New Features of ZK 6.5.1

Introduction

ZK 6.5.1 concentrates on fixing bugs and introducing a few new features including a default command for MVVM, page visibility with HTML 5 API and others.

ZK 6.5 series focuses on taking developers to achieve real device transparency in one codebase and component set, exploring the area of combined desktop & tablet UI and touch experiences. Introducing responsive design and responsive components to always fit your device screen resolution and tablet-specific user interaction methods such as swiping and device orientation detection which are done automatically to save developers time, effort and to increase massive productivity.

The Default Command for MVVM

ZK 6.5.1 brings a default command for MVVM. When a binder receives a command, it starts to find ViewModel’s command methods by matching its name. If the binder cannot find a matched method, it invokes default command method.

Assume that there are only two command methods in the below ViewModel. If we trigger a command “exit”, a binder invokes the default command method defaultAction() because it cannot find a command method named “exit”.

public class OrderVM {

    @Command
    public void newOrder(){
    ...
    }
  
    @DefaultCommand
    public void defaultAction(){
    ...
    }
}

Control Page Visibility with HTML 5 API in ZK

In order to develop power and CPU efficient web applications, W3C publishes a specification named Page Visibility in HTML 5 which defines a means for site developers to programmatically determine the current visibility state of the page. In this specification, there are two attributes defined: hidden and visibilityState, where hidden is a boolean value representing whether the current page is visible or not and visibilityState represents that the current page has four states: hidden, visible, prerender, and unloaded.

In ZK 6.5.1, the API with onVisibilityChange event was implemented which provides the ability to find out when a page is visible or hidden. This has a lot of benefit as it enables saving of CPU cycles as well as bandwidth. The following is a very simple example:

<window title="window" border="normal">
    <attribute name="onVisibilityChange">
        if (!event.isHidden())
            lbl.setValue("Welcome back");
    </attribute>
    <label id="lbl"></label>
</window>

For more information please check the blog post here and the ZK Developer’s Reference.

Comet Server Push Support

The visibility functionality has also been extended to comet server push to reduce the server loading by default.

Messagebox without Buttons

With ZK 6.5.1, if you’d like to show a non-buttons dialog, you can use org.zkoss.zul.Messagebox with an empty array as follows.

Messagebox.show("Cancel the operation?",
    new Messagebox.Button[0], null);

This messagebox will show without any buttons.

DefaultTreeNode - Empty Node Can Be Treated as a Leaf Node

In ZK 6.5.1, org.zkoss.zul.DefaultTreeModel provides a boolean argument to its constructor for configuring to treat the zero size of children node as a leaf node.

// @param emptyChildAsLeaf whether to treat the zero size of children node as a leaf node.
DefaultTreeModel model2 = new DefaultTreeModel(root, true);

For more information please refer to ZK Developer’s Reference.

Download & Other Resources

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