Flex Image 自适应

<mx:Image 	
		  maintainAspectRatio="true"
		  scaleContent="true"
		  horizontalCenter="0"
		  verticalCenter="0"
		  source="{source}"/>

在加载完图片后

Bitmap(img.content).smoothing = true;
img.percentHeight = 100;
img.percentWidth = 100;