Add offline support

2 files changed, 68 insertions, 1 deletions

diff --git a/appcache.js b/appcache.js
new file mode 100644
index 0000000..87d5e80
--- /dev/null
+++ b/appcache.js
@@ -0,0 +1,60 @@
+/*
+ * appcache.js
+ * Part of Pointless Viewer, a Beamer presentation viewer
+ * Copyright 2018 Pacien TRAN-GIRARD
+ * License: GNU GPL v3
+ */
+
+"use strict";
+
+class AppCache {
+  constructor() {
+    this.cacheName = "cache";
+    this.filesToCache = [
+      "viewer.html",
+      "appcache.js",
+
+      "pointless/pdfjs/pdf.js",
+      "pointless/pdfjs/pdf.worker.js",
+
+      "pointless/viewer/viewer.css",
+      "pointless/viewer/init.js",
+      "pointless/viewer/viewer.js",
+      "pointless/viewer/presentation.js",
+      "pointless/viewer/stage.js",
+      "pointless/viewer/screen.js",
+      "pointless/viewer/timer.js"
+    ];
+
+    var appCache = this;
+    self.addEventListener("install", function(event) {
+      event.waitUntil(appCache._onInstall());
+    });
+
+    self.addEventListener("fetch", function(event) {
+      event.respondWith(appCache._onFetch(event.request));
+    });
+  }
+
+  _onInstall() {
+    var self = this;
+    return caches.open(this.cacheName).then(function(cache) {
+      return cache.addAll(self.filesToCache);
+    });
+  }
+
+  _onFetch(request) {
+    return navigator.onLine ? this._fetchUpdate(request) : caches.match(request);
+  }
+
+  _fetchUpdate(request) {
+    return caches.open(this.cacheName).then(function(cache) {
+      return fetch(request).then(function(response) {
+        cache.put(request, response.clone());
+        return response
+      });
+    });
+  }
+}
+
+var appCache = new AppCache();
diff --git a/pointless/viewer/init.js b/pointless/viewer/init.js
index 9454a23..9ba881c 100644
--- a/pointless/viewer/init.js
+++ b/pointless/viewer/init.js
@@ -20,9 +20,16 @@ function isController() {
   return window.opener == null || window.opener.location.href != window.location.href;
 }
 
+function initCache() {
+  if (!navigator.serviceWorker) return;
+  navigator.serviceWorker.register("appcache.js");
+}
+
 function init() {
+  initCache();
+
   var viewer = new Viewer();
-  
+
   if ("file" in params)
     viewer.load(params["file"]);
 }