Cipher Decode · How it works & code
Text initially displays as randomly changing garbled characters, then gradually decodes from left to right into real characters, like a hacker interface in a movie.
Runtime logic
Visiting `/text-fx/decode`, DemoHost lazy-loads `demos/kits/kit-text.js` (registry `mod: 'kit-text'`) and calls `mount(host, { variant: 'decode' })`. mount resolves the variant to family `decode`; `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°); fmt — Number formatting (fixed decimals); F — Formula block HTML; getLang — Current UI language (zh/en); 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.save() — Saves the drawing state (transform, styles, clip); ctx.measureText() — Measures text width; ctx.restore() — Restores the saved drawing state; ctx.fillRect() — Fills a rectangle; ctx.rect() — Adds a rectangle to the path; ctx.clip() — Turns the current path into the clipping region; ctx.translate() — Translates the coordinate system
Source code
frontend/src/demos/kits/kit-text.js: FAM.decode (L289-L297)
Code walkthrough
L289-297: Calls the factory `tFam()` to produce the full definition (spec + doc + build) from the options below. L289-289: Title shown in the info and control panels: “Cipher Decode”. L289-289: Range/default of the count slider. L289-289: Extra demo-specific slider/toggle: Garbled Code Refresh Rate. L289-289: Default main colour. L289-289: Help text of the extra parameter. L289-289: Preset buttons: name → parameter overrides (5). L290-290: Body of the “Notes” section. L290-290: Main formula of the “Formula” section. L290-290: Second formula line. L291-297: Per-frame draw function: draws with Canvas 2D `fillText`; math via `Math.floor`; returns readouts `mode`, `g` to the info panel.
Principles
= 0.12 · i Spoil = character table [hash(i), browsing rate] · t⌋)] Password decoding: The text is shown as a constantly changing cipher, then from a left to a right "break" to a real word, like the hacker interface in the movie. Unlock all and stop for a moment and reencode. 文字被拆成一个个字(字形),每个字的位置、颜色、透明度都由「字的序号 i + Time t」Count it out so you can make animated verbatim.