JS放大镜

作者: sky丶星如雨 | 来源:发表于2017-07-01 16:06 被阅读25次

js放大镜
JS放大镜
2018-12-01
js 放大镜效果
JS 放大镜效果
js放大镜效果
放大镜 js版
js放大镜效果
js实现放大镜
js 放大镜效果

<!doctype html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport"
          content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        *{
            margin:0;
            padding:0;
        }
        #box{
            width: 350px;
            height: 350px;
            border:1px solid #ccc;
            position: relative;
            margin:100px;
        }
        #small{
            position: relative;
        }
        #mask{
            width: 100px;
            height: 100px;
            position: absolute;
            top:0;
            left:0;
            background: rgba(255,255,0,.4);
            cursor: move;
            display: none;
        }
        #big{
            width: 450px;
            height: 450px;
            position: absolute;
            top:0;
            left: 360px;
            overflow: hidden;
            display: none;
        }
        #big img{
            position: absolute;
            top:0;
            left:0;
        }
    </style>
</head>
<body>
<div id="box">
    <div id="small">
        ![](images/001.jpg)
        <div id="mask"></div>
    </div>
    <div id="big">
        ![](images/0001.jpg)
    </div>
</div>
<script>
    // 获取元素
    var box = document.getElementById("box");
    var small = document.getElementById("small");
    var mask = document.getElementById("mask");
    var big = document.getElementById("big");
    var bigImg = big.querySelector("img");

    small.onmouseover = function () {
        mask.style.display  = "block";
        big.style.display = "block";
    };
    small.onmouseout = function () {
        mask.style.display  = "none";
        big.style.display = "none";
    };

    small.onmousemove = function (event) {
       var e = event ||window.event;
       // 获取鼠标位置（可视区域）
       var mX = e.clientX;
       var mY = e.clientY;
       // 计算放大镜的移动范围
        var maxLeft = box.offsetWidth - mask.offsetWidth;
        var maxTop = box.offsetHeight - mask.offsetHeight;
        // 设置临时位置
        var tempLeft = mX - box.offsetLeft - mask.offsetWidth / 2;
        var tempTop = mY - box.offsetTop - mask.offsetHeight / 2;
       //  设置最终位置
        var nowLeft = 0;
        var nowTop = 0;
        if(tempLeft >= maxLeft){
            nowLeft = maxLeft;
        }else if(tempLeft>0 && tempLeft < maxLeft){
            nowLeft = tempLeft;
        }
        if(tempTop >= maxTop){
            nowTop = maxTop;
        }else if(tempTop > 0 && tempTop < maxTop){
            nowTop = tempTop;
        }

        // 遮罩跟随鼠标
        mask.style.left = nowLeft + "px";
        mask.style.top = nowTop + "px";

        // 计算移动比例
        var ratioX = box.offsetWidth / bigImg.offsetWidth;
        var ratioY = box.offsetHeight / bigImg.offsetHeight;
        // 大图位置
        bigImg.style.left = - nowLeft / ratioX + "px";
        bigImg.style.top = - nowTop / ratioY + "px";

    }

</script>
</body>
</html>

这种布局方式相对来说更好操作，小图和大图在同一个盒子里；
难点在于获取鼠标在盒子中的位置，不明白的朋友可以自己画图，可以更直观的理解。
再一点就是遮罩移动，大图移动，强调下，移动的不是大图的父级盒子，而是图片本身，根据图片比例移动，比如，遮罩在小图上移动1px，那么在大盒子上移动的就是 1 / 小图 / 大图。代码中有所体现，如有哪里不清楚，请在下方留言，我会第一时间回复！