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序一（08/07/06）
看到 alibaba 的一个图片切换效果，感觉不错，想拿来用用。但代码一大堆的，看着昏，还是自己来吧。
由于有了做 图片滑动展示效果 的经验，做这个就容易得多了。
序二（09/03/19）
自写了 Tween缓动 之后就很想重新写过这个效果，近来有点时间，终于可以动手了。
除了改成Tween缓动，也改进了程序算法，不过原理还是一样的。
效果预览：运行代码框
<!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=gb2312" />
<title>JavaScript 图片滑动切换效果</title>
<script type="text/javascript">
var $ = function (id) {
return "string" == typeof id ? document.getElementById(id) : id;
};
var Extend = function(destination, source) {
for (var property in source) {
destination[property] = source[property];
}
return destination;
}
var CurrentStyle = function(element){
return element.currentStyle || document.defaultView.getComputedStyle(element, null);
}
var Bind = function(object, fun) {
var args = Array.prototype.slice.call(arguments).slice(2);
return function() {
return fun.apply(object, args.concat(Array.prototype.slice.call(arguments)));
}
}
var Tween = {
Quart: {
easeOut: function(t,b,c,d){
return -c * ((t=t/d-1)*t*t*t - 1) + b;
}
},
Back: {
easeOut: 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;
}
},
Bounce: {
easeOut: 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;
}
}
}
}
//容器对象,滑动对象,切换数量
var SlideTrans = function(container, slider, count, options) {
this._slider = $(slider);
this._container = $(container);//容器对象
this._timer = null;//定时器
this._count = Math.abs(count);//切换数量
this._target = 0;//目标值
this._t = this._b = this._c = 0;//tween参数
this.Index = 0;//当前索引
this.SetOptions(options);
this.Auto = !!this.options.Auto;
this.Duration = Math.abs(this.options.Duration);
this.Time = Math.abs(this.options.Time);
this.Pause = Math.abs(this.options.Pause);
this.Tween = this.options.Tween;
this.onStart = this.options.onStart;
this.onFinish = this.options.onFinish;
var bVertical = !!this.options.Vertical;
this._css = bVertical ? "top" : "left";//方向
//样式设置
var p = CurrentStyle(this._container).position;
p == "relative" || p == "absolute" || (this._container.style.position = "relative");
this._container.style.overflow = "hidden";
this._slider.style.position = "absolute";
this.Change = this.options.Change ? this.options.Change :
this._slider[bVertical ? "offsetHeight" : "offsetWidth"] / this._count;
};
SlideTrans.prototype = {
//设置默认属性
SetOptions: function(options) {
this.options = {//默认值
Vertical: true,//是否垂直方向（方向不能改）
Auto: true,//是否自动
Change: 0,//改变量
Duration: 50,//滑动持续时间
Time: 10,//滑动延时
Pause: 2000,//停顿时间(Auto为true时有效)
onStart: function(){},//开始转换时执行
onFinish: function(){},//完成转换时执行
Tween: Tween.Quart.easeOut//tween算子
};
Extend(this.options, options || {});
},
//开始切换
Run: function(index) {
//修正index
index == undefined && (index = this.Index);
index < 0 && (index = this._count - 1) || index >= this._count && (index = 0);
//设置参数
this._target = -Math.abs(this.Change) * (this.Index = index);
this._t = 0;
this._b = parseInt(CurrentStyle(this._slider)[this.options.Vertical ? "top" : "left"]);
this._c = this._target - this._b;
this.onStart();
this.Move();
},
//移动
Move: function() {
clearTimeout(this._timer);
//未到达目标继续移动否则进行下一次滑动
if (this._c && this._t < this.Duration) {
this.MoveTo(Math.round(this.Tween(this._t++, this._b, this._c, this.Duration)));
this._timer = setTimeout(Bind(this, this.Move), this.Time);
}else{
this.MoveTo(this._target);
this.Auto && (this._timer = setTimeout(Bind(this, this.Next), this.Pause));
}
},
//移动到
MoveTo: function(i) {
this._slider.style[this._css] = i + "px";
},
//下一个
Next: function() {
this.Run(++this.Index);
},
//上一个
Previous: function() {
this.Run(--this.Index);
},
//停止
Stop: function() {
clearTimeout(this._timer); this.MoveTo(this._target);
}
};
</script>
</head>
<body>
<style type="text/css">
.container, .container img{width:280px; height:200px;}
.container{border:1px solid #333;}
.container img{border:0;}
</style>
