一、缓冲
过程到底是匀速的、还是先快后慢、先慢后快呢？这就是 缓冲，英语叫做tween。
缓冲的实现，非常简单，就是我们的数学家给我们提供了非常多的缓冲算法，都很好用，一个经典的缓冲。
function linear(t , b , c , d){
return c * t / d + b;
}
function easeIn(t,b,c,d){
return c * ( t /= d) * t + b;
}
function easeOut(t,b,c,d){
return -c *(t/=d)*(t-2) + b;
}
他们的参数，都是t、b、c、d：
第一个参数t表示当前帧编号
第二个参数b表示起始位置
第三个参数c表示变化量
第四个参数d表示总帧数
函数的返回值，就是t这一帧，元素应该在的位置。
<!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" xml:lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html;charset=UTF-8">
<title>Document</title>
<style type="text/css">
div{
width: 60px;
height: 60px;
background-color: orange;
position: absolute;
top: 100px;
left: 100px;
}
.no0{top: 0px;}
.no1{top: 100px;}
.no2{top: 200px;}
.no3{top: 300px;}
.no4{top: 400px;}
.no5{top: 500px;}
.no6{top: 900px;}
</style>
</head>
<body>
<div class="no0"></div>
<div class="no1"></div>
<div class="no2"></div>
<div class="no3"></div>
<div class="no4"></div>
<div class="no5"></div>
<div class="no6"></div>
var Tween = {
Linear: function(t, b, c, d) {
return c * t / d + b;
},
//二次的
QuadEaseIn: function(t, b, c, d) {
return c * (t /= d) * t + b;
},
QuadEaseOut: function(t, b, c, d) {
return -c * (t /= d) * (t - 2) + b;
},
QuadEaseInOut: function(t, b, c, d) {
if ((t /= d / 2) < 1) return c / 2 * t * t + b;
return -c / 2 * ((--t) * (t - 2) - 1) + b;
},
//三次的
CubicEaseIn: function(t, b, c, d) {
return c * (t /= d) * t * t + b;
},
CubicEaseOut: function(t, b, c, d) {
return c * ((t = t / d - 1) * t * t + 1) + b;
},
CubicEaseInOut: function(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;
},
//四次的
QuartEaseIn: function(t, b, c, d) {
return c * (t /= d) * t * t * t + b;
},
QuartEaseOut: function(t, b, c, d) {
return -c * ((t = t / d - 1) * t * t * t - 1) + b;
},
QuartEaseInOut: function(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;
},
QuartEaseIn: function(t, b, c, d) {
return c * (t /= d) * t * t * t * t + b;
},
QuartEaseOut: function(t, b, c, d) {
return c * ((t = t / d - 1) * t * t * t * t + 1) + b;
},
QuartEaseInOut: function(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;
},
//正弦的
SineEaseIn: function(t, b, c, d) {
return -c * Math.cos(t / d * (Math.PI / 2)) + c + b;
},
SineEaseOut: function(t, b, c, d) {
return c * Math.sin(t / d * (Math.PI / 2)) + b;
},
SineEaseInOut: function(t, b, c, d) {
return -c / 2 * (Math.cos(Math.PI * t / d) - 1) + b;
},
ExpoEaseIn: function(t, b, c, d) {
return (t == 0) ? b : c * Math.pow(2, 10 * (t / d - 1)) + b;
},
ExpoEaseOut: function(t, b, c, d) {
return (t == d) ? b + c : c * (-Math.pow(2, -10 * t / d) + 1) + b;
},
ExpoEaseInOut: function(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;
},
CircEaseIn: function(t, b, c, d) {
return -c * (Math.sqrt(1 - (t /= d) * t) - 1) + b;
},
CircEaseOut: function(t, b, c, d) {
return c * Math.sqrt(1 - (t = t / d - 1) * t) + b;
},
CircEaseInOut: function(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;
},
ElasticEaseIn: function(t, b, c, d, a, p) {
if (t == 0) return b;
if ((t /= d) == 1) return b + c;
if (!p) p = d * .3;
if (!a || 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;
},
