User Guide

494 Chapter 2: ActionScript Language Reference

MovieClip._alpha

Availability

Flash Player 4.

Usage

my_mc._alpha:Number

Description

Property; the alpha transparency value of the movie clip specified by my_mc. Valid values are 0

(fully transparent) to 100 (fully opaque). The default value is 100. Objects in a movie clip with

_alpha set to 0 are active, even though they are invisible. For example, you can still click a button

in a movie clip whose

_alpha property is set to 0. To disable the button completely, you can set

the movie clip's

_visible property to false.

You can extend the methods and event handlers of the MovieClip class by creating a subclass. For

more information, see “Assigning a class to a movie clip symbol” in Using ActionScript in Flash.

Example

The following code sets the _alpha property of a dynamically created movie clip named

holder_mc to 50% when the mouse rolls over the movie clip. Add the following ActionScript to

your FLA or AS file:

this.createEmptyMovieClip("holder_mc", this.getNextHighestDepth());

holder_mc.createEmptyMovieClip("image_mc", holder_mc.getNextHighestDepth());

// replace with your own image or use the following

holder_mc.image_mc.loadMovie("http://www.macromedia.com/devnet/mx/blueprint/

articles/nielsen/spotlight_jnielsen.jpg");

holder_mc.onRollOver = function() {

this._alpha = 50;

};

holder_mc.onRollOut = function() {

this._alpha = 100;

};