JS---案例:高清放大镜

案例:高清放大镜

 

分3步

1. 鼠标进入和离开,显示和隐藏遮挡层和大图div

2. 鼠标在小层上移动,鼠标横纵坐标,为可视区域坐标-遮挡层的宽高,鼠标移动的时候,在一个区域内移动,需要判断和定义下移动区间

3. 在小图移动,对应大图的坐标,用比例来做 a/b =c/d ,a=bc/d

4. 移动设置,用大图的marginleft和top实现,负的移动距离

 

DOCTYPE html>
<html>

<head lang="en">
  <meta charset="UTF-8">
  <title>哈哈title>
  <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">
      
      <img src="images/small.png" width="350" alt="" />
      <div class="mask">div>
      
    div>
    
    <div class="big">
      
      <img src="images/big.jpg" width="800" alt="" />
      
    div>
    
  div>
  
  <script src="common.js">script>
  <script>

    //获取需要的元素
    var box = my$("box");
    //获取小图的div
    var small = box.children[0];
    //遮挡曾
    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";

    };

    //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
      //设置鼠标在遮挡层的中间显示
      var x = parseInt(e.clientX - mask.offsetWidth / 2);
      var y = parseInt(e.clientY - mask.offsetHeight / 2);
      //设置margin的100px的问题 (先让鼠标在遮挡层左上角显示)
      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

      //大图的横向最大移动距离
      var maxX = bigImg.offsetHeight - big.offsetHeight;

      //大图的纵向最大移动距离
      // var maxY = bigImg.offsetHeight - big.offsetHeight;

      //大图的横向移动坐标
      var bigImgMoveX = x * maxX / (small.offsetWidth - mask.offsetWidth);
      //大图的纵向移动坐标
      var bigImgMoveY = y * maxX / (small.offsetWidth - mask.offsetWidth);

      //设置图片的移动
      bigImg.style.marginLeft = -bigImgMoveX + "px";
      bigImg.style.marginTop = -bigImgMoveY + "px";

    };
  script>


body>

html>

你可能感兴趣的:(JS---案例:高清放大镜)