ElasticEaseOut: function(t, b, c, d, a, p) {
if (t == 0) return b;
if ((t /= d) == 1) return b + c;
if (!p) p = d * .3;
if (!a || 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);
},
ElasticEaseInOut: function(t, b, c, d, a, p) {
if (t == 0) return b;
if ((t /= d / 2) == 2) return b + c;
if (!p) p = d * (.3 * 1.5);
if (!a || 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;
},
//冲过头系列
BackEaseIn: function(t, b, c, d, s) {
if (s == undefined) s = 1.70158;
return c * (t /= d) * t * ((s + 1) * t - s) + b;
},
BackEaseOut: function(t, b, c, d, s) {
if (s == undefined) s = 1.70158;
return c * ((t = t / d - 1) * t * ((s + 1) * t + s) + 1) + b;
},
BackEaseInOut: function(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;
},
//弹跳系列
BounceEaseIn: function(t, b, c, d) {
return c - Tween.BounceEaseOut(d - t, 0, c, d) + b;
},
BounceEaseOut: function(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;
}
},
BounceEaseInOut: function(t, b, c, d) {
if (t < d / 2) return Tween.BounceEaseIn(t * 2, 0, c, d) * .5 + b;
else return Tween.BounceEaseOut(t * 2 - d, 0, c, d) * .5 + c * .5 + b;
}
}
<script type="text/javascript">
var oDivs = document.getElementsByTagName("div");
var frameNumber = 0;
var timer = setInterval(function(){
frameNumber++;
if(frameNumber == 150){
clearInterval(timer);
}
oDivs[0].style.left = Tween.Linear(frameNumber , 100 , 900 , 150) + "px";
oDivs[1].style.left = Tween.QuadEaseIn(frameNumber , 100 , 900 , 150) + "px";
oDivs[2].style.left = Tween.CubicEaseIn(frameNumber , 100 , 900 , 150) + "px";
oDivs[3].style.left = Tween.QuartEaseIn(frameNumber , 100 , 900 , 150) + "px";
oDivs[4].style.left = Tween.BackEaseOut(frameNumber , 100 , 900 , 150 , 3) + "px";
oDivs[5].style.left = Tween.BounceEaseOut(frameNumber , 100 , 900 , 150) + "px";
},20);
</script>
</body>
</html>
一、缓冲的封装
将缓冲功能封装在我们的运动框架中，比如：
aimate(oDiv,{“left”:600},3000,”bounceEaseOut”,function(){
});
<!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" xml:lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html;charset=UTF-8">
<title>Document</title>
<style type="text/css">
div{
width: 80px;
height: 80px;
background-color: yellowgreen;
position: absolute;
left: 100px;
top: 100px;
}
</style>
</head>
<body>
<div></div>
// version2.0.1
// 这个版本主要修改:
// 1)修改了变量名frameNumber
// 2)让回调函数中的this就是elem
// 3)增加了缓冲功能
// 4)函数的重载
// 5)为了函数节流方便，我们给运动的这个对象添加了一个属性isanimated，动画的时候这个属性是true，动画停止就是false。
/*
* animate函数是动画封装函数
* @para0 elem参数就是运动的对象
* @para1 targetJSON参数就是运动的终点状态，可以写px，也可以不写px
* @para2 time是运动总时间，毫秒为单位
* @para3 tweenString缓冲描述词，比如"Linear"，可选
* @para4 callback是回调函数，可选
* return 本函数没有返回值
*/
function animate(elem , targetJSON , time , tweenString , callback){
//函数重载，用户传进来的参数数量、类型可能不一样
//检查数量和类型
if(arguments.length < 3 || typeof arguments[0] != "object" || typeof arguments[1] != "object" || typeof arguments[2] != "number"){
throw new Error("对不起，你传进来的参数数量不对或者参数类型不对，请仔细检查哦！");
return;
}else if(arguments.length == 3){
//用户只传进来3个参数，表示tweenString、callback被省略了，那么我们默认使用Linear当做缓冲词
tweenString = "Linear";
//默认回调函数是null
callback = null;
}else if(arguments.length == 4){
