[AS3]as3中flash里的图片等比例缩放的算法

[AS3]as3中flash里的图片等比例缩放的算法，禁止缩放对齐方式用左上

stage.align=StageAlign.TOP_LEFT; 
stage.scaleMode=StageScaleMode.NO_SCALE; 
function setSize(_evt:Event):void { 
     image.width=stage.stageWidth; 
     imageimage.scaleY=image.scaleX; 
     if (image.height<stage.stageHeight) { 
         image.height=stage.stageHeight; 
         imageimage.scaleX=image.scaleY; 
     } 
     image.x=(stage.stageWidth-image.width)*.5; 
     image.y=(stage.stageHeight-image.height)*.5; 
} 
setSize(null); 
stage.addEventListener(Event.RESIZE,setSize);