本文實例講述了js實作圖片放大和拖曳特效程式碼。分享給大家供大家參考。具體如下：
js實現圖片放大和拖曳特效是一款非常實用的js特效，實現了圖片的放大和拖曳功能，沒用到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，還可以使用滑鼠的滾輪控制圖片的縮放。
運作效果圖： ----------------------看效果 ---------------
小提示：瀏覽器中如果無法正常運作，可以嘗試切換瀏覽模式。
<!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>
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;
}
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;
}
