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名站技术分析 — tudou网首页下列菜单的弹出效果

2010-07-02 08:40 375 查看
// jQuery.extend(jQuery.easing,{
def : "easeOutQuad",
swing : function(o, p, n, r, q) {
return jQuery.easing[jQuery.easing.def](o, p, n, r,q)
},
easeOutBounce : function(o, p, n, r, q) {
if ((p /= q) < (1 / 2.75)) {
return r * (7.5625 * p * p) + n
} else {
if (p < (2 / 2.75)) {
return r * (7.5625 * (p -= (1.5 / 2.75)) * p + 0.75) + n
} else {
if (p < (2.5 / 2.75)) {
return r * (7.5625 * (p -= (2.25 / 2.75)) * p + 0.9375) + n
} else {
return r * (7.5625 * (p -= (2.625 / 2.75)) * p + 0.984375) + n
}
}
}
}
});
function b_showMenu(){
b_resetMenu();
$("#b_menu").animate({height:100},500,"easeOutBounce");
}
function b_resetMenu(){
$("#b_menu").show();
$("#b_menu").height(0);
}
// ]]>

  土豆(tudou.com)首页的导航条,当鼠标移到到“社区”菜单时,对应的菜单的弹出效果比较有意思,类似于一个弹球落地的效果,对于有意思的东西,当然要研究研究。有兴趣的朋友可以自己先去看看效果,然后再来看文章。

tudou代码

看了tudou的js代码,发现他们也是使用jquery来实现动画效果的,代码如下:

f.style.height=0;

this.style.visibility="visible";

$(f).animate({height:g},500,"easeOutBounce");

$(i).addClass("hover")

最重要的是上面第三行代码,使用jquery的animate的函数,其中重点就是tudou自定义了animate的easing函数,即easeOutBounce函数,easeOutBounce函数如下。

我的菜单(点击我)

菜单一

菜单二

菜单三

菜单四

代码:

<!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>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<script type="text/javascript" src="http://common.cnblogs.com/script/jquery.js"></script>
<script type="text/javascript">
jQuery.extend(jQuery.easing,{
def : "easeOutQuad",
swing : function(o, p, n, r, q) {
return jQuery.easing[jQuery.easing.def](o, p, n, r,q)
},
easeOutBounce : function(o, p, n, r, q) {
if ((p /= q) < (1 / 2.75)) {
return r * (7.5625 * p * p) + n
} else {
if (p < (2 / 2.75)) {
return r * (7.5625 * (p -= (1.5 / 2.75)) * p + 0.75) + n
} else {
if (p < (2.5 / 2.75)) {
return r * (7.5625 * (p -= (2.25 / 2.75))	* p + 0.9375) + n
} else {
return r * (7.5625 * (p -= (2.625 / 2.75)) * p + 0.984375) + n
}
}
}
}
});
function showMenu(){
resetMenu();
$("#b_menu").animate({height:100},500,"easeOutBounce");
}
function resetMenu(){
$("#b_menu").show();
$("#b_menu").height(0);
}
</script>

<style type="text/css">
#b_menu{border:1px solid #F56E0B;width:100px;list-style:none;padding:0;height:0;overflow:hidden;display:none;}
#b_menu li{line-height:25px;width:100px;text-align:center;}
</style>
</head>
<body>
<a href="javascript:showMenu();void(0)">我的菜单</a><br />
<ul id="b_menu">
<li>菜单一</li>
<li>菜单二</li>
<li>菜单三</li>
<li>菜单四</li>
</ul>
</body>
</html>


easing函数
  jquery默认定义了2个easing函数,分别是swing和linear,easing函数格式如下:function(o, p, n, r, q)
但对于该几个参数的具体说明,jquery官方也没有文档说明(不知道是否是我没有找到),经过我看源代码和自己的理解,对几个参数理解如下:
o = p/q
p: 当前时间 - animate开始时间的毫秒值
n: 起始值,一直为0
r: 这个个人认为是递增值,一直为1
q: animate中的duration参数,即设置的动画效果运行完毕需要的时间
返回值:返回1个大于0,小于等于1的百分比值,animate方法通过这个百分比去计算各个参数的值

