as3 操作图片，获取，设置实际像素，扣除透明区域

 　　　　 private var a:Loader = new Loader();
         private function test():void
         {
             a.load(new URLRequest("assets/冷却液管.png"));
             a.contentLoaderInfo.addEventListener(Event.COMPLETE, an);
         }
         private function an(evt:Event):void
         {
             var hh:BitmapData = new BitmapData(a.content.width,a.content.height,false,0xcccccc);
             var kk:Bitmap = new Bitmap(hh);
             addChild(kk);
             kk.x = 200;

             var tu2:Bitmap=Bitmap(a.content as Bitmap);
 //            addChild(tu2);
             var yan:uint;
             for (var i:uint = 0; i<tu2.width; i++)
             {
                 for (var j:uint = 0; j<tu2.height; j++)
                 {
                     yan = (a.content as Bitmap).bitmapData. getPixel32 (i, j);
                     if (yan<=0)  // 要抠取的颜色
                     {
 //                        tu2.bitmapData. setPixel32 (i,j,0xffff0000);
                         hh. setPixel (i,j,0xff0000);
                     }
                 }
             }
         }