使用JS实现具有凸透镜效果的放大镜-原创手记-慕课网

基本布局：

输入代码<><!DOCTYPE html>
<html>
    <head>
        <meta charset="UTF-8">
        <title></title>
        <link rel="stylesheet" type="text/css" href="index.css"/>
        <script src="index.js" type="text/javascript" charset="utf-8"></script>
    </head>
    <body>
        <div class="img-box">
            <img src="1.png"/>
            <div class="fdj" style="display: none;">
                <!--放大镜里面也放一张图片-->
                <img src="1.png"/>
            </div>
        </div>
        <div class="show-box" style="display: none;">
            <img src="1.png"/>
        </div>
    </body>
</html>

CSS样式：

.img-box{
    position: relative;
    float: left;
    width: 400px;
    height: 300px;
    border: 10px solid #000;
    margin-right: 50px;
    margin: 50px;
}
.img-box img{
    width: 100%;
    height: 100%;
}
.fdj{
    position: absolute;
    top: 0;
    left: 0;
    width: 100px;
    height: 100px;
    overflow: hidden;
    border-radius: 50px;
    border: 1px solid rgba(0,0,0,.5);
}
.fdj img{
    position: absolute;
    top: 0;
    left: 0;
/*放大镜里面的图片是原图片的1.02倍，要设置的很小*/
    width: 408px;
    height:306px;
}
.show-box{
    float: left;
    position: relative;
    width: 400px;
    height: 400px;
    overflow: hidden;
    border-radius: 200px;
}
.show-box img{
    position: absolute;
    top: 0;
    left: 0;
    width: 1600px;
    height: 1200px;
}

JS：

window.onload = function(){

    //获取元素
    var imgBox = document.querySelector('.img-box');//图片盒子
    var fdj = document.querySelector('.fdj');//放大镜
    var img1 = fdj.querySelector('img');//放大镜里面的图片
    var showBox = document.querySelector('.show-box');//显示大图的盒子
    var img2 = showBox.querySelector('img');//显示放大的图片

    imgBox.onmousemove = function(ev){
        var ev = ev||event;

        //显示放大镜
        fdj.style.display = 'block';
        showBox.style.display = 'block';

        //设置放大镜的定位位置
        var left = ev.clientX - imgBox.offsetLeft - imgBox.clientLeft - fdj.offsetWidth/2;
        var top = ev.clientY - imgBox.offsetTop - imgBox.clientTop - fdj.offsetHeight/2;

        //边界处理
        if(left<0){
            left = 0;
        }else if(left>imgBox.clientWidth-fdj.offsetWidth){
            left = imgBox.clientWidth-fdj.offsetWidth
        }
        if(top<0){
            top = 0;
        }else if(top>imgBox.clientHeight-fdj.offsetHeight){
            top = imgBox.clientHeight-fdj.offsetHeight;
        }

        //放大镜位置的变化
        fdj.style.left = left + 'px';
        fdj.style.top = top + 'px';

        //放大镜图片偏移量
        var l = fdj.offsetWidth*(left/fdj.offsetWidth);
        var t = fdj.offsetHeight*(top/fdj.offsetHeight);

        //显示图片偏移量
        var left_ = showBox.offsetWidth*(left/fdj.offsetWidth);
        var top_ = showBox.offsetHeight*(top/fdj.offsetHeight);

        //放大镜
        img1.style.left = -l + 'px';
        img1.style.top = -t+ 'px';

        //显示
        img2.style.left = -left_ + 'px';
        img2.style.top = -top_ + 'px';

    };

    imgBox.onmouseout =function(){
        fdj.style.display = 'none';
        showBox.style.display = 'none';
    };

};