Centrer un bitmap dans un clip avec MovieClipLoader et LoadBitmapSmoothed

tn_group["tn"+i].tn_button.onRelease = function(){
		_root.p = this._parent.tn_no;
		function loadBitmapSmoothed(url:String, cible:MovieClip) { 
		var bmc:MovieClip = cible.createEmptyMovieClip("bmc", cible.getNextHighestDepth()); 
		
		var listener:Object = new Object();

		listener.tmc = cible;
		
		listener.onLoadProgress = function(mc:MovieClip, bytesLoaded:Number, bytesTotal:Number):Void{
			var pourcentage:Number = bytesLoaded/bytesTotal*100;
			if(pourcentage<100){
				_root.clipRoue._visible = true;
			}
			if(pourcentage == 100){
				_root.clipRoue._visible = false;
			}
		}

		listener.onLoadInit = function(mc:MovieClip){
		mc._visible = false;
		mc._x = mc._width/2;
		mc._y = mc._height/2;
		myMC._x = clipImage._x-mc._width/2;
		myMC._y = clipImage._y-mc._height/2;
		if(mc._width > 750){
			myMC._xscale = 750/mc._width*100;
			myMC._yscale = myMC._xscale;
			myMC._x = clipImage._x-mc._width/2*750/mc._width;
			myMC._y = clipImage._y-mc._height/2*750/mc._width;
		}
		if(mc._height > 550){
			myMC._yscale = 550/mc._height*100;
			myMC._xscale = myMC._yscale;
			myMC._x = clipImage._x-mc._width/2*550/mc._height;
			myMC._y = clipImage._y-mc._height/2*550/mc._height;
		}
		
		bitmap.dispose();
		bitmap = new BitmapData(mc._width, mc._height, true);
		
		this.tmc.attachBitmap(bitmap, this.tmc.getNextHighestDepth(),"auto",true); 
		bitmap.draw(mc);
		}	

		var loader:MovieClipLoader = new MovieClipLoader(); 
		loader.addListener(listener); 
		loader.loadClip(url, bmc);
		}
		createEmptyMovieClip("myMC",getNextHighestDepth()-2);
		loadBitmapSmoothed(folder + visuels_noms[p], myMC);
		new Tween(myMC, "_alpha", Elastic.easeOut, 0, 100, 20, true);
		clipMenu.designation.text = visuels_titres[p];
		}