "mediumblue"sv,           Color((std::uint8_t)0,   (std::uint8_t)0,   (std::uint8_t)205) },
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        { "mediumorchid"sv,         Color((std::uint8_t)186, (std::uint8_t)85,  (std::uint8_t)211) },
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        { "mediumpurple"sv,         Color((std::uint8_t)147, (std::uint8_t)112, (std::uint8_t)219) },
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        { "mediumseagreen"sv,       Color((std::uint8_t)60,  (std::uint8_t)179, (std::uint8_t)113) },
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        { "mediumslateblue"sv,      Color((std::uint8_t)123, (std::uint8_t)104, (std::uint8_t)238) },
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        { "mediumspringgreen"sv,    Color((std::uint8_t)0,   (std::uint8_t)250, (std::uint8_t)154) },
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        { "mediumturquoise"sv,      Color((std::uint8_t)72,  (std::uint8_t)209, (std::uint8_t)204) },
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        { "mediumvioletred"sv,      Color((std::uint8_t)199, (std::uint8_t)21,  (std::uint8_t)133) },
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        { "midnightblue"sv,         Color((std::uint8_t)25,  (std::uint8_t)25,  (std::uint8_t)112) },
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        { "mintcream"sv,            Color((std::uint8_t)245, (std::uint8_t)255, (std::uint8_t)250) },
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        { "mistyrose"sv,            Color((std::uint8_t)255, (std::uint8_t)228, (std::uint8_t)225) },
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        { "moccasin"sv,             Color((std::uint8_t)255, (std::uint8_t)228, (std::uint8_t)181) },
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        { "navajowhite"sv,          Color((std::uint8_t)255, (std::uint8_t)222, (std::uint8_t)173) },
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        { "navy"sv,                 Color((std::uint8_t)0,   (std::uint8_t)0,   (std::uint8_t)128) },
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        { "oldlace"sv,              Color((std::uint8_t)253, (std::uint8_t)245, (std::uint8_t)230) },
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        { "olive"sv,                Color((std::uint8_t)128, (std::uint8_t)128, (std::uint8_t)0)   },
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        { "olivedrab"sv,            Color((std::uint8_t)107, (std::uint8_t)142, (std::uint8_t)35)  },
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        { "orange"sv,               Color((std::uint8_t)255, (std::uint8_t)165, (std::uint8_t)0)   },
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        { "orangered"sv,            Color((std::uint8_t)255, (std::uint8_t)69,  (std::uint8_t)0)   },
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        { "orchid"sv,               Color((std::uint8_t)218, (std::uint8_t)112, (std::uint8_t)214) },
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        { "palegoldenrod"sv,        Color((std::uint8_t)238, (std::uint8_t)232, (std::uint8_t)170) },
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        { "palegreen"sv,            Color((std::uint8_t)152, (std::uint8_t)251, (std::uint8_t)152) },
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        { "paleturquoise"sv,        Color((std::uint8_t)175, (std::uint8_t)238, (std::uint8_t)238) },
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        { "palevioletred"sv,        Color((std::uint8_t)219, (std::uint8_t)112, (std::uint8_t)147) },
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        { "papayawhip"sv,           Color((std::uint8_t)255, (std::uint8_t)239, (std::uint8_t)213) },
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        { "peachpuff"sv,            Color((std::uint8_t)255, (std::uint8_t)218, (std::uint8_t)185) },
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        { "peru"sv,                 Color((std::uint8_t)205, (std::uint8_t)133, (std::uint8_t)63)  },
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        { "pink"sv,                 Color((std::uint8_t)255, (std::uint8_t)192, (std::uint8_t)203) },
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        { "plum"sv,                 Color((std::uint8_t)221, (std::uint8_t)160, (std::uint8_t)221) },
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        { "powderblue"sv,           Color((std::uint8_t)176, (std::uint8_t)224, (std::uint8_t)230) },
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        { "purple"sv,               Color((std::uint8_t)128, (std::uint8_t)0,   (std::uint8_t)128) },
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        { "red"sv,                  Color((std::uint8_t)255, (std::uint8_t)0,   (std::uint8_t)0)   },
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        { "rosybrown"sv,            Color((std::uint8_t)188, (std::uint8_t)143, (std::uint8_t)143) },
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        { "royalblue"sv,            Color((std::uint8_t)65,  (std::uint8_t)105, (std::uint8_t)225) },
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        { "saddlebrown"sv,          Color((std::uint8_t)139, (std::uint8_t)69,  (std::uint8_t)19)  },
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        { "salmon"sv,               Color((std::uint8_t)250, (std::uint8_t)128, (std::uint8_t)114) },
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        { "sandybrown"sv,           Color((std::uint8_t)244, (std::uint8_t)164, (std::uint8_t)96)  },
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        { "seagreen"sv,             Color((std::uint8_t)46,  (std::uint8_t)139, (std::uint8_t)87)  },
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        { "seashell"sv,             Color((std::uint8_t)255, (std::uint8_t)245, (std::uint8_t)238) },
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        { "sienna"sv,               Color((std::uint8_t)160, (std::uint8_t)82,  (std::uint8_t)45)  },
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        { "silver"sv,               Color((std::uint8_t)192, (std::uint8_t)192, (std::uint8_t)192) },
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        { "skyblue"sv,              Color((std::uint8_t)135, (std::uint8_t)206, (std::uint8_t)235) },
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        { "slateblue"sv,            Color((std::uint8_t)106, (std::uint8_t)90,  (std::uint8_t)205) },
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        { "slategray"sv,            Color((std::uint8_t)112, (std::uint8_t)128, (std::uint8_t)144) },
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        { "snow"sv,                 Color((std::uint8_t)255, (std::uint8_t)250, (std::uint8_t)250) },
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        { "springgreen"sv,          Color((std::uint8_t)0,   (std::uint8_t)255, (std::uint8_t)127) },
