Flow initial pwa

flow-server/src/main/java/com/vaadin/flow/dom/Icon.java

@@ -0,0 +1,321 @@
+package com.vaadin.flow.dom;
+
+import javax.imageio.ImageIO;
+import java.awt.image.BufferedImage;
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.OutputStream;
+import java.io.Serializable;
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.Map;
+
+import org.jsoup.nodes.Element;
+
+/**
+ * Implementation of icon -element.
+ *
+ * Creates the href automatically based on
+ * - baseName (the file name with path, as "icons/icon.png"
+ * - width (width of icon)
+ * - height (height of icon)
+ * - (possibly) fileHash (the hashcode of image file)
+ *
+ * The href will be set as:
+ * [basename]-[width]x[height].png{?[filehash]}
+ *
+ * The trailing ?[filehash] will be added if icon cache is not controlled
+ * by service worker: cached = false
+ *
+ * So caching of a icon is left left for browser if it's not cached with
+ * service worker.
+ *
+ */
+public class Icon implements Serializable {
+    /**
+     * Where icon belongs to.
+     *
+     * In header or manifest.json.
+     *
+     */
+    public enum Domain {
+        HEADER,
+        MANIFEST;
+    }
+
+    private boolean cached = false;
+    private int width = 0;
+    private int height = 0;
+    private long fileHash = 0;
+    private String baseName = "icons/icon.png";
+    private Domain domain = Domain.HEADER;
+    private boolean hrefOverride = false;
+    private byte[] data;
+
+    private Map<String, String> attributes = new HashMap<>();
+    private String tag = "link";
+
+    public Icon() {
+        attr("type", "image/png");
+        rel("icon");
+    }
+
+    /**
+     * Chaining setter for size.
+     *
+     * @param width width of icon
+     * @param height height of icon
+     * @return self
+     */
+    public Icon size(int width, int height) {
+        this.width = width;
+        this.height = height;
+
+        attr("sizes", width + "x" + height);
+        setRelativeName();
+        return this;
+    }
+
+    /**
+     * Gets an {@link Element} presentation of the icon.
+     *
+     * @return an {@link Element} presentation of the icon
+     */
+    public Element asElement() {
+        Element element = new Element(tag);
+        attributes.entrySet().forEach(entry -> {
+            element.attr(entry.getKey(), entry.getValue());
+        });
+        return element;
+    }
+
+    private Icon attr(String key, String value) {
+        attributes.put(key, value);
+        return this;
+    }
+
+    private String attr(String key) {
+        return attributes.get(key);
+    }
+
+    /**
+     * Width of icon.
+     *
+     * @return Width of icon
+     */
+    public int getWidth() {
+        return width;
+    }
+
+    /**
+     * Height of icon.
+     *
+     * @return Height of icon
+     */
+    public int getHeight() {
+        return height;
+    }
+
+    /**
+     * Should the icon be cached viá Service Worker.
+     *
+     * @return Should the icon be cached viá Service Worker.
+     */
+    public boolean cached() {
+        return cached;
+    }
+
+    /**
+     * Chained setter for chained.
+     *
+     * @param cached Should the icon cached viá Service Worker
+     * @return
+     */
+    public Icon cached(boolean cached) {
+        this.cached = cached;
+        return this;
+    }
+
+    /**
+     * Sets the href based on icon values.
+     *
+     */
+    private void setRelativeName() {
+        if (!hrefOverride) {
+            int split = baseName.lastIndexOf(".");
+            String link = baseName.substring(0,split) + "-" + sizes() +
+                    baseName.substring(split);
+            if (!cached) {
+                link = link + "?" + fileHash;
+            }
+            attr("href", link);
+        }
+    }
+
+    /**
+     * Gets string for sizes -attribute.
+     *
+     *
+     * @return a String as [size]x[size]
+     */
+    public String sizes() {
+        return attr("sizes");
+    }
+
+    /**
+     * Chaining setter of href -attribute.
+     *
+     * Href is forced as relative, so all [./] -chars are removed from the
+     * start of the href.
+     *
+     * Href is always set when either size or basename is set.
+     *
+     * @param href href
+     * @return self
+     */
+    public Icon href(String href) {
+        hrefOverride = true;
+        attr("href", href.replaceAll("^[\\./]+", ""));
+        return this;
+    }
+
+    /**
+     * href attribute.
+     *
+     * @return href attribute
+     */
+    public String href() {
+        return attr("href");
+    }
+
+    /**
+     * Return href with '/' -prefix and removed possible ?[fileHash].
+     *
+     * Used in matching, when serving images.
+     *
+     * @return Return href with '/' -prefix and removed possible ?[fileHash]
+     */
+    public String relHref() {
+        String[] splitted = href().split("\\?");
+        return "/" + splitted[0];
+    }
+
+    /**'
+     * Gets the cache-string used in Google Workbox caching.
+     *
+     * @return "{ url: '[href]', revision: '[fileHash' }"
+     */
+    public String cache() {
+        return String.format("{ url: '%s', revision: '%s' }", href(),
+                fileHash);
+    }
+
+    /**
+     * Getter for rel attribute.
+     *
+     * @return rel attribute
+     */
+    public String rel() {
+        return attr("rel");
+    }
+
+    /**
+     * Chaining setter for rel-attribute.
+     *
+     * @param rel rel value
+     * @return self
+     */
+    public Icon rel(String rel) {
+        attr("rel", rel);
+        return this;
+    }
+
+    /**
+     * Type attribute.
+     *
+     * @return type -attribute
+     */
+    public String type() {
+        return attr("type");
+    }
+
+    /**
+     * Chaining setter for domain.
+     *
+     * @param domain Domain
+     * @return self
+     */
+    public Icon domain(Domain domain) {
+        this.domain = domain;
+        return this;
+    }
+
+    /**
+     * Domain of icon.
+     *
+     * @return Domain of icon
+     */
+    public Domain domain() {
+        return this.domain;
+    }
+
+    /**
+     * Media attribute.
+     *
+     * @return Media attribute
+     */
+    public String media() {
+        return attr("media");
+    }
+
+    /**
+     * Chaining setter for media attribute.
+     *
+     * @param media media
+     * @return self
+     */
+    public Icon media(String media) {
+        attr("media", media);
+        return this;
+    }
+
+    /**
+     * Chaining setter of basename.
+     *
+     * @param baseName image full name with path, like "icon/icon.png"
+     * @return self
+     */
+    public Icon baseName(String baseName) {
+        this.baseName = baseName;
+        setRelativeName();
+        return this;
+    }
+
+    /**
+     * Sets the image presenting the icon.
+     *
+     * @param image image in png -format
+     * @throws IOException
+     */
+    public void setImage(BufferedImage image) throws IOException {
+        ByteArrayOutputStream baos = new ByteArrayOutputStream();
+        ImageIO.write( image, "png", baos );
+        baos.flush();
+        data = baos.toByteArray();
+        fileHash = Arrays.hashCode(data);
+        setRelativeName();
+        baos.close();
+    }
+
+    /**
+     * Writes the image to output stream.
+     *
+     * @param outputStream  output stream
+     * @throws IOException
+     */
+    public synchronized void write(OutputStream outputStream)
+            throws IOException {
+        outputStream.write(data);
+    }
+
+}