//用户只传进来4个参数，第4个参数可能传进来的是tweenString，也可能是callback
switch(typeof arguments[3]){
case "string" :
//用户传进来的是缓冲描述词儿，所以就把callback补为null
callback = null;
break;
case "function" :
callback = arguments[3];
arguments[3] = "Linear";
break;
default :
throw new Error("抱歉，第4个参数要么是缓冲描述词，要么是回调函数，请检查！");
}
}
//动画间隔要根据不同浏览器来设置：
if(window.navigator.userAgent.indexOf("MSIE") != -1){
var interval = 50;
}else{
var interval = 20;
}
//强行给我们的动画元素增加一个isanimated的属性，是否正在运动
elem.isanimated = true;
//初始状态，放在origninalJSON里面
var originalJSON = {};
//变化的多少，放在deltaJSON里面
var deltaJSON = {};
//给信号量对象添加属性，添加什么属性，目标对象中有什么属性，这里就添加什么属性
//值就是当前的计算样式
for(var k in targetJSON){
//初试JSON
originalJSON[k] = parseFloat(fetchComputedStyle(elem , k));
//把每个targetJSON中的值都去掉px
targetJSON[k] = parseFloat(targetJSON[k]);
//变化量JSON
deltaJSON[k] = targetJSON[k] - originalJSON[k];
}
// 至此我们得到了三个JSON：
// originalJSON 初始状态集合，这个JSON永远不变
// targetJSON 目标状态集合，这个JSON永远不变
// deltaJSON 差值集合，这个JSON永远不变
// console.log(originalJSON);
// console.log(targetJSON);
// console.log(deltaJSON);
//总执行函数次数：
var maxFrameNumber = time / interval;
//当前帧编号
var frameNumber = 0;
//这是一个临时变量一会儿用
var n;
//定时器
var timer = setInterval(function(){
//要让所有的属性发生变化
for(var k in originalJSON){
//动：
// n就表示这一帧应该在的位置：
n = Tween[tweenString](frameNumber , originalJSON[k] , deltaJSON[k] , maxFrameNumber);
//根据是不是opacity来设置单位
if(k != "opacity"){
elem.style[k] = n + "px";
}else{
elem.style[k] = n;
elem.style.filter = "alpha(opacity=" + n * 100 + ")";
}
}
//计数器
frameNumber++;
if(frameNumber == maxFrameNumber){
//次数够了，所以停表。
//这里抖一个小机灵，我们强行让elem跑到targetJSON那个位置
for(var k in targetJSON){
if(k != "opacity"){
elem.style[k] = targetJSON[k] + "px";
}else{
elem.style[k] = targetJSON[k];
elem.style.filter = "alpha(opacity=" + (targetJSON[k] * 100) + ")";
}
}
//停表
clearInterval(timer);
//拿掉是否在动属性，设为false
elem.isanimated = false;
//调用回调函数，并且让回调函数中的this表示运动的对象
//我们加上了判断，如果callback存在，再执行函数
callback && callback.apply(elem);
}
},interval);
//之前的轮子，计算后样式
function fetchComputedStyle(obj , property){
//能力检测
if(window.getComputedStyle){
//现在要把用户输入的property中检测一下是不是驼峰，转为连字符写法
//强制把用户输入的词儿里面的大写字母，变为小写字母加-
//paddingLeft → padding-left
property = property.replace(/([A-Z])/g , function(match,$1){
return "-" + $1.toLowerCase();
});
return window.getComputedStyle(obj)[property];
}else{
//IE只认识驼峰，我们要防止用户输入短横，要把短横改为大写字母
//padding-left → paddingLeft
property = property.replace(/\-([a-z])/g , function(match,$1){
return $1.toUpperCase();
});
return obj.currentStyle[property];
}
}
//缓冲的各种公式
var Tween = {
Linear: function(t, b, c, d) {
return c * t / d + b;
},
//二次的
QuadEaseIn: function(t, b, c, d) {
return c * (t /= d) * t + b;
},
QuadEaseOut: function(t, b, c, d) {
return -c * (t /= d) * (t - 2) + b;
},
QuadEaseInOut: function(t, b, c, d) {
if ((t /= d / 2) < 1) return c / 2 * t * t + b;
return -c / 2 * ((--t) * (t - 2) - 1) + b;
},
//三次的
CubicEaseIn: function(t, b, c, d) {
return c * (t /= d) * t * t + b;
},
CubicEaseOut: function(t, b, c, d) {
return c * ((t = t / d - 1) * t * t + 1) + b;
},
CubicEaseInOut: function(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;
