Clyune Component GalleryAspect-ratio Cards · How it works & code
Video covers and card thumbnails need fixed aspect ratio.
Runtime logic
Visiting `/layout/aspect`, DemoHost lazy-loads `demos/kits/kit-layout.js` (registry `mod: 'kit-layout'`) and calls `mount(host, { variant: 'aspect' })`. mount resolves the variant to family `aspect`; `withControls` builds the control panel (6 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; fmt — Number formatting (fixed decimals); 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.fill() — Fills the current path; ctx.stroke() — Strokes the current path; 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
Source code
frontend/src/demos/kits/kit-layout.js: FAM.aspect (L508-L543), TITLES['aspect'] (L648-L648)
Code walkthrough
L510-510: Control definitions (colour/speed/size/count/extras): Emphasis color, Card Scale, Column Count, Aspect ratio band, Gap, Lock ratio. L511-511: Preset buttons: name → parameter overrides (6). L512-520: Info-panel content: live rows(v), formula, notes, params, steps. L521-542: Init function: sets up state and returns the per-frame callback: draws with Canvas 2D `fill`, `stroke`; math via `Math.round`, `Math.sin`, `Math.floor`, `Math.min`; returns readouts `ar`, `cols`, `meas`, `cell`, `lock`, `dim` to the info panel. L648-648: This demo's entry in the `TITLES` table (title).
Principles
aspect-ratio: W / H Height when width is determined by grid = Width × (H/W) object-fit always matches pictures to ensure that the contents remain unchanged Video covers and card thumbnails need fixed aspect ratio. CSS aspect-ratio Let the browser scale out the other side without writing padding Black technology.