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image.tsx
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import React from 'react'
import Head from '../next-server/lib/head'
import { toBase64 } from '../next-server/lib/to-base-64'
import {
ImageConfig,
imageConfigDefault,
LoaderValue,
VALID_LOADERS,
} from '../next-server/server/image-config'
import { useIntersection } from './use-intersection'
if (typeof window === 'undefined') {
;(global as any).__NEXT_IMAGE_IMPORTED = true
}
const VALID_LOADING_VALUES = ['lazy', 'eager', undefined] as const
type LoadingValue = typeof VALID_LOADING_VALUES[number]
export type ImageLoader = (resolverProps: ImageLoaderProps) => string
export type ImageLoaderProps = {
src: string
width: number
quality?: number
}
type DefaultImageLoaderProps = ImageLoaderProps & { root: string }
const loaders = new Map<
LoaderValue,
(props: DefaultImageLoaderProps) => string
>([
['imgix', imgixLoader],
['cloudinary', cloudinaryLoader],
['akamai', akamaiLoader],
['default', defaultLoader],
])
const VALID_LAYOUT_VALUES = [
'fill',
'fixed',
'intrinsic',
'responsive',
undefined,
] as const
type LayoutValue = typeof VALID_LAYOUT_VALUES[number]
type PlaceholderValue = 'blur' | 'empty'
type ImgElementStyle = NonNullable<JSX.IntrinsicElements['img']['style']>
export type ImageProps = Omit<
JSX.IntrinsicElements['img'],
'src' | 'srcSet' | 'ref' | 'width' | 'height' | 'loading' | 'style'
> & {
src: string
loader?: ImageLoader
quality?: number | string
priority?: boolean
loading?: LoadingValue
unoptimized?: boolean
objectFit?: ImgElementStyle['objectFit']
objectPosition?: ImgElementStyle['objectPosition']
} & (
| {
width?: never
height?: never
/** @deprecated Use `layout="fill"` instead */
unsized: true
}
| { width?: never; height?: never; layout: 'fill' }
| {
width: number | string
height: number | string
layout?: Exclude<LayoutValue, 'fill'>
}
) &
(
| {
placeholder?: Exclude<PlaceholderValue, 'blur'>
blurDataURL?: never
}
| { placeholder: 'blur'; blurDataURL: string }
)
const {
deviceSizes: configDeviceSizes,
imageSizes: configImageSizes,
loader: configLoader,
path: configPath,
domains: configDomains,
enableBlurryPlaceholder: configEnableBlurryPlaceholder,
} =
((process.env.__NEXT_IMAGE_OPTS as any) as ImageConfig) || imageConfigDefault
// sort smallest to largest
const allSizes = [...configDeviceSizes, ...configImageSizes]
configDeviceSizes.sort((a, b) => a - b)
allSizes.sort((a, b) => a - b)
function getWidths(
width: number | undefined,
layout: LayoutValue,
sizes: string | undefined
): { widths: number[]; kind: 'w' | 'x' } {
if (sizes && (layout === 'fill' || layout === 'responsive')) {
// Find all the "vw" percent sizes used in the sizes prop
const viewportWidthRe = /(^|\s)(1?\d?\d)vw/g
const percentSizes = []
for (let match; (match = viewportWidthRe.exec(sizes)); match) {
percentSizes.push(parseInt(match[2]))
}
if (percentSizes.length) {
const smallestRatio = Math.min(...percentSizes) * 0.01
return {
widths: allSizes.filter(
(s) => s >= configDeviceSizes[0] * smallestRatio
),
kind: 'w',
}
}
return { widths: allSizes, kind: 'w' }
}
if (
typeof width !== 'number' ||
layout === 'fill' ||
layout === 'responsive'
) {
return { widths: configDeviceSizes, kind: 'w' }
}
const widths = [
...new Set(
// > This means that most OLED screens that say they are 3x resolution,
// > are actually 3x in the green color, but only 1.5x in the red and
// > blue colors. Showing a 3x resolution image in the app vs a 2x
// > resolution image will be visually the same, though the 3x image
// > takes significantly more data. Even true 3x resolution screens are
// > wasteful as the human eye cannot see that level of detail without
// > something like a magnifying glass.