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

@@ -44,6 +44,7 @@
 import com.vaadin.flow.component.page.Inline;
 import com.vaadin.flow.component.page.Push;
 import com.vaadin.flow.component.page.Viewport;
+import com.vaadin.flow.dom.Icon;
 import com.vaadin.flow.function.DeploymentConfiguration;
 import com.vaadin.flow.internal.AnnotationReader;
 import com.vaadin.flow.internal.ReflectTools;
@@ -570,6 +571,7 @@ private static void writeBootstrapPage(VaadinResponse response, String html)
     private static List<Element> setupDocumentHead(Element head,
             BootstrapContext context) {
         setupMetaAndTitle(head, context);
+        setupPWA(head);
         setupCss(head, context);
 
         JsonObject initialUIDL = getInitialUidl(context.getUI());
@@ -701,6 +703,42 @@ private static void setupMetaAndTitle(Element head,
         });
     }
 
+    private static void setupPWA(Element head) {
+        PWARegistry registry = VaadinService.getCurrent().getPwaRegistry();
+
+        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("theme-color", config.getThemeColor());
+            head.appendElement(META_TAG)
+                    .attr("apple-mobile-web-app-status-bar-style",
+                            config.getThemeColor());
+
+            // Add manifest
+            head.appendElement("link").attr("rel", "manifest")
+                    .attr("href", config.getManifestPath());
+
+            // Add icons
+            for (Icon icon : registry.getHeaderIcons()) {
+                head.appendChild(icon.asElement());
+            }
+
+            // Add service worker initialization
+            head.appendElement("script").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();