User Guide

Creating custom components 21

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

reference all of the properties of the ComboBox control in the MXML tag of your custom

component, or in the ActionScript specified in an

<mx:Script> tag. For example, the

following example specifies the

ComboBox.rowCount property and a listener for the

ComboBox.close event for your custom control:

<?xml version="1.0"?>

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

xmlns:MyComp="myComponents.*">

<mx:Script>

<![CDATA[

import flash.events.Event;

private function handleCloseEvent(eventObj:Event):void {

// ...

}

]]>

</mx:Script>

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

</mx:Application>

For more information on MXML components, see “Creating Simple MXML Components”

on page 77.

Creating ActionScript components

You create ActionScript components by defining ActionScript classes. You can create the

following types of components in ActionScript:

User-interface, or visual, components User-interface components contain both

processing logic and visual elements. You create custom user-interface components to modify

existing behavior or add new functionality to the component. These components usually

extend the Flex component hierarchy. You can extend from the UIComponent class, or any of

the Flex components, such as Button, ComboBox, or DataGrid. Your custom ActionScript

component inherits all of the methods, properties, events, styles, and effects of its superclass.

Nonvisual components Nonvisual components define nonvisual elements. Flex includes

several types of nonvisual components that you can create, including formatters, validators,

and effects. You create nonvisual components by creating a subclass from the Flex component

hierarchy. For validators, you create subclasses of the Validator class; for formatters you create

subclasses of the Formatter class; and for effects, you create subclasses of the Effect class.