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        { "steelblue"sv,            Color((std::uint8_t)70,  (std::uint8_t)130, (std::uint8_t)180) },
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        { "tan"sv,                  Color((std::uint8_t)210, (std::uint8_t)180, (std::uint8_t)140) },
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        { "teal"sv,                 Color((std::uint8_t)0,   (std::uint8_t)128, (std::uint8_t)128) },
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        { "thistle"sv,              Color((std::uint8_t)216, (std::uint8_t)191, (std::uint8_t)216) },
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        { "tomato"sv,               Color((std::uint8_t)255, (std::uint8_t)99,  (std::uint8_t)71)  },
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        { "turquoise"sv,            Color((std::uint8_t)64,  (std::uint8_t)224, (std::uint8_t)208) },
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        { "violet"sv,               Color((std::uint8_t)238, (std::uint8_t)130, (std::uint8_t)238) },
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        { "wheat"sv,                Color((std::uint8_t)245, (std::uint8_t)222, (std::uint8_t)179) },
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        { "white"sv,                Color((std::uint8_t)255, (std::uint8_t)255, (std::uint8_t)255) },
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        { "whitesmoke"sv,           Color((std::uint8_t)245, (std::uint8_t)245, (std::uint8_t)245) },
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        { "yellow"sv,               Color((std::uint8_t)255, (std::uint8_t)255, (std::uint8_t)0)   },
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        { "yellowgreen"sv,          Color((std::uint8_t)154, (std::uint8_t)205, (std::uint8_t)50)  },
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    };
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}
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bool parseHexColor(std::string_view s, Color& c)
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{
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    using celestia::compat::from_chars;
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    std::uint32_t value;
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    switch (s.size())
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    {
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    case 3: // rgb
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        if (auto [ptr, ec] = from_chars(s.data(), s.data() + s.size(), value, 16);
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            ec == std::errc{} && ptr == s.data() + s.size())
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        {
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            c = Color(static_cast<std::uint8_t>((value >> 8) * UINT32_C(0x11)),
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                    static_cast<std::uint8_t>(((value & UINT32_C(0x0f0)) >> 4) * UINT32_C(0x11)),
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                    static_cast<std::uint8_t>((value & UINT32_C(0x00f)) * UINT32_C(0x11)));
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            return true;
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        }
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        break;
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    case 6: // rrggbb
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        if (auto [ptr, ec] = from_chars(s.data(), s.data() + s.size(), value, 16);
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            ec == std::errc{} && ptr == s.data() + s.size())
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        {
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            c = Color(static_cast<std::uint8_t>(value >> 16),
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                    static_cast<std::uint8_t>((value & UINT32_C(0x00ff00)) >> 8),
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                    static_cast<std::uint8_t>(value & UINT32_C(0x0000ff)));
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            return true;
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        }
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        break;
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    case 8: // rrggbbaa
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        if (auto [ptr, ec] = from_chars(s.data(), s.data() + s.size(), value, 16);
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            ec == std::errc{} && ptr == s.data() + s.size())
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        {
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            c = Color(static_cast<std::uint8_t>(value >> 24),
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                    static_cast<std::uint8_t>((value & UINT32_C(0x00ff0000)) >> 16),
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                    static_cast<std::uint8_t>((value & UINT32_C(0x0000ff00)) >> 8),
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                    static_cast<std::uint8_t>(value & UINT32_C(0x000000ff)));
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            return true;
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        }
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        break;
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    default:
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        break;
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    }
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    return false;
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}
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} // end unnamed namespace
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/*!
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 * @brief Convert HSV to RGB.
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 * @param h Hue, [0, 360]
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 * @param s Saturation, [0, 1]
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 * @param v Value, [0, 1]
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 * @return RGBA color
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 */
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Color Color::fromHSV(float h, float s, float v)
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{
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    if (s == 0.0f)
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    {
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        // achromatic (grey)
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        return { v, v, v };
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    }
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234

