Clyune Component GallerySankey Diagram · How it works & code
Source → Page → Flow chart to go, intermediate node in = Out.
Runtime logic
Visiting `/dataviz/sankey`, DemoHost lazy-loads `demos/kits/kit-dataviz.js` (registry `mod: 'kit-dataviz'`) and calls `mount(host, { variant: 'sankey' })`. mount resolves the variant to family `sankey`; `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; rng — Seeded deterministic PRNG (same seed, same result); 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.get — Reads current control values; S.onFrame — Registers a per-frame callback; its return value feeds the info panel; ctx.beginPath() — Starts a new path; ctx.lineTo() — Adds a straight line to a point; ctx.moveTo() — Moves the pen without drawing; ctx.stroke() — Strokes the current path; ctx.arc() — Adds a circular arc (center, radius, start/end angle); ctx.fill() — Fills the current path; ctx.arcTo() — Adds an arc using tangent lines; ctx.closePath() — Closes the current sub-path; ctx.fillText() — Draws filled text; ctx.measureText() — Measures text width
Source code
frontend/src/demos/kits/kit-dataviz.js: FAM.sankey (L159-L214)
Code walkthrough
L160-160: Control definitions (colour/speed/size/count/extras): Flow band primary color, Node width, Number of nodes per column, Connection density, Curvature, Node spacing. L161-161: Preset buttons: name → parameter overrides (6). L162-170: Info-panel content: live rows(v), formula, notes, params, steps. L171-213: Init function: sets up state and returns the per-frame callback: draws with Canvas 2D `beginPath`, `lineTo`, `moveTo`, `stroke`, `arc`, `fill`; math via `Math.round`, `Math.min`, `Math.max`, `Math.abs`, `Math.random`; returns readouts `nn`, `nl`, `tot`, `hov`, `hv`, `hs`, `io` … to the info panel.
Principles
Bandwidth wᵢⱼ = flow rateᵢⱼ / Total traffic × Available Height Constant: midpoint Σ Inflow = Σ Outflow Streamline Central Line = Three times, Bézier B(s), Control Point Horizontal Offset = Curvature × Column spacing Sankey Diagram The painting is"flow rate"：左边是来源（比如访客渠道），中间是经过的页面，右边是去向（下单、离开…）。Every tape Width is exactly the same as flow , So that's the main path. Midbar node content Conservation ：流进来多少就流出去多少，节点高度等于它的总流量。带子里流动的小点表示真实的"Stream of people"，The bigger the tape, the bigger it is. Put the pointer on any tape or node, and the right side shows a specific flow and percentage.