  知道这几个参数的含义后,再看看tudou的easeOutBounce,就发现其第一行代码写的有问题,if ((p /= q) < (1 / 2.75)) 其实可以直接写成 if ((o) < (1 / 2.75)) 。
可以看出tudou的开发人员对easing函数的几个参数也不太理解,不然就不会这样写了(也有可能easeOutBounce函数,tudou也是直接从其他地方copy过来的,呵呵)

胡言乱语
  在查询jquery的easing参数的时候,无意间发现1个专门做easing效果的网站(http://gsgd.co.uk/sandbox/jquery/easing/),而土豆的几个easing效果代码跟该网站的easing效果代码是惊人的相似,除了参数名不同外(这也出现我前面copy 代码的猜测),其实是不是copy都无所谓的,偶也是胡言乱语下,大家也别想太多,贴出2段代码,大家自己看看吧。

下面tudou的代码:

(o, p, n, r,q)
},
easeInQuad : function(o, p, n, r, q) {
return r * (p /= q) * p + n
},
easeOutQuad : function(o, p, n, r, q) {
return -r * (p /= q) * (p - 2) + n
},
easeInOutQuad : function(o, p, n, r, q) {
if ((p /= q / 2) <]http://gsgd.co.uk/sandbox/jquery/easing/jquery.easing.1.3.js 代码