},
//四次的
QuartEaseIn: function(t, b, c, d) {
return c * (t /= d) * t * t * t + b;
},
QuartEaseOut: function(t, b, c, d) {
return -c * ((t = t / d - 1) * t * t * t - 1) + b;
},
QuartEaseInOut: function(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;
},
QuartEaseIn: function(t, b, c, d) {
return c * (t /= d) * t * t * t * t + b;
},
QuartEaseOut: function(t, b, c, d) {
return c * ((t = t / d - 1) * t * t * t * t + 1) + b;
},
QuartEaseInOut: function(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;
},
//正弦的
SineEaseIn: function(t, b, c, d) {
return -c * Math.cos(t / d * (Math.PI / 2)) + c + b;
},
SineEaseOut: function(t, b, c, d) {
return c * Math.sin(t / d * (Math.PI / 2)) + b;
},
SineEaseInOut: function(t, b, c, d) {
return -c / 2 * (Math.cos(Math.PI * t / d) - 1) + b;
},
ExpoEaseIn: function(t, b, c, d) {
return (t == 0) ? b : c * Math.pow(2, 10 * (t / d - 1)) + b;
},
ExpoEaseOut: function(t, b, c, d) {
return (t == d) ? b + c : c * (-Math.pow(2, -10 * t / d) + 1) + b;
},
ExpoEaseInOut: function(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;
},
CircEaseIn: function(t, b, c, d) {
return -c * (Math.sqrt(1 - (t /= d) * t) - 1) + b;
},
CircEaseOut: function(t, b, c, d) {
return c * Math.sqrt(1 - (t = t / d - 1) * t) + b;
},
CircEaseInOut: function(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;
},
ElasticEaseIn: function(t, b, c, d, a, p) {
if (t == 0) return b;
if ((t /= d) == 1) return b + c;
if (!p) p = d * .3;
if (!a || 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;
},
ElasticEaseOut: function(t, b, c, d, a, p) {
if (t == 0) return b;
if ((t /= d) == 1) return b + c;
if (!p) p = d * .3;
if (!a || 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);
},
ElasticEaseInOut: function(t, b, c, d, a, p) {
if (t == 0) return b;
if ((t /= d / 2) == 2) return b + c;
if (!p) p = d * (.3 * 1.5);
if (!a || 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;
},
//冲过头系列
BackEaseIn: function(t, b, c, d, s) {
if (s == undefined) s = 1.70158;
return c * (t /= d) * t * ((s + 1) * t - s) + b;
},
BackEaseOut: function(t, b, c, d, s ) {
if (s == undefined) s = 1.70158;
return c * ((t = t / d - 1) * t * ((s + 1) * t + s) + 1) + b;
},
BackEaseInOut: function(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;
},
//弹跳系列
BounceEaseIn: function(t, b, c, d) {
return c - Tween.BounceEaseOut(d - t, 0, c, d) + b;
},
BounceEaseOut: function(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;
}
},
BounceEaseInOut: function(t, b, c, d) {
if (t < d / 2) return Tween.BounceEaseIn(t * 2, 0, c, d) * .5 + b;
else return Tween.BounceEaseOut(t * 2 - d, 0, c, d) * .5 + c * .5 + b;
}
};
}
<script type="text/javascript">
var oDiv = document.getElementsByTagName("div")[0];
// 函数重载很成功
// 3个参数：
// animate(oDiv,{"left":700},300);
// 2个参数：
// animate(oDiv,{"left":700},300,"BounceEaseOut");
// 4个参数：
animate(oDiv,{"left":900,"top":300},1300,"BounceEaseOut",function(){
this.style.background = "red";
});
// 4个参数：
//animate(oDiv,{"left":700},300,function(){
// this.style.display = "none";
//});
</script>
</body>
</html>
