feat: ability to exclude fallback font formats on google provider

src/providers/google.ts

@@ -23,6 +23,12 @@ interface ProviderOption {
     glyphs?: {
       [fontFamily: string]: string[]
     }
+    /**
+     * Experimental: include only modern font format without fallback for old browsers
+     */
+    modernFormatsOnly?: boolean | {
+      [fontFamily: string]: boolean
+    }
   }
 }
 
@@ -113,7 +119,18 @@ export default defineFontProvider<ProviderOption>('google', async (_options = {}
     let priority = 0
     const resolvedFontFaceData: FontFaceData[] = []
 
-    for (const extension in userAgents) {
+    let formats = Object.keys(userAgents)
+    const modernFormatsOnly = _options.experimental?.modernFormatsOnly
+    if (
+      modernFormatsOnly === true
+      || (modernFormatsOnly
+        && typeof modernFormatsOnly === 'object'
+        && modernFormatsOnly?.[family] === true)
+    ) {
+      formats = formats.slice(0, 1) // keep only 1st user agent
+    }
+
+    for (const extension of formats) {
       const rawCss = await $fetch<string>('/css2', {
         baseURL: 'https://fonts.googleapis.com',
         headers: {

test/providers/google.test.ts

@@ -215,4 +215,32 @@ body {
     })
     expect(fonts.length).toBe(18)
   })
+
+  it('experimental.modernFormatsOnly', async () => {
+    const unifont = await createUnifont([
+      providers.google({
+        experimental: {
+          modernFormatsOnly: {
+            Poppins: true,
+          },
+        },
+      }),
+    ])
+    {
+      const { fonts } = await unifont.resolveFont('Poppins', {})
+      const remoteFontSources = fonts.flatMap(fnt =>
+        fnt.src.flatMap(src => ('url' in src ? src : [])),
+      )
+      expect(remoteFontSources).not.toEqual([])
+      expect(remoteFontSources.filter(s => s.format !== 'woff2')).toEqual([])
+    }
+    {
+      const { fonts } = await unifont.resolveFont('Geist', {})
+      const remoteFontSources = fonts.flatMap(fnt =>
+        fnt.src.flatMap(src => ('url' in src ? src : [])),
+      )
+      expect(remoteFontSources).not.toEqual([])
+      expect(remoteFontSources.filter(s => s.format !== 'woff2')).not.toEqual([])
+    }
+  })
 })