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自动播放——幻灯片缓冲效果

时间:2012-11-11 10:56:42  来源:  作者:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>自动播放——幻灯片缓冲效果</title>
<style>
body,div,ul,li{margin:0;padding:0;}
ul{list-style-type:none;}
body{background:#000;text-align:center;font:12px/20px Arial;}
#box{position:relative;width:492px;height:172px;background:#fff;border-radius:5px;border:8px solid #fff;margin:10px auto;cursor:pointer;}
#box .list{position:relative;width:490px;height:170px;overflow:hidden;}
#box .list ul{position:absolute;top:0;left:0;}
#box .list li{width:490px;height:170px;overflow:hidden;}
#box .count{position:absolute;right:0;bottom:5px;}
#box .count li{color:#fff;float:left;width:20px;height:20px;cursor:pointer;margin-right:5px;overflow:hidden;background:#F90;opacity:0.7;filter:alpha(opacity=70);border-radius:20px;}
#box .count li.current{color:#fff;opacity:1;filter:alpha(opacity=100);font-weight:700;background:#f60;}
#tmp{width:100px;height:100px;background:red;position:absolute;}
</style>
<script type="text/javascript">
window.onload = function ()
{
 var oBox = document.getElementById("box");
 var oList = oBox.getElementsByTagName("ul")[0];
 var aImg = oBox.getElementsByTagName("img");
 var timer = playTimer = null;
 var index = i = 0;
 var bOrder = true;
 var aTmp = [];
 
 //天生数字按钮
 for (i = 0; i < aImg.length; i++)
 {
  aTmp.push("<li>" + (i + 1) + "</li>")
 }
 
 //插入元素
 var oCount = document.createElement("ul");
 oCount.className = "count"
 oCount.innerHTML = aTmp.join("");
 oBox.appendChild(oCount);
 
 //初始化状态
 var aBtn = oBox.getElementsByTagName("ul")[1].getElementsByTagName("li");
 aBtn[index].className = "current";
 
 //按钮点击切换
 for (i = 0; i < aBtn.length; i++)
 {
  aBtn[i].index = i;
  aBtn[i].onclick = function ()
  {
   index = this.index;
   for (i = 0; i < aBtn.length; i++) aBtn[i].className = "";
   this.className = "current";   
   startMove(-(this.index * aImg[0].offsetHeight))  
  }
 }
 
 //鼠标移入展示区停止自动播放
 oBox.onmouseover = function ()
 {
  clearInterval(playTimer)
 };
 
 //鼠标离开展示区开始自动播放
 oBox.onmouseout = function ()
 {
  autoPlay()
 };
 
 //页面加载即调用自动播放
 oBox.onmouseout();
 
 //自动播放函数
 function autoPlay()
 {
  playTimer = setInterval(function ()
  {
   bOrder ? index++ : index--;   
   index == aBtn.length - 1 && (bOrder = false);
   index == 0 && (bOrder = true);
   aBtn[index].onclick();
   startMove(-(index * aImg[0].offsetHeight))
  }, 3000)
 }
 function startMove(iTarget)
 {
  clearInterval(timer);
  timer = setInterval(function ()
  {
   doMove(iTarget)
  }, 30) 
 }
 function doMove (iTarget)
 {
  var iSpeed = (iTarget - oList.offsetTop) / 10;
  iSpeed = iSpeed > 0 ? Math.ceil(iSpeed) : Math.floor(iSpeed);  
  oList.offsetTop == iTarget ? clearInterval(timer) : oList.style.top = oList.offsetTop + iSpeed + "px"
 }
};
</script>
</head>
<body>
<div id="box">
    <div class="list">
        <ul>
            <li><img src="http://www.codefans.net/jscss/demoimg/wall5.jpg" width="490" height="170" /></li>
            <li><img src="http://www.codefans.net/jscss/demoimg/wall6.jpg" width="490" height="170" /></li>
            <li><img src="http://www.codefans.net/jscss/demoimg/wall7.jpg" width="490" height="170" /></li>
        </ul>
    </div>
</div>
</body>
</html>