MACROMEDIA FLASH 8-COMPONENTS LANGUAGE Reference page 143

The first usage example uses a dispatcher-listener event model. A component instance
( ) dispatches an event (in this case, ), and the event is handled by a
checkBoxInstance click
function, also called a handler, on a listener object ( ) that you create. You
listenerObject
define a method with the same name as the event on the listener object; the method is called
when the event is triggered. When the event is triggered, it automatically passes an event
object ( ) to the listener object method. The event object has properties that
eventObject
contain information about the event. You can use these properties to write code that handles
the event. Finally, you call the method (see
addEventListener()
) on the component instance that broadcasts the
EventDispatcher.addEventListener()
event to register the listener with the instance. When the instance dispatches the event, the
listener is called.
For more information, see "EventDispatcher class" on page 499.
The second usage example uses an handler and must be attached directly to a CheckBox
on()
instance. The keyword , used inside an handler attached to a component, refers to
this on()
the component instance. For example, the following code, attached to the check box
, sends "_level0.myCheckBox" to the Output panel:
myCheckBox
on (click) {
trace(this);
}
Example
The following example enables a button when the check box is selected. This example
assumes you have a Button component instance on the Stage with instance name
, and a CheckBox component instance on the Stage with the instance name
submit_button
. Add the following code to the first frame of the main timeline:
agree_ch
agree_ch.label = "I agree";
submit_button.enabled = false;
// Create Listener Object.
var form_obj:Object = new Object();
// Assign function to Listener Object.
form_obj.click = function(event_obj:Object) {
submit_button.enabled = event_obj.target.selected;
};
// Add Listener.
agree_ch.addEventListener("click", form_obj);
CheckBox.click 141