User Guide

690 Chapter 6: Components Dictionary
The second usage example uses a dispatcher/listener event model. A component instance
(
buttonInstance) dispatches an event (in this case, click) and the event is handled by a
function, also called a handler, on a listener object (
listenerObject) that you create. You define
a method with the same name as the event on the listener object; the method is called when the
event occurs. When the event occurs, it automatically passes an event object (
eventObject) to
the listener object method. The event object has properties that contain information about the
event. You can use these properties to write code that handles the event. Finally, you call
addEventListener() (see EventDispatcher.addEventListener()) on the component
instance that broadcasts the 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 415.
Example
This example, written on a frame of the Timeline, sends a message to the Output panel when a
button called
buttonInstance is clicked. The first line specifies that the button act like a toggle
switch. The second line creates a listener object called
form. The third line defines a function for
the
click event on the listener object. Inside the function is a trace() statement that uses the
event object that is automatically passed to the function (in this example,
eventObj) to generate a
message. The
target property of an event object is the component that generated the event (in
this example,
buttonInstance). The SimpleButton.selected property is accessed from the
event object’s
target property. The last line calls addEventListener() from buttonInstance
and passes it the
click event and the form listener object as parameters.
buttonInstance.toggle = true;
form = new Object();
form.click = function(eventObj){
trace("The selected property has changed to " + eventObj.target.selected);
}
buttonInstance.addEventListener("click", form);
The following code also sends a message to the Output panel when buttonInstance is clicked.
The
on() handler must be attached directly to buttonInstance.
on(click){
trace("button component was clicked");
}
SimpleButton.emphasized
Availability
Flash Player 6 (6.0 79.0).
Edition
Flash MX 2004.
Usage
buttonInstance.emphasized