Clyune Component GallerySaturation · How it works & code
First calculate the 'grayscale' (a uniform shade of gray with the same brightness), then amplify or reduce the difference between the color and this grayscale.
Runtime logic
Visiting `/filters/saturate`, DemoHost lazy-loads `demos/kits/kit-filters.js` (registry `mod: 'kit-filters'`) and calls `mount(host, { variant: 'saturate' })`. mount resolves the variant to family `saturate`; `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.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.fill() — Fills the current path; ctx.stroke() — Strokes the current path; ctx.createLinearGradient() — Creates a linear gradient; ctx.fillRect() — Fills a rectangle; ctx.arc() — Adds a circular arc (center, radius, start/end angle); ctx.lineTo() — Adds a straight line to a point; ctx.save() — Saves the drawing state (transform, styles, clip); ctx.clip() — Turns the current path into the clipping region; ctx.drawImage() — Draws an image or offscreen canvas
Source code
frontend/src/demos/kits/kit-filters.js: FAM.saturate (L235-L238)
Code walkthrough
L235-238: Calls the factory `colorFam()` to produce the full definition (spec + doc + build) from the options below. L235-235: Title shown in the info and control panels: “Saturation”. L235-235: Label of the on-stage input pill. L235-235: Minimum. L235-235: Maximum. L235-235: Step. L235-235: Default value. L235-235: Default main colour. L235-235: Equivalent CSS (for reference). L236-236: Help text of the extra parameter. L237-237: Preset buttons: name → parameter overrides (5). L238-238: Body of the “Notes” section. L238-238: Main formula of the “Formula” section. L238-238: Second formula line.
Principles
Result = Greyscale + s · ( Building Colour - Greyscale) Greyscale = 0.213R + 0.715G + 0.072B Saturation saturate()：先算出颜色的「灰度」（亮度相同的灰色），再把颜色与这个灰色的差距放大或缩小。差距放大颜色更鲜艳，缩小到 0 Just gray. W3C Standardize one 3×3 The color matrix is achieved. 为了在所有浏览器里效果一致，这里没有直接调用 CSS 的 filter，而是把一张会动的风景「照片」先画到一块小画布上，再按 W3C 规范里每个滤镜的公式逐个像素计算颜色，最后放大显示。中间那条竖线左边是原图、右边是滤镜后的结果，竖线会跟着指针移动；把指针放在图上，信息面板会显示这一点滤镜前后的颜色。