{"$schema":"https://ui.shadcn.com/schema/registry-item.json","name":"pixel-loader","type":"registry:component","title":"Pixel loader","description":"A tiny pixel grid that cycles spiral, snake, pulse and checker, then draws a check when done.","author":"Yash Bavadiya ","dependencies":[],"registryDependencies":["utils"],"files":[{"path":"components/pixel-loader.tsx","type":"registry:component","content":"\"use client\";\n\nimport { useEffect, useMemo, useRef, useState } from \"react\";\nimport { cn } from \"@/lib/utils\";\nimport { usePreviewPlay } from \"@/lib/preview-play\";\n\nexport type PixelPattern = \"spiral\" | \"snake\" | \"pulse\" | \"checker\";\n\ntype Frames = number[][];\n\n// Each pattern is a list of frames; a frame is the set of lit cell indexes.\n// Frames only say what turns ON. Turning off is a slow fade (see the pixel classes), so\n// any moving pattern leaves a short comet trail for free.\nfunction buildPattern(pattern: PixelPattern, n: number): Frames {\n const cells = Array.from({ length: n * n }, (_, i) => i);\n const at = (r: number, c: number) => r * n + c;\n\n if (pattern === \"spiral\") {\n const order: number[] = [];\n let top = 0;\n let left = 0;\n let bottom = n - 1;\n let right = n - 1;\n while (top <= bottom && left <= right) {\n for (let c = left; c <= right; c++) order.push(at(top, c));\n for (let r = top + 1; r <= bottom; r++) order.push(at(r, right));\n if (top < bottom) for (let c = right - 1; c >= left; c--) order.push(at(bottom, c));\n if (left < right) for (let r = bottom - 1; r > top; r--) order.push(at(r, left));\n top++;\n left++;\n bottom--;\n right--;\n }\n // Winds in, then winds back out, so the loop never jumps.\n const there = order.map((cell) => [cell]);\n return [...there, ...there.slice(1, -1).reverse()];\n }\n\n if (pattern === \"snake\") {\n const order = cells.map((i) => {\n const r = Math.floor(i / n);\n const c = i % n;\n return at(r, r % 2 ? n - 1 - c : c);\n });\n // A two-cell body; the fade adds the tail.\n return order.map((cell, i) => (i ? [order[i - 1], cell] : [cell]));\n }\n\n if (pattern === \"pulse\") {\n const mid = (n - 1) / 2;\n const ring = (i: number) =>\n Math.floor(Math.max(Math.abs(Math.floor(i / n) - mid), Math.abs((i % n) - mid)));\n const rings = Math.floor(mid) + 1;\n const frames: Frames = [];\n for (let k = 0; k < rings; k++) frames.push(cells.filter((i) => ring(i) === k));\n // One dark beat so each ripple reads as its own breath.\n return [...frames, []];\n }\n\n // Checker: the two halves trade places twice.\n const even = cells.filter((i) => (Math.floor(i / n) + (i % n)) % 2 === 0);\n const odd = cells.filter((i) => (Math.floor(i / n) + (i % n)) % 2 === 1);\n return [even, odd, even, odd];\n}\n\n// A pixel check: short arm down, long arm up. On 3x3 the long arm has to turn\n// upward in the last column, which still reads as a tick at this size.\nconst CHECKS: Record = {\n 3: [3, 7, 5, 2],\n 4: [8, 13, 10, 7],\n};\n\n// ~110ms a step: fast enough to feel busy, slow enough that single pixels\n// are still followable at 24px.\nconst STEP = 110;\n// Every pattern plays for about the same time before handing over.\nconst PATTERN_MS = 1800;\n\nexport function PixelLoader({\n size = 3,\n patterns = [\"spiral\", \"snake\", \"pulse\", \"checker\"],\n done = false,\n shape = \"square\",\n label = \"Loading\",\n doneLabel = \"Done\",\n paused = false,\n className,\n}: {\n size?: 3 | 4;\n patterns?: PixelPattern[];\n done?: boolean;\n shape?: \"square\" | \"round\";\n label?: string;\n doneLabel?: string;\n /** Holds one still frame instead of stepping. For pages that show many\n * loaders that aren't actually waiting on anything. */\n paused?: boolean;\n className?: string;\n}) {\n const grid = useRef(null);\n const key = patterns.join();\n const sequence = useMemo(\n () => key.split(\",\").map((p) => buildPattern(p as PixelPattern, size)),\n [key, size],\n );\n\n useEffect(() => {\n const el = grid.current;\n if (!el) return;\n const pixels = Array.from(el.children) as HTMLElement[];\n const light = (lit: Set) => {\n pixels.forEach((p, i) => {\n p.dataset.on = String(lit.has(i));\n });\n };\n\n if (done) {\n const check = CHECKS[size];\n // Clears the grid first, then lays the check pixel by pixel in stroke\n // order through a per-pixel transition delay.