<div class="container" id="idContainer">
<table id="idSlider" border="0" cellpadding="0" cellspacing="0">
<tr>
<td><a href="http://www.cnblogs.com/cloudgamer/archive/2009/01/06/Tween.html"><img src="/articleimg/2009/09/7031/r_rt_1.jpg"/></a></td>
</tr>
<tr>
<td><a href="http://www.cnblogs.com/cloudgamer/archive/2008/07/21/ImgCropper.html"><img src="/articleimg/2009/09/7031/r_rt_5.jpg"/></a></td>
</tr>
<tr>
<td><a href="http://www.cnblogs.com/cloudgamer/archive/2008/11/17/Drag.html"><img src="/articleimg/2009/09/7031/r_rt_3.jpg"/></a></td>
</tr>
</table>
</div>
<br />
<br />
<style type="text/css">
.num{ position:absolute; right:5px; bottom:5px;}
.num li{
float: left;
list-style:none;
color: #fff;
text-align: center;
line-height: 16px;
width: 16px;
height: 16px;
font-family: Arial;
font-size: 12px;
cursor: pointer;
margin: 1px;
border: 1px solid #707070;
background-color: #060a0b;
}
.num li.on{
line-height: 18px;
width: 18px;
height: 18px;
font-size: 14px;
border: 0;
background-color: #ce0609;
font-weight: bold;
}
</style>
<div class="container" id="idContainer2">
<table id="idSlider2" border="0" cellpadding="0" cellspacing="0">
<tr>
<td><a href="http://www.cnblogs.com/cloudgamer/archive/2009/03/11/color.html"><img src="/articleimg/2009/09/7031/r_4.jpg"/></a></td>
<td><a href="http://www.cnblogs.com/cloudgamer/archive/2008/12/24/Slider.html"><img src="/articleimg/2009/09/7031/r_3.jpg"/></a></td>
<td><a href="http://www.cnblogs.com/cloudgamer/archive/2008/12/03/Resize.html"><img src="/articleimg/2009/09/7031/r_rt_2.jpg"/></a></td>
</tr>
</table>
<ul class="num" id="idNum">
</ul>
</div>
<br />
<div>
<input id="idAuto" type="button" value="停止" />
<input id="idPre" type="button" value="<<" />
<input id="idNext" type="button" value=">>" />
<select id="idTween">
<option value="0">默认缓动</option>
<option value="1">方式1</option>
<option value="2">方式2</option>
</select>
</div>
<script>
new SlideTrans("idContainer", "idSlider", 3).Run();
///////////////////////////////////////////////////////////
var forEach = function(array, callback, thisObject){
if(array.forEach){
array.forEach(callback, thisObject);
}else{
for (var i = 0, len = array.length; i < len; i++) { callback.call(thisObject, array[i], i, array); }
}
}
var st = new SlideTrans("idContainer2", "idSlider2", 3, { Vertical: false });
var nums = [];
//插入数字
for(var i = 0, n = st._count - 1; i <= n;){
(nums[i] = $("idNum").appendChild(document.createElement("li"))).innerHTML = ++i;
}
forEach(nums, function(o, i){
o.onmouseover = function(){ o.className = "on"; st.Auto = false; st.Run(i); }
o.onmouseout = function(){ o.className = ""; st.Auto = true; st.Run(); }
})
//设置按钮样式
st.onStart = function(){
forEach(nums, function(o, i){ o.className = st.Index == i ? "on" : ""; })
}
$("idAuto").onclick = function(){
if(st.Auto){
st.Auto = false; st.Stop(); this.value = "自动";
}else{
st.Auto = true; st.Run(); this.value = "停止";
}
}
$("idNext").onclick = function(){ st.Next(); }
$("idPre").onclick = function(){ st.Previous(); }
$("idTween").onchange = function(){
switch (parseInt(this.value)){
case 2 :
st.Tween = Tween.Bounce.easeOut; break;
case 1 :
st.Tween = Tween.Back.easeOut; break;
default :
st.Tween = Tween.Quart.easeOut;
}
}
st.Run();
</script>
</body>
</html>
程序说明原理就是通过不断设置滑动对象的left(水平切换)和top(垂直切换)来实现图片切换的动态效果。
首先需要一个容器，程序会自动设置容器overflow为hidden，如果不是相对或绝对定位会同时设置position为relative，
滑动对象会设置为绝对定位：var p = CurrentStyle(this._container).position;
p == "relative" || p == "absolute" || (this._container.style.position = "relative");
this._container.style.overflow = "hidden";
this._slider.style.position = "absolute";如果没有设置Change切换参数属性，会自动根据滑动对象获取：
this.Change = this.options.Change ? this.options.Change :
this._slider[bVertical ? "offsetHeight" : "offsetWidth"] / this._count;执行Run方法就会开始进入切换，其中有一个可选参数用来重新设置要切换的图片索引：
