User Guide

Adding properties and methods to a component 135
When you define a property by using getter and setter methods so that the property is usable
as the source for data binding, you include the
[Bindable] metadata tag before the getter
method, and optionally include the name of the event dispatched by the setter method when
the property changes, as the following example shows:
package myComponents
{
// as/myComponents/TextAreaFontControlBinding.as
import mx.controls.TextArea;
import flash.events.KeyboardEvent;
import flash.events.Event;
public class TextAreaFontControlBinding extends TextArea
{
public function TextAreaFontControlBinding()
{
super();
addEventListener("keyDown", myKeyDown);
addEventListener("creationComplete", myCreationComplete);
}
private var currentFontSize:Number;
public var minFontSize:Number = 5;
// Define private variable for maxFontSize.
public var _maxFontSize:Number = 15;
// Define public getter method, mark the property
// as usable for the source of data binding,
// and specify the name of the binding event.
[Bindable("maxFontSizeChanged")]
public function get maxFontSize():Number {
return _maxFontSize;
}
// Define public setter method.
public function set maxFontSize(value:Number):void {
if (value <= 30) {
_maxFontSize = value;
} else _maxFontSize = 30;
// Dispatch the event to trigger data binding.
dispatchEvent(new Event("maxFontSizeChanged"));
}
private function myCreationComplete(eventObj:Event):void {
// Get current font size
currentFontSize = getStyle('fontSize');
}