HSL management with MySQL

hsl.sql

-- HSL functions, manage HSL CSS colors
-- Author : sfaut <https://github.com/sfaut>
-- Publication date : 2022-09-05
-- Tested with MySQL 8.0.30 (@@sql_mode='ANSI,TRADITIONAL')

/*
Summary :

hsl()                   Create a CSS HSL representation of a color

hsl_as_json()           Extract CSS HSL color components in a JSON object { hue, lightness, saturation }

hsl_get_hue()           Extract hue component from CSS HSL color
hsl_get_saturation()    Extract saturation component from CSS HSL color
hsl_get_lightness()     Extract lightness component from CSS HSL color

hsl_set_hue()           Set a new hue to a CSS HSL color
hsl_set_saturation()    Set a new saturation to a CSS HSL color
hsl_set_lightness()     Set a new lightness to a CSS HSL color

hsl_rotate()            Apply a rotation to the hue from a CSS HSL color
hsl_saturate()          Apply a saturation to the CSS HSL color
hsl_desaturate()        Apply a desaturation to the CSS HSL color
hsl_lighten()           Lighten a CSS HSL color
hsl_darken()            Darken a CSS HSL color
*/

DELILITER ;;

SET @@sql_mode = 'ANSI,TRADITIONAL';;

CREATE FUNCTION hsl(hue SMALLINT, saturation TINYINT UNSIGNED, lightness TINYINT UNSIGNED)
RETURNS TINYTEXT DETERMINISTIC
COMMENT 'Create a CSS HSL representation of a color'
RETURN CONCAT('hsl(', hue, 'deg ', saturation, '% ', lightness, '%)');;

CREATE FUNCTION hsl_as_json(hsl TINYTEXT)
RETURNS JSON DETERMINISTIC
COMMENT 'Extract CSS HSL color components in a JSON object { hue, lightness, saturation }'
RETURN JSON_OBJECT(
    'hue', hsl_get_hue(hsl),
    'saturation', hsl_get_saturation(hsl),
    'lightness', hsl_get_lightness(hsl)
);;

CREATE FUNCTION hsl_get_hue(hsl TINYTEXT)
RETURNS SMALLINT DETERMINISTIC
COMMENT 'Extract hue component from CSS HSL color'
RETURN REGEXP_SUBSTR(hsl, '\\d+', 1, 1);;

CREATE FUNCTION hsl_get_saturation(hsl TINYTEXT)
RETURNS TINYINT UNSIGNED DETERMINISTIC
COMMENT 'Extract saturation component from CSS HSL color'
RETURN REGEXP_SUBSTR(hsl, '\\d+', 1, 2);;

CREATE FUNCTION hsl_get_lightness(hsl TINYTEXT)
RETURNS TINYINT UNSIGNED DETERMINISTIC
COMMENT 'Extract lightness component from CSS HSL color'
RETURN REGEXP_SUBSTR(hsl, '\\d+', 1, 3);;

CREATE FUNCTION hsl_set_hue(hsl TINYTEXT, new_hue SMALLINT)
RETURNS TINYTEXT DETERMINISTIC
COMMENT 'Set a new hue to a CSS HSL color'
BEGIN
    IF new_hue <= -360 OR new_hue >= 360 THEN
        SET new_hue = hue MOD 360;
    END IF;
    IF new_hue < 0 THEN
        SET new_hue = 360 + new_hue;
    END IF;
    RETURN hsl(new_hue, hsl_get_saturation(hsl), hsl_get_lightness(hsl));;
END;;

CREATE FUNCTION hsl_set_saturation(hsl TINYTEXT, new_saturation TINYINT)
RETURNS TINYTEXT DETERMINISTIC
COMMENT 'Set a new saturation to a CSS HSL color'
BEGIN
    IF new_saturation < 0 THEN
        SET new_saturation = 0;
    ELSEIF new_saturation > 100 THEN
        SET new_saturation = 100;
    END IF;
    RETURN hsl(hsl_get_hue(hsl), new_saturation, hsl_get_lightness(hsl));
END;;

CREATE FUNCTION hsl_set_lightness(hsl TINYTEXT, new_lightness TINYINT)
RETURNS TINYTEXT DETERMINISTIC
COMMENT 'Set a new lightness to a CSS HSL color'
BEGIN
    IF new_lightness < 0 THEN
        SET new_lightness = 0;
    ELSEIF new_lightness > 100 THEN
        SET new_lightness = 100;
    END IF;
    RETURN hsl(hsl_get_hue(hsl), hsl_get_saturation(hsl), new_lightness);
END;;

CREATE FUNCTION hsl_rotate(hsl TINYTEXT, rotation SMALLINT)
RETURNS TINYTEXT DETERMINISTIC
COMMENT 'Apply a hue to a CSS HSL color'
BEGIN
	DECLARE new_hue SMALLINT DEFAULT hsl_get_hue(hsl) + rotation;
	IF new_hue <= -360 OR new_hue >= 360 THEN
		SET new_hue = new_hue MOD 360;
	END IF;
	IF new_hue < 0 THEN
		SET new_hue = 360 + new_hue;
	END IF;
	RETURN hsl_set_hue(hsl, new_hue);
END;;

CREATE FUNCTION hsl_saturate(hsl TINYTEXT, amount TINYINT)
RETURNS TINYTEXT DETERMINISTIC
COMMENT 'Apply a saturation to the CSS HSL color'
BEGIN
    DECLARE new_saturation TINYINT DEFAULT hsl_get_saturation(hsl) + amount;
	IF new_saturation < 0 THEN
		SET new_saturation = 0;
	ELSEIF new_saturation > 100 THEN
		SET new_saturation = 100;
	END IF;
	RETURN hsl_set_saturation(hsl, new_saturation);
END;;

CREATE FUNCTION hsl_desaturate(hsl TINYTEXT, amount TINYINT)
RETURNS TINYTEXT DETERMINISTIC
COMMENT 'Apply a desaturation to the CSS HSL color'
RETURN hsl_saturate(hsl, -amount);;

CREATE FUNCTION hsl_lighten(hsl TINYTEXT, amount TINYINT)
RETURNS TINYTEXT DETERMINISTIC
COMMENT 'Lighten a CSS HSL color'
BEGIN
	DECLARE new_lightness TINYINT DEFAULT hsl_get_lightness(hsl) + amount;
	IF new_lightness < 0 THEN
		SET new_lightness = 0;
	ELSEIF new_lightness > 100 THEN
		SET new_lightness = 100;
	END IF;
	RETURN hsl_set_lightness(hsl, new_lightness);
END;;

CREATE FUNCTION hsl_darken(hsl TINYTEXT, amount TINYINT)
RETURNS TINYTEXT DETERMINISTIC
COMMENT 'Darken a CSS HSL color'
RETURN hsl_lighten(hsl, -amount);;

DELIMITER ;