鼠标滚轮图片放大缩小功能，使用layer弹框后不起作用

时间：2023-03-21 19:15:14

今天在项目中遇到的一个问题：点击按钮使用layer弹框弹出一张图片，需要加一个鼠标滚轮放大缩小，图片也跟着放大缩小的功能。于是在网上找了一个demo。

DEMO:

 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

 <html xmlns="http://www.w3.org/1999/xhtml" >

 <head>

     <title>图片放大缩小</title>

     <style type="text/css">

       div{

           width: 100px;

           height: 100px;

       }

     </style>

     <script type="text/javascript" src="jquery-1.9.1.js"></script>

     <script type="text/javascript" src="layer.js"></script>

 </head>

 <body>

     <div id="mqp">

         <img id="myimage" src="kmlogo.png" alt="my image" />

     </div>

     <script type="text/javascript">

         var myimage = document.getElementById("myimage");

             // IE9, Chrome, Safari, Opera

             myimage.addEventListener("mousewheel", MouseWheelHandler, false);

             // Firefox

             myimage.addEventListener("DOMMouseScroll", MouseWheelHandler, false);

             myimage.attachEvent("onmousewheel", MouseWheelHandler);

         function MouseWheelHandler(e) {

             // cross-browser wheel delta

             var e = window.event || e; // old IE support

             var delta = Math.max(-1, Math.min(1, (e.wheelDelta || -e.detail)));

             myimage.style.width = Math.max(50, Math.min(1800, myimage.width + (30 * delta))) + "px";

             return false;

         }

     </script>

 </body>

 </html>

这个例子没有引用layer，而是直接显示图片，滚轮放大缩小图片是正常的，当加入layer后，代码如下：

 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

 <html xmlns="http://www.w3.org/1999/xhtml" >

 <head>

     <title>�����ַŴ�ͼƬ</title>

     <style type="text/css">

       div{

           width: 100px;

           height: 100px;

       }

     </style>

     <script type="text/javascript" src="jquery-1.9.1.js"></script>

     <script type="text/javascript" src="layer.js"></script>

 </head>

 <body>

     <div id="mqp">

         <img id="myimage" src="kmlogo.png" alt="my image" />

     </div>

     <script type="text/javascript">

         layer.open({

             type: 1,

             shade: false,

             title: false, //不显示标题

             content: document.getElementById("mqp"), //捕获的元素，注意：最好该指定的元素要存放在body最外层，否则可能被其它的相对元素所影响

             cancel: function(){

                 layer.msg('捕获就是从页面已经存在的元素上，包裹layer的结构', {time: 5000, icon:6});

             }

         });

         var myimage = document.getElementById("myimage");

             // IE9, Chrome, Safari, Opera

             myimage.addEventListener("mousewheel", MouseWheelHandler, false);

             // Firefox

             myimage.addEventListener("DOMMouseScroll", MouseWheelHandler, false);

             myimage.attachEvent("onmousewheel", MouseWheelHandler);

         function MouseWheelHandler(e) {

             // cross-browser wheel delta

             var e = window.event || e; // old IE support

             var delta = Math.max(-1, Math.min(1, (e.wheelDelta || -e.detail)));

             myimage.style.width = Math.max(50, Math.min(1800, myimage.width + (30 * delta))) + "px";

             return false;

         }

     </script>

 </body>

 </html>

使用layer后，图片无法随着鼠标滚轮的放大、缩小做出相应的变化，于是就想是不是layer把鼠标滚轮事件屏蔽掉了，问同事并在网上搜索了一通，没有找到好的解决方案，后来临近下班时，就想颠倒一下layer的顺序看看，代码如下：

 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

 <html xmlns="http://www.w3.org/1999/xhtml" >

 <head>

     <title>�����ַŴ�ͼƬ</title>

     <style type="text/css">

       div{

           width: 100px;

           height: 100px;

       }

     </style>

     <script type="text/javascript" src="jquery-1.9.1.js"></script>

     <script type="text/javascript" src="layer.js"></script>

 </head>

 <body>

     <div id="mqp">

         <img id="myimage" src="kmlogo.png" alt="my image" />

     </div>

     <script type="text/javascript">

         var myimage = document.getElementById("myimage");

             // IE9, Chrome, Safari, Opera

             myimage.addEventListener("mousewheel", MouseWheelHandler, false);

             // Firefox

             myimage.addEventListener("DOMMouseScroll", MouseWheelHandler, false);

             myimage.attachEvent("onmousewheel", MouseWheelHandler);

         function MouseWheelHandler(e) {

             // cross-browser wheel delta

             var e = window.event || e; // old IE support

             var delta = Math.max(-1, Math.min(1, (e.wheelDelta || -e.detail)));

             myimage.style.width = Math.max(50, Math.min(1800, myimage.width + (30 * delta))) + "px";

             return false;

         } 

         layer.open({

             type: 1,

             shade: false,

             title: false, //不显示标题

             content: document.getElementById("mqp"), //捕获的元素，注意：最好该指定的元素要存放在body最外层，否则可能被其它的相对元素所影响

             cancel: function(){

                 layer.msg('捕获就是从页面已经存在的元素上，包裹layer的结构', {time: 5000, icon:6});

             }

         });

     </script>

 </body>

 </html>

结果鼠标滚轮使图片放大缩小功能正常了，然后就想这是为什么呢？是因为js执行顺序问题还是浏览器渲染机制问题或是其他什么原因，希望了解的大神指点一二~~~

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