Error diffusion revealPro

The classic Mac look as a loading state: Atkinson or Floyd-Steinberg dithers that get finer, computed once in a worker and cached, then resolved into the photo.

Markdown

On this page

ProAtkinson or Floyd-Steinberg frames at 6, 3 and 2 px, computed in a worker, then the photo.

Installation

$ pnpm dlx shadcn@latest add @chatcn-pro/error-diffusion-reveal

Usage

tsx

import { ErrorDiffusionReveal } from "@/components/ui/chatcn/pro/error-diffusion-reveal"

<ErrorDiffusionReveal src={image.url} alt={image.prompt} kernel="atkinson" progress={job.progress} />

Error diffusion is serial and does not run in a shader, so each step is computed in a worker the moment the image loads, coarse first, and cached by size. If a step is not ready when it is due, the finest ready frame holds instead of a blank.

Examples

States

Waiting for the image, running at 40%, running with no numbers, held by revealed={false}, revealed, a missing file, a timer and right to left.

ProEvery state of the error diffusion reveal.

Props

Prop	Type	Notes
`src`, `alt`	`string`	`alt` is required: the accessible name, announced once the image is in
`progress`	`number \| null`	Real job progress, 0 to 1. `null` means running with no numbers. Leave it out for timer mode
`revealed`	`boolean`	Timer mode: `false` holds the first frame, `true` plays once the image loads. Default `true`
`duration`	`number`	Timer length in ms. Default 1800
`onRevealed`	`() => void`	Once per image, when the plain image shows
`onStatusChange`	`(status: "loading" \| "ready" \| "revealing" \| "revealed" \| "error") => void`
`aspectRatio`, `width`, `height`		Set the frame before the image loads, so nothing shifts
`paper`	`string`	The ground under the effect. Token or CSS color. Default `var(--chatcn-bg)`
`announcement`	`string \| false`	What the live region says once revealed. Default `Image ready: <alt>`
`errorText`, `retryLabel`		Copy for the error state and its reload button
`kernel`	`"atkinson" \| "floyd-steinberg"`	Default `atkinson`
`steps`	`number[]`	Cell sizes in CSS px, coarse to fine. Default `[6, 3, 2]`
`ink`	`string`	Default `var(--chatcn-fg)`
`contrast`	`number`	Default 1.15
`maxPixels`	`number`	Default 1.5 MP

Keyboard

Key	Action
`Tab`	Reaches the Reload image button in the error state. The reveal itself takes no focus

Accessibility

The effect layer is aria-hidden. The real <img> with your alt is always there, and the frame is aria-busy until the reveal ends.
A polite live region says Image ready: <alt> once, when the plain image shows. Progress ticks are never announced.
Under forced-colors: active the effect hides and the plain image shows with system colors.
A broken file shows what happened and a Reload image button that retries the download.

Motion

Each step is held for an equal share of 70% of the run; the last 30% crossfades the finest frame into the photo.
Under reduced motion one still frame holds while the job runs, then the image crossfades in over 200 ms. Nothing moves.
The timer only runs on screen in a visible tab; offscreen it waits where it was.