Colour, a standard type

A colour, written #1e6fd9, or #1e6fd980 when it isn't fully opaque.

Use it for brand colours and themes. colour.contrast tells you whether two are readable together, and colour.mix blends them.

Shape

Field	Type	Required?
`red`	`Int`	Yes
`green`	`Int`	Yes
`blue`	`Int`	Yes
`alpha`	`Int`	Yes

Example

example

Colour { red: 30 green: 111 blue: 217 alpha: 255 }

text.parse(raw, as: Colour) reads one from text that comes from outside. Text that isn't one at all fails malformed, such as 1e6fd9, #1e6fd or #1e6fd9f.

These operations give one: colour.from_hsl, colour.from_oklch, colour.mix and colour.with_lightness.

Good to know

Each part runs from 0 to 255. alpha of 255 is fully opaque.
It is lower case with a #, in sRGB.
== tells you whether two are the same. < and list.sort_by don't take it, so sort by one of its parts instead.

In JSON

A string, in a request, a response or json.write:

json

"#000000""#ffffff""#1e6fd9"

Details

Text form, storage, how it is shown, and operations

Colour is in the group Media and visual, and has been in Jadpo since 0.1.0.

Text form

text.from writes one standard text form, the same form text.parse reads back: #000000, #ffffff and #1e6fd9.

How it is stored

It is stored in 4 columns, each named for the field, _ and its suffix. This is #1e6fd9:

Column	Type	Holds
`<field>_red`	`smallint`	`30`
`<field>_green`	`smallint`	`111`
`<field>_blue`	`smallint`	`217`
`<field>_alpha`	`smallint`	`255`

How it is shown to people

text.format(value, locale:) shows it to people in their locale.

With locale: Locale.en_gb:

Value	Shown
`#000000`	`#000000`
`#ffffff`	`#ffffff`
`#1e6fd9`	`#1e6fd9`
`#1e6fd980`	`#1e6fd980`
`#00000000`	`#00000000`

Operations

colour.contrast(a: Colour, b: Colour) -> Decimal: WCAG 2's contrast ratio between a and b, from 1.00 to 21.00, rounded down to 2 places, so >= 4.5 never passes a ratio below it. Alpha isn't read: WCAG 2 defines contrast for opaque colours.
colour.from_hsl(hue: Angle, saturation: Percentage, lightness: Percentage) -> Colour: The colour of a CSS Color 4 HSL hue, saturation and lightness, the percentages clamped to 0% to 100%: colour.from_hsl(120deg, 100%, 25%) is #008000.
colour.from_oklch(lightness: Percentage, chroma: Decimal, hue: Angle) -> Colour: The colour of an OKLCH lightness, chroma and hue, clipped into sRGB, the lightness clamped to 0% to 100% and the chroma to 0 or more: colour.from_oklch(62.8%, 0.2577, 29.23deg) is #ff0000.
colour.mix(a: Colour, b: Colour, ratio: Percentage) -> Colour: a and b mixed in OKLCH as CSS's color-mix(in oklch, a, b ratio) mixes them: ratio of b, the rest of a, the hue the shorter way round, with their alphas.
colour.with_lightness(value: Colour, lightness: Percentage) -> Colour: value with its OKLCH lightness set to lightness, its chroma, hue and alpha kept, clipped into sRGB.

It also takes text.parse, text.from, text.format, json.read, json.write and ==. How every standard type behaves says how they work.