MovieClipAsset  - AS3 Flex

Package	mx.core
Class	public class MovieClipAsset
Inheritance	MovieClipAsset FlexMovieClip MovieClip Sprite DisplayObjectContainer InteractiveObject DisplayObject EventDispatcher Object
Implements	IFlexAsset, IFlexDisplayObject, IBorder
Subclasses	MovieClipLoaderAsset

Language Version:

ActionScript 3.0

Product Version:

Flex 3

Runtime Versions:

Flash Player 9, AIR 1.1

MovieClipAsset is a subclass of the flash.display.MovieClip class which represents movieclip symbols that you embed in a Flex application from a SWF file produced by Flash. It implements the IFlexDisplayObject interface, which makes it possible for the MovieClip to be displayed in an Image control, or to be used as a container background or a component skin.

The MovieClip that you're embedding must be a movieclip symbol that is in a SWF file. A common reason for using an embedded movieclip is that you have created a frame-based animation in Flash and want to use it in a Flex application. The MXML compiler autogenerates a class that extends MovieClipAsset to represent the embedded animation.

You don't generally have to use the MovieClipAsset class directly when you write a Flex application. For example, you can use a movieclip animation as an application's background image by writing the following:

  <mx:Application backgroundImage="@Embed(source='Assets.swf', symbol='BackgroundAnimation')"/>

or

  <fx:Style>
      @namespace mx "library://ns.adobe.com/flex/mx"
      mx|Application {
          backgroundImage: Embed(source="Assets.swf", symbol="BackgroundAnimation")
      }
  <fx:Style/>

without having to understand that the MXML compiler has created a subclass of MovieClipAsset for you.

However, it may be useful to understand what is happening at the ActionScript level. To embed a movieclip in ActionScript, you declare a variable of type Class, and put [Embed] metadata on it. For example:

  [Bindable]
  [Embed(source="Assets.swf", symbol="BackgroundAnimation")]
  private var backgroundAnimationClass:Class;

The MXML compiler notices that the BackgroundAnimation symbol in Assets.swf is a movie clip, autogenerates a subclass of the MovieClipAsset class to represent it, and sets your variable to be a reference to this autogenerated class. You can then use this class reference to create instances of the MovieClipAsset using the new operator, and you can use APIs of the MovieClip class on them:

  var backgroundAnimation:MovieClipAsset =
      MovieClipAsset(new backgroundAnimationClass());
  var n:int = backgroundAnimation.totalFrames;

However, you rarely need to create MovieClipAsset instances yourself because image-related properties and styles can be set to an image-producing class, and components will create instances as necessary. For example, to set the application background to this animation, you can simply write the following:

  <mx:Application backgroundImage="{backgroundAnimationClass}"/>

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