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ROCK GWT UI'S WITH POLYMER ELEMENTS
1. Motivations2. What are web components3. What’s polymer4. JsInterop5. GWT consuming web components6. introducing gwt-polymer-elements7. Demo: full-stack gwt app using polymer and rest
services.
Agenda
Motivationspublic void onScrollMove(ScrollMoveEvent event) { int y = scrollPanel.getY(); if (header != null) { if (y > header.getStateSwitchPosition() && headerState != PullState.PULLED) { headerState = PullState.PULLED; scrollPanel.setMinScrollY(0); if (headerPullhandler != null) headerPullhandler.onPullStateChanged(header, headerState); } else { if (y <= header.getStateSwitchPosition() && headerState != PullState.NORMAL) { headerState = PullState.NORMAL; scrollPanel.setMinScrollY(-header.getHeight()); if (headerPullhandler != null) headerPullhandler.onPullStateChanged(header, headerState); } } header.onScroll(y); }
int y_off = y; if (footer != null && y < -footer.getHeight()) { if (footerState == PullState.PULLED) { y_off = y_off - footer.getHeight(); } if (footerState == PullState.NORMAL) { y_off = y_off + footer.getHeight(); } if (y_off < (scrollPanel.getMaxScrollY() - footer.getStateSwitchPosition()) && footerState != PullState.PULLED) { footerState = PullState.PULLED; scrollPanel.setMaxScrollY(scrollPanel.getMaxScrollY() - footer.getHeight()); if (footerPullhandler != null) { footerPullhandler.onPullStateChanged(footer, footerState); } } else { if (y_off > (scrollPanel.getMaxScrollY() - footer.getStateSwitchPosition()) && footerState != PullState.NORMAL) { footerState = PullState.NORMAL; scrollPanel.setMaxScrollY(scrollPanel.getMaxScrollY() + footer.getHeight()); if (footerPullhandler != null) { footerPullhandler.onPullStateChanged(footer, footerState); } } } footer.onScroll(y_off - scrollPanel.getMaxScrollY()); }}
Former Gwt Ui Development- Verbose code- Slow Debug & Test- Difficult to share- Ugly widgetset & no
mobile
Gwt + Web Components- Standard specs.- Ready to use elements- Designers friendly- Active Development
- Google- Vaadin
gwt-classic vs gwt-polymer
6.500 LOChttp://gwt-mobilewebapp.appspot.com/
750 LOChttp://manolo.github.io/gwt-polymer-chat-app/demo/
Vaadin vision of Web Components
What are Web Components?
Problem: DOM unique treebody { background-color: white; }
Solution: Shadow DOM
body { background-color: white; }
Encapsulation
Composition
Community
Web ComponentsState of the art
Browser support
Polyfill
Activity
What’s Polymer
Polymer- Polymer makes it easier and faster to create anything
from a button to a complete application across desktop, mobile, and beyond.
- Polymer ecosystem enables sharing UI components between developers.
- JS estable API & polyfills- Production ready reusable components- Documentation system
- Let's GWT take advantage of the JS ecosystem to create amazing UIs.
Catalog- Iron Elements- Paper Elements -> Material Design- Neon Elements- Platinum Elements- Google Elements
- Vaadin Elements
JsInterop
1. Why JsInteropa. Nowadays most GWT big projects interact with JS libs.b. JSNI is a bad option for complex scenarios
2. JsInterop magic allows interact natively with Js. No JSNI anymore!a. @JsTypeb. @JsProperty @JsConstructor @JsMethod @JsFunction c. Issues ? : experimental, does not extend JSO
3. Elemental-2.0 Interfaces for all HTMLa. Window, Document, Element, Style, Events, …b. Issue: not available yet 2.8.x ?
4. Code generationa. Let’s explore ways to create java boilerplate code
GWT JsInterop
GWT:Consuming Web Components
1. Code Interfaces for Native Objects (Elemental-2)2. Code methods for interacting with Web
Components Spec (create, import ...).3. Define an annotated Java Interface per component,
