图片切换特效的分析和学习

效果

实现功能1 自动切换

               2鼠标移动到图片上暂停

               3鼠标移动到数字上切换到指定图片

                4图片切换动画平滑

基本布局

通过查看元素分布可以发现

每个图片占据1个TD单元格，横向平铺

2 表格table 决定定位---------------------------》动画内容独立于当前文档流，避免dom 的重绘和重排

几个基本的辅助js代码

 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)));
            }
        }

1：$根据ID获取元素

2：Extend 通过拷贝属性世面自定义值覆盖默认值

3：CurrentStyle 获取dom中实际展示的样式  ps：这里的方式我第一次见以前还不知道呢

4：函数绑定     以前始终找不见闭包最基本的使用场景，这不是闭包这是啥？

Tween 算子，   以前一直不知道 其妙的动画是怎么实现，这次终于找到了，不过这里的源代码并没有解释这些参数 是啥意思

这里是详细介绍：http://blog.csdn.net/pointerfree/article/details/6777693

                              http://www.cnblogs.com/NNUF/archive/2013/01/16/2857784.html

Tween中的方法接受4个参数t,b,c,d 。返回值为计算后的当前位置.

t => time(初始记步次数)   b => begin(初始位置)   c => change(变化量)   d => duration(持续次数)

        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;
                    }
                }
            }
        }

现在来看看 初始化构造函数

   //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;                          PS:!!能够将任何值转化为布尔值
            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:  4000,//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";
                console.log(i)
            },
            //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);
            }
        };

相关方法说明

ps:我以前一直不清楚 定义的默认对象有好多属性,传入的自定义参数如何赋值,原来通过浅层拷贝就可以了

Run 启动方法

Move 移动方法

MoveTo 移动到指定位置方法

Next 切换到下一个图片

Previous 切换到上一张图片

Stop 停止

在细看这几个方法前 先看一下默认值

         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:  4000,//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
                };

动画到底是什么原理呢????这个还得在看看源代码dom树动态运行结果

通过不断的变化可以发现是通过决定定位+控制left 定位来实现 所有图片的滚动切换,其实就是图片在反复按照算法移动

先从run 方法看看

看看运行时 点击4 时候参数run,这些值的变化

看到change 值是610 在那进行赋值的???

搜索发现  在这里进行的赋值 

也就是可见 offsetwidth在JS中是获区元素的宽. 除以 图片的数量

什么是 offsetwidth ?==> http://blog.csdn.net/xuantian868/article/details/3116442

也就是 初始化后change  是不变的

this._b = parseInt(CurrentStyle(this._slider)[this.options.Vertical ? "top" : "left"]);

可见_b 的值是读取执行动画前的left的值 是会

this._target = -Math.abs(this.Change) * (this.Index = index);

_target 是执行动画要移动的距离 是变化量*图片的位置[]

this._c = this._target - this._b;

_c  就是当前位置和目标位置的差距也就是移动的真实距离

RUN 方法最后调用 this.onStart();   和      this.Move();

onStart 主要用户控制下面1,2,3,4的现实情况
        this.Move()  则负责具体的图片移动

下面看看move 方法

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));
                }
            }

Move 方法第一步是清除 Timeout,然后判断当前位置是否移动完成

this._c && this._t < this.Duration  通过这个条件来判断

_c  是要移动距离

this._t  是初始化的时间,每次移动结束应该会变为0  每次run开始的时候 _t归为0

!_c 为负值也是true 因为  if(-1){}      !!-1==true

如果没有移动完毕,就调用MoveTo修改一次left,谈后setTimeout 调用下一次移动

this.MoveTo(Math.round(this.Tween(this._t++, this._b, this._c, this.Duration)));
                   this._timer = setTimeout(Bind(this, this.Move), this.Time);

如果移动完毕

就就调用

this.MoveTo(this._target);   准确的移动到指定位置
                 this.Auto && (this._timer = setTimeout(Bind(this, this.Next), this.Pause));  绑定下一次移动

