效果预览:
一、模拟抽奖的实现过程
旋转原理:当支持CSS3属性采用transform: rotate(角度deg)设置,当角度为正数时顺时针旋转,当为负数时逆时针旋转。如果是IE8及其以下,采用采用绝对定位设置top和left,模拟角度旋转。
run方法,参数angle指角度
if (isIE) {
cosDeg = Math.cos(angle * Math.PI / 180);
sinDeg = Math.sin(angle * Math.PI / 180);
with (target.filters.item(0)) {
M11 = M22 = cosDeg; M12 = -(M21 = sinDeg);
}
target.style.top = (orginH - target.offsetHeight) / 2 + "px";
target.style.left = (orginW - target.offsetWidth) / 2 + "px";
} else if (target.style.MozTransform !== undefined) {
target.style.MozTransform = "rotate(" + angle + "deg)";
} else if (target.style.OTransform !== undefined) {
target.style.OTransform = "rotate(" + angle + "deg)";
} else if (target.style.webkitTransform !== undefined) {
target.style.webkitTransform = "rotate(" + angle + "deg)";
} else {
target.style.transform = "rotate(" + angle + "deg)";
}
}
模拟转盘加速,匀速和减速。当角度小于某个数值时,让其处于加速此处采用1.01的系数作为加速度,当大于某个数值时处于高速匀速状态,当角度大于设置的最大数值时,让其减速采用系数为0.99。设置负数作为减速的值(即变量 tmp),随即获取负360中的值(即变量 m),当大于这个值时,转盘停止。
var m = -parseInt(Math.random() * 360);
timer = setInterval(function () {
if (i > 3000) {
tmp = parseInt(tmp * 0.99);
if (tmp > m) {
tmp = m;
clearInterval(timer);
msg(m);
}
run(tmp);
}
else if (i > 1000) {
i = i + 45;
run(i);
}
else {
i = parseInt((i + 1) * 1.01);
run(i);
}
}, 50);
启动抽奖和重新设置抽奖
<input id="restart" style="display: none;" type="button" value="再抽一次" />
m$('test').onclick = function () {
m$('test').style.display = "none";
showMsg();
}
m$('restart').onclick = function () {
m$('restart').style.display = "none";
if (isIE) {
m$("demo").style.top = "0px";
m$("demo").style.left = "0px";
} else if (m$("demo").style.MozTransform !== undefined) {
m$("demo").style.MozTransform = 'rotate(0deg)';
} else if (m$("demo").style.OTransform !== undefined) {
m$("demo").style.OTransform = 'rotate(0deg)';
} else if (m$("demo").style.webkitTransform !== undefined) {
m$("demo").style.webkitTransform = 'rotate(0deg)';
} else {
m$("demo").style.transform = 'rotate(0deg)';
}
m$('test').style.display = "block";
i = 0;
}
二、完整代码demo:
<html>
<head>
<title>抽奖</title>
<style type="text/css">
#container{width: 400px;height: 400px;position: relative;margin: 0 auto;}
#demo{position: absolute;filter: progid:DXImageTransform.Microsoft.Matrix(sizingmethod="auto expand");}
</style>
</head>
<body style="height: 1000px;">
<div id="container">
<div id="demo">
<img alt="" src="//bbsmax.ikafan.com/static/L3Byb3h5L2h0dHAvZmlsZXMuamI1MS5uZXQvZmlsZV9pbWFnZXMvYXJ0aWNsZS8yMDE0MDYvMjAxNDYzOTQ4MTkyNzkucG5nPzIwMTQ1Mzk0OTI2.jpg" width="400" height="400" />
</div>
</div>
<input id="test" type="button" value="抽奖" />
<input id="restart" style="display: none;" type="button" value="再抽一次" />
<div id="msg">
</div>
<script type="text/javascript">
var m$ = function (id) { return document.getElementById(id); }
var ua = navigator.userAgent;
var isIE = /msie/i.test(ua) && !window.opera;
var i = 1, sinDeg = 0, cosDeg = 0, timer = null;
var mRotate = function () {
var rotate = function (target, msg) {
target = m$(target);
var orginW = target.clientWidth, orginH = target.clientHeight;
clearInterval(timer);
function run(angle) {
if (isIE) {
cosDeg = Math.cos(angle * Math.PI / 180);
sinDeg = Math.sin(angle * Math.PI / 180);
with (target.filters.item(0)) {
M11 = M22 = cosDeg; M12 = -(M21 = sinDeg);
}
target.style.top = (orginH - target.offsetHeight) / 2 + "px";
target.style.left = (orginW - target.offsetWidth) / 2 + "px";
} else if (target.style.MozTransform !== undefined) {
target.style.MozTransform = "rotate(" + angle + "deg)";
} else if (target.style.OTransform !== undefined) {
target.style.OTransform = "rotate(" + angle + "deg)";
} else if (target.style.webkitTransform !== undefined) {
target.style.webkitTransform = "rotate(" + angle + "deg)";
} else {
target.style.transform = "rotate(" + angle + "deg)";
}
}
var tmp = -900;
var m = -parseInt(Math.random() * 360);
timer = setInterval(function () {
if (i > 3000) {
tmp = parseInt(tmp * 0.99);
if (tmp > m) {
tmp = m;
clearInterval(timer);
msg(m);
}
run(tmp);
}
else if (i > 1000) {
i = i + 45;
run(i);
}
else {
i = parseInt((i + 1) * 1.01);
run(i);
}
}, 50);
}
return { rotate: rotate }
} ();
function showMsg() {
