Clyune Component GalleryFade-in Reveal · How it works & code
The card is transparent and biased when it's not in sight; when it's in sight from the bottom, progress e from 0 to 1, transparency becomes 1, Bit
Runtime logic
Visiting `/scroll-fx/reveal`, DemoHost lazy-loads `demos/kits/kit-scroll.js` (registry `mod: 'kit-scroll'`) and calls `mount(host, { variant: 'reveal' })`. mount resolves the variant to family `reveal`; `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; TAU — Constant 2π; fmt — Number formatting (fixed decimals); 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.moveTo() — Moves the pen without drawing; ctx.arcTo() — Adds an arc using tangent lines; ctx.closePath() — Closes the current sub-path; ctx.fill() — Fills the current path; ctx.stroke() — Strokes the current path; ctx.fillRect() — Fills a rectangle; ctx.save() — Saves the drawing state (transform, styles, clip); ctx.rect() — Adds a rectangle to the path; ctx.clip() — Turns the current path into the clipping region; ctx.translate() — Translates the coordinate system; ctx.restore() — Restores the saved drawing state
Source code
frontend/src/demos/kits/kit-scroll.js: FAM.reveal (L229-L242)
Code walkthrough
L229-242: Calls the factory `scFam()` to produce the full definition (spec + doc + build) from the options below. L229-229: Title shown in the info and control panels: “Fade-in Reveal”. L229-229: Range/default of the count slider. L229-229: Extra demo-specific slider/toggle: Displacement distance. L229-229: Range/default of the size slider. L229-229: Default main colour. L230-230: Help text of the count parameter. L230-230: Help text of the extra parameter. L230-230: Help text of the size parameter. L231-231: Preset buttons: name → parameter overrides (5). L232-232: Body of the “Notes” section. L233-233: Main formula of the “Formula” section. L233-233: Second formula line. L234-242: Per-frame draw function: math via `Math.min`, `Math.round`; returns readouts `mode`, `cell`, `pageH` to the info panel.
Principles
e = slow motion (the bottom of the vision - the top of the card) / (0.3 · I don't know Transparency = e, offset = (1 - e) · Displacement distance Dilution reveals that the card is transparent and biased when it is not in sight; when it enters from the bottom, progress e from 0 to 1, transparency becomes 1, Turning back to zero, it looks like "sliding up and emerging." This is the most common use of Intersection Observer. Image simulates a scrollable web page: scrollY 表示页面已经向上滚过了多少像素，这里它自动来回滚动（右侧细条就是滚动条）。元素在屏幕上的位置 = Page Location − scrollY；The degree to which the elements enter the vision is usually used scroll Event or event IntersectionObserver Let's figure this out 0~1 The progress is driven by animations such as transparency, offset, scaling, etc.