本文實例講述了js實現圖片放大和拖拽特效代碼。分享給大家供大家參考。具體如下：
js實現圖片放大和拖拽特效是一款非常實用的js特效，實現了圖片的放大和拖拽功能，沒用用到jquery插件，是用原生javascript實現的，除了點擊放大和縮小按鈕來控制圖片的放大縮小，還可以使用鼠標的滾輪控制圖片的縮放。
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為大家分享的js實現圖片放大和拖拽特效代碼如下
<!DOCTYPE html><html><head> <meta charset="utf-8"> <title>js實現圖片放大和拖拽特效</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="還原" 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="縮小" 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>核心代碼如下：
function onWheelZoom(obj){ //滾輪縮放 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關鍵代碼：
drag = 0move = 0var 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){ //滾輪縮放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;}以上就是為大家分享的js實現圖片放大和拖拽特效代碼，希望大家可以喜歡。
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