JS滚轮控制图片缩放大小和拖动的实例代码

具体代码如下所示：

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>Document</title>
  <style>
  .dragAble {
    position: relative;
    cursor: move;
  }
  .img-con {
    position: relative;
    width: 713px;
    height: 455px;
    overflow: hidden;
    border: 1px solid red;
  }
  </style>
</head>
<body>
  <p class="img-con"><img src="/uploads/allimg/18/193TM559-0.jpg" class="dragAble" /></p>
  <script type="text/javascript" charset="utf-8">
  window.onload = function() {
      var oImg = document.getElementsByTagName("img")[0];
      function fnWheel(obj, fncc) {
        obj.onmousewheel = fn;
        if (obj.addEventListener) {
          obj.addEventListener('DOMMouseScroll', fn, false);
        }
        function fn(ev) {
          var oEvent = ev || window.event;
          var down = true;
          if (oEvent.detail) {
            down = oEvent.detail > 0
          } else {
            down = oEvent.wheelDelta < 0
          }
          if (fncc) {
            fncc.call(this, down, oEvent);
          }
          if (oEvent.preventDefault) {
            oEvent.preventDefault();
          }
          return false;
        }
      };
      fnWheel(oImg, function(down, oEvent) {
        var oldWidth = this.offsetWidth;
        var oldHeight = this.offsetHeight;
        var oldLeft = this.offsetLeft;
        var oldTop = this.offsetTop;
        var scaleX = (oEvent.clientX - oldLeft) / oldWidth; //比例
        var scaleY = (oEvent.clientY - oldTop) / oldHeight;
        if (down) {
          this.style.width = this.offsetWidth * 0.9 + "px";
          this.style.height = this.offsetHeight * 0.9 + "px";
        } else {
          this.style.width = this.offsetWidth * 1.1 + "px";
          this.style.height = this.offsetHeight * 1.1 + "px";
        }
        var newWidth = this.offsetWidth;
        var newHeight = this.offsetHeight;
        this.style.left = oldLeft - scaleX * (newWidth - oldWidth) + "px";
        this.style.top = oldTop - scaleY * (newHeight - oldHeight) + "px";
      });
    }
    <!--
    //拖拽
  var ie = document.all;
  var nn6 = document.getElementByIdx && !document.all;
  var isdrag = false;
  var y, x;
  var oDragObj;
  function moveMouse(e) {
    if (isdrag) {
      oDragObj.style.top = (nn6 ? nTY + e.clientY - y : nTY + event.clientY - y) + "px";
      oDragObj.style.left = (nn6 ? nTX + e.clientX - x : nTX + event.clientX - x) + "px";
      return false;
    }
  }
  function initDrag(e) {
    var oDragHandle = nn6 ? e.target : event.srcElement;
    var topElement = "HTML";
    while (oDragHandle.tagName != topElement && oDragHandle.className != "dragAble") {
      oDragHandle = nn6 ? oDragHandle.parentNode : oDragHandle.parentElement;
    }
    if (oDragHandle.className == "dragAble") {
      isdrag = true;
      oDragObj = oDragHandle;
      nTY = parseInt(oDragObj.style.top + 0);
      y = nn6 ? e.clientY : event.clientY;
      nTX = parseInt(oDragObj.style.left + 0);
      x = nn6 ? e.clientX : event.clientX;
      document.onmousemove = moveMouse;
      return false;
    }
  }
  document.onmousedown = initDrag;
  document.onmouseup = new Function("isdrag=false");
  </script>
</body>
</html>

只缩放

<!DOCTYPE html>
<html>
<head>
<title></title>
</head>
<body>
<img border="0" src="/uploads/allimg/18/193TM559-0.jpg" onmousewheel="return rollImg(this)">
</body>
<script language="javascript">
function rollImg(o){
  /* 获取当前页面的缩放比
    若未设置zoom缩放比，则为默认100%，即1，原图大小
  */ 
  var zoom=parseInt(o.style.zoom)||100;
  /* event.wheelDelta 获取滚轮滚动值并将滚动值叠加给缩放比zoom
    wheelDelta统一为±120，其中正数表示为向上滚动，负数表示向下滚动
  */
  zoom+=event.wheelDelta/12;
  /* 如果缩放比大于0，则将缩放比加载到页面元素 */
  if (zoom>0) o.style.zoom=zoom+'%';
  /* 如果缩放比不大于0，则返回false，不执行操作 */
  return false;
}
</script>
</html>

总结

以上所述是小编给大家介绍的JS滚轮控制图片缩放大小和拖动的实例代码，希望对大家有所帮助！