$(function(){
var mouseX = 0; //鼠標移動的位置X
var mouseY = 0; //鼠標移動的位置Y
var maxLeft = 0; //最右邊
var maxTop = 0; //最下邊
var markLeft = 0; //放大鏡移動的左部距離
var markTop = 0; //放大鏡移動的頂部距離
var perX = 0; //移動的X百分比
var perY = 0; //移動的Y百分比
var bigLeft = 0; //大圖要移動left的距離
var bigTop = 0; //大圖要移動top的距離
//改變放大鏡的位置
function updataMark($mark){
//通過判斷，讓小框只能在小圖區(qū)域中移動
if(markLeft<0){
markLeft = 0;
}else if(markLeft>maxLeft){
markLeft = maxLeft;
}

if(markTop<0){
markTop = 0;
}else if(markTop>maxTop){
markTop = maxTop;
}
//獲取放大鏡的移動比例，即這個小框在區(qū)域中移動的比例
perX = markLeft/$(".small").outerWidth();
perY = markTop/$(".small").outerHeight();
bigLeft = -perX*$(".big").outerWidth();
bigTop = -perY*$(".big").outerHeight();
//設定小框的位置
$mark.css({"left":markLeft,"top":markTop,"display":"block"});
}
//改變大圖的位置
function updataBig(){
$(".big").css({"display":"block","left":bigLeft,"top":bigTop});
}
//鼠標移出時
function cancle(){
$(".big").css({"display":"none"});
$(".mark").css({"display":"none"});
}
//鼠標小圖上移動時
function imgMouseMove(event){
var $this = $(this);
var $mark = $(this).children(".mark");
//鼠標在小圖的位置
mouseX = event.pageX-$this.offset().left - $mark.outerWidth()/2;
mouseY = event.pageY-$this.offset().top - $mark.outerHeight()/2;
//最大值
maxLeft =$this.width()- $mark.outerWidth();
maxTop =$this.height()- $mark.outerHeight();
markLeft = mouseX;
markTop = mouseY;
updataMark($mark);
updataBig();
}

$(".small").bind("mousemove",imgMouseMove).bind("mouseleave",cancle);
})