Colour

A colour in sRGB with its alpha, each channel from 0 to 255, written #1e6fd9, or #1e6fd980 when it isn't opaque. colour's operations convert, mix and compare colours.

Media and visual; not ordered; since Jadpo 0.1.0.

Make one

Build one from its fields, Colour { red: ... green: ... blue: ... }.

text.parse(raw, as: Colour) reads one from its text; 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.

Fields

Text, JSON and storage

text.from writes its canonical text, the one form text.parse reads back. JSON sends its canonical text as a string.

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

Shown to people

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

With locale: Locale.en_gb:

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.

Like every standard type, it also has the contract's own operations: text.parse, text.from, text.format, json.read, json.write and ==. It isn't ordered, so < and sorting don't take it. Every standard type meets one contract says how they work.