46 lines
1.7 KiB
JavaScript
46 lines
1.7 KiB
JavaScript
import { decode as decodeBlurHash } from 'blurhash'
|
|
import QuickLRU from 'quick-lru'
|
|
|
|
const RESOLUTION = 32
|
|
const OFFSCREEN_CANVAS = typeof OffscreenCanvas === 'function'
|
|
? new OffscreenCanvas(RESOLUTION, RESOLUTION) : null
|
|
const OFFSCREEN_CANVAS_CONTEXT_2D = OFFSCREEN_CANVAS
|
|
? OFFSCREEN_CANVAS.getContext('2d') : null
|
|
const CACHE = new QuickLRU({ maxSize: 100 })
|
|
|
|
self.addEventListener('message', ({ data: { encoded } }) => {
|
|
try {
|
|
if (CACHE.has(encoded)) {
|
|
if (OFFSCREEN_CANVAS) {
|
|
postMessage({ encoded, decoded: CACHE.get(encoded), imageData: null, error: null })
|
|
} else {
|
|
postMessage({ encoded, imageData: CACHE.get(encoded), decoded: null, error: null })
|
|
}
|
|
} else {
|
|
const pixels = decodeBlurHash(encoded, RESOLUTION, RESOLUTION)
|
|
|
|
if (pixels) {
|
|
const imageData = new ImageData(pixels, RESOLUTION, RESOLUTION)
|
|
|
|
if (OFFSCREEN_CANVAS) {
|
|
OFFSCREEN_CANVAS_CONTEXT_2D.putImageData(imageData, 0, 0)
|
|
OFFSCREEN_CANVAS.convertToBlob().then(blob => {
|
|
const decoded = URL.createObjectURL(blob)
|
|
CACHE.set(encoded, decoded)
|
|
postMessage({ encoded, decoded, imageData: null, error: null })
|
|
}).catch(error => {
|
|
postMessage({ encoded, decoded: null, imageData: null, error })
|
|
})
|
|
} else {
|
|
CACHE.set(encoded, imageData)
|
|
postMessage({ encoded, imageData, decoded: null, error: null })
|
|
}
|
|
} else {
|
|
postMessage({ encoded, decoded: null, imageData: null, error: new Error('decode did not return any pixels') })
|
|
}
|
|
}
|
|
} catch (error) {
|
|
postMessage({ encoded, decoded: null, imageData: null, error })
|
|
}
|
|
})
|