// https://blog.twitter.com/engineering/en_us/topics/infrastructure/2019/capping-image-fidelity-on-ultra-high-resolution-devices.html
[width, width * 2 /*, width * 3*/].map(
(w) => allSizes.find((p) => p >= w) || allSizes[allSizes.length - 1]
)
),
]
return { widths, kind: 'x' }
}
type GenImgAttrsData = {
src: string
unoptimized: boolean
layout: LayoutValue
loader: ImageLoader
width?: number
quality?: number
sizes?: string
}
type GenImgAttrsResult = {
src: string
srcSet: string | undefined
sizes: string | undefined
}
function generateImgAttrs({
src,
unoptimized,
layout,
width,
quality,
sizes,
loader,
}: GenImgAttrsData): GenImgAttrsResult {
if (unoptimized) {
return { src, srcSet: undefined, sizes: undefined }
}
const { widths, kind } = getWidths(width, layout, sizes)
const last = widths.length - 1
return {
sizes: !sizes && kind === 'w' ? '100vw' : sizes,
srcSet: widths
.map(
(w, i) =>
`${loader({ src, quality, width: w })} ${
kind === 'w' ? w : i + 1
}${kind}`
)
.join(', '),
// It's intended to keep `src` the last attribute because React updates
// attributes in order. If we keep `src` the first one, Safari will
// immediately start to fetch `src`, before `sizes` and `srcSet` are even
// updated by React. That causes multiple unnecessary requests if `srcSet`
// and `sizes` are defined.
// This bug cannot be reproduced in Chrome or Firefox.
src: loader({ src, quality, width: widths[last] }),
}
}
function getInt(x: unknown): number | undefined {
if (typeof x === 'number') {
return x
}
if (typeof x === 'string') {
return parseInt(x, 10)
}
return undefined
}
function defaultImageLoader(loaderProps: ImageLoaderProps) {
const load = loaders.get(configLoader)
if (load) {
return load({ root: configPath, ...loaderProps })
}
throw new Error(
`Unknown "loader" found in "next.config.js". Expected: ${VALID_LOADERS.join(
', '
)}. Received: ${configLoader}`
)
}
// See https://stackoverflow.com/q/39777833/266535 for why we use this ref
// handler instead of the img's onLoad attribute.
function removePlaceholder(
element: HTMLImageElement | null,
placeholder: PlaceholderValue
) {
if (placeholder === 'blur' && element) {
if (element.complete) {
// If the real image fails to load, this will still remove the placeholder.
// This is the desired behavior for now, and will be revisited when error
// handling is worked on for the image component itself.
element.style.backgroundImage = 'none'
} else {
element.onload = () => {
element.style.backgroundImage = 'none'
}
}
}
}
export default function Image({
src,
sizes,
unoptimized = false,
priority = false,
loading,
className,
quality,
width,
height,
objectFit,
objectPosition,
loader = defaultImageLoader,
placeholder = 'empty',
blurDataURL,
...all
}: ImageProps) {
let rest: Partial<ImageProps> = all
let layout: NonNullable<LayoutValue> = sizes ? 'responsive' : 'intrinsic'
let unsized = false
if ('unsized' in rest) {
unsized = Boolean(rest.unsized)
// Remove property so it's not spread into image:
delete rest['unsized']
} else if ('layout' in rest) {
// Override default layout if the user specified one:
if (rest.layout) layout = rest.layout
// Remove property so it's not spread into image:
delete rest['layout']
}
if (!configEnableBlurryPlaceholder) {
placeholder = 'empty'
}
if (process.env.NODE_ENV !== 'production') {
if (!src) {
throw new Error(
`Image is missing required "src" property. Make sure you pass "src" in props to the \`next/image\` component. Received: ${JSON.stringify(
{ width, height, quality }
)}`
)
}
if (!VALID_LAYOUT_VALUES.includes(layout)) {
throw new Error(
`Image with src "${src}" has invalid "layout" property. Provided "${layout}" should be one of ${VALID_LAYOUT_VALUES.map(
String
).join(',')}.`
)
}
if (!VALID_LOADING_VALUES.includes(loading)) {
throw new Error(
`Image with src "${src}" has invalid "loading" property. Provided "${loading}" should be one of ${VALID_LOADING_VALUES.map(
String
).join(',')}.`
)
}
if (priority && loading === 'lazy') {
throw new Error(
`Image with src "${src}" has both "priority" and "loading='lazy'" properties. Only one should be used.`
)
}
if (unsized) {
throw new Error(
`Image with src "${src}" has deprecated "unsized" property, which was removed in favor of the "layout='fill'" property`
)
}
}
let isLazy =
!priority && (loading === 'lazy' || typeof loading === 'undefined')
