emilk · ktmeaton · Oct 30, 2024
diff --git a/web_demo/index.html b/web_demo/index.html
@@ -7,6 +7,7 @@
 
 <head>
     <title>egui – An immediate mode GUI written in Rust</title>
+    <link rel="manifest" href="./manifest.json" />
     <style>
         html {
             /* Remove touch delay: */
@@ -116,6 +117,13 @@
         // `no_modules.js` script doesn't have access to it. You won't need this
         // hack when deploying over HTTP.
         delete WebAssembly.instantiateStreaming;
+        // Service Workflow for Progressive Web App (PWA)
+        if (navigator.serviceWorker) {
+            navigator.serviceWorker
+                .register("./sw.js")
+                .then(res => console.log("service worker registered"))
+                .catch(err => console.log("service worker not registered", err))
+        }
     </script>
 
     <!-- this is the JS generated by the `wasm-bindgen` CLI tool -->

diff --git a/web_demo/manifest.json b/web_demo/manifest.json
@@ -0,0 +1,19 @@
+{
+    "name": "egui demo app",
+    "short_name": "egui demo",
+    "start_url": "index.html",
+    "display": "standalone",
+    "description": "The egui demo app",
+    "dir": "auto",
+    "theme_color": "#000000",
+    "background_color": "#000000",
+    "orientation": "any",
+    "icons": [
+        {
+            "src": "https://ui-avatars.com/api/?name=Egui?s=512",
+            "sizes": "512x512",
+            "type": "image/png",
+            "purpose": "any"
+        }
+    ]
+}
diff --git a/web_demo/sw.js b/web_demo/sw.js
@@ -0,0 +1,93 @@
+
+// Based off of https://github.com/pwa-builder/PWABuilder/blob/main/docs/sw.js
+
+/*
+  Welcome to our basic Service Worker! This Service Worker offers a basic offline experience
+  while also being easily customizable. You can add in your own code to implement the capabilities
+  listed below, or change anything else you would like.
+
+
+  Need an introduction to Service Workers? Check our docs here: https://docs.pwabuilder.com/#/home/sw-intro
+  Want to learn more about how our Service Worker generation works? Check our docs here: https://docs.pwabuilder.com/#/studio/existing-app?id=add-a-service-worker
+
+  Did you know that Service Workers offer many more capabilities than just offline?
+    - Background Sync: https://microsoft.github.io/win-student-devs/#/30DaysOfPWA/advanced-capabilities/06
+    - Periodic Background Sync: https://web.dev/periodic-background-sync/
+    - Push Notifications: https://microsoft.github.io/win-student-devs/#/30DaysOfPWA/advanced-capabilities/07?id=push-notifications-on-the-web
+    - Badges: https://microsoft.github.io/win-student-devs/#/30DaysOfPWA/advanced-capabilities/07?id=application-badges
+*/
+
+const HOSTNAME_WHITELIST = [
+    self.location.hostname,
+    'fonts.gstatic.com',
+    'fonts.googleapis.com',
+    'cdn.jsdelivr.net'
+]
+
+// The Util Function to hack URLs of intercepted requests
+const getFixedUrl = (req) => {
+    var now = Date.now()
+    var url = new URL(req.url)
+
+    // 1. fixed http URL
+    // Just keep syncing with location.protocol
+    // fetch(httpURL) belongs to active mixed content.
+    // And fetch(httpRequest) is not supported yet.
+    url.protocol = self.location.protocol
+
+    // 2. add query for caching-busting.
+    // Github Pages served with Cache-Control: max-age=600
+    // max-age on mutable content is error-prone, with SW life of bugs can even extend.
+    // Until cache mode of Fetch API landed, we have to workaround cache-busting with query string.
+    // Cache-Control-Bug: https://bugs.chromium.org/p/chromium/issues/detail?id=453190
+    if (url.hostname === self.location.hostname) {
+        url.search += (url.search ? '&' : '?') + 'cache-bust=' + now
+    }
+    return url.href
+}
+
+/**
+ *  @Lifecycle Activate
+ *  New one activated when old isnt being used.
+ *
+ *  waitUntil(): activating ====> activated
+ */
+self.addEventListener('activate', event => {
+    event.waitUntil(self.clients.claim())
+})
+
+/**
+ *  @Functional Fetch
+ *  All network requests are being intercepted here.
+ *
+ *  void respondWith(Promise<Response> r)
+ */
+self.addEventListener('fetch', event => {
+    // Skip some of cross-origin requests, like those for Google Analytics.
+    if (HOSTNAME_WHITELIST.indexOf(new URL(event.request.url).hostname) > -1) {
+        // Stale-while-revalidate
+        // similar to HTTP's stale-while-revalidate: https://www.mnot.net/blog/2007/12/12/stale
+        // Upgrade from Jake's to Surma's: https://gist.github.com/surma/eb441223daaedf880801ad80006389f1
+        const cached = caches.match(event.request)
+        const fixedUrl = getFixedUrl(event.request)
+        const fetched = fetch(fixedUrl, { cache: 'no-store' })
+        const fetchedCopy = fetched.then(resp => resp.clone())
+
+        // Call respondWith() with whatever we get first.
+        // If the fetch fails (e.g disconnected), wait for the cache.
+        // If there’s nothing in cache, wait for the fetch.
+        // If neither yields a response, return offline pages.
+        event.respondWith(
+            Promise.race([fetched.catch(_ => cached), cached])
+                .then(resp => resp || fetched)
+                .catch(_ => { /* eat any errors */ })
+        )
+
+        // Update the cache with the version we fetched (only for ok status)
+        event.waitUntil(
+            Promise.all([fetchedCopy, caches.open("pwa-cache")])
+                .then(([response, cache]) => response.ok && cache.put(event.request, response))
+                .catch(_ => { /* eat any errors */ })
+        )
+    }
+})