path: root/libs/litehtml/src/web_color.cpp

#include "html.h"
#include "web_color.h"
#include "css_parser.h"

namespace litehtml
{

const web_color web_color::transparent   = web_color(0, 0, 0, 0);
const web_color web_color::black         = web_color(0, 0, 0, 255);
const web_color web_color::white         = web_color(255, 255, 255, 255);
const web_color web_color::current_color = web_color(true);

gradient gradient::transparent;

struct def_color
{
	const char* name;
	const char* rgb;
};

def_color g_def_colors[] = 
{
	{"transparent","rgba(0, 0, 0, 0)"},
	{"AliceBlue","#F0F8FF"},
	{"AntiqueWhite","#FAEBD7"},
	{"Aqua","#00FFFF"},
	{"Aquamarine","#7FFFD4"},
	{"Azure","#F0FFFF"},
	{"Beige","#F5F5DC"},
	{"Bisque","#FFE4C4"},
	{"Black","#000000"},
	{"BlanchedAlmond","#FFEBCD"},
	{"Blue","#0000FF"},
	{"BlueViolet","#8A2BE2"},
	{"Brown","#A52A2A"},
	{"BurlyWood","#DEB887"},
	{"CadetBlue","#5F9EA0"},
	{"Chartreuse","#7FFF00"},
	{"Chocolate","#D2691E"},
	{"Coral","#FF7F50"},
	{"CornflowerBlue","#6495ED"},
	{"Cornsilk","#FFF8DC"},
	{"Crimson","#DC143C"},
	{"Cyan","#00FFFF"},
	{"DarkBlue","#00008B"},
	{"DarkCyan","#008B8B"},
	{"DarkGoldenRod","#B8860B"},
	{"DarkGray","#A9A9A9"},
	{"DarkGrey","#A9A9A9"},
	{"DarkGreen","#006400"},
	{"DarkKhaki","#BDB76B"},
	{"DarkMagenta","#8B008B"},
	{"DarkOliveGreen","#556B2F"},
	{"Darkorange","#FF8C00"},
	{"DarkOrchid","#9932CC"},
	{"DarkRed","#8B0000"},
	{"DarkSalmon","#E9967A"},
	{"DarkSeaGreen","#8FBC8F"},
	{"DarkSlateBlue","#483D8B"},
	{"DarkSlateGray","#2F4F4F"},
	{"DarkSlateGrey","#2F4F4F"},
	{"DarkTurquoise","#00CED1"},
	{"DarkViolet","#9400D3"},
	{"DeepPink","#FF1493"},
	{"DeepSkyBlue","#00BFFF"},
	{"DimGray","#696969"},
	{"DimGrey","#696969"},
	{"DodgerBlue","#1E90FF"},
	{"FireBrick","#B22222"},
	{"FloralWhite","#FFFAF0"},
	{"ForestGreen","#228B22"},
	{"Fuchsia","#FF00FF"},
	{"Gainsboro","#DCDCDC"},
	{"GhostWhite","#F8F8FF"},
	{"Gold","#FFD700"},
	{"GoldenRod","#DAA520"},
	{"Gray","#808080"},
	{"Grey","#808080"},
	{"Green","#008000"},
	{"GreenYellow","#ADFF2F"},
	{"HoneyDew","#F0FFF0"},
	{"HotPink","#FF69B4"},
	{"Ivory","#FFFFF0"},
	{"Khaki","#F0E68C"},
	{"Lavender","#E6E6FA"},
	{"LavenderBlush","#FFF0F5"},
	{"LawnGreen","#7CFC00"},
	{"LemonChiffon","#FFFACD"},
	{"LightBlue","#ADD8E6"},
	{"LightCoral","#F08080"},
	{"LightCyan","#E0FFFF"},
	{"LightGoldenRodYellow","#FAFAD2"},
	{"LightGray","#D3D3D3"},
	{"LightGrey","#D3D3D3"},
	{"LightGreen","#90EE90"},
	{"LightPink","#FFB6C1"},
	{"LightSalmon","#FFA07A"},
	{"LightSeaGreen","#20B2AA"},
	{"LightSkyBlue","#87CEFA"},
	{"LightSlateGray","#778899"},
	{"LightSlateGrey","#778899"},
	{"LightSteelBlue","#B0C4DE"},
	{"LightYellow","#FFFFE0"},
	{"Lime","#00FF00"},
	{"LimeGreen","#32CD32"},
	{"Linen","#FAF0E6"},
	{"Magenta","#FF00FF"},
	{"Maroon","#800000"},
	{"MediumAquaMarine","#66CDAA"},
	{"MediumBlue","#0000CD"},
	{"MediumOrchid","#BA55D3"},
	{"MediumPurple","#9370D8"},
	{"MediumSeaGreen","#3CB371"},
	{"MediumSlateBlue","#7B68EE"},
	{"MediumSpringGreen","#00FA9A"},
	{"MediumTurquoise","#48D1CC"},
	{"MediumVioletRed","#C71585"},
	{"MidnightBlue","#191970"},
	{"MintCream","#F5FFFA"},
	{"MistyRose","#FFE4E1"},
	{"Moccasin","#FFE4B5"},
	{"NavajoWhite","#FFDEAD"},
	{"Navy","#000080"},
	{"OldLace","#FDF5E6"},
	{"Olive","#808000"},
	{"OliveDrab","#6B8E23"},
	{"Orange","#FFA500"},
	{"OrangeRed","#FF4500"},
	{"Orchid","#DA70D6"},
	{"PaleGoldenRod","#EEE8AA"},
	{"PaleGreen","#98FB98"},
	{"PaleTurquoise","#AFEEEE"},
	{"PaleVioletRed","#D87093"},
	{"PapayaWhip","#FFEFD5"},
	{"PeachPuff","#FFDAB9"},
	{"Peru","#CD853F"},
	{"Pink","#FFC0CB"},
	{"Plum","#DDA0DD"},
	{"PowderBlue","#B0E0E6"},
	{"Purple","#800080"},
	{"Red","#FF0000"},
	{"RosyBrown","#BC8F8F"},
	{"RoyalBlue","#4169E1"},
	{"SaddleBrown","#8B4513"},
	{"Salmon","#FA8072"},
	{"SandyBrown","#F4A460"},
	{"SeaGreen","#2E8B57"},
	{"SeaShell","#FFF5EE"},
	{"Sienna","#A0522D"},
	{"Silver","#C0C0C0"},
	{"SkyBlue","#87CEEB"},
	{"SlateBlue","#6A5ACD"},
	{"SlateGray","#708090"},
	{"SlateGrey","#708090"},
	{"Snow","#FFFAFA"},
	{"SpringGreen","#00FF7F"},
	{"SteelBlue","#4682B4"},
	{"Tan","#D2B48C"},
	{"Teal","#008080"},
	{"Thistle","#D8BFD8"},
	{"Tomato","#FF6347"},
	{"Turquoise","#40E0D0"},
	{"Violet","#EE82EE"},
	{"Wheat","#F5DEB3"},
	{"White","#FFFFFF"},
	{"WhiteSmoke","#F5F5F5"},
	{"Yellow","#FFFF00"},
	{"YellowGreen","#9ACD32"},
};

