User Guide

80 Creating Simple MXML Components

The StateComboBox.mxmlfile specifies the ComboBox control as its root tag, so you can

reference all of the properties of the ComboBox control within the MXML tag of your

custom component, or in the ActionScript specified within an

<mx:Script> tag. For

example, the following example specifies the

rowCount property and a listener for the close

event for your custom control:

<?xml version="1.0"?>

<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"

xmlns:local="*">

<mx:Script>

<![CDATA[

import flash.events.Event;

private function handleCloseEvent(eventObj:Event):void {

myTA.text="foo";

}

]]>

</mx:Script>

<local:StateComboBox rowCount="5" close="handleCloseEvent(event);"/>

<mx:TextArea id="myTA" />

</mx:Application>

MXML components and ActionScript classes

When you create a custom MXML component, you define a new ActionScript class where the

class name corresponds to the filename of the MXML component. Your new class is a subclass

of the component’s root tag and, therefore, inherits all of the properties and methods of the

root tag. However, because you are defining the component in MXML, many of the

intricacies of creating an ActionScript class are hidden from you.

For example, in “Creating MXML components” on page 78, you defined the component

StateComboBox.mxml by using the

<mx:ComboBox> tag as its root tag. Therefore,

StateComboBox.mxml defines a subclass of the ComboBox class.