原生js拖拽实现图形伸缩效果

时间:2020-05-17 crazy的蓝色梦想人气:0
本文实例为大家分享了js拖拽实现图形伸缩效果的具体代码，供大家参考，具体内容如下
点击矩形的四个角和四个边实现不同的效果
<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Document</title>
  <style>
    *{
      padding: 0;
      margin:0;
    }
    .div1{
      width: 200px;
      height: 200px;
      background-color: #71e4ff;
      position: absolute;
      top: 200px;
      left: 200px;
    }
    .t,
    .b{
      width: 100%;
      height: 20px;
      background-color:#ffa2d3;
      position: absolute;
    }
    .t{
      left: 0;
      top:0;
    }
    .b{
      left: 0;
      bottom:0;
    }
    .r,
    .l{
      width: 20px;
      height: 100%;
      background-color:#ffa2d3;
      position: absolute;
    }
    .r{
      right: 0;
      top:0;
    }
    .l{
      left: 0;
      top:0;
    }
    .lt,
    .lb,
    .rt,
    .rb{
      width: 20px;
      height: 20px;
      background-color: #93ff6b;
      position: absolute;
    }
    .lt{
      left: 0;
      top:0;
    }
    .rt{
      right: 0;
      top:0;
    }
    .lb{
      left: 0;
      bottom: 0;
    }
    .rb{
      right: 0;
      bottom:0;
    }
    
  </style>
</head>
<body>
  <div class="div1" id="_div1">
    <div class="t"></div>
    <div class="r"></div>
    <div class="b"></div>
    <div class="l"></div>
    <div class="lt"></div>
    <div class="lb"></div>
    <div class="rt"></div>
    <div class="tb"></div>
  </div>
</body>
</html>
<script>
  // 获取元素
  var _div1 = document.getElementById("_div1");
  var divs = _div1.children;
  // 遍历每个可以拖拽的元素
  for(var i = 0;i < divs.length ;i++)
  {
    drag(divs[i]);
  }
  // 封装一个拖拽函数
   function drag(obj){
    obj.onmousedown = function(event){
      // 捕获事件
      var event = event || window.event;
      // 存储当前的_div1的宽高
      var divW = _div1.offsetWidth;
      var divH = _div1.offsetHeight;
      // 获得当前_div1的offsetLeft 和 offsetTop
      var divL = _div1.offsetLeft;
      var divT = _div1.offsetTop;
      // 存储鼠标按下时的位置
      var clientx = event.clientX;
      var clienty = event.clientY;
      document.onmousemove = function(event){
        var event = event || window.event;
        if(obj.className.indexOf('t') != -1){
          _div1.style.height = divH + ( clienty- event.clientY) + 'px';
          _div1.style.top = divT -( clienty- event.clientY)+ 'px';
        }
        if(obj.className.indexOf('b') != -1){
          _div1.style.height = divH + ( event.clientY -clienty ) + 'px';
        }
         if(obj.className.indexOf('r')!= -1){
          _div1.style.width = divW + ( event.clientX - clientx) + 'px';
        }
         if(obj.className.indexOf('l')!= -1){
          _div1.style.width = divW + ( clientx - event.clientX) + 'px';
          _div1.style.left = event.clientX + 'px';
        }

      }
      document.onmouseup = function(){
        document.onmousemove = null;
        document.onmouseup = null;
      }
      
    }
    
      return false;
   }
      
</script>
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