We have been using GWT for around 4 years now. One of the most often discussed features missing in native GWT is data binding. Reading across AngularJs another Google offering, i came across http://devgirl.org/2013/03/21/fun-with-angularjs/ . I do not wish to use GXT or any other third party tools. I also wish to avoid generator related solution.
Is there any way this will ever be implementable in pure native GWT?
Is there any specific reason why GWT cannot provide this out of the BOX?
Have you tried GWT Pectin?
I have used it successfully in a larger project some time ago.
I suggest you try HexaBinding, which is non invasive and only focused on data binding. Here is the link : https://github.com/ltearno/hexa.tools/blob/master/hexa.binding/README.md
It works with pure Java, GWT and will soon work also with Android and JavaFX. It may even work with J2Objc but not sure yet...
I read the post you mention on devgirl about AngularJS. In that post the "2 way data binding" refers to the property of the code to reflect automatically on the view the changes that occurs to the data that the view is currently displaying.
This is achieved in GWT since version 2.1 with the Cell Widgets
In the first paragraph of the Cell Widgets documentation I linked above it is clearly stated that:
A cell widget can accept data from any type of data source. The data
model handles asynchronous updates as well as push updates. When you
change the data, the view is automatically updated.
If you want to do in GWT something as basic as the example in the devGirl post you need to write a onKeyup handler (in AngularJS you should write a Scope to this purpose) that would copy what you entered to the linked label. Something like this:
...
final TextBox nameField = new TextBox();
final Label enteredName = new Label("");
...
public void onKeyUp(KeyUpEvent event) {
enteredName.setText(nameField.getText());
}
...
I'm building a website using GWT and would like to add Image Cropping capability so users can upload their profile image and then crop it as they need to. I'm looking for something similar to Jcrop but in GWT.
I found THIS and THIS code samples how to crop an image on the client side but there is no UI part where user can select part of their image that needs to be cropped.
There were also couple of similar questions on SO (for example and this GWT with Jcrop) but nobody gave an example of the selection part of the image that uses pure GWT.
If you have an idea how to do it please share and I'm sure other people will leverage from this in the future.
Here is the example of what I'm looking for:
I recommend that you take route #1. I've been working full time in GWT for awhile and spend a lot of time looking for libraries, and this is one that I just don't think exists yet.
Here are your options:
Wrap Jcrop using a JSNI interface.
Pros: You have to include JQuery and JCrop, which are small and robust
Cons: Learning how to build your first JSNI wrapper can be a pain
Build your own from GWT Drag and Drop
Pros: "Pure GWT"
Cons: You probably won't handle all the edge cases that JCrop has figured out over time, nor be as featureful.
Port JCrop to GQuery
Pros: JCrop is open source and only around ~1600 lines of code
Cons: It's ~1600 lines of code, which is likely to be much bigger when ported to Java
If you decide to do any of the above, please open source it! I'd be happy to contribute, and it looks like something that I could use in my GWT projects as well.
GWT Cropper is a widget that allows cropping an image.
https://code.google.com/p/gwt-cropper/
Edited in 2015: as long as Google Code is about to be closed, the project has been moved to GitHub. The new address is https://github.com/w32blaster/gwt-cropper
Currently I am programming the Web Application based on Vaadin. I am quite happy with the learning cycle and the way how easy UI can be designed.
In general pluses of Vaadin are:
"Native" UI programming for Java users (component hierarchy / event listeners / drag & drop / validation).
Out-of-box nice collection of components (tree / table / list / ...).
The minuses are:
Big and complex HTML output. That slows down the browser response time (also mentioned here and there) and leads to some rendering peculiarities from browser to browser.
Difficulties in handling big number of components (see Can CustomLayout handle 5000 components?).
The need to recompile the widget set if you use 3rd party components.
My question to community is:
What Web Framework fits best the following requirements:
Separation of presentation with event/action handlers.
Common components out of box (with advanced features like table column drag&drop, lazy loading).
Layout support (no headache with padding and alignment of components).
Event propagation to server and server-side event processing.
Possibility to generate your HTML (if framework is not HTML-based) and also capture events for it (e.g. mouse clicks).
Possibility to register key stoke callbacks (e.g. Ctrl-S) is a plus.
Short learning curve for Java developer is a plus.
The sensible mix of approaches would fit as well. Please, provide the link for "Hello World" application, implemented based on the framework that you suggest. I am considering Apache Wicket / Echo2 / Tapestry / Click / GWT, but it's difficult to make a choice without playing for couple of months (hopefully with no deep disappointment).
I completely agree with all your mentioned minuses and can not say very much against. Because I'm quite new in GWT I can only share my little experience I have collected other last 2 months.
Separation of presentation with event/action handlers.
I think UiBinder with annotation #UiHandler("closeButton") #UiField in GWT 2.0 and later is exactly for separation HTML form code and handlers. Also MVP pattern with event bus is perfect answer from GWT team.
Short learning curve for Java developer is a plus.
I'm not naive and I don't think that it's possible to get quality result only with java knowledge without understanding WEB technologies.