\n pixels.forEach((p, i) => {\n const order = check.indexOf(i);\n p.style.transitionDelay = order < 0 ? \"0ms\" : `${120 + order * 55}ms`;\n });\n light(new Set(check));\n return;\n }\n\n const reduce = window.matchMedia(\"(prefers-reduced-motion: reduce)\").matches;\n // A diagonal stagger: when one pattern morphs into the next, the change\n // sweeps across the grid instead of every pixel flipping at once.\n pixels.forEach((p, i) => {\n p.style.transitionDelay = `${(Math.floor(i / size) + (i % size)) * 18}ms`;\n });\n\n let pattern = 0;\n let frame = 0;\n let elapsed = 0;\n let timer: ReturnType | undefined;\n const tick = () => {\n const frames = sequence[pattern];\n light(new Set(frames[frame % frames.length]));\n frame++;\n elapsed += STEP;\n // Hands over only at the end of a loop, so no pattern is cut mid-shape.\n if (elapsed >= PATTERN_MS && frame % frames.length === 0) {\n pattern = (pattern + 1) % sequence.length;\n frame = 0;\n elapsed = 0;\n }\n };\n // A resting frame from the middle of the first pattern, so a paused\n // loader still looks like one mid-thought rather than a dim grid.\n if (paused) {\n frame = Math.floor(sequence[0].length / 3);\n tick();\n return;\n }\n\n const start = () => {\n if (timer) return;\n tick();\n // Reduced motion keeps the loader alive but slow and without scale.\n timer = setInterval(tick, reduce ? STEP * 4 : STEP);\n };\n const stop = () => {\n clearInterval(timer);\n timer = undefined;\n };\n\n // Stops stepping whenever it is off screen or the tab is hidden.\n let visible = false;\n const sync = () => (visible && !document.hidden ? start() : stop());\n const io = new IntersectionObserver(([entry]) => {\n visible = entry.isIntersecting;\n sync();\n });\n io.observe(el);\n document.addEventListener(\"visibilitychange\", sync);\n return () => {\n stop();\n io.disconnect();\n document.removeEventListener(\"visibilitychange\", sync);\n };\n }, [done, sequence, size, paused]);\n\n const cell = size === 3 ? 6 : 4.5;\n const gap = size === 3 ? 2 : 1.5;\n\n return (\n \n \n {Array.from({ length: size * size }, (_, i) => (\n \n ))}\n \n {done ? doneLabel : label}\n \n );\n}\n\nexport default function PixelLoaderDemo() {\n const [done, setDone] = useState(false);\n const play = usePreviewPlay();\n // In an index card the grids only step while the card is hovered.\n const paused = play === false;\n\n // Index preview: it loads for a beat, finishes with a check, then goes\n // back to loading, the way the Finish button plays it by hand.\n useEffect(() => {\n if (!play) return;\n let timer: ReturnType;\n const cycle = (next: boolean) => {\n setDone(next);\n // Holds the check long enough to read, then a calmer loading stretch.\n timer = setTimeout(() => cycle(!next), next ? 1800 : 2200);\n };\n timer = setTimeout(() => cycle(true), 700);\n return () => {\n clearTimeout(timer);\n setDone(false);\n };\n }, [play]);\n\n return (\n
\n
\n \n \n \n
\n setDone((d) => !d)}\n className=\"h-8 rounded-full px-3 text-sm text-muted-foreground outline-hidden transition-[scale,color,background-color] duration-150 ease-out hover:bg-muted hover:text-foreground focus-visible:outline-2 focus-visible:outline-solid focus-visible:outline-foreground active:scale-[0.96]\"\n >\n {done ? \"Load again\" : \"Finish\"}\n \n
\n );\n}\n"},{"path":"lib/preview-play.ts","type":"registry:lib","target":"lib/preview-play.ts","content":"\"use client\";\n\nimport { createContext, useContext } from \"react\";\n\n// Lets a demo know whether it's showing in an index card, and whether that\n// card is hovered or focused. Demos use it to act themselves out on hover:\n// a star button stars itself, a checkbox scribbles, and so on.\n//\n// null: not in a preview (the component's own page, or real use).\n// false: in a preview, at rest.\n// true: in a preview, being hovered or focused: play the show.\nexport const PreviewPlayContext = createContext(null);\n\nexport function usePreviewPlay() {\n return useContext(PreviewPlayContext);\n}\n"}],"categories":["feedback"],"docs":"From ui lab: https://lab.xevrion.dev/lab/pixel-loader"}