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    h /= 60.0f; // sector 0 to 5
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    float j = std::floor(h);
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    float f = h - j; // fractional part of h
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    float p = v * (1.0f - s);
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    float q = v * (1.0f - s * f);
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    float t = v * (1.0f - s * (1.0f - f));
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243
    switch(static_cast<int>(j))
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    {
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    case 0:
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        return { v, t, p };
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    case 1:
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        return { q, v, p };
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    case 2:
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        return { p, v, t };
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    case 3:
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        return { p, q, v };
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    case 4:
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        return { t, p, v };
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    default:
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        return { v, p, q };
257
    }
258
}
259

260
const Color Color::White = Color(1.0f, 1.0f, 1.0f);
261
const Color Color::Black = Color(0.0f, 0.0f, 0.0f);
262

263
/*! Parse a color string and return true if it was a valid color, otherwise
264
 *  false.  Accetable inputs are HTML/X11 style #xxxxxx colors (where x is
265
 *  hexadecimal digit) or one of a list of named colors.
266
 */
267
bool Color::parse(std::string_view s, Color& c)
268
{
269
    using celestia::compat::from_chars;
270

271
    if (s.empty()) { return false; }
272

273
    if (s[0] == '#')
274
    {
275
        return parseHexColor(s.substr(1), c);
276
    }
277
    else
278
    {
279
        static const ColorMap* x11Colors = nullptr;
280

281
        // Initialize the color dictionary if this is the first
282
        // time Color::parse has been called for a non-hex value.
283
        if (x11Colors == nullptr)
284
        {
285
            x11Colors = buildX11ColorMap();
286
        }
287

288
        auto it = x11Colors->find(s);
289
        if (it != x11Colors->end())
290
        {
291
            c = it->second;
292
            return true;
293
        }
294
    }
295

296
    return false;
297
}
298