vitejs · yyx990803 · Feb 24, 2021 · Feb 23, 2021 · Feb 23, 2021 · Feb 23, 2021
diff --git a/packages/playground/assets/__tests__/assets.spec.ts b/packages/playground/assets/__tests__/assets.spec.ts
@@ -81,6 +81,20 @@ describe('css url() references', () => {
     expect(await getBg('.css-url-relative')).toMatch(assetMatch)
   })
 
+  test('image-set relative', async () => {
+    let imageSet = await getBg('.css-image-set-relative')
+    imageSet.split(', ').forEach((s) => {
+      expect(s).toMatch(assetMatch)
+    })
+  })
+
+  test('image-set without the url() call', async () => {
+    let imageSet = await getBg('.css-image-set-without-url-call')
+    imageSet.split(', ').forEach((s) => {
+      expect(s).toMatch(assetMatch)
+    })
+  })
+
   test('relative in @import', async () => {
     expect(await getBg('.css-url-relative-at-imported')).toMatch(assetMatch)
   })
@@ -117,6 +131,20 @@ describe('css url() references', () => {
   }
 })
 
+describe('image', () => {
+  test('srcset', async () => {
+    const img = await page.$('.img-src-set')
+    const srcset = await img.getAttribute('srcset')
+    srcset.split(', ').forEach((s) => {
+      expect(s).toMatch(
+        isBuild
+          ? /\/foo\/assets\/asset\.\w{8}\.png \d{1}x/
+          : /\.\/nested\/asset\.png \d{1}x/
+      )
+    })
+  })
+})
+
 describe('svg fragments', () => {
   // 404 is checked already, so here we just ensure the urls end with #fragment
   test('img url', async () => {

diff --git a/packages/playground/assets/css/css-url.css b/packages/playground/assets/css/css-url.css
@@ -10,6 +10,22 @@
   background-size: 10px;
 }
 
+.css-image-set-relative {
+  background-image: -webkit-image-set(
+    url('../nested/asset.png') 1x,
+    url('../nested/asset.png') 2x
+  );
+  background-size: 10px;
+}
+
+.css-image-set-without-url-call {
+  background-image: -webkit-image-set(
+    '../nested/asset.png' 1x,
+    '../nested/asset.png' 2x
+  );
+  background-size: 10px;
+}
+
 .css-url-public {
   background: url('/icon.png');
   background-size: 10px;

diff --git a/packages/playground/assets/index.html b/packages/playground/assets/index.html
@@ -30,6 +30,16 @@ <h2>CSS url references</h2>
 <div class="css-url-relative">
   <span style="background: #fff">CSS background (relative)</span>
 </div>
+<div class="css-image-set-relative">
+  <span style="background: #fff"
+    >CSS background with image-set() (relative)</span
+  >
+</div>
+<div class="css-image-set-without-url-call">
+  <span style="background: #fff"
+    >CSS background with image-set() (relative)</span
+  >
+</div>
 <div class="css-url-relative-at-imported">
   <span style="background: #fff"
     >CSS background (relative from @imported file in different dir)</span
@@ -56,6 +66,16 @@ <h2>CSS url references</h2>
   <span style="background: #fff">CSS background (aliased)</span>
 </div>
 
+<h2>Image Src Set</h2>
+<div>
+  <img
+    class="img-src-set"
+    src="./nested/asset.png"
+    srcset="./nested/asset.png 1x, ./nested/asset.png 2x"
+    alt=""
+  />
+</div>
+
 <h2>SVG Fragments</h2>
 <div>
   <img

diff --git a/packages/vite/src/node/plugins/css.ts b/packages/vite/src/node/plugins/css.ts
@@ -8,7 +8,8 @@ import {
   generateCodeFrame,
   isDataUrl,
   isObject,
-  normalizePath
+  normalizePath,
+  processSrcSet
 } from '../utils'
 import { Plugin } from '../plugin'
 import { ResolvedConfig } from '../config'
@@ -500,7 +501,7 @@ async function compileCSS(
   // although at serve time it can work without processing, we do need to
   // crawl them in order to register watch dependencies.
   const needInlineImport = code.includes('@import')
-  const hasUrl = cssUrlRE.test(code)
+  const hasUrl = cssUrlRE.test(code) || cssImageSetRE.test(code)
   const postcssConfig = await resolvePostcssConfig(config)
   const lang = id.match(cssLangRE)?.[1]
 
