Monday, November 29, 2010

ActionScript 3 Objects, Properties and Methods

Actionscript 3

Objects

ActionScript objects provide a means of moving graphic elements dynamically, building applications, organizing data, and more. You accomplish these tasks by using or setting object property values and invoking object methods.

Global objects

In your Flash application there are some objects that are classified asglobal, or unique to the movie as a whole. The mouse, for example, is defined as a global object, like a Mouse object. The mouse is global because you can only have one mouse in your application and can not create an instance of it. Objects like movie clips, text fields, and sounds must be created with components and instances to be used.

Flash Global Objects:

  • Math
  • Accessibility
  • Key
  • Mouse
  • Selection
  • Stage
  • System

Object classes

A class of objects represents a group of object instances within your project that share the same basic structure and functionality. For example, all movie clip instances belong to the MovieClip class of objects

import flash.display.MovieClip;
var myMovie:MovieClip = new MovieClip();

Properties

Certain objects, such as MovieClips for example, have properties and attributes which can be configured via ActionScript. Properties are simple attributes of the object, such as its width, its height, its horizontal position and its vertical position. In order for a property to be configured you need to use the dot (.) operator to access the property and the assignment (=) operator to set a new value for it.

var myMovie:MovieClip = new MovieClip();
myMovie.x = 300;
myMovie.y = 100;

myMovie is the object, x is the property, 300 is the value

Methods

Objects also have methods, or functionality actions that the object can perform. If your object is a video object, you can tell this object to play the video. Any action that the object can perform is called a method.

import flash.media.Video;

var myVideo:Video = new Video();
myVideo.play();

Some methods require additional information to execute the action. The Loader Class is responsible for loading external graphical elements into your movie, in order for it to perform the .load() method you must specify the URL of the file to be loaded:

import flash.display.Loader;

var myLoader:Loader = new Loader();
myLoader.load(new URLRequest("MyPic.png"));

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