Most of GWT UI frameworks I have reviewed and read about, introduces more problems than solutions. They somehow manages to and one or few benefits and restrict you from other features which comes in the new releases of GWT. I have chosen not to use vaadin because I felt like It will force me to do webapp development in their way, which I agree is fast easy to understand, but somehow limited. I like to have some freedom by choosing classic GWT without fancy controls.
Also I also feel that GWT UI Components are limited and there is no quality alternatives. Something is wrong here. I think google team have to do something on this part.
Regards RemisB
You can use a Vaadin Table to solve the original problem, more or less like this. The trick is to create a Vaadin Container and put components in it, as data. On the text side, wrap a label in VerticalLayout then add a click listener. This yields the ability to display "paragraphs" of XHTML text, detect clicks on them with relative locations, and still be able to handle large numbers of paragraphs.
You might need to modify your styles.css to allow wrapping of text within a table row, so you'll get ragged rows.
package com.soletta.clickytable;
import com.vaadin.Application;
import com.vaadin.data.util.IndexedContainer;
import com.vaadin.event.LayoutEvents.LayoutClickEvent;
import com.vaadin.event.LayoutEvents.LayoutClickListener;
import com.vaadin.terminal.Sizeable;
import com.vaadin.terminal.gwt.server.WebApplicationContext;
import com.vaadin.ui.Button;
import com.vaadin.ui.Label;
import com.vaadin.ui.Table;
import com.vaadin.ui.VerticalLayout;
import com.vaadin.ui.Window;
import com.vaadin.ui.Window.CloseEvent;
import com.vaadin.ui.Window.CloseListener;
public class ClickytableApplication extends Application {
#Override
public void init() {
Window mainWindow = new Window("Clickytable 2 Application");
setMainWindow(mainWindow);
mainWindow.addListener(new CloseListener(){
public void windowClose(CloseEvent e) {
WebApplicationContext context = (WebApplicationContext) getContext();
context.getHttpSession().invalidate();
close();
}});
IndexedContainer container = new IndexedContainer();
container.addContainerProperty("text", VerticalLayout.class, new VerticalLayout());
container.addContainerProperty("edit", Button.class, new Button("Edit"));
for (int i = 0; i < 10; i++) {
final int index = i;
Object item = container.addItem();
Label lbl = new Label("Text Content " + i);
VerticalLayout vl = new VerticalLayout();
vl.setWidth(100, Sizeable.UNITS_PERCENTAGE);
vl.addComponent(lbl);
vl.addListener(new LayoutClickListener() {
public void layoutClick(LayoutClickEvent event) {
System.out.println(String.format("Clicked on text %,d at client(%,d,%,d), relative(%,d %,d)\n", index, event.getClientX(), event.getClientY(), event.getRelativeX(), event.getRelativeY()));
}
});
container.getItem(item).getItemProperty("text").setValue(vl);
container.getItem(item).getItemProperty("edit").setValue(new Button("Button " + i));
}
Table table = new Table("ClickyTable 2", container);
table.setColumnExpandRatio("text", 1);
table.setColumnExpandRatio("edit", 0);
table.setSizeFull();
VerticalLayout fl = new VerticalLayout();
fl.setSizeFull();
fl.addComponent(table);
mainWindow.setContent(fl);
}
}
With some style changes in place, the result can look something like this:
ClickTable Screen Shot http://www.soletta.com/images/ClickyTable.PNG
If you ever find yourself putting hundreds of components on web page in Vaadin, you probably should reconsider your application structure. Why not implement a custom widget for the part of the UI that requires such huge number of widgets? It is just GWT and thus fairly easy. Then you can have the best of the both worlds - simplicity of Vaadin with full control of HTML5 on the client side.
Vaadin Flow
You must have been using the previous generation of Vaadin, versions 6, 7, and 8.
Because of the limitations and incompatibilities of earlier browsers, the long delays in producing CSS 3, and predating HTML5, Vaadin did indeed generate large and complicated pages. Given the relatively poor performance of JavaScript runtimes back then, some elaborate web apps may not have performed as well as you would have liked.
Web Components versus GWT
Fast forward some years now since your Question was posted. Vaadin Flow has arrived. Versions 10 and later are longer based on GWT. Instead they use the open standards that have emerged, collectively known as Web Components.
CSS 3
CSS 3 has finally arrived, and matured. Browsers now offer built-in sophisticated page layout with Flexbox and Grid, in addition to the previous Float. So no longer must page layout be hacked together with abuse of table and crazy assortment of div & span tag soup. Page layout can now be built with short, simple, and clean code.
Modern browsers
Other modern advancements include:
HTML5 designed expressly for building web apps (as opposed to web documents)
The consolidation in browser engines (basically only 2 left standing: WebKit/Chromium & Quantum/Gecko)
Dramatic advances in the performance of JavaScript runtimes, plus important new features of JavaScript 6
Close cooperation between browser makers in writing and implementing web standards with much more consistent behaviors
The "evergreen" rapid-release model of modern browsers
All these taken together mean the burden on Vaadin to deliver high-quality consistent web-app experiences has been greatly decreased. You should see much shorter, simpler, and faster page code.
