ActionScript for Flash MX: The Definitive Guide, Second Edition

This is the Title of the Book, eMatter Edition

Copyright © 2007 O’Reilly & Associates, Inc. All rights reserved.

Event Handler Scope

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onClipEvent (keyDown) {

this._visible = false;

}

onClipEvent (keyUp) {

this._visible = true;

}

7. Select Control ➝ Test Movie.

8. Click the movie to make sure it has keyboard focus, then press and hold any key.

Each time you depress a key, the

rectangle movie clip disappears. Each time you

release the depressed key,

rectangle reappears.

Unlike Flash 6’s event handler properties and event listeners, Flash 5’s on( ) and

onClipEvent( ) handlers cannot be attached and removed via ActionScript while the

movie is playing. Therefore, in Flash 5 the following event handler property assign-

ment is illegal:

theClip.onKeyDown = function ( ) {

_visible = 0;

};

We’ll see how to work around this shortcoming later in this chapter under “Dynamic

Movie Clip Event Handlers.”

Event Handler Lifespan

The lifespan of event handlers is tied to the life of the objects with which they are

associated. When a clip or button is removed from the Stage, or when an XML or

TextField object is deleted, any event handlers associated with those objects die with

them. An object must be present on stage or in code for its handlers to remain active.

Event Handler Scope

As with any function, the statements in an event handler or listener execute within a

predefined scope. Scope dictates where the interpreter ...