Flow initial pwa

flow-server/src/main/java/com/vaadin/flow/server/BootstrapHandler.java

@@ -74,7 +74,6 @@
 import elemental.json.JsonObject;
 import elemental.json.JsonValue;
 import elemental.json.impl.JsonUtil;
-
 import static java.nio.charset.StandardCharsets.UTF_8;
 
 /**
@@ -94,6 +93,7 @@ public class BootstrapHandler extends SynchronizedRequestHandler {
     private static final String DEFER_ATTRIBUTE = "defer";
     static final String VIEWPORT = "viewport";
     private static final String META_TAG = "meta";
+    private static final String SCRIPT_TAG = "script";
 
     /**
      * Location of client nocache file, relative to the context root.
@@ -461,7 +461,7 @@ private static void exportUsageStatistics(Document document) {
         }).collect(Collectors.joining("\n"));
 
         if (!registerScript.isEmpty()) {
-            document.body().appendElement("script").text(registerScript);
+            document.body().appendElement(SCRIPT_TAG).text(registerScript);
         }
     }
 
@@ -569,6 +569,7 @@ private static void writeBootstrapPage(VaadinResponse response, String html)
     private static List<Element> setupDocumentHead(Element head,
             BootstrapContext context) {
         setupMetaAndTitle(head, context);
+        setupPwa(head, context);
         setupCss(head, context);
 
         JsonObject initialUIDL = getInitialUidl(context.getUI());
@@ -701,6 +702,51 @@ private static void setupMetaAndTitle(Element head,
         });
     }
 
+    private static void setupPwa(Element head, BootstrapContext context) {
+        VaadinService vaadinService = context.getSession().getService();
+        if (vaadinService == null) {
+            return;
+        }
+
+        PwaRegistry registry = vaadinService.getPwaRegistry();
+        if (registry == null) {
+            return;
+        }
+
+        PwaConfiguration config = registry.getPwaConfiguration();
+
+        if (config.isEnabled()) {
+            // Describe PWA capability for iOS devices
+            head.appendElement(META_TAG)
+                    .attr("name", "apple-mobile-web-app-capable")
+                    .attr(CONTENT_ATTRIBUTE, "yes");
+
+            // Theme color
+            head.appendElement(META_TAG).attr("name", "theme-color")
+                    .attr(CONTENT_ATTRIBUTE, config.getThemeColor());
+            head.appendElement(META_TAG)
+                    .attr("name", "apple-mobile-web-app-status-bar-style")
+                    .attr(CONTENT_ATTRIBUTE, config.getThemeColor());
+
+            // Add manifest
+            head.appendElement("link").attr("rel", "manifest").attr("href",
+                    config.getManifestPath());
+
+            // Add icons
+            for (PwaIcon icon : registry.getHeaderIcons()) {
+                head.appendChild(icon.asElement());
+            }
+
+            // Add service worker initialization
+            head.appendElement(SCRIPT_TAG)
+                    .text("if ('serviceWorker' in navigator) {\n"
+                            + "  window.addEventListener('load', function() {\n"
+                            + "    navigator.serviceWorker.register('"
+                            + config.getServiceWorkerPath() + "');\n"
+                            + "  });\n" + "}");
+        }
+    }
+
     private static void appendWebComponentsPolyfills(Element head,
             BootstrapContext context) {
         VaadinSession session = context.getSession();
@@ -751,7 +797,7 @@ private static Element createInlineJavaScriptElement(
 
     private static Element createJavaScriptElement(String sourceUrl,
             boolean defer) {
-        Element jsElement = new Element(Tag.valueOf("script"), "")
+        Element jsElement = new Element(Tag.valueOf(SCRIPT_TAG), "")
                 .attr("type", "text/javascript").attr(DEFER_ATTRIBUTE, defer);
         if (sourceUrl != null) {
             jsElement = jsElement.attr("src", sourceUrl);

