Wrote a function to center image it works, it maybe a starting point for you so
that you can write your own function. using 4.01
public var oldImage:String;
private function centerImage(rImage:Image):void {
var capImg:Image = new Image();
var newImage:Bitmap = new Bitmap();
var ch:Number = 0;
var cw:Number = 0;
var ih:Number = 0;
var iw:Number = 0;
var mX:Number = 0;
var mY:Number = 0;
capImg = rImage;
/* the following is to reduce the image flicker in a list using
an itemrenderer*/
if (oldImage != null && capImg.source == oldImage)
return;
else
oldImage = String(capImg.source);
newImage = new Bitmap(Bitmap(capImg.content).bitmapData);
ch = HEIGHTNUMBER;
cw = WIDTHNUMBER;
ih = capImg.content.height;
iw = capImg.content.width;
if (ih> iw){
cw = iw*ch/ih;
} else if (ih<iw){
ch = ih*cw/iw;
}
mX = (WIDTHNUMBER - cw) /2;
mY = (HEIGHTNUMBER - ch) /2;
capImg.x = mX;
capImg.y = mY;
capImg.width = cw;
capImg.height = ch;
capImg.source = newImage;
}