Colorspec class with conversion methods

minetest.lua

@@ -395,3 +395,255 @@ function raycast(_pos1, _pos2, objects, liquids)
     end
     return setmetatable({next = next}, {__call = next})
 end
+
+-- As in src/util/string.cpp
+named_colors = {
+	aliceblue = 0xf0f8ff,
+	antiquewhite = 0xfaebd7,
+	aqua = 0x00ffff,
+	aquamarine = 0x7fffd4,
+	azure = 0xf0ffff,
+	beige = 0xf5f5dc,
+	bisque = 0xffe4c4,
+	black = 0x000000,
+	blanchedalmond = 0xffebcd,
+	blue = 0x0000ff,
+	blueviolet = 0x8a2be2,
+	brown = 0xa52a2a,
+	burlywood = 0xdeb887,
+	cadetblue = 0x5f9ea0,
+	chartreuse = 0x7fff00,
+	chocolate = 0xd2691e,
+	coral = 0xff7f50,
+	cornflowerblue = 0x6495ed,
+	cornsilk = 0xfff8dc,
+	crimson = 0xdc143c,
+	cyan = 0x00ffff,
+	darkblue = 0x00008b,
+	darkcyan = 0x008b8b,
+	darkgoldenrod = 0xb8860b,
+	darkgray = 0xa9a9a9,
+	darkgreen = 0x006400,
+	darkgrey = 0xa9a9a9,
+	darkkhaki = 0xbdb76b,
+	darkmagenta = 0x8b008b,
+	darkolivegreen = 0x556b2f,
+	darkorange = 0xff8c00,
+	darkorchid = 0x9932cc,
+	darkred = 0x8b0000,
+	darksalmon = 0xe9967a,
+	darkseagreen = 0x8fbc8f,
+	darkslateblue = 0x483d8b,
+	darkslategray = 0x2f4f4f,
+	darkslategrey = 0x2f4f4f,
+	darkturquoise = 0x00ced1,
+	darkviolet = 0x9400d3,
+	deeppink = 0xff1493,
+	deepskyblue = 0x00bfff,
+	dimgray = 0x696969,
+	dimgrey = 0x696969,
+	dodgerblue = 0x1e90ff,
+	firebrick = 0xb22222,
+	floralwhite = 0xfffaf0,
+	forestgreen = 0x228b22,
+	fuchsia = 0xff00ff,
+	gainsboro = 0xdcdcdc,
+	ghostwhite = 0xf8f8ff,
+	gold = 0xffd700,
+	goldenrod = 0xdaa520,
+	gray = 0x808080,
+	green = 0x008000,
+	greenyellow = 0xadff2f,
+	grey = 0x808080,
+	honeydew = 0xf0fff0,
+	hotpink = 0xff69b4,
+	indianred = 0xcd5c5c,
+	indigo = 0x4b0082,
+	ivory = 0xfffff0,
+	khaki = 0xf0e68c,
+	lavender = 0xe6e6fa,
+	lavenderblush = 0xfff0f5,
+	lawngreen = 0x7cfc00,
+	lemonchiffon = 0xfffacd,
+	lightblue = 0xadd8e6,
+	lightcoral = 0xf08080,
+	lightcyan = 0xe0ffff,
+	lightgoldenrodyellow = 0xfafad2,
+	lightgray = 0xd3d3d3,
+	lightgreen = 0x90ee90,
+	lightgrey = 0xd3d3d3,
+	lightpink = 0xffb6c1,
+	lightsalmon = 0xffa07a,
+	lightseagreen = 0x20b2aa,
+	lightskyblue = 0x87cefa,
+	lightslategray = 0x778899,
+	lightslategrey = 0x778899,
+	lightsteelblue = 0xb0c4de,
+	lightyellow = 0xffffe0,
+	lime = 0x00ff00,
+	limegreen = 0x32cd32,
+	linen = 0xfaf0e6,
+	magenta = 0xff00ff,
+	maroon = 0x800000,
+	mediumaquamarine = 0x66cdaa,
+	mediumblue = 0x0000cd,
+	mediumorchid = 0xba55d3,
+	mediumpurple = 0x9370db,
+	mediumseagreen = 0x3cb371,
+	mediumslateblue = 0x7b68ee,
+	mediumspringgreen = 0x00fa9a,
+	mediumturquoise = 0x48d1cc,
+	mediumvioletred = 0xc71585,
+	midnightblue = 0x191970,
+	mintcream = 0xf5fffa,
+	mistyrose = 0xffe4e1,
+	moccasin = 0xffe4b5,
+	navajowhite = 0xffdead,
+	navy = 0x000080,
+	oldlace = 0xfdf5e6,
+	olive = 0x808000,
+	olivedrab = 0x6b8e23,
+	orange = 0xffa500,
+	orangered = 0xff4500,
+	orchid = 0xda70d6,
+	palegoldenrod = 0xeee8aa,
+	palegreen = 0x98fb98,
+	paleturquoise = 0xafeeee,
+	palevioletred = 0xdb7093,
+	papayawhip = 0xffefd5,
+	peachpuff = 0xffdab9,
+	peru = 0xcd853f,
+	pink = 0xffc0cb,
+	plum = 0xdda0dd,
+	powderblue = 0xb0e0e6,
+	purple = 0x800080,
+	red = 0xff0000,
+	rosybrown = 0xbc8f8f,
+	royalblue = 0x4169e1,
+	saddlebrown = 0x8b4513,
+	salmon = 0xfa8072,
+	sandybrown = 0xf4a460,
+	seagreen = 0x2e8b57,
