[]image.drawToCanvas方法获取的一直是空的png

package

{

	import laya.display.Sprite;

	import laya.display.Stage;

	import laya.resource.HTMLCanvas;

	import laya.resource.Texture;

	import laya.ui.Image;

	import laya.utils.Handler;

	import laya.webgl.WebGL;

	

	public class LayaAirDemo

	{

		private var img:Image;

		public function LayaAirDemo()

		{

			Laya.init(800, 600, WebGL);

			Laya.stage.alignV = Stage.ALIGN_MIDDLE;

			Laya.stage.alignH = Stage.ALIGN_CENTER;

			Laya.stage.scaleMode = Stage.SCALE_SHOWALL;

			Laya.stage.bgColor = "#232628";

			Laya.loader.load("res/logo.png",Handler.create(this,onLoaded));

		}

		

		private function onLoaded():void

		{

			img=new Image();

			img.skin="res/logo.png";

			Laya.stage.addChild(img);

			Laya.timer.once(500,this,onClick);

			//Laya.stage.on(Event.CLICK,this,onClick);

		}

		

		private function onClick():void

		{

			var htmlCanvas:HTMLCanvas=img.drawToCanvas(100,100,0,0) as HTMLCanvas;

			var texture:Texture=new Texture(htmlCanvas);

			var sp:Sprite=new Sprite();

			sp.graphics.drawTexture(texture,0,0,100,100);

			Laya.stage.addChild(sp);

			sp.x=200;

		}

	}

}