[HTML5] Add PWA support to the editor page.

This allows to install it as an app, and provide offline support (after the first run). Practically, this boils down to adding a JSON file as a manifest, an offline page to be displayed when the cached files are not avaialble, and a JS file to cache resources and return them. The reason for the "first run requirements" is that some browsers, will emit an "install" by just visiting the page (to see if the JS code is compatibile), and we do not want to force casual visitors to just download the 10 MiB+ compressed editor WebAssembly file without pressing the start button. Special thanks to Hugo Locurcio (Calinou) for the initial work.
author: Fabio Alessandrelli <fabio.alessandrelli@gmail.com> 2021-03-08 15:39:14 +0100
committer: Fabio Alessandrelli <fabio.alessandrelli@gmail.com> 2021-03-08 17:06:24 +0100
commit: d8bd54fbf2c3d10ece692da1a9b47e766cc95fee (patch)
tree: fd094e00d1784378d291aa8be72056356e56df75 /misc
parent: 0816011e86a5ec4dba8e551d602afdbd6b874a09 (diff)
4 files changed, 162 insertions, 2 deletions
diff --git a/misc/dist/html/editor.html b/misc/dist/html/editor.html
index 535721f418..3bf87f3506 100644
--- a/misc/dist/html/editor.html
+++ b/misc/dist/html/editor.html
@@ -2,8 +2,18 @@
 <html xmlns='http://www.w3.org/1999/xhtml' lang='' xml:lang=''>
 <head>
 	<meta charset='utf-8' />
-	<meta name='viewport' content='width=device-width, user-scalable=no' />
+	<meta name='viewport' content='width=device-width, initial-scale=1, minimum-scale=1, maximum-scale=1, user-scalable=no' />
+	<meta name="mobile-web-app-capable" content="yes" />
+	<meta name="apple-mobile-web-app-capable" content="yes" />
+	<meta name="application-name" content="Godot" />
+	<meta name="apple-mobile-web-app-title" content="Godot" />
+	<meta name="theme-color" content="#478cbf" />
+	<meta name="msapplication-navbutton-color" content="#478cbf" />
+	<meta name="apple-mobile-web-app-status-bar-style" content="black-translucent" />
+	<meta name="msapplication-starturl" content="/latest" />
 	<link id='-gd-engine-icon' rel='icon' type='image/png' href='favicon.png' />
+	<link rel="apple-touch-icon" type="image/png" href="favicon.png" />
+	<link rel="manifest" href="manifest.json" />
 	<title>Godot Engine Web Editor (@GODOT_VERSION@)</title>
 	<style>
 		*:focus {
@@ -250,7 +260,13 @@
 			<div id='status-notice' class='godot' style='display: none;'></div>
 		</div>
 	</div>
-
+	<script>
+		window.addEventListener("load", () => {
+			if ("serviceWorker" in navigator) {
+				navigator.serviceWorker.register("service.worker.js");
+			}
+		});
+	</script>
 	<script src='godot.tools.js'></script>
 	<script>//<![CDATA[
 
diff --git a/misc/dist/html/manifest.json b/misc/dist/html/manifest.json
new file mode 100644
index 0000000000..6e0053c23c
--- /dev/null
+++ b/misc/dist/html/manifest.json
@@ -0,0 +1,18 @@
+{
+  "name": "Godot Engine",
+  "short_name": "Godot",
+  "description": "Multi-platform 2D and 3D game engine with a feature-rich editor",
+  "lang": "en",
+  "start_url": "/godot.tools.html",
+  "display": "standalone",
+  "orientation": "landscape",
+  "theme_color": "#478cbf",
+  "icons": [
+    {
+      "src": "favicon.png",
+      "sizes": "256x256",
+      "type": "image/png"
+    }
+  ],
+  "background_color": "#333b4f"
+}
diff --git a/misc/dist/html/offline.html b/misc/dist/html/offline.html
new file mode 100644
index 0000000000..000c21b4d3
--- /dev/null
+++ b/misc/dist/html/offline.html
@@ -0,0 +1,42 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+	<meta charset="utf-8" />
+	<meta http-equiv="X-UA-Compatible" content="IE=edge" />
+	<meta name="viewport" content="width=device-width, initial-scale=1" />
+	<title>You are offline</title>
+	<style>
+		html {
+			background-color: #333b4f;
+			color: #e0e0e0;
+		}
+
+		body {
+			font-family: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans", sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol", "Noto Color Emoji";
+			margin: 2rem;
+		}
+
+		p {
+			margin-block: 1rem;
+		}
+
+		button {
+			display: block;
+			padding: 1rem 2rem;
+			margin: 3rem auto 0;
+		}
+	</style>
+</head>
+<body>
+	<h1>You are offline</h1>
+	<p>This application requires an Internet connection to run for the first time.</p>
+	<p>Press the button below to try reloading:</p>
+	<button type="button">Reload</button>
+
+	<script>
+		document.querySelector("button").addEventListener("click", () => {
+			window.location.reload();
+		});
+	</script>
+</body>
+</html>
diff --git a/misc/dist/html/service-worker.js b/misc/dist/html/service-worker.js
new file mode 100644
index 0000000000..d4eaed2b17
--- /dev/null
+++ b/misc/dist/html/service-worker.js
@@ -0,0 +1,84 @@
+// This service worker is required to expose an exported Godot project as a
+// Progressive Web App. It provides an offline fallback page telling the user
+// that they need an Internet conneciton to run the project if desired.