// <hex-color>  https://drafts.csswg.org/css-color-4/#typedef-hex-color
bool parse_hash_color(const css_token& tok, web_color& color)
{
	if (tok.type != HASH) return false;

	string s = tok.str;
	int len = (int)s.size();
	if (!is_one_of(len, 3, 4, 6, 8)) return false;
	for (auto ch : s) if (!is_hex_digit(ch)) return false;

	string r, g, b, a = "ff";
	if (len == 3 || len == 4)
	{
		r = {s[0], s[0]};
		g = {s[1], s[1]};
		b = {s[2], s[2]};
		if (len == 4)
			a = {s[3], s[3]};
	}
	else // 6 or 8
	{
		r = {s[0], s[1]};
		g = {s[2], s[3]};
		b = {s[4], s[5]};
		if (len == 8)
			a = {s[6], s[7]};
	}
	auto read_two_hex_digits = [](auto str)
	{
		return byte(16 * digit_value(str[0]) + digit_value(str[1]));
	};

	color = web_color(
		read_two_hex_digits(r),
		read_two_hex_digits(g),
		read_two_hex_digits(b),
		read_two_hex_digits(a));
	return true;
}

float clamp(float x, float min, float max)
{
	if (x < min) return min;
	if (x > max) return max;
	return x;
}