if (src && src.startsWith('data:')) {
// https://developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_HTTP/Data_URIs
unoptimized = true
isLazy = false
}
const [setRef, isIntersected] = useIntersection<HTMLImageElement>({
rootMargin: '200px',
disabled: !isLazy,
})
const isVisible = !isLazy || isIntersected
const widthInt = getInt(width)
const heightInt = getInt(height)
const qualityInt = getInt(quality)
const MIN_IMG_SIZE_FOR_PLACEHOLDER = 5000
const tooSmallForBlurryPlaceholder =
widthInt && heightInt && widthInt * heightInt < MIN_IMG_SIZE_FOR_PLACEHOLDER
const shouldShowBlurryPlaceholder =
placeholder === 'blur' && !tooSmallForBlurryPlaceholder
let wrapperStyle: JSX.IntrinsicElements['div']['style'] | undefined
let sizerStyle: JSX.IntrinsicElements['div']['style'] | undefined
let sizerSvg: string | undefined
let imgStyle: ImgElementStyle | undefined = {
position: 'absolute',
top: 0,
left: 0,
bottom: 0,
right: 0,
boxSizing: 'border-box',
padding: 0,
border: 'none',
margin: 'auto',
display: 'block',
width: 0,
height: 0,
minWidth: '100%',
maxWidth: '100%',
minHeight: '100%',
maxHeight: '100%',
objectFit,
objectPosition,
...(shouldShowBlurryPlaceholder
? {
backgroundSize: 'cover',
backgroundImage: `url("${blurDataURL}")`,
}
: undefined),
}
if (
typeof widthInt !== 'undefined' &&
typeof heightInt !== 'undefined' &&
layout !== 'fill'
) {
// <Image src="i.png" width="100" height="100" />
const quotient = heightInt / widthInt
const paddingTop = isNaN(quotient) ? '100%' : `${quotient * 100}%`
if (layout === 'responsive') {
// <Image src="i.png" width="100" height="100" layout="responsive" />
wrapperStyle = {
display: 'block',
overflow: 'hidden',
position: 'relative',
boxSizing: 'border-box',
margin: 0,
}
sizerStyle = { display: 'block', boxSizing: 'border-box', paddingTop }
} else if (layout === 'intrinsic') {
// <Image src="i.png" width="100" height="100" layout="intrinsic" />
wrapperStyle = {
display: 'inline-block',
maxWidth: '100%',
overflow: 'hidden',
position: 'relative',
boxSizing: 'border-box',
margin: 0,
}
sizerStyle = {
boxSizing: 'border-box',
display: 'block',
maxWidth: '100%',
}
sizerSvg = `<svg width="${widthInt}" height="${heightInt}" xmlns="http://www.w3.org/2000/svg" version="1.1"/>`
} else if (layout === 'fixed') {
// <Image src="i.png" width="100" height="100" layout="fixed" />
wrapperStyle = {
overflow: 'hidden',
boxSizing: 'border-box',
display: 'inline-block',
position: 'relative',
width: widthInt,
height: heightInt,
}
}
} else if (
typeof widthInt === 'undefined' &&
typeof heightInt === 'undefined' &&
layout === 'fill'
) {
// <Image src="i.png" layout="fill" />
wrapperStyle = {
display: 'block',
overflow: 'hidden',
position: 'absolute',
top: 0,
left: 0,
bottom: 0,
right: 0,
boxSizing: 'border-box',
margin: 0,
}
} else {
// <Image src="i.png" />
if (process.env.NODE_ENV !== 'production') {
throw new Error(
`Image with src "${src}" must use "width" and "height" properties or "layout='fill'" property.`
)
}
}
let imgAttributes: GenImgAttrsResult = {
src:
'data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7',
srcSet: undefined,
sizes: undefined,
}
if (isVisible) {
imgAttributes = generateImgAttrs({
src,
unoptimized,
layout,
width: widthInt,
quality: qualityInt,
sizes,
loader,
})
}
if (unsized) {
wrapperStyle = undefined
sizerStyle = undefined
imgStyle = undefined
}
return (
<div style={wrapperStyle}>
{sizerStyle ? (
<div style={sizerStyle}>
{sizerSvg ? (
<img
style={{
maxWidth: '100%',
display: 'block',
margin: 0,
border: 'none',
padding: 0,
}}
alt=""
aria-hidden={true}
role="presentation"
src={`data:image/svg+xml;base64,${toBase64(sizerSvg)}`}
/>
) : null}
</div>
) : null}
{!isVisible && (
<noscript>
<img
{...rest}
{...generateImgAttrs({
src,
unoptimized,
layout,
width: widthInt,
quality: qualityInt,
sizes,
loader,
})}
src={src}
decoding="async"
sizes={sizes}
style={imgStyle}
className={className}
/>
</noscript>
)}
<img
{...rest}
{...imgAttributes}
decoding="async"
className={className}
ref={(element) => {
setRef(element)
removePlaceholder(element, placeholder)
}}
style={imgStyle}
/>
{priority ? (
// Note how we omit the `href` attribute, as it would only be relevant
// for browsers that do not support `imagesrcset`, and in those cases
// it would likely cause the incorrect image to be preloaded.
