User Guide

174 Creating Advanced Visual Components in ActionScript
However, if a child component dispatches an event, and you want that opportunity to handle
the event outside of the component, you must add logic to your custom component to
propagate the event. Notice that the event listener for the
change event for the TextArea
control propagates the event. This lets you handle the event in your application, as the
following example shows:
<?xml version="1.0"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
xmlns:MyComp="myComponents.*">
<mx:Script>
<![CDATA[
import flash.events.Event;
function handleText(eventObj:Event)
{
...
}
]]>
</mx:Script>
<MyComp:ModalText changed="handleText(event);"/>
</mx:Application>
Creating the ModalText component
The following code example implements the class definition for the ModalText component.
The ModalText component is a composite component that contains a Button control and a
Te xt A rea control. The following image shows this control:
This control has the following attributes:
■ You cannot edit the TextArea control by default.
■ You click the Button control to toggle editing of the TextArea control.
■ You use the textPlacement property of the control to make the TextArea appear on the
right side or the left side of the control.
■ Editing the textPlacement property of the control dispatches the placementChanged
event.
■ You use the text property to programmatically write content to the TextArea control.
■ Editing the text property of the control dispatches the textChanged event.
■ Editing the text in the TextArea control dispatches the change event.