MACROMEDIA FLEX 2-MIGRATING APPLICATIONS TO FLEX 2 Manual do Utilizador descarregar pdf (Página 109)

Binding from a property 109

Dispatching binding events from a custom

component

To dispatch an event to trigger data binding for a property, the property’s class must either

extend EventDispatcher or implement the IEventDispatcher interface. Be sure to update the

object that is passed to the

dispatchEvent() method. You must use the new Event class and

not a generic Object. For more information on converting events, see “Migrating the Event

object” on page 113.

If the class already extends EventDispatcher, you do not need to make any changes. If the class

already implements IEventDispatcher, it must implement

dispatchEvent(), too. If the class

does not implement

dispatchEvent(), the MXML compiler reports a warning.

If the class does not extend EventDispatcher or implement IEventDispatcher and one of your

properties is marked

[Bindable] or the class is marked [Bindable], the MXML compiler

modifies the class to implement IEventDispatcher. This requires the compiler to generate the

following code for you:

■ Implements the IEventDispatcher interface.

■ Adds an addEventListener() method.

■ Adds a removeEventListener() method.

■ Adds a dispatchEvent() method.

For example, the following declaration:

class Foo {

}

Is converted by the Flex compiler to the following:

class Foo implements IEventDispatcher {

private var bar:EventDispatcher = new EventDispatcher(this);

public function addEventListener(type:String, listener:Object,

useCapture:Boolean = false, priority:int = 0):Boolean {

return bar.addEventListener(type, listener, useCapture, priority);

}

public function removeEventListener(type:String, listener:Object,

useCapture:Boolean = false):Boolean {

return bar.removeEventListener(type, listener, useCapture);

}

public function dispatchEvent(event:Event):void {

bar.dispatchEvent(event);

}

For more information, see Creating and Extending Flex 2 Components.

1 2 ... 104 105 106 107 108 109 110 111 112 113 114 ... 183 184

Sem comentários

MACROMEDIA FLEX 2-MIGRATING APPLICATIONS TO FLEX 2 Manual do Utilizador Página 109