[Javascript]層的拖動

javascript
var Drag=
{
"obj":null,
"init":function(a, aRoot){
a.onmousedown=Drag.start;
a.root = aRoot;
if(isNaN(parseInt(a.root.style.left)))a.root.style.left="0px";
if(isNaN(parseInt(a.root.style.top)))a.root.style.top="0px";
a.root.onDragStart=new Function();
a.root.onDragEnd=new Function();
a.root.onDrag=new Function();
},
"start":function(a){
var b=Drag.obj=this;
a=Drag.fixE(a);
var c=parseInt(b.root.style.top);
var d=parseInt(b.root.style.left);
b.root.onDragStart(d,c,a.clientX,a.clientY);
b.lastMouseX=a.clientX;
b.lastMouseY=a.clientY;
document.onmousemove=Drag.drag;
document.onmouseup=Drag.end;
return false;
},
"drag":function(a){
a=Drag.fixE(a);
var b=Drag.obj;
var c=a.clientY;
var d=a.clientX;
var e=parseInt(b.root.style.top);
var f=parseInt(b.root.style.left);
var h,g;
h=f+d-b.lastMouseX;
g=e+c-b.lastMouseY;
b.root.style.left=h+"px";
b.root.style.top=g+"px";
b.lastMouseX=d;
b.lastMouseY=c;
b.root.onDrag(h,g,a.clientX,a.clientY);
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;
},
"fixE":function(a){
if(typeof a=="undefined")a=window.event;
if(typeof a.layerX=="undefined")a.layerX=a.offsetX;
if(typeof a.layerY=="undefined")a.layerY=a.offsetY;
return a;
}
};