mRotate.rotate("demo", function msg(m) {
if (m > -90 && m < -30) {
m$("msg").innerHTML += "22222222";
}
else if (m > -150 && m < -90) {
m$("msg").innerHTML += "333333333";
}
else if (m > -210 && m < -150) {
m$("msg").innerHTML += "444444";
}
else if (m > -270 && m < -210) {
m$("msg").innerHTML += "5555555";
}
else if (m > -330 && m < -270) {
m$("msg").innerHTML += "6666666";
} else {
m$("msg").innerHTML += "111111111";
}
m$('restart').style.display = "block";
});
}
window.onload = function () {
m$('test').onclick = function () {
m$('test').style.display = "none";
showMsg();
}
m$('restart').onclick = function () {
m$('restart').style.display = "none";
if (isIE) {
m$("demo").style.top = "0px";
m$("demo").style.left = "0px";
} else if (m$("demo").style.MozTransform !== undefined) {
m$("demo").style.MozTransform = 'rotate(0deg)';
} else if (m$("demo").style.OTransform !== undefined) {
m$("demo").style.OTransform = 'rotate(0deg)';
} else if (m$("demo").style.webkitTransform !== undefined) {
m$("demo").style.webkitTransform = 'rotate(0deg)';
} else {
m$("demo").style.transform = 'rotate(0deg)';
}
m$('test').style.display = "block";
i = 0;
}
}
</script>
</body>
</html>
该方法的关键是Cookie技术和动态图像特性的综合运用。使用Cookie,可以在用户端的硬盘上记录用户的数据,下次访问此站点时,即可读取用户端硬盘的Cookie,直接得知来访者的身份和访问次数等有关信息。JavaScript中通过document.cookie属性访问Cookie,这个属性包括名字、失效日期、有效域名、有效URL路径等。用等号分开的名字和其值是Cookie的实际数据,本例中用来存储该访问者访问该页面的次数。通过把Web页中的图像映射到一个Images数组,一定条件下修改该数组项的特性,可以实现动态图像显示。本例中,首先预载入一组图像,每次调用该Web页时,随机产生新的一组图像,通过覆盖原图像实现动态的趣味性效果。
源程序count.html
< html> < head> < meta http-equiv=″Content-Type″ content=″text/html; charset=gb2312″> < title>趣味计数器< /title> < /head> < body> < p>< script language=″JavaScript″> var expdays=60; var exp=new Date(); exp.setTime(exp.getTime() (expdays*24*60*60*1000)); function count(info){ //若是该访客的第一次访问,将计数器值赋1,否则加1累积 var wwhcount=getcookie(′wwhcount′); if (wwhcount==null){ wwhcount=1; } else{wwhcount++;} setcookie(′wwhcount′,wwhcount,exp); return countdisp(wwhcount) } function countdisp(countvar){ //实现随机显示,不足6位以0补全,可以自己调整显示位数 var countvar1=″000000″+countvar; var howFar1=countvar1.length; countvar1=countvar1.substring(howFar1, howFar1-1) var index=″ ″+Math.floor(Math.random()*10); if (index==″10″){ index=″0″}; for (var icount=0;icount< 6;icount++){ var g=countvar1.substring(icount,icount+1); document.images[icount].src=″http: //localhost/images/″+index+g+″.gif″; } } function getCookieVal(offset){ //获取该访问者的已访问次数 var endstr=document.cookie.indexOf(″;″,offset); if (endstr==-1) endstr=document.cookie.length; return unescape(document.cookie.substring(offset,endstr)); } function getcookie(name){ //截取Cookie中的name信息段 var arg=name+″=″; var alen=arg.length; var clen=document.cookie.length; var i=0; while (i< clen){ var j=i+alen; if (document.cookie.substring(i,j)==arg) return getCookieVal(j); i=document.cookie.indexOf(″ ″,i)+1; if (i==0) break;} return null; } function setcookie(name,value){ //存储该访客计数器的数值 var argv=setcookie.arguments; var argc=setcookie.arguments.length; var expires=(argc>2)?argv[2]:null;var path=(argc>3)?argv[3]:null; var domain=(argc>4)?argv[4]:null; var secure=(argc〉5)?argv[5]:false; document.cookie=name+″=″+escape(value) +((expires==null)?″ ″:(″;expires=″+expires.toGMTString())) +((path==null)?″ ″:(″;path=″+path))+((domain==null)?″ ″:(″;domain=″+domain))+((secure==true)?″;secure″:″ ″); } function deletecookie(name){ //使该信息行失效,删除该用户关于访问次数的信息 var exp=new Date(); exp.setTime(exp.getTime()-1); var cval=getcookie(name); document.cookie=name+″=″+cval+″;expires=″+exp.toGMTString(); } < /script>< /p> < ! --预载入图像数组--> 您是第 < img src=″http://localhost/images/00.gif″ height=20 width=20> < img src=″http://localhost/images/00.gif″ height=20 width=20> < img src=″http://localhost/images/00.gif″ height=20 width=20> < img src=″http://localhost/images/00.gif″ height=20 width=20> < I mg src=″http://localhost/images/00.gif″ height=20 width=20> < img src=″http://localhost/images/00.gif″ height=20 width=20>次光临! < script language=″JavaScript″> //调用count()函数,实现计数器的动态图像显示 count(); < /script> < /body> < /html>
注意事项
由于使用了JavaScript语言,因此该方法具有与应用平台的无关性,可以适用于Unix、Windows等多种平台。另外,此计数器不同于一般意义上的访客计数器,专门用于记录某一访客对某一网站的访问次数。