//获取坐标位置
function getPosition(ev){
	ev = ev || window.event;
	var point = {x:0,y:0};
    if(ev.pageX || ev.pageY){
	    point.x = ev.pageX;
	    point.y = ev.pageY;
    } else {//兼容ie
	    point.x = ev.clientX + document.body.scrollLeft - document.body.clientLeft;
	    point.y = ev.clientY + document.documentElement.scrollTop;
    }
    return point;
	}