Clyune Component GalleryColor Picker · How it works & code
Hue Ring + Preset Palette
Runtime logic
Visiting `/ui/colorpick`, DemoHost lazy-loads `demos/kits/kit-ui.js` (registry `mod: 'kit-ui'`) and calls `mount(host, { variant: 'colorpick' })`. mount resolves the variant to family `colorpick`; `withControls` builds the control panel (4 presets + sliders). `createCanvasStage` creates the `<canvas>` (HiDPI ≤ 2×, ResizeObserver) and the info panel. The family’s `build(S)` initialises state and returns the per-frame callback. Every `requestAnimationFrame`: read controls, advance a speed-scaled clock (dt ≤ 50 ms), run the frame callback; returned readouts go to the info panel. Changing parameters: colour/speed/size apply live; structural ones remount; leaving the page cancels rAF, removes listeners and frees resources.
Environment
Canvas 2D: 2D canvas drawing; requestAnimationFrame: Display-synced animation loop; ResizeObserver: Canvas follows container size; Pointer Events: Unified mouse/touch/pen events; devicePixelRatio: Crisp HiDPI rendering (capped at 2×) · react 18.3.1, react-router-dom 6.30.6, vite 5.4.21
Dependencies
react 18.3.1
Imported APIs
withControls — Wraps the demo in the shared control panel (presets, sliders, reset); hot-updates or remounts on change; paramsFromSpec — Turns the spec (colour/speed/size/count/extras) into control-panel parameter definitions; createCanvasStage — Shared Canvas 2D stage: canvas + info panel, HiDPI, one rAF loop, pointer state, idle auto-pointer; hueOf — Hue of a colour (0–360°); clamp — Clamps a value to a range; TAU — Constant 2π; F — Formula block HTML; S.clear — Clears with the background colour (translucent = trails); S.isAutoDemo — Whether auto demo is on; S.onFrame — Registers a per-frame callback; its return value feeds the info panel; ctx.beginPath() — Starts a new path; ctx.arc() — Adds a circular arc (center, radius, start/end angle); ctx.stroke() — Strokes the current path; ctx.fill() — Fills the current path; ctx.fillText() — Draws filled text; ctx.moveTo() — Moves the pen without drawing; ctx.arcTo() — Adds an arc using tangent lines; ctx.closePath() — Closes the current sub-path; ctx.fillRect() — Fills a rectangle
Source code
frontend/src/demos/kits/kit-ui.js: FAM.colorpick (L505-L519)
Code walkthrough
L505-519: Calls the factory `uiFam()` to produce the full definition (spec + doc + build) from the options below. L505-505: Title shown in the info and control panels: “Color Picker”. L505-505: Range/default of the size slider: Palette Size. L505-505: Range/default of the count slider: Palette Count. L506-506: List of extra controls: Brightness. L506-506: Preset buttons: name → parameter overrides (4). L507-507: Body of the “Notes” section. L507-507: Main formula of the “Formula” section. L507-507: Second formula line. L508-519: Per-frame draw function: draws with Canvas 2D `beginPath`, `arc`, `stroke`, `fill`; math via `Math.min`, `Math.max`, `Math.hypot`, `Math.atan2`, `Math.cos`, `Math.sin`; returns readouts `mode`, `cell` to the info panel.
Principles
H = atan2(y−cy, x−cx) Colour = hsl (H, 80%, visibility) Colour remover: Color ring + preset palette. The pointer has a color (H) angle on the rings, a bright slide L, a real-time preview on the right.