Serve the MealQuest favicon instead of the browser default (Maestro 7c778111) (#213)

Co-authored-by: orchestrator-agent <20+orchestrator-agent@code.cubecraftcreations.com>

web/index.html

@@ -4,6 +4,9 @@
     <meta charset="UTF-8" />
     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
     <meta name="theme-color" content="#5a358c" />
+    <link rel="icon" href="/favicon.ico" sizes="16x16 32x32 48x48" />
+    <link rel="icon" type="image/png" sizes="32x32" href="/icons/favicon-32.png" />
+    <link rel="icon" type="image/png" sizes="16x16" href="/icons/favicon-16.png" />
     <link rel="apple-touch-icon" href="/apple-touch-icon.png" />
     <title>MealQuest</title>
   </head>

web/scripts/generate-icons/main.go

@@ -1,5 +1,5 @@
-// Command generate-icons writes the PWA icons in web/public from the
+// Command generate-icons writes the PWA icons and favicons in web/public from
-// MealQuest logo. Run it from the repository root:
+// the MealQuest logo. Run it from the repository root:
 //
 //	go run ./web/scripts/generate-icons
 //
@@ -9,10 +9,13 @@
 package main
 
 import (
+	"bytes"
+	"encoding/binary"
 	"fmt"
 	"image"
 	"image/color"
 	"image/png"
+	"io"
 	"math"
 	"os"
 	"path/filepath"
@@ -27,6 +30,9 @@ const (
 	maskableScale = 0.66
 )
 
+// faviconSizes are the images packed into favicon.ico.
+var faviconSizes = []int{16, 32, 48}
+
 func main() {
 	if err := run(); err != nil {
 		fmt.Fprintln(os.Stderr, "generate-icons:", err)
@@ -49,6 +55,8 @@ func run() error {
 		{"icons/icon-192.png", resized(logo, 192)},
 		{"icons/icon-512.png", resized(logo, 512)},
 		{"icons/icon-maskable-512.png", maskable(logo, 512)},
+		{"icons/favicon-16.png", resized(logo, 16)},
+		{"icons/favicon-32.png", resized(logo, 32)},
 		{"apple-touch-icon.png", resized(logo, 180)},
 	}
 	for _, out := range outputs {
@@ -58,9 +66,53 @@ func run() error {
 		}
 		fmt.Printf("wrote %s (%dx%d)\n", path, out.image.Rect.Dx(), out.image.Rect.Dy())
 	}
+	ico, err := favicon(logo)
+	if err != nil {
+		return err
+	}
+	path := filepath.Join(public, "favicon.ico")
+	if err := os.WriteFile(path, ico, 0o644); err != nil {
+		return err
+	}
+	fmt.Printf("wrote %s (%v)\n", path, faviconSizes)
 	return nil
 }
 
+// favicon is an ICO file holding the logo at each of faviconSizes as an
+// embedded PNG: a 6-byte header, a 16-byte directory entry per image, then
+// the images.
+func favicon(logo image.Image) ([]byte, error) {
+	var images [][]byte
+	for _, size := range faviconSizes {
+		var buf bytes.Buffer
+		if err := encode(&buf, resized(logo, size)); err != nil {
+			return nil, fmt.Errorf("encode favicon %dx%d: %w", size, size, err)
+		}
+		images = append(images, buf.Bytes())
+	}
+	var out bytes.Buffer
+	le := binary.LittleEndian
+	out.Write(le.AppendUint16(nil, 0))                   // reserved
+	out.Write(le.AppendUint16(nil, 1))                   // type: icon
+	out.Write(le.AppendUint16(nil, uint16(len(images)))) // image count
+	offset := 6 + 16*len(images)
+	for i, size := range faviconSizes {
+		out.WriteByte(byte(size))           // width
+		out.WriteByte(byte(size))           // height
+		out.WriteByte(0)                    // palette size: none
+		out.WriteByte(0)                    // reserved
+		out.Write(le.AppendUint16(nil, 1))  // colour planes
+		out.Write(le.AppendUint16(nil, 32)) // bits per pixel
+		out.Write(le.AppendUint32(nil, uint32(len(images[i]))))
+		out.Write(le.AppendUint32(nil, uint32(offset)))
+		offset += len(images[i])
+	}
+	for _, img := range images {
+		out.Write(img)
+	}
+	return out.Bytes(), nil
+}
+
 // load decodes the logo. The file is a PNG despite its .jpg name, so the
 // format is sniffed rather than taken from the extension.
 func load(path string) (image.Image, error) {
@@ -84,14 +136,18 @@ func save(path string, img image.Image) error {
 	if err != nil {
 		return err
 	}
-	enc := png.Encoder{CompressionLevel: png.BestCompression}
+	if err := encode(f, img); err != nil {
-	if err := enc.Encode(f, img); err != nil {
 		f.Close()
 		return fmt.Errorf("encode %s: %w", path, err)
 	}
 	return f.Close()
 }
 