Give it a try.
For more discussion, see my Answer to the Question, Understanding Vaadin Flow / Vaadin 10.
The minuses are:
Big and complex HTML output. That slows down the browser response time (also mentioned here and there) and leads to some rendering peculiarities from browser to browser.
No longer big and complex, as discussed above, because of modern web technology improving so much.
Difficulties in handling big number of components (see Can CustomLayout handle 5000 components?).
Web Components is an open standard, composed of four specifications.
Many components have been built over the last several years, now available for you to use in your Vaadin Flow web apps.
Most of the UI widgets you knew in Vaadin 6/7/8 have been rebuilt as Web Components (see Comparison Matrix). This means these Vaadin components can be used in other web projects without the Vaadin Flow server-side Java binding.
You can easily wrap other non-Vaadin-specific components built on Web Components to be available to your in your Java code running on the server-side Vaadin Flow framework. See Integrating a Web Component. To get you started, here are a couple thousand to choose from.
You can create your own components.
The need to recompile the widget set if you use 3rd party components.
No more WidgetSet in Vaadin Flow, because there are no more GWT widgets. Supplanted by Web Components as discussed above.
What Web Framework fits best the following requirements:
Vaadin Flow ticks all the boxes you listed in your Question: event handlers, common components with advanced features, sophisticated page layout, user-events propagating from client to server (and the other direction via built-in Push technologies), keyboard shortcuts, and a short learning curve for Java programmers.
Furthermore, from the server-side you can now invoke JavaScript snippets on the browser. And Vaadin 15 this spring brings client-side coding in TypeScript while still integrating with the Java code running server-side in Vaadin Flow.
Web Firm Framework is the best alternative. It's an opensource Java framework under Apache License 2.0. I also had to load heavy components in my application it was smooth with this framework.
It is like a collection of java classes for all HTML5 tags and attributes. Using these classes we can build the UI just like we do using the pure HTML. It can handle heavy HTML because the data coming from the server to client is like a stream through websocket, eg:-
//creates table
Table tableObj = new Table(null,
new Style("width:100%")).give(table -> {
new TBody(table);
});
//finding tbody object in the table
TBody tBody = TagRepository.findOneTagAssignableToTag(TBody.class, tableObj);
for (int i = 0; i < 10; i++) {
int count = i;
Tr trObj = new Tr(null).give(tr -> {
new Th(tr).give(th -> {
new NoTag(th, "Firstname " + count);
});
new Th(tr).give(th1 -> {
new NoTag(th1, "Lastname " + count);
});
new Th(tr).give(th2 -> {
new NoTag(th2, "Age " + count);
});
});
//appending tr in the table
tBody.appendChild(trObj);
}
Whenever trObj is appended it will be immediately available in the UI it will not wait to finish the for loop. Check their demo app which contains a button to stream 1000 rows.
We can handle events without much effort eg:
to handle click event of a button
//This will create a button in the UI.
new Button(null, new Type(Type.BUTTON), new OnClick((data, ev) -> {
System.out.println("Button clicked");
return null;
}));
In this git repo you can find sample projects for it.
We can also try this tool to convert HTML5 to Java/Kotlin code. This video and developers guide will be helpful to understand it better.
There's a question about using layout managers in GWT, which was however answered in the sense that no direct porting of Swing apps is possible. But I don't need this, I only want to use a sane way of positioning.
Is there a a port of MigLayout (or alike) to GWT?
Since a LayoutManager is mostly a way to set the component sizes and positions using some user preferences, it should be possible. Doing this for a HTML component is possible (and AFAIK some frameworks compute all sizes and positions on the server and avoid all associated HTML/CSS problems).
Depending on your definition of crazy, the LayoutPanels built in to GWT are quite sane. There's a DockLayoutPanel with familiar north/south/east/west behavior, and also panels that allow more arbitrary percentages and positions. Combining them with CSS is very powerful and flexible.
http://code.google.com/webtoolkit/doc/latest/DevGuideUiPanels.html
Although requested years ago, it looks like it hasn't been done yet.
Just one quotation:
I'm just getting started with GWT and I feel like I just stepped back into the dark ages with all the various layout panels and layout managers.
There's gxt-jglayout, which is JGoodies form layout implementation for Ext-GWT (GXT), but Ext-GWT is not free (it's dual licensed).
now according to "http://www.zackgrossbart.com/hackito/tags-first-gwt/"
told that it is recommended to use html&css to build the application user interface and then do the logic using GWT.
i made that UI using html. and added it to HtmlPanl.
now the Question is :
how to send the htmlPanel content to the server and get the response on the client side ?
i need a simple example that describe this.
thanks,
The link that you point to is one year and half old, and that's an eternity in our world ;)
The main point of using pure HTML is to reduce the HTML complexity level when GWT generates it.
I would recommend you to check the documentation about UIBinder and follow the standard ways.