User Guide

422 DateChooser component (Flash Professional only)
Description
Event; broadcast to all registered listeners when a date is selected.
The first usage example uses a dispatcher/listener event model. A component instance
(
dataChooserInstance) dispatches an event (in this case, change) and the event is handled
by a function, also called a handler, on a listener object (
listenerObject) that you create.
You define a method with the same name as the event on the listener object; the method is
called when the event is triggered. When the event is triggered, it automatically passes an
event object (
eventObject) to the listener object method. Each event object has properties
that contain information about the event. You can use these properties to write code that
handles the event. Finally, you call the
EventDispatcher.addEventListener() method on
the component instance that broadcasts the event to register the listener with the instance.
When the instance dispatches the event, the listener is called.
For more information, see “EventDispatcher class” on page 499.
The second usage example uses an
on() handler and must be attached directly to a
DateChooser instance. The keyword
this, used inside an on() handler attached to a
component, refers to the component instance. For example, the following code, attached to
the date chooser
my_dc, sends “_level0.my_dc” to the Output panel:
on (change) {
trace(this);
}
Example
This example, written on a frame of the timeline, sends a message to the Output panel when a
DateChooser instance called
my_dc is changed. The first line of code creates a listener object
called
form. The second line defines a function for the change event on the listener object.
Inside the function is a
trace() statement that uses the event object that is automatically
passed to the function, in this example
eventObj, to generate a message. The target
property of an event object is the component that generated the event (in this example,
my_dc).
// Create listener object.
var dcListener:Object = new Object();
dcListener.change = function(evt_obj:Object) {
var thisDate:Date = evt_obj.target.selectedDate;
trace("date selected: " + thisDate);
};
// Add listener object to date chooser.
my_dc.addEventListener("change", dcListener);