//
// https://html.spec.whatwg.org/multipage/semantics.html#attr-link-imagesrcset
<Head>
<link
key={
'__nimg-' +
imgAttributes.src +
imgAttributes.srcSet +
imgAttributes.sizes
}
rel="preload"
as="image"
href={imgAttributes.srcSet ? undefined : imgAttributes.src}
// @ts-ignore: imagesrcset is not yet in the link element type
imagesrcset={imgAttributes.srcSet}
// @ts-ignore: imagesizes is not yet in the link element type
imagesizes={imgAttributes.sizes}
></link>
</Head>
) : null}
</div>
)
}
//BUILT IN LOADERS
function normalizeSrc(src: string): string {
return src[0] === '/' ? src.slice(1) : src
}
function imgixLoader({
root,
src,
width,
quality,
}: DefaultImageLoaderProps): string {
// Demo: https://static.imgix.net/daisy.png?format=auto&fit=max&w=300
const params = ['auto=format', 'fit=max', 'w=' + width]
let paramsString = ''
if (quality) {
params.push('q=' + quality)
}
if (params.length) {
paramsString = '?' + params.join('&')
}
return `${root}${normalizeSrc(src)}${paramsString}`
}
function akamaiLoader({ root, src, width }: DefaultImageLoaderProps): string {
return `${root}${normalizeSrc(src)}?imwidth=${width}`
}
function cloudinaryLoader({
root,
src,
width,
quality,
}: DefaultImageLoaderProps): string {
// Demo: https://res.cloudinary.com/demo/image/upload/w_300,c_limit,q_auto/turtles.jpg
const params = ['f_auto', 'c_limit', 'w_' + width, 'q_' + (quality || 'auto')]
let paramsString = params.join(',') + '/'
return `${root}${paramsString}${normalizeSrc(src)}`
}
function defaultLoader({
root,
src,
width,
quality,
}: DefaultImageLoaderProps): string {
if (process.env.NODE_ENV !== 'production') {
const missingValues = []
// these should always be provided but make sure they are
if (!src) missingValues.push('src')
if (!width) missingValues.push('width')
if (missingValues.length > 0) {
throw new Error(
`Next Image Optimization requires ${missingValues.join(
', '
)} to be provided. Make sure you pass them as props to the \`next/image\` component. Received: ${JSON.stringify(
{ src, width, quality }
)}`
)
}
if (src.startsWith('//')) {
throw new Error(
`Failed to parse src "${src}" on \`next/image\`, protocol-relative URL (//) must be changed to an absolute URL (http:// or https://)`
)
}
if (!src.startsWith('/') && configDomains) {
let parsedSrc: URL
try {
parsedSrc = new URL(src)
} catch (err) {
console.error(err)
throw new Error(
`Failed to parse src "${src}" on \`next/image\`, if using relative image it must start with a leading slash "/" or be an absolute URL (http:// or https://)`
)
}
if (!configDomains.includes(parsedSrc.hostname)) {
throw new Error(
`Invalid src prop (${src}) on \`next/image\`, hostname "${parsedSrc.hostname}" is not configured under images in your \`next.config.js\`\n` +
`See more info: https://nextjs.org/docs/messages/next-image-unconfigured-host`
)
}
}
}
return `${root}?url=${encodeURIComponent(src)}&w=${width}&q=${quality || 75}`
}