HSLColor

An HSLColor is a color representation that encodes color using the Hue-Saturation-Lightness (HSL) color space, often with an optional alpha component to indicate transparency. It is used in many graphics and UI frameworks to support intuitive color manipulation, since adjustments to hue, saturation, and lightness often correlate with perceptual changes in color.

A typical HSLColor consists of four components: hue, saturation, lightness, and alpha. Hue is measured in degrees from 0 to 360, describing the angle around the color wheel. Saturation and lightness describe the color’s vividness and brightness, usually expressed as a normalized value from 0 to 1 (or 0 to 100%). Alpha, when present, ranges from 0 (fully transparent) to 1 (fully opaque). Some libraries store saturation and lightness as percentages and may vary in whether hue is kept strictly within 0–360 or wrapped.

Conversions and interoperability are central to HSLColor. Most rendering frameworks ultimately convert HSL values to RGB (or RGBA) for painting. The conversion handles chroma calculations and edge cases such as zero saturation, which yields a shade of gray regardless of hue. Many implementations offer convenience methods to convert to RGB, as well as operations to adjust lightness, saturation, or hue directly (for example, lighten, darken, saturate, or rotateHue).

Applications of HSLColor include design tools, color pickers, and theming systems where perceptual adjustments are more intuitive than manipulating RGB components. In web development, CSS supports hsl() and hsla() color functions, reflecting the widespread utility of the HSL model in styling and UI design. See also HSV, RGB, and broader color space concepts.