jQuery.extend( jQuery.easing,{
def: 'easeOutQuad',
swing: function (x, t, b, c, d) {
//alert(jQuery.easing.default);
return jQuery.easing[jQuery.easing.def](x, t, b, c, d);
},
easeInQuad: function (x, t, b, c, d) {
return c*(t/=d)*t + b;
},
easeOutQuad: function (x, t, b, c, d) {
return -c *(t/=d)*(t-2) + b;
},
easeInOutQuad: function (x, t, b, c, d) {
if ((t/=d/2) < 1) return c/2*t*t + b;
return -c/2 * ((--t)*(t-2) - 1) + b;
},
easeInCubic: function (x, t, b, c, d) {
return c*(t/=d)*t*t + b;
},
easeOutCubic: function (x, t, b, c, d) {
return c*((t=t/d-1)*t*t + 1) + b;
},
easeInOutCubic: function (x, t, b, c, d) {
if ((t/=d/2) < 1) return c/2*t*t*t + b;
return c/2*((t-=2)*t*t + 2) + b;
},
easeInQuart: function (x, t, b, c, d) {
return c*(t/=d)*t*t*t + b;
},
easeOutQuart: function (x, t, b, c, d) {
return -c * ((t=t/d-1)*t*t*t - 1) + b;
},
easeInOutQuart: function (x, t, b, c, d) {
if ((t/=d/2) < 1) return c/2*t*t*t*t + b;
return -c/2 * ((t-=2)*t*t*t - 2) + b;
},
easeInQuint: function (x, t, b, c, d) {
return c*(t/=d)*t*t*t*t + b;
},
easeOutQuint: function (x, t, b, c, d) {
return c*((t=t/d-1)*t*t*t*t + 1) + b;
},
easeInOutQuint: function (x, t, b, c, d) {
if ((t/=d/2) < 1) return c/2*t*t*t*t*t + b;
return c/2*((t-=2)*t*t*t*t + 2) + b;
},
easeInSine: function (x, t, b, c, d) {
return -c * Math.cos(t/d * (Math.PI/2)) + c + b;
},
easeOutSine: function (x, t, b, c, d) {
return c * Math.sin(t/d * (Math.PI/2)) + b;
},
easeInOutSine: function (x, t, b, c, d) {
return -c/2 * (Math.cos(Math.PI*t/d) - 1) + b;
},
easeInExpo: function (x, t, b, c, d) {
return (t==0) ? b : c * Math.pow(2, 10 * (t/d - 1)) + b;
},
easeOutExpo: function (x, t, b, c, d) {
return (t==d) ? b+c : c * (-Math.pow(2, -10 * t/d) + 1) + b;
},
easeInOutExpo: function (x, t, b, c, d) {
if (t==0) return b;
if (t==d) return b+c;
if ((t/=d/2) < 1) return c/2 * Math.pow(2, 10 * (t - 1)) + b;
return c/2 * (-Math.pow(2, -10 * --t) + 2) + b;
},
easeInCirc: function (x, t, b, c, d) {
return -c * (Math.sqrt(1 - (t/=d)*t) - 1) + b;
},
easeOutCirc: function (x, t, b, c, d) {
return c * Math.sqrt(1 - (t=t/d-1)*t) + b;
},
easeInOutCirc: function (x, t, b, c, d) {
if ((t/=d/2) < 1) return -c/2 * (Math.sqrt(1 - t*t) - 1) + b;
return c/2 * (Math.sqrt(1 - (t-=2)*t) + 1) + b;
},
easeInElastic: function (x, t, b, c, d) {
var s=1.70158;var p=0;var a=c;
if (t==0) return b;  if ((t/=d)==1) return b+c;  if (!p) p=d*.3;
if (a < Math.abs(c)) { a=c; var s=p/4; }
else var s = p/(2*Math.PI) * Math.asin (c/a);
return -(a*Math.pow(2,10*(t-=1)) * Math.sin( (t*d-s)*(2*Math.PI)/p )) + b;
},
easeOutElastic: function (x, t, b, c, d) {
var s=1.70158;var p=0;var a=c;
if (t==0) return b;  if ((t/=d)==1) return b+c;  if (!p) p=d*.3;
if (a < Math.abs(c)) { a=c; var s=p/4; }
else var s = p/(2*Math.PI) * Math.asin (c/a);
return a*Math.pow(2,-10*t) * Math.sin( (t*d-s)*(2*Math.PI)/p ) + c + b;
},
easeInOutElastic: function (x, t, b, c, d) {
var s=1.70158;var p=0;var a=c;
if (t==0) return b;  if ((t/=d/2)==2) return b+c;  if (!p) p=d*(.3*1.5);
if (a < Math.abs(c)) { a=c; var s=p/4; }
else var s = p/(2*Math.PI) * Math.asin (c/a);
if (t < 1) return -.5*(a*Math.pow(2,10*(t-=1)) * Math.sin( (t*d-s)*(2*Math.PI)/p )) + b;
return a*Math.pow(2,-10*(t-=1)) * Math.sin( (t*d-s)*(2*Math.PI)/p )*.5 + c + b;
},
easeInBack: function (x, t, b, c, d, s) {
if (s == undefined) s = 1.70158;
return c*(t/=d)*t*((s+1)*t - s) + b;
},
easeOutBack: function (x, t, b, c, d, s) {
if (s == undefined) s = 1.70158;
return c*((t=t/d-1)*t*((s+1)*t + s) + 1) + b;
},
easeInOutBack: function (x, t, b, c, d, s) {
if (s == undefined) s = 1.70158;
if ((t/=d/2) < 1) return c/2*(t*t*(((s*=(1.525))+1)*t - s)) + b;
return c/2*((t-=2)*t*(((s*=(1.525))+1)*t + s) + 2) + b;
},
easeInBounce: function (x, t, b, c, d) {
return c - jQuery.easing.easeOutBounce (x, d-t, 0, c, d) + b;
},
easeOutBounce: function (x, t, b, c, d) {
if ((t/=d) < (1/2.75)) {
return c*(7.5625*t*t) + b;
} else if (t < (2/2.75)) {
return c*(7.5625*(t-=(1.5/2.75))*t + .75) + b;
} else if (t < (2.5/2.75)) {
return c*(7.5625*(t-=(2.25/2.75))*t + .9375) + b;
} else {
return c*(7.5625*(t-=(2.625/2.75))*t + .984375) + b;
}
},
easeInOutBounce: function (x, t, b, c, d) {
if (t < d/2) return jQuery.easing.easeInBounce (x, t*2, 0, c, d) * .5 + b;
return jQuery.easing.easeOutBounce (x, t*2-d, 0, c, d) * .5 + c*.5 + b;
}
});


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