js实现图片放大和拖拽特效代码分享

本文实例讲述了js实现图片放大和拖拽特效代码。分享给大家供大家参考。具体如下：
js实现图片放大和拖拽特效是一款非常实用的js特效，实现了图片的放大和拖拽功能，没用用到jquery插件，是用原生javascript实现的，除了点击放大和缩小按钮来控制图片的放大缩小，还可以使用鼠标的滚轮控制图片的缩放。
运行效果图：                               ----------------------查看效果 源码下载-----------------------

小提示：浏览器中如果不能正常运行，可以尝试切换浏览模式。
 为大家分享的js实现图片放大和拖拽特效代码如下

<!DOCTYPE html>
<html>
<head>
 <meta charset="utf-8">
 <title>js实现图片放大和拖拽特效</title>
 <meta name="viewport" content="width=device-width, initial-scale=1, minimum-scale=1, maximum-scale=1, user-scalable=no">
 <link rel="stylesheet" href="css/style.css">
 <script type="text/javascript" src="js/drag_map.js"></script>
 <style type="text/css">
  body{font-size: 12px;font-family: "Verdana" , "Arial" , "Helvetica" , "sans-serif";} td{font-size: 12px; line-height: 150%;} TD{font-size: 12px; color: #000000;} A{font-size: 12px; color: #000000;} #Layer1{z-index: 100; position: absolute; top: 150px;} #Layer2{z-index: 1; position: absolute;}
 </style>
 <script type="text/JavaScript">
  function MM_reloadPage(init) {
   if (init == true) with (navigator) {
    if ((appName == "Netscape") && (parseInt(appVersion) == 4)) {
     document.MM_pgW = innerWidth; document.MM_pgH = innerHeight; onresize = MM_reloadPage;
    }
   }
   else if (innerWidth != document.MM_pgW || innerHeight != document.MM_pgH) location.reload();
  }
  MM_reloadPage(true);
 </script>
</head>
<body onLoad="" onmouseup="document.selection.empty()" oncontextmenu="return false"
 onselectstart="return false" ondragstart="return false" onbeforecopy="return false"
 style="overflow-y: hidden; overflow-x: hidden" oncopy="document.selection.empty()"
 leftmargin="0" topmargin="0" onselect="document.selection.empty()" marginheight="0"
 marginwidth="0">

 <div id="Layer1">
  <table cellspacing="2" cellpadding="0" border="0">
   <tbody>
    <tr>
     <td> 

     </td>
     <td>
      <img title="向上" style="cursor: hand" onClick="clickMove('down')" height="20" src="images/up.gif"
       width="20">
     </td>
     <td> 

     </td>
    </tr>
    <tr>
     <td>
      <img title="向左" style="cursor: hand" onClick="clickMove('right')" height="20" src="images/left.gif"
       width="20">
     </td>
     <td>
      <img title="还原" style="cursor: hand" onClick="realsize();" height="20" src="images/zoom.gif"
       width="20">
     </td>
     <td>
      <img title="向右" style="cursor: hand" onClick="clickMove('left')" height="20" src="images/right.gif"
       width="20">
     </td>
    </tr>
    <tr>
     <td> 

     </td>
     <td>
      <img title="向下" style="cursor: hand" onClick="clickMove('up')" height="20" src="images/down.gif"
       width="20">
     </td>
     <td> 

     </td>
    </tr>
    <tr>
     <td> 

     </td>
     <td>
      <img title="放大" style="cursor: hand" onClick="bigit();" height="20" src="images/zoom_in.gif"
       width="20">
     </td>
     <td> 

     </td>
    </tr>
    <tr>
     <td> 

     </td>
     <td>
      <img title="缩小" style="cursor: hand" onClick="smallit();" height="20" src="images/zoom_out.gif"
       width="20">
     </td>
     <td> 

     </td>
    </tr>
   </tbody>
  </table>
 </div>
 <p>
  <br>
 </p>
 <div id="hiddenPic" style="z-index: 1; left: 0px; visibility: hidden; width: 0px;
  position: absolute; top: 150px; height: 0px">
  <img src="http://ww2.sinaimg.cn/large/adde8400gw1eeazlmtqa8j20qd0mdadm.jpg" border="0" name="images2">
 </div>
 <div class="dragAble" id="block1" onMouseOver="dragObj=block1; drag=1;" style="z-index: 10;
  left: 0px; width: 0px; position: absolute; top: 150px; height: 0px" onMouseOut=""
  drag="0">
  <img onmousewheel="return onWheelZoom(this)" style="zoom: 0.7" src="images/adde8400gw1eeazlmtqa8j20qd0mdadm.jpg"
   border="0" name="images1">
 </div>
<div style="text-align:center;margin:50px 0; font:normal 14px/24px 'MicroSoft YaHei';">
</div>
</body>
</html>

核心代码如下：

function onWheelZoom(obj){ //滚轮缩放
 zoom = parseFloat(obj.style.zoom);
 tZoom = zoom + (event.wheelDelta>0 ? 0.05 : -0.05);
 if(tZoom<0.1 ) return true;
 obj.style.zoom=tZoom;
 return false;
}

js关键代码：

drag = 0
move = 0

var ie=document.all;
var nn6=document.getElementById&&!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");

function clickMove(s){
 if(s=="up"){
 dragObj.style.top = parseInt(dragObj.style.top) + 100;
 }else if(s=="down"){
 dragObj.style.top = parseInt(dragObj.style.top) - 100;
 }else if(s=="left"){
 dragObj.style.left = parseInt(dragObj.style.left) + 100;
 }else if(s=="right"){
 dragObj.style.left = parseInt(dragObj.style.left) - 100;
 }

}

function smallit(){
 var height1=images1.height;
 var width1=images1.width;
 images1.height=height1/1.2;
 images1.width=width1/1.2;
}    

function bigit(){
 var height1=images1.height;
 var width1=images1.width;
 images1.height=height1*1.2;
 images1.width=width1*1.2;
}
function realsize()
{
 images1.height=images2.height;
 images1.width=images2.width;
 block1.style.left = 0;
 block1.style.top = 0;

}
function featsize()
{
 var width1=images2.width;
 var height1=images2.height;
 var width2=701;
 var height2=576;
 var h=height1/height2;
 var w=width1/width2;
 if(height1<height2&&width1<width2)
 {
 images1.height=height1;
 images1.width=width1;
 }
 else
 {
 if(h>w)
 {
 images1.height=height2;
 images1.width=width1*height2/height1;
 }
 else
 {
 images1.width=width2;
 images1.height=height1*width2/width1;
 }
 }
 block1.style.left = 0;
 block1.style.top = 0;
}

function onWheelZoom(obj){ //滚轮缩放
zoom = parseFloat(obj.style.zoom);
tZoom = zoom + (event.wheelDelta>0 ? 0.05 : -0.05);
if(tZoom<0.1 ) return true;
obj.style.zoom=tZoom;
return false;
}

以上就是为大家分享的js实现图片放大和拖拽特效代码，希望大家可以喜欢。