Client Activity Watches

In most cases, a widget or an application needs only to listen Event as described in the Client-side Event listening section. However, there are some activities not available as a DOM event (Event) or a ZK event (Event), such as when a widget is becoming invisible, or a window is brought to top. This kind of activity can be listened by so-called watch (zWatch)

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Listen and Unlisten

To add a watch (i.e., listen to a client activity), you could use zWatch.listen(Map) as follows:

zWatch.listen({
    onSize: this,
    onShow: this,
    onHide: [this, this._onHide]
});

As shown, the key of each entry in the given map is the name of the client activity (aka., the watch name), and the value could be one of the following:

• An object that has a method with the same name. In the above case, this must have the onSize and onSHow methods
• A two-element array, where the first element is the target, and the second is the method

The signature of the method is as follows.

function onWhatever(ctl, arg0, arg1...) {
}

where ctl is a controller allowing you to have better control of the invocation sequence of the listeners, and arg0 and others are the arguments that passed to zWatch.fire(String, Object, Map) or zWatch.fireDown(String, Object, Map).

To unlisten, you could use zWatch.unlisten(Map) as follows:

zWatch.unlisten({
    onSize: this,
    onShow: this,
    onHide: [this, this._onHide]
});

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