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Instantiating and displaying MovieClips from loaded SWF

March 7th, 2008

So you want to dynamically load a .swf, instantiate it and add to to a SWFLoader control.

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("className") 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)