var Drag={

    "obj":null,

	"init":function(handle, dragBody, e){

		if (e == null) {

			handle.onmousedown=Drag.start;

		}

		handle.root = dragBody;

		

		if(isNaN(parseInt(handle.root.style.left)))handle.root.style.left="0px";

		if(isNaN(parseInt(handle.root.style.top)))handle.root.style.top="0px";//ȷ����4�ܹ�ȡ��topֵ

		handle.root.onDragStart=new Function();

		handle.root.onDragEnd=new Function();

		handle.root.onDrag=new Function();

		if (e !=null) {

			var handle=Drag.obj=handle;

			e=Drag.fixe(e);

			var top=parseInt(handle.root.style.top);

			var left=parseInt(handle.root.style.left);

			handle.root.onDragStart(left,top,e.pageX,e.pageY);

			handle.lastMouseX=e.pageX;

			handle.lastMouseY=e.pageY;

			document.onmousemove=Drag.drag;

			document.onmouseup=Drag.end;

		}

	},

	"start":function(e){

		var handle=Drag.obj=this;

		e=Drag.fixEvent(e);

		var top=parseInt(handle.root.style.top);



		var left=parseInt(handle.root.style.left);

		

		handle.root.onDragStart(left,top,e.pageX,e.pageY);

		handle.lastMouseX=e.pageX;		

		handle.lastMouseY=e.pageY;



		document.onmousemove=Drag.drag;

		document.onmouseup=Drag.end;

		return false;

	},	

	"drag":function(e){//�����thisΪdocument �����϶�����ֻ�ܱ�����Drag.obj��

		e=Drag.fixEvent(e);

		var handle=Drag.obj;

		var mouseY=e.pageY;

		var mouseX=e.pageX;

		var top=parseInt(handle.root.style.top);

		var left=parseInt(handle.root.style.left);//�����top��left��handle.root���������߿���ϱ߾����߾�

		

		var currentLeft,currentTop;

		currentLeft=left+mouseX-handle.lastMouseX;

		currentTop=top+(mouseY-handle.lastMouseY);

	

		

		//��һ˲����ϱ߾���������}��˲���ƶ��ľ��� �õ����ڵ��ϱ߾�

		

		handle.root.style.left=currentLeft+"px";

		handle.root.style.top=currentTop+"px";





		handle.lastMouseX=mouseX;

		handle.lastMouseY=mouseY;



		//������һ˲������ֵ ������һ�μ���λ��

		

		handle.root.onDrag(currentLeft,currentTop,e.pageX,e.pageY);//���������Ӧ�ĺ���

		return false;

	},

	"end":function(){

		document.onmousemove=null;

		document.onmouseup=null;

		Drag.obj.root.onDragEnd(parseInt(Drag.obj.root.style.left),parseInt(Drag.obj.root.style.top));

		Drag.obj=null;

	},

	"fixEvent":function(e){//��ʽ���¼��������

		if(typeof e=="undefined")e=window.event;

		if(typeof e.layerX=="undefined")e.layerX=e.offsetX;

		if(typeof e.layerY=="undefined")e.layerY=e.offsetY;

		if(typeof e.pageX == "undefined")e.pageX = e.clientX + document.body.scrollLeft - document.body.clientLeft;

		if(typeof e.pageY == "undefined")e.pageY = e.clientY + document.body.scrollTop - document.body.clientTop;   	

		return e;

	}

};