event or behavior.- Extends HTMLElement or Event
4. Optionally Wrap each Interface in a Widget class for classic GWT apps.
Steps to consume WC in Java
Interfaces for native JS objects
@JsTypepublic interface HTMLElement extends Element {}
@JsTypepublic interface Element extends Node { @JsProperty String getInnerHTML(); @JsProperty DOMTokenList getClassList();
void setAttribute(String name, String value); String getAttribute(String name); void removeAttribute(String name);}
@JsTypepublic interface Node extends EventTarget {}
@JsTypepublic interface EventTarget { void addEventListener(String type, EventListener listener);}
Elemental-2 (gwt-2.8.1)
Utility methods public class Polymer { ... // Ensures that the tagName has been registered, otherwise injects // the appropriate <import> tag in the document header public static void ensureHTMLImport(String tagName) { if ( !registered(tagName)) { String href = GWT.getModuleBaseForStaticFiles() + "bower_components/" + tagName + "/" + tagName + ".html";
Polymer.Base.importHref(href); } } // Returns a new instance of the Element. It loads the webcomponent // if not loaded yet. public static <T> T createElement(String tagName) { ensureHTMLImport(tagName); return (T)Document.get().createElement(tagName); } ...}
The WebComponentElement.java
@JsTypepublic interface PaperButton extends HTMLElement {
@JsProperty PaperButton setLabel(String val); @JsProperty String getLabel();
@JsProperty PaperButton setRaisedButton(boolean val); @JsProperty boolean getRaisedButton();
@JsProperty PaperButton setIcon(String val); @JsProperty String getIcon();
}
Consuming WC in Java (Element API)
// Create a new instance of PaperButton PaperButtonElement button = Polymer.create(PaperButtonElement.TAG);
// Set some properties button.icon("polymer"); button.label("Polymer"); button.raisedButton(false);
// Add event listeners button.addEventListener("click", e -> { });
// Append to the document document.get().ppendChild(button);
The WebComponentWidget.javapublic class PaperButton extends PolymerWidget { //Default Constructor. public PaperButton() { this(""); } //Constructor used by UIBinder public PaperButton(String html) { this(PaperButtonElement.TAG, html); } // Used when this element is extended by another. protected PaperButton(String tag, String html) { super(tag, html); }
// Gets a handle to the Polymer object's underlying DOM element. public PaperButtonElement getPolymerElement() { return (PaperButtonElement) getElement(); } public boolean isRaised() { return getPolymerElement().isRaised(); }}
public class PolymerWidget extends HTMLPanel { public PolymerWidget(String tag, String src, String html) { super(tag, html); Polymer.ensureCustomElement(getElement(), src); } ...}
Consuming WC in Java (Widget API)
// Widgets allow consume WC using the GWT classic way.PaperButton button = new PaperButton();
button.addClickHandler(new ClickHandler() { public void onClick(ClickEvent event) { // ... }});
RootPanel.get().add(button);
Consuming WC in UIBinder<ui:UiBinder xmlns:ui='urn:ui:com.google.gwt.uibinder' xmlns:g='urn:import:com.google.gwt.user.client.ui' xmlns:p='urn:import:com.vaadin.components.gwt.polymer.client.widget'>
<ui:style> .container paper-button.colored { background: #4285f4; color: #fff; }</ui:style>
<g:HTMLPanel> <!-- to use widgets we don’t need to import webcomponents by hand --> <p:PaperButton toggle="" raised="" active="" addStyleNames="{style.colored}">active</p:PaperButton>
<!-- to use elements it’s mandatory to import webcomponents previously --> <paper-button raised="" noink="">Click me</paper-button></g:HTMLPanel>
IntroducingVaadin gwt-polymer
Two Projects1. gwt-api-generator: It’s a code generator to produce
GWT wrappers for JS componentsa. Scrapes source documentationb. Right now polymer, but considering other sources.c. Uses standard JS libraries to parse components.
- node.js, npm, bower, gulp- hydrolysis parser + lodash.template
2. gwt-polymer-elements: a ready-to-use library for using polymer elements in gwt (iron, paper, neon, vaadin)a. Version 1.2.1.0.alpha1 (polymer 1.2.1)
b. Still under definition, expect package name changes, etc
gwt-polymer-elements
GWT
PaperButtonWidget
PolymerWidget
HTMLElement
PaperButtonElement
Polymer
paper-button.html
polimer.jsJsInterop
Vaadingwt-api-generator
1. Add java dependency to your project.- vaadin-gwt-polymer-elements-1.2.1.0-alpha1.jar
2. Inherit it in your GWT module- <inherits name="com.vaadin.polymer.Elements"/>
3. Use new Widgets or Elements as usual- Document.get().createElement("PaperSliderElement")
4. Run mvn clean install to produce your package .jar5. Everything is contained in the artefact
- polyfill, components, java code.
gwt-polymer-elements (bundle)
1. Install the generator - sudo npm install gwt-api-generator -g
2. Install all the components you need for your project.- bower install my-github-account/my-custom-polymer-element
3. Run the script to generate .java classes- gwt-api-generator [--pom --groupId=xx --artifactId=xx]
4. Run mvn clean install to produce your gwt-package .jar
gwt-api-generator (custom elements)
gwt-api-generator goals
1. Very little code to maintain.a. 1500 LOC / 100 KB
2. But it produces a lot of java codea. 50000 LOC (paper & core elements)
3. It uses native JS parsers for JS code.a. The same tools that polymer developers useb. No GWT generators nor APT processors.
4. Standard tools for web developers.a. They can deliver gwt libraries without knowing any java
Demo:Building a full stack app
Demo Application
GWT
Polymer
PouchDB CouchDB
- Responsive- Material Design- Online/Offline- Real Time
Demo Components
- GWT + Polymer- CouchDB is a database that completely embraces
the web. - Store your data with JSON documents- Access your data via HTTP- Serve pages directly
- PouchDB is database inspired by Apache CouchDB that is designed to run well within the browser.
Demo
http://manolo.github.io/gwt-polymer-chat-app/demo/https://github.com/manolo/gwt-polymer-chat-app
