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import isAnimated from 'next/dist/compiled/is-animated'
import { optimizeImage } from '../../../../server/image-optimizer'
const BLUR_IMG_SIZE = 8
const BLUR_QUALITY = 70
const VALID_BLUR_EXT = ['jpeg', 'png', 'webp', 'avif'] // should match other usages
export async function getBlurImage(
content: Buffer,
extension: string,
imageSize: { width: number; height: number },
{
basePath,
outputPath,
isDev,
tracing = () => ({
traceFn:
(fn) =>
(...args: any) =>
fn(...args),
traceAsyncFn:
(fn) =>
(...args: any) =>
fn(...args),
}),
}: {
basePath: string
outputPath: string
isDev: boolean
tracing: (name?: string) => {
traceFn(fn: Function): any
traceAsyncFn(fn: Function): any
}
}
) {
let blurDataURL: string | undefined
let blurWidth: number = 0
let blurHeight: number = 0
if (VALID_BLUR_EXT.includes(extension) && !isAnimated(content)) {
// Shrink the image's largest dimension
if (imageSize.width >= imageSize.height) {
blurWidth = BLUR_IMG_SIZE
blurHeight = Math.max(
Math.round((imageSize.height / imageSize.width) * BLUR_IMG_SIZE),
1
)
} else {
blurWidth = Math.max(
Math.round((imageSize.width / imageSize.height) * BLUR_IMG_SIZE),
1
)
blurHeight = BLUR_IMG_SIZE
}
if (isDev) {
// During `next dev`, we don't want to generate blur placeholders with webpack
// because it can delay starting the dev server. Instead, we inline a
// special url to lazily generate the blur placeholder at request time.
const prefix = 'http://localhost'
const url = new URL(`${basePath || ''}/_next/image`, prefix)
url.searchParams.set('url', outputPath)
url.searchParams.set('w', String(blurWidth))
url.searchParams.set('q', String(BLUR_QUALITY))
blurDataURL = url.href.slice(prefix.length)
} else {
const resizeImageSpan = tracing('image-resize')
const resizedImage = await resizeImageSpan.traceAsyncFn(() =>
optimizeImage({
buffer: content,
width: blurWidth,
height: blurHeight,
contentType: `image/${extension}`,
quality: BLUR_QUALITY,
})
)
const blurDataURLSpan = tracing('image-base64-tostring')
blurDataURL = blurDataURLSpan.traceFn(
() =>
`data:image/${extension};base64,${resizedImage.toString('base64')}`
)
}
}
return {
dataURL: blurDataURL,
width: blurWidth,
height: blurHeight,
}
}
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