// [ <number> | <percentage> | none ]{3}  [ / [<alpha-value> | none] ]?
bool parse_modern_syntax(const css_token_vector& tokens, bool is_hsl,
	css_length& x, css_length& y, css_length& z, css_length& a)
{
	auto n = tokens.size();
	if (!(n == 3 || n == 5)) return false;
	if (is_hsl)
	{
		// [<hue> | none] [<number> | <percentage> | none]{2} [ / [<alpha-value> | none] ]?
		// <hue> = <number> | <angle>
		if (!x.from_token(tokens[0], f_number, "none"))
		{
			float hue;
			if (!parse_angle(tokens[0], hue)) return false;
			x.set_value(hue, css_units_none);
		}
	}
	else if (!x.from_token(tokens[0], f_number | f_percentage, "none")) return false;
	if (!y.from_token(tokens[1], f_number | f_percentage, "none")) return false;
	if (!z.from_token(tokens[2], f_number | f_percentage, "none")) return false;
	if (n == 5)
	{
		if (tokens[3].ch != '/') return false;
		// <alpha-value> = <number> | <percentage>
		if (!a.from_token(tokens[4], f_number | f_percentage, "none")) return false;
	}
	// convert nones to zeros
	// https://drafts.csswg.org/css-color-4/#missing
	// For all other purposes, a missing component behaves as a zero value...
	for (auto t : {&x,&y,&z,&a}) if (t->is_predefined()) t->set_value(0, css_units_none);
	return true;
}

// https://drafts.csswg.org/css-color-4/#rgb-functions
// Values outside these ranges are not invalid, but are clamped to the ranges defined here at parsed-value time.
byte calc_percent_and_clamp(const css_length& val, float max = 255)
{
	float x = val.val();
	if (val.units() == css_units_percentage) x = (x / 100) * max;
	x = clamp(x, 0, max);
	return (byte)round(max == 1 ? x * 255 : x);
}

// https://drafts.csswg.org/css-color-4/#rgb-functions
bool parse_rgb_func(const css_token& tok, web_color& color)
{
	if (tok.type != CV_FUNCTION || !is_one_of(lowcase(tok.name), "rgb", "rgba"))
		return false;

	auto list = parse_comma_separated_list(tok.value);
	int n = (int)list.size();
	if (!is_one_of(n, 1, 3, 4))
		return false;
	
	css_length r, g, b, a(1, css_units_none);
	// legacy syntax: <percentage>#{3} , <alpha-value>? | <number>#{3} , <alpha-value>?
	if (n != 1)
	{
		for (const auto& item : list) if (item.size() != 1) return false;
		auto type = list[0][0].type;
		if (!is_one_of(type, PERCENTAGE, NUMBER)) return false;
		int options = type == PERCENTAGE ? f_percentage : f_number;
		if (!r.from_token(list[0][0], options)) return false;
		if (!g.from_token(list[1][0], options)) return false;
		if (!b.from_token(list[2][0], options)) return false;
		// <alpha-value> = <number> | <percentage>
		if (n == 4 && !a.from_token(list[3][0], f_number | f_percentage)) return false;
	}
	// modern syntax:  [ <number> | <percentage> | none ]{3}  [ / [<alpha-value> | none] ]?
	else if (!parse_modern_syntax(tok.value, false, r, g, b, a)) return false;

	color = web_color(
		calc_percent_and_clamp(r),
		calc_percent_and_clamp(g),
		calc_percent_and_clamp(b),
		calc_percent_and_clamp(a, 1));
	return true;
}

// https://drafts.csswg.org/css-color-4/#hsl-to-rgb
void hsl_to_rgb(float hue, float sat, float light, float& r, float& g, float& b)
{
	hue = fmod(hue, 360.f);

	if (hue < 0)
		hue += 360;

	sat /= 100;
	light /= 100;

	auto f = [=](float n)
	{
		float k = fmod(n + hue / 30, 12.f);
		float a = sat * min(light, 1 - light);
		return light - a * max(-1.f, min({k - 3, 9 - k, 1.f}));
	};

	r = f(0);
	g = f(8);
	b = f(4);
}

// https://drafts.csswg.org/css-color-4/#the-hsl-notation
bool parse_hsl_func(const css_token& tok, web_color& color)
{
	if (tok.type != CV_FUNCTION || !is_one_of(lowcase(tok.name), "hsl", "hsla"))
		return false;

