Here are a few considerations when loading MovieClips into Flex:

• If you embed a symbol, you will lose all timeline actions. Embed the whole SWF instead.

 

• If you have a stop on the first frame of a multi-frame MovieClip, it might never execute. Add the action on the second frame.

 

• When you say gotoAndStop (or gotoAndPlay), you cannot immediately reference the children on that frame. You have 3 choices:
    
  • Use stage.invalidate() and listen to RENDER events

   

  • Listen to ADDED events and check if the target of the event is the object that you need.

   

  • Forget about frames and do like Flex intended: one symbol per MovieClip state (button states for example)

   

 

• If your MovieClip is 1-frame long, it will still loop indefinitely, consuming precious resources. Use stop() on the first frame.

 

• When you use the addChild method with the MovieClip, the clip will not be copied. It will be removed from its previous parent (firing the REMOVED_FROM_STAGE event) and then added to the new parent.

 

• You cannot duplicate a MovieClip. If you want to be able to create multiple instances, link these MovieClips in you SWFlibrary and instantiate as many as you want.

 

• A MovieClip cannot be added directly to Flex containers. Add it as a child of a SWFLoader or an Image and add that control.

 

• The Loader class is a DisplayObject but has trouble resizing itself. You can always grab the loader.content as a MovieClip and add it where you need it.

 

First, loading the .swf:

var loader:Loader = new Loader();
loader.load(url);

Now, to get its classes, we need to listen for the loading completion:

loader.addEventListener(Event.INIT, callbackFunction);

Once done, the callbackFunction will get and instantiate a class:

var mcClass:Class =
loader.content.loaderInfo.applicationDomain
  .getDefinition("instanceName") as Class;
var mc:MovieClip = MovieClip(new mcClass());

Hurray! Now we can add it to some appropriate container:

someSwfLoader.addChild(mc);

Now we want to scale it to fit the available space:

mc.scaleX = mc.scaleY = someSwfLoader.width / mc.width;

(a more complex algorithm may be used)

A problem may arise if your clip content is not at 0,0 coordinates:

var bounds:Rectangle = mc.getBounds(Application.application.stage);
mc.x -= bounds.left * mc.scaleX;
mc.y -= bounds.top * mc.scaleX;

(if you have an ActionScript project instead of Flex, you’ll need to access the stage by other means)