+	seashell = 0xfff5ee,
+	sienna = 0xa0522d,
+	silver = 0xc0c0c0,
+	skyblue = 0x87ceeb,
+	slateblue = 0x6a5acd,
+	slategray = 0x708090,
+	slategrey = 0x708090,
+	snow = 0xfffafa,
+	springgreen = 0x00ff7f,
+	steelblue = 0x4682b4,
+	tan = 0xd2b48c,
+	teal = 0x008080,
+	thistle = 0xd8bfd8,
+	tomato = 0xff6347,
+	turquoise = 0x40e0d0,
+	violet = 0xee82ee,
+	wheat = 0xf5deb3,
+	white = 0xffffff,
+	whitesmoke = 0xf5f5f5,
+	yellow = 0xffff00,
+	yellowgreen = 0x9acd32
+}
+
+colorspec = {}
+
+local colorspec_metatable = {__index = colorspec}
+
+function colorspec.new(table)
+    return setmetatable({
+        r = assert(table.r),
+        g = assert(table.g),
+        b = assert(table.b),
+        a = table.a or 255
+    }, colorspec_metatable)
+end
+
+colorspec.from_table = colorspec.new
+
+function colorspec.from_string(string)
+    local hex = "#([A-Fa-f%d])+"
+    local number, alpha = named_colors[string], 0xFF
+    if not number then
+        local name, alpha_text = string:match("^([a-z])+" .. hex .. "$")
+        assert(alpha_text:len() == 2)
+        number = assert(named_colors[name])
+        alpha = tonumber(alpha_text, 16)
+    end
+    if number then
+        return colorspec.from_number(number * 0xFF + alpha)
+    end
+    local hex_text = string:match(hex)
+    local len, num = hex_text:len(), tonumber(hex_text, 16)
+    if len == 8 then
+        return colorspec.from_number(num)
+    end
+    if len == 6 then
+        return colorspec.from_number(num * 0xFF + 0xFF)
+    end
+    local floor = math.floor
+    if len == 4 then
+        return colorspec.from_table{
+            a = (num % 16) * 17,
+            b = (floor(num / 16) % 16) * 17,
+            g = (floor(num / (16 ^ 2)) % 16) * 17,
+            r = (floor(num / (16 ^ 3)) % 16) * 17
+        }
+    end
+    if len == 3 then
+        return colorspec.from_table{
+            b = (num % 16) * 17,
+            g = (floor(num / 16) % 16) * 17,
+            r = (floor(num / (16 ^ 2)) % 16) * 17
+        }
+    end
+    error("Invalid colorstring: " .. string)
+end
+
+colorspec.from_text = colorspec.from_string
+
+function colorspec.from_number(number)
+    local floor = math.floor
+    return colorspec.from_table{
+        a = number % 0xFF,
+        b = floor(number / 0xFF) % 0xFF,
+        g = floor(number / 0xFFFF) % 0xFF,
+        r = floor(number / 0xFFFFFF)
+    }
+end
+
+function colorspec.from_any(value)
+    local type = type(value)
+    if type == "table" then
+        return colorspec.from_table(value)
+    end
+    if type == "string" then
+        return colorspec.from_string(value)
+    end
+    if type == "number" then
+        return colorspec.from_number(value)
+    end
+    error("Unsupported type " .. type)
+end
+
+function colorspec:to_table()
+    return self
+end
+
+--> hex string, omits alpha if possible (if opaque)
+function colorspec:to_string()
+    if self.a == 255 then
+        return ("%02X02X02X"):format(self.r, self.g, self.b)
+    end
+    return ("%02X02X02X02X"):format(self.r, self.g, self.b, self.a)
+end
+
+function colorspec:to_number()
+    return self.r * 0xFFFFFF + self.g * 0xFFFF + self.b * 0xFF + self.a
+end
+
+colorspec_to_colorstring = _G.minetest.colorspec_to_colorstring or function(spec)
+    return colorspec.from_any(spec):to_string()
+end
+