Clyune Component GalleryRange Area · How it works & code
The band-shaped region bounded by upper and lower limits, often representing confidence intervals or temperature ranges.
Runtime logic
Visiting `/charts/areaRange`, DemoHost lazy-loads `demos/kits/kit-charts.js` (registry `mod: 'kit-charts'`) and calls `mount(host, { variant: 'areaRange' })`. mount resolves the variant to family `areaRange`; `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; fmt — Number formatting (fixed decimals); rng — Seeded deterministic PRNG (same seed, same result); F — Formula block HTML; S.clear — Clears with the background colour (translucent = trails); S.onFrame — Registers a per-frame callback; its return value feeds the info panel; ctx.fillText() — Draws filled text; ctx.beginPath() — Starts a new path; ctx.moveTo() — Moves the pen without drawing; ctx.arcTo() — Adds an arc using tangent lines; ctx.closePath() — Closes the current sub-path; ctx.measureText() — Measures text width; ctx.fill() — Fills the current path; ctx.stroke() — Strokes the current path; ctx.lineTo() — Adds a straight line to a point; ctx.bezierCurveTo() — Adds a cubic Bézier curve segment; ctx.arc() — Adds a circular arc (center, radius, start/end angle)
Source code
frontend/src/demos/kits/kit-charts.js: FAM.areaRange (L481-L489)
Code walkthrough
L482-485: Control definitions (colour/speed/size/count/extras): Primary Color, Line width, Data Points, Curve Tension, Fill, Legend. L486-486: Preset buttons: name → parameter overrides (6). L487-487: Info-panel content: live rows(v), formula, notes, params, steps. L488-488: Init function: sets up state and returns the per-frame callback.
Principles
Value map to canvas: x = pad+ (i+0.5) / N × width y = pad + High × (1 − v / yMax) The band-shaped region bounded by upper and lower limits, often representing confidence intervals or temperature ranges.