+// Incrementing CACHE_VERSION will kick off the install event and force
+// previously cached resources to be updated from the network.
+const CACHE_VERSION = "@GODOT_VERSION@";
+const CACHE_NAME = "@GODOT_NAME@-cache";
+const OFFLINE_URL = "offline.html";
+// Files that will be cached on load.
+const CACHED_FILES = [
+	"godot.tools.html",
+	"offline.html",
+	"godot.tools.js",
+	"godot.tools.worker.js",
+	"godot.tools.audio.worklet.js",
+	"logo.svg",
+	"favicon.png",
+];
+
+// Files that we might not want the user to preload, and will only be cached on first load.
+const CACHABLE_FILES = [
+	"godot.tools.wasm",
+];
+const FULL_CACHE = CACHED_FILES.concat(CACHABLE_FILES);
+
+self.addEventListener("install", (event) => {
+	event.waitUntil(async function () {
+		const cache = await caches.open(CACHE_NAME);
+		// Clear old cache (including optionals).
+		await Promise.all(FULL_CACHE.map(path => cache.delete(path)));
+		// Insert new one.
+		const done = await cache.addAll(CACHED_FILES);
+		return done;
+	}());
+});
+
+self.addEventListener("activate", (event) => {
+	event.waitUntil(async function () {
+		if ("navigationPreload" in self.registration) {
+			await self.registration.navigationPreload.enable();
+		}
+	}());
+	// Tell the active service worker to take control of the page immediately.
+	self.clients.claim();
+});
+
+self.addEventListener("fetch", (event) => {
+	const isNavigate = event.request.mode === "navigate";
+	const url = event.request.url || "";
+	const referrer = event.request.referrer || "";
+	const base = referrer.slice(0, referrer.lastIndexOf("/") + 1);
+	const local = url.startsWith(base) ? url.replace(base, "") : "";
+	const isCachable = FULL_CACHE.some(v => v === local) || (base === referrer && base.endsWith(CACHED_FILES[0]));
+	if (isNavigate || isCachable) {
+		event.respondWith(async function () {
+			try {
+				// Use the preloaded response, if it's there
+				let request = event.request.clone();
+				let response = await event.preloadResponse;
+				if (!response) {
+					// Or, go over network.
+					response = await fetch(event.request);
+				}
+				if (isCachable) {
+					// Update the cache
+					const cache = await caches.open(CACHE_NAME);
+					cache.put(request, response.clone());
+				}
+				return response;
+			} catch (error) {
+				const cache = await caches.open(CACHE_NAME);
+				if (event.request.mode === "navigate") {
+					// Check if we have full cache.
+					const cached = await Promise.all(FULL_CACHE.map(name => cache.match(name)));
+					const missing = cached.some(v => v === undefined);
+					const cachedResponse = missing ? await caches.match(OFFLINE_URL) : await caches.match(CACHED_FILES[0]);
+					return cachedResponse;
+				}
+				const cachedResponse = await caches.match(event.request);
+				return cachedResponse;
+			}
+		}());
+	}
+});
author	Fabio Alessandrelli <fabio.alessandrelli@gmail.com>	2021-03-08 15:39:14 +0100
committer	Fabio Alessandrelli <fabio.alessandrelli@gmail.com>	2021-03-08 17:06:24 +0100
commit	d8bd54fbf2c3d10ece692da1a9b47e766cc95fee (patch)
tree	fd094e00d1784378d291aa8be72056356e56df75 /misc
parent	0816011e86a5ec4dba8e551d602afdbd6b874a09 (diff)