	auto list = parse_comma_separated_list(tok.value);
	int n = (int)list.size();
	if (!is_one_of(n, 1, 3, 4))
		return false;

	css_length h, s, l, a(1, css_units_none);
	// legacy syntax: <hue>, <percentage>, <percentage>, <alpha-value>?
	if (n != 1)
	{
		for (const auto& item : list) if (item.size() != 1) return false;
		const auto& tok0 = list[0][0];
		float hue;
		// <hue> = <number> | <angle>
		// number is interpreted as a number of degrees  https://drafts.csswg.org/css-color-4/#typedef-hue
		if (tok0.type == NUMBER) hue = tok0.n.number;
		else if (!parse_angle(tok0, hue)) return false;
		h.set_value(hue, css_units_none);

		if (!s.from_token(list[1][0], f_percentage)) return false;
		if (!l.from_token(list[2][0], f_percentage)) return false;
		if (n == 4 && !a.from_token(list[3][0], f_number | f_percentage)) return false;
	}
	// modern syntax:  [<hue> | none] [<percentage> | <number> | none]{2} [ / [<alpha-value> | none] ]?
	else if (!parse_modern_syntax(tok.value, true, h, s, l, a)) return false;

	float hue = h.val();
	// no percent calculation needed for sat and lit because 0% ~ 0, 100% ~ 100
	float sat = s.val();
	float lit = l.val();
	// For historical reasons, if the saturation is less than 0% it is clamped to 0% at parsed-value time, before being converted to an sRGB color.
	if (sat < 0) sat = 0;
	
	// Note: Chrome and Firefox treat invalid hsl values differently.
	// 
	// Note: at this point, sat is not clamped at 100, and lit is not clamped at all. The standard 
	// mentions only clamping sat at 0. As a result, returning rgb values may not be inside [0,1].
	float r, g, b;
	hsl_to_rgb(hue, sat, lit, r, g, b);
	
	r = clamp(r, 0, 1);
	g = clamp(g, 0, 1);
	b = clamp(b, 0, 1);
	
	color = web_color(
		(byte)round(r * 255),
		(byte)round(g * 255),
		(byte)round(b * 255),
		calc_percent_and_clamp(a, 1));
	return true;
}

// https://drafts.csswg.org/css-color-5/#typedef-color-function
bool parse_func_color(const css_token& tok, web_color& color)
{
	return parse_rgb_func(tok, color) || parse_hsl_func(tok, color);
}

string resolve_name(const string& name, document_container* container)
{
	for (auto clr : g_def_colors)
	{
		if (equal_i(name, clr.name))
			return clr.rgb;
	}

	if (container)
		return container->resolve_color(name);

	return "";
}

bool parse_name_color(const css_token& tok, web_color& color, document_container* container)
{
	if (tok.type != IDENT) return false;
	if (tok.ident() == "currentcolor")
	{
		color = web_color::current_color;
		return true;
	}
	string str = resolve_name(tok.name, container);
	auto tokens = normalize(str, f_componentize | f_remove_whitespace);
	if (tokens.size() != 1) return false;
	return parse_color(tokens[0], color, container);
}

// https://drafts.csswg.org/css-color-5/#typedef-color
bool parse_color(const css_token& tok, web_color& color, document_container* container)
{
	return 
		parse_hash_color(tok, color) || 
		parse_func_color(tok, color) || 
		parse_name_color(tok, color, container);
}

web_color web_color::darken(double fraction) const
{
	int v_red = (int)red;
	int v_blue = (int)blue;
	int v_green = (int)green;
	v_red = (int)max(v_red - (v_red * fraction), 0.0);
	v_blue = (int)max(v_blue - (v_blue * fraction), 0.0);
	v_green = (int)max(v_green - (v_green * fraction), 0.0);
	return {(byte)v_red, (byte)v_green, (byte)v_blue, alpha};
}


string web_color::to_string() const
{
	char str[9];
	if(alpha)
	{
		t_snprintf(str, 9, "%02X%02X%02X%02X", red, green, blue, alpha);
	} else
	{
		t_snprintf(str, 9, "%02X%02X%02X", red, green, blue);
	}
	return str;
}

} // namespace litehtml