Macromedia flex 2 Manual

Defining a custom effect trigger

247

    x="0" y="0" width="100" height="100"
    click="currentState='One'" >
    <mx:Label fontSize="24" text="One"/>
  </mx:Panel>
  <mx:Panel id="p2" title="Two"
    x="0" y="110" width="100" height="100"
    click="currentState='Two'" >
    <mx:Label fontSize="24" text="Two"/>
  </mx:Panel>
  <mx:Panel id="p3" title="Three"
    x="110" y="0" width="200" height="210"
    click="currentState=''" >
    <mx:Label fontSize="24" text="Three"/>
  </mx:Panel>
</mx:Canvas>
</mx:Application>

Defining a custom effect trigger

You can create a custom effect trigger to handle situations for which the standard Flex triggers
do not meet your needs. An effect trigger is paired with a corresponding event that invokes
the trigger. For example, a

Button

control has a

mouseDown

event and a

mouseDownEffect

trigger. The event initiates the corresponding effect trigger when a user clicks a component.
You use the

mouseDown

event to specify the event listener that executes when the user selects

the component. You use the

mouseDownEffect

trigger to associate an effect with the trigger.

Suppose that you want to apply an effect that sets the brightness level of a component when a
user action occurs. The following example shows a custom Button control that uses a new
property,

bright

, and dispatches two new events,

darken

and

brighten

, based on changes to

the

bright

property. The control also defines two new effect triggers,

darkenEffect

and

brightenEffect

, which are paired with the

darken

event and the

brighten

event.

<?xml version="1.0"?>

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

<mx:Metadata>
  
  [Event(name="darken", type="flash.events.Event")]
  [Event(name="brighten", type="flash.events.Event")]
  [Effect(name="darkenEffect", event="darken")]
  [Effect(name="brightenEffect", event="brighten")]
</mx:Metadata>

<mx:Script>
  <![CDATA[
    import flash.events.Event;