index == undefined && (index = this.Index);
index < 0 && (index = this._count - 1) || index >= this._count && (index = 0);
== undefined && (index = this.Index);
index < 0 && (index = this._count - 1) || index >= this._count && (index = 0);之后就到设置使用 tween缓动 时需要的参数了，
包括_target(目标值)、_t(时间)、_b(初始值)和_c(变化量)：this._target = -Math.abs(this.Change) * (this.Index = index);
this._t = 0;
this._b = parseInt(CurrentStyle(this._slider)[this.options.Vertical ? "top" : "left"]);
this._c = this._target - this._b;还有Duration(持续时间)是自定义属性。
参数设置好后就执行Move程序开始移动了。
里面很简单，首先判断_c是否有值（等于0表示不需要移动）和_t是否到达Duration，
未满足条件就继续移动，否则直接移动到目标值并进行下一次切换：if (this._c && this._t < this.Duration) {
this.MoveTo(Math.round(this.Tween(this._t++, this._b, this._c, this.Duration)));
this._timer = setTimeout(Bind(this, this.Move), this.Time);
}else{
this.MoveTo(this._target);
this.Auto && (this._timer = setTimeout(Bind(this, this.Next), this.Pause));
}{[csc:pagelist]}
使用说明
实例化需要3个参数，分别是容器对象，滑动对象和切换数量，之后可以直接执行Run方法运行：
new SlideTrans("idContainer", "idSlider", 3).Run();
还有以下可选属性：
Vertical: true,//是否垂直方向（方向不能改）
Auto: true,//是否自动
Change: 0,//改变量
Duration: 50,//滑动持续时间
Time: 10,//滑动延时
Pause: 2000,//停顿时间(Auto为true时有效)
onStart: function(){},//开始转换时执行
onFinish: function(){},//完成转换时执行
Tween: Tween.Quart.easeOut//tween算子
其中Vertical初始化后就不能修改，Tween算子可参照这里的缓动效果选择（实例中选了其中3个）。还有提供了以下方法：
Next: 切换下一个
Previous: 切换上一个
Stop: 停止自动切换
还有上面说到的Run
程序代码：代码拷贝框
var SlideTrans = function(container, slider, count, options) {
this._slider = $(slider);
this._container = $(container);//容器对象
this._timer = null;//定时器
this._count = Math.abs(count);//切换数量
this._target = 0;//目标值
this._t = this._b = this._c = 0;//tween参数
this.Index = 0;//当前索引
this.SetOptions(options);
this.Auto = !!this.options.Auto;
this.Duration = Math.abs(this.options.Duration);
this.Time = Math.abs(this.options.Time);
this.Pause = Math.abs(this.options.Pause);
this.Tween = this.options.Tween;
this.onStart = this.options.onStart;
this.onFinish = this.options.onFinish;
var bVertical = !!this.options.Vertical;
this._css = bVertical ? "top" : "left";//方向
//样式设置
var p = CurrentStyle(this._container).position;
p == "relative" || p == "absolute" || (this._container.style.position = "relative");
this._container.style.overflow = "hidden";
this._slider.style.position = "absolute";
this.Change = this.options.Change ? this.options.Change :
this._slider[bVertical ? "offsetHeight" : "offsetWidth"] / this._count;
};
SlideTrans.prototype = {
//设置默认属性
SetOptions: function(options) {
this.options = {//默认值
Vertical: true,//是否垂直方向（方向不能改）
Auto: true,//是否自动
Change: 0,//改变量
Duration: 50,//滑动持续时间
Time: 10,//滑动延时
Pause: 2000,//停顿时间(Auto为true时有效)
onStart: function(){},//开始转换时执行
onFinish: function(){},//完成转换时执行
Tween: Tween.Quart.easeOut//tween算子
};
Extend(this.options, options || {});
},
//开始切换
Run: function(index) {
//修正index
index == undefined && (index = this.Index);
index < 0 && (index = this._count - 1) || index >= this._count && (index = 0);
//设置参数
this._target = -Math.abs(this.Change) * (this.Index = index);
this._t = 0;
this._b = parseInt(CurrentStyle(this._slider)[this.options.Vertical ? "top" : "left"]);
this._c = this._target - this._b;
this.onStart();
this.Move();
},
//移动
Move: function() {
clearTimeout(this._timer);
//未到达目标继续移动否则进行下一次滑动
if (this._c && this._t < this.Duration) {
this.MoveTo(Math.round(this.Tween(this._t++, this._b, this._c, this.Duration)));
this._timer = setTimeout(Bind(this, this.Move), this.Time);
}else{
this.MoveTo(this._target);
this.Auto && (this._timer = setTimeout(Bind(this, this.Next), this.Pause));
}
},
//移动到
MoveTo: function(i) {
this._slider.style[this._css] = i + "px";
},
//下一个
Next: function() {
this.Run(++this.Index);
},
//上一个
Previous: function() {
this.Run(--this.Index);
},
//停止
Stop: function() {
clearTimeout(this._timer); this.MoveTo(this._target);
}
};