flow-server/src/main/java/com/vaadin/flow/server/PWA.java

@@ -0,0 +1,150 @@
+/*
+ * Copyright 2000-2018 Vaadin Ltd.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not
+ * use this file except in compliance with the License. You may obtain a copy of
+ * the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations under
+ * the License.
+ */
+package com.vaadin.flow.server;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Defines application PWA properties.
+ *
+ * Annotation activates automatic
+ * <a href="https://developer.mozilla.org/en-US/Apps/Progressive">PWA</a>
+ * injecting.
+ * <p>
+ * Only one annotation for application is supported. Annotation must be placed
+ * to master layout.
+ *
+ * Application annotated the annotation will add following capabilities to Flow
+ * application:
+ *
+ * <ul>
+ * <li>handle manifest.json
+ * <li>handle sw.js (service worker), which will enable simple offline fallback
+ * and file caching
+ * <li>handle default (static) offline html page
+ * <li>handle different versions (sizes) of the given logo
+ * <li>inject needed tags to the app's page header
+ * </ul>
+ *
+ * Any of the handled resources can be explicitly overridden with static file in
+ * public resources. For example, if {@literal manifest.json} is available in
+ * webapp root folder it will be served instead of generated
+ * {@literal manifest.json}. Same applies for service worker and generated
+ * icons.
+ *
+ * @see <a href=
+ *      "https://developer.mozilla.org/en-US/Apps/Progressive">https://developer.mozilla.org/en-US/Apps/Progressive</a>
+ */
+@Retention(RetentionPolicy.RUNTIME)
+@Target(ElementType.TYPE)
+public @interface PWA {
+
+    /**
+     * Path to the static offline html file.
+     *
+     * Defaults to (relative) {@literal offline.html} with default configuration
+     * that is {@literal webapp/offline.html}
+     *
+     * If offline file is not found, falls back to default offline page.
+     *
+     * @return path to the static offline html file
+     */
+    String offlinePath() default PwaConfiguration.DEFAULT_OFFLINE_PATH;
+
+    /**
+     * Path to the manifest file.
+     *
+     * Defaults to (relative) {@literal manifest.json} with default
+     * configuration that is {@literal webapp/manifest.json}
+     *
+     * @return path to the manifest file
+     */
+    String manifestPath() default PwaConfiguration.DEFAULT_PATH;
+
+    /**
+     * Path to the application logo file.
+     *
+     * Defaults to (relative) {@literal icons/logo.png} with default
+     * configuration that is {@literal webapp/manifest.json}
+     *
+     * If the specified logo file is not found, the default one will be used.
+     * The file is also used to create different sizes of logo.
+     *
+     * @return path to the application logo file
+     */
+    String logoPath() default PwaConfiguration.DEFAULT_LOGO;
+
+    /**
+     * Name of the application.
+     *
+     * @return name of the application
+     */
+    String name();
+
+    /**
+     * Short name for the application. Maximum of 12 characters.
+     *
+     * @return short name for the application
+     */
+    String shortName();
+
+    /**
+     * Description of the application.
+     *
+     * @return description of the application
+     */
+    String description() default "";
+
+    /**
+     * Theme color of the application.
+     *
+     * The theme color sets the color of the application's tool bar and
+     * application's color in the task switcher.
+     *
+     * @return theme color of the application
+     */
+    String themeColor() default PwaConfiguration.DEFAULT_THEME_COLOR;
+
+    /**
+     * Background color of the application.
+     *
+     * The background color property is used on the splash screen when the
+     * application is first launched.
+     *
+     * @return Background color of the application
+     */
+    String backgroundColor() default PwaConfiguration.DEFAULT_BACKGROUND_COLOR;
+
+    /**
+     * Defines the developers’ preferred display mode for the website.
+     *
+     * Possible values: fullscreen, standalone, minimal-ui, browser
+     *
+     * @return display mode of application
+     */
+    String display() default PwaConfiguration.DEFAULT_DISPLAY;
+
+    /**
+     * Offline resources to be cached using the service worker.
+     *
+     * @return offline resources to be cached
+     */
+    String[] offlineResources() default {};
+
+}