@@ -698,6 +699,7 @@ type CssUrlReplacer = (
   importer?: string
 ) => string | Promise<string>
 const cssUrlRE = /url\(\s*('[^']+'|"[^"]+"|[^'")]+)\s*\)/
+const cssImageSetRE = /image-set\(([^)]+)\)/
 
 const UrlRewritePostcssPlugin: Postcss.PluginCreator<{
   replacer: CssUrlReplacer
@@ -711,13 +713,16 @@ const UrlRewritePostcssPlugin: Postcss.PluginCreator<{
     Once(root) {
       const promises: Promise<void>[] = []
       root.walkDecls((decl) => {
-        if (cssUrlRE.test(decl.value)) {
+        const isCssUrl = cssUrlRE.test(decl.value)
+        const isCssImageSet = cssImageSetRE.test(decl.value)
+        if (isCssUrl || isCssImageSet) {
           const replacerForDecl = (rawUrl: string) => {
             const importer = decl.source?.input.file
             return opts.replacer(rawUrl, importer)
           }
+          const rewriterToUse = isCssUrl ? rewriteCssUrls : rewriteCssImageSet
           promises.push(
-            rewriteCssUrls(decl.value, replacerForDecl).then((url) => {
+            rewriterToUse(decl.value, replacerForDecl).then((url) => {
               decl.value = url
             })
           )
@@ -737,19 +742,40 @@ function rewriteCssUrls(
 ): Promise<string> {
   return asyncReplace(css, cssUrlRE, async (match) => {
     let [matched, rawUrl] = match
-    let wrap = ''
-    const first = rawUrl[0]
-    if (first === `"` || first === `'`) {
-      wrap = first
-      rawUrl = rawUrl.slice(1, -1)
-    }
-    if (isExternalUrl(rawUrl) || isDataUrl(rawUrl) || rawUrl.startsWith('#')) {
-      return matched
-    }
-    return `url(${wrap}${await replacer(rawUrl)}${wrap})`
+    return await doUrlReplace(rawUrl, matched, replacer)
   })
 }
 
+function rewriteCssImageSet(
+  css: string,
+  replacer: CssUrlReplacer
+): Promise<string> {
+  return asyncReplace(css, cssImageSetRE, async (match) => {
+    let [matched, rawUrl] = match
+    const url = await processSrcSet(rawUrl, ({ url }) =>
+      doUrlReplace(url, matched, replacer)
+    )
+    return `image-set(${url})`
+  })
+}
+async function doUrlReplace(
+  rawUrl: string,
+  matched: string,
+  replacer: CssUrlReplacer
+) {
+  let wrap = ''
+  const first = rawUrl[0]
+  if (first === `"` || first === `'`) {
+    wrap = first
+    rawUrl = rawUrl.slice(1, -1)
+  }
+  if (isExternalUrl(rawUrl) || isDataUrl(rawUrl) || rawUrl.startsWith('#')) {
+    return matched
+  }
+
+  return `url(${wrap}${await replacer(rawUrl)}${wrap})`
+}
+
 let CleanCSS: any
 
 async function minifyCSS(css: string, config: ResolvedConfig) {

diff --git a/packages/vite/src/node/plugins/html.ts b/packages/vite/src/node/plugins/html.ts
@@ -8,7 +8,8 @@ import {
   cleanUrl,
   isExternalUrl,
   isDataUrl,
-  generateCodeFrame
+  generateCodeFrame,
+  processSrcSet
 } from '../utils'
 import { ResolvedConfig } from '../config'
 import MagicString from 'magic-string'
@@ -69,7 +70,7 @@ export const assetAttrsConfig: Record<string, string[]> = {
   link: ['href'],
   video: ['src', 'poster'],
   source: ['src'],
-  img: ['src'],
+  img: ['src', 'srcset'],
   image: ['xlink:href', 'href'],
   use: ['xlink:href', 'href']
 }
@@ -233,7 +234,13 @@ export function buildHtmlPlugin(config: ResolvedConfig): Plugin {
         for (const attr of assetUrls) {
           const value = attr.value!
           try {
-            const url = await urlToBuiltUrl(value.content, id, config, this)
+            const url =
+              attr.name === 'srcset'
+                ? await processSrcSet(value.content, ({ url }) =>
+                    urlToBuiltUrl(url, id, config, this)
+                  )
+                : await urlToBuiltUrl(value.content, id, config, this)
+
             s.overwrite(
               value.loc.start.offset,
               value.loc.end.offset,

diff --git a/packages/vite/src/node/utils.ts b/packages/vite/src/node/utils.ts
@@ -352,3 +352,38 @@ export function ensureWatchedFile(
     watcher.add(path.resolve(file))
   }
 }
+
+interface ImageCandidate {
+  url: string
+  descriptor: string
+}
+const escapedSpaceCharacters = /( |\\t|\\n|\\f|\\r)+/g
+export async function processSrcSet(
+  srcs: string,
+  replacer: (arg: ImageCandidate) => Promise<string>
+) {
+  const imageCandidates: ImageCandidate[] = srcs.split(',').map((s) => {
+    const [url, descriptor] = s
+      .replace(escapedSpaceCharacters, ' ')
+      .trim()
+      .split(' ', 2)
+    return { url, descriptor }
+  })
+
+  const ret = await Promise.all(
+    imageCandidates.map(async ({ url, descriptor }) => {
+      return {
+        url: await replacer({ url, descriptor }),
+        descriptor
+      }
+    })
+  )
+
+  const url = ret.reduce((prev, { url, descriptor }, index) => {
+    descriptor = descriptor || ''
+    return (prev +=
+      url + ` ${descriptor}${index === ret.length - 1 ? '' : ', '}`)
+  }, '')
+
+  return url
+}