+func encode(w io.Writer, img image.Image) error {
+	enc := png.Encoder{CompressionLevel: png.BestCompression}
+	return enc.Encode(w, img)
+}
+
 func resized(logo image.Image, size int) *image.RGBA {
 	dst := image.NewRGBA(image.Rect(0, 0, size, size))
 	draw.CatmullRom.Scale(dst, dst.Rect, logo, logo.Bounds(), draw.Src, nil)

web/src/pwa.test.ts

@@ -1,7 +1,8 @@
 // @vitest-environment node
 // Builds the app with the production config and serves the result, so the
 // assertions cover what ships in dist: the web manifest, the service worker,
-// every icon, and the service worker registration that only builds include.
+// every icon and favicon, and the service worker registration that only builds
+// include.
 import { afterAll, beforeAll, describe, expect, it } from 'vitest'
 import { build, createServer, preview, type PreviewServer, type ViteDevServer } from 'vite'
 import tokens from './styles/tokens.css?raw'
@@ -12,9 +13,13 @@ const icons = [
   { path: '/icons/icon-192.png', size: 192 },
   { path: '/icons/icon-512.png', size: 512 },
   { path: '/icons/icon-maskable-512.png', size: 512 },
+  { path: '/icons/favicon-16.png', size: 16 },
+  { path: '/icons/favicon-32.png', size: 32 },
   { path: '/apple-touch-icon.png', size: 180 },
 ]
 
+const faviconSizes = [16, 32, 48]
+
 function token(name: string): string {
   const value = tokens.match(new RegExp(`^\\s*${name}:\\s*([^;\\s]+);`, 'm'))?.[1]
   if (!value) throw new Error(`${name} is not defined in tokens.css`)
@@ -38,6 +43,18 @@ function pngSize(bytes: Uint8Array): { width: number; height: number } {
   return { width: view.getUint32(16), height: view.getUint32(20) }
 }
 
+// The images in an ICO file: a 6-byte header (reserved, type 1, count), then
+// a 16-byte directory entry per image giving its byte length and offset.
+function icoImages(bytes: Uint8Array): Uint8Array[] {
+  const view = new DataView(bytes.buffer, bytes.byteOffset, bytes.byteLength)
+  expect([view.getUint16(0, true), view.getUint16(2, true)]).toEqual([0, 1])
+  return Array.from({ length: view.getUint16(4, true) }, (_, i) => {
+    const entry = 6 + 16 * i
+    const offset = view.getUint32(entry + 12, true)
+    return bytes.subarray(offset, offset + view.getUint32(entry + 8, true))
+  })
+}
+
 describe('production build', () => {
   let server: PreviewServer
   let origin: string
@@ -94,13 +111,25 @@ describe('production build', () => {
     expect(pngSize(bytes)).toEqual({ width: size, height: size })
   })
 
+  it('ships /favicon.ico holding the logo as PNGs at every favicon size', async () => {
+    const bytes = new Uint8Array(await (await get('/favicon.ico')).arrayBuffer())
+    expect(icoImages(bytes).map((png) => pngSize(png))).toEqual(
+      faviconSizes.map((size) => ({ width: size, height: size })),
+    )
+  })
+
   it('emits sw.js with the precache list injected', async () => {
     const sw = await (await get('/sw.js')).text()
     expect(sw).not.toContain('self.__WB_MANIFEST')
     expect(sw).toContain('"url":"index.html"')
-    for (const { path } of icons.slice(0, 3)) {
+  })
-      expect(sw).toContain(`"url":"${path.slice(1)}"`)
+
+  it('precaches every icon and favicon so the offline shell keeps them', async () => {
+    const urls = precacheEntries(await (await get('/sw.js')).text()).map((entry) => entry.url)
+    for (const path of [...icons.map((icon) => icon.path), '/favicon.ico']) {
+      expect(urls).toContain(path.slice(1))
     }
+    expect(new Set(urls).size, 'precache URLs are unique').toBe(urls.length)
   })
 
   it('precaches the shell, JS, CSS and every self-hosted font', async () => {
@@ -129,6 +158,17 @@ describe('production build', () => {
     expect(html).toContain('<link rel="apple-touch-icon" href="/apple-touch-icon.png" />')
   })
 
+  it('links the favicons from index.html', async () => {
+    const html = await (await get('/')).text()
+    expect(html).toContain('<link rel="icon" href="/favicon.ico" sizes="16x16 32x32 48x48" />')
+    expect(html).toContain(
+      '<link rel="icon" type="image/png" sizes="32x32" href="/icons/favicon-32.png" />',
+    )
+    expect(html).toContain(
+      '<link rel="icon" type="image/png" sizes="16x16" href="/icons/favicon-16.png" />',
+    )
+  })
+
   it('registers /sw.js at scope / from index.html', async () => {
     const html = await (await get('/')).text()
     expect(html).toContain('<script id="vite-plugin-pwa:register-sw" src="/registerSW.js"></script>')

web/vite.config.ts

@@ -17,8 +17,11 @@ export default defineConfig({
       srcDir: 'src',
       filename: 'sw.ts',
       injectRegister: 'script',
-      // Precache the shell, JS, CSS and the self-hosted fonts.
+      // Precache the shell, JS, CSS, the self-hosted fonts and every icon
-      injectManifest: { globPatterns: ['**/*.{html,js,css,woff2}'] },
+      // and favicon. The glob already covers the manifest icons, so the
+      // plugin does not add them a second time.
+      injectManifest: { globPatterns: ['**/*.{html,js,css,woff2,png,ico}'] },
+      includeManifestIcons: false,
       // The web manifest lives in manifest.json: its theme and background
       // colours are --color-accent and --color-bg from src/styles/tokens.css,
       // and hex colours may not be written in TypeScript.