<style>
* {
margin: 0;
padding: 0;
}
.box {
width: 350px;
height: 350px;
margin: 100px;
border: 1px solid #ccc;
position: relative;
}
.big {
width: 400px;
height: 400px;
position: absolute;
top: 0;
left: 360px;
border: 1px solid #ccc;
overflow: hidden;
display: none;
}
.mask {
width: 175px;
height: 175px;
background: rgba(255, 255, 0, 0.4);
position: absolute;
top: 0px;
left: 0px;
cursor: move;
display: none;
}
.small {
position: relative;
}
</style>
</head>
<body>
<div class="box" id="box">
<div class="small"><!--小层-->
<img src="images/small.png" width="350" alt=""/>
<div class="mask"></div><!--遮挡层-->
</div><!--小图-->
<div class="big"><!--大层-->
<img src="images/big.jpg" width="800" alt=""/><!--大图-->
</div><!--大图-->
</div>
//获取需要的元素
var box = my$("box");
//获取小图的div
var small = box.children[0];
//遮挡层
var mask = small.children[1];
//获取大图的div
var big = box.children[1];
//获取大图
var bigImg = big.children[0];
//鼠标进入显示遮挡层和大图的div
box.onmouseover = function () {
mask.style.display = "block";
big.style.display = "block";
};
//鼠标离开隐藏遮挡层和大图的div
box.onmouseout = function () {
mask.style.display = "none";
big.style.display = "none";
};
//鼠标的移动事件---鼠标是在小层上移动
small.onmousemove = function (e) {
//鼠标此时的可视区域的横坐标和纵坐标
//主要是设置鼠标在遮挡层的中间显示
var x = e.clientX - mask.offsetWidth / 2;
var y = e.clientY - mask.offsetHeight / 2;
//主要是margin的100px的问题
x = x - 100;
y = y - 100;
//横坐标的最小值
x = x < 0 ? 0 : x;
//纵坐标的最小值
y = y < 0 ? 0 : y;
//横坐标的最大值
x = x > small.offsetWidth - mask.offsetWidth ? small.offsetWidth - mask.offsetWidth : x;
//纵坐标的最大值
y = y > small.offsetHeight - mask.offsetHeight ? small.offsetHeight - mask.offsetHeight : y;
//为遮挡层的left和top赋值
mask.style.left = x + "px";
mask.style.top = y + "px";
//遮挡层的移动距离/大图的移动距离=遮挡层的最大移动距离/大图的最大移动距离
//大图的移动距离=遮挡层的移动距离*大图的最大移动距离/遮挡层的最大移动距离
//大图的横向的最大移动距离
var maxX = bigImg.offsetWidth - big.offsetWidth;
//大图的纵向的最大移动距离
//var maxY = bigImg.offsetHeight - big.offsetHeight;
//大图的横向移动的坐标
var bigImgMoveX = x * maxX / (small.offsetWidth - mask.offsetWidth);
//大图的纵向移动的坐标
var bigImgMoveY = y * maxX / (small.offsetWidth - mask.offsetWidth);
//设置图片移动
bigImg.style.marginLeft = -bigImgMoveX + "px";
bigImg.style.marginTop = -bigImgMoveY + "px";
};