到这里 和动画相关的基本方法和原理就分析差不多

下面还有一些js工具

forEach 工具 如果浏览器不支持forEach就自己遍历一遍

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", 5, { 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" : ""; })
    }

var st = new SlideTrans("idContainer2", "idSlider2", 5, { Vertical: false });

负责初始化

nums 主要用来处理下面的几个小图片数字并负责绑定 .onmouseover和onmouseout事件

<HTML>
<HEAD>
    <TITLE>腾讯软件-图片滑动效果，阿里西西整理收集。</TITLE>
    <style>
        BODY {
            PADDING-BOTTOM: 0px; MARGIN: 0px; PADDING-LEFT: 0px; PADDING-RIGHT: 0px; PADDING-TOP: 0px
        }
        UL {
            PADDING-BOTTOM: 0px; MARGIN: 0px; PADDING-LEFT: 0px; PADDING-RIGHT: 0px; PADDING-TOP: 0px
        }
        .container {
            WIDTH: 610px; HEIGHT: 205px
        }
        .container A IMG {
            WIDTH: 610px; HEIGHT: 205px
        }
        .container IMG {
            BORDER-BOTTOM-STYLE: none; BORDER-RIGHT-STYLE: none; BORDER-TOP-STYLE: none; BORDER-LEFT-STYLE: none
        }
        .td_f A IMG {
            PADDING-BOTTOM: 0px; MARGIN: 0px; PADDING-LEFT: 0px; PADDING-RIGHT: 0px; PADDING-TOP: 0px
        }
        .num {
            POSITION: absolute; WIDTH: 90px; FLOAT: right; TOP: 180px; LEFT: 520px
        }
        .num LI {
            TEXT-ALIGN: center; LINE-HEIGHT: 15px; LIST-STYLE-TYPE: none; MARGIN: 1px; WIDTH: 15px; FONT-FAMILY: Arial; BACKGROUND: url(http://pc.qq.com/pc/images/flashbutton.gif) no-repeat -15px 0px; FLOAT: left; HEIGHT: 15px; COLOR: #86a2b8; FONT-SIZE: 12px; CURSOR: pointer
        }
        .num LI.on {
            LINE-HEIGHT: 15px; WIDTH: 15px; BACKGROUND: url(http://pc.qq.com/pc/images/flashbutton.gif) no-repeat; HEIGHT: 15px; COLOR: #ffffff
        }
        .more {
            FLOAT: right
        }
        .more1 A {
            TEXT-ALIGN: left; LINE-HEIGHT: 25px; MARGIN: 0px 0px 0px 10px; COLOR: #3373a3
        }
    </style>

    <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:  4000,//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";
                console.log(i)
            },
            //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>
<BODY>
告诉你一个应有尽有的网页特效网址：<a href="http://js.alixixi.com">http://js.alixixi.com</a>
<hr />
<DIV id=idContainer2 class=container>
    <TABLE id=idSlider2 border=0 cellSpacing=0 cellPadding=0>
        <TBODY>
        <TR>
            <TD class=td_f><A onclick="pgvSendClick({hottag:'ISD.SHOW.BANNER.SOFTMGR'});" href="http://js.alixixi.com"><IMG src="http://pc.qq.com/pc/images/manage.jpg"></A></TD>
            <TD class=td_f><A onclick="pgvSendClick({hottag:'ISD.SHOW.BANNER.PY'});" href="http://js.alixixi.com"><IMG src="http://pc.qq.com/pc/images/py.jpg"></A></TD>
            <TD class=td_f><A onclick="pgvSendClick({hottag:'ISD.SHOW.BANNER.PLAYER'});" href="http://js.alixixi.com"><IMG src="http://pc.qq.com/pc/images/player.jpg"></A></TD>
            <TD class=td_f><A onclick="pgvSendClick({hottag:'ISD.SHOW.BANNER.XF'});"  href="http://js.alixixi.com"><IMG src="http://pc.qq.com/pc/images/xf.jpg"></A></TD>
            <TD class=td_f><A onclick="pgvSendClick({hottag:'ISD.SHOW.BANNER.TT'});"  href="http://js.alixixi.com"><IMG  src="http://pc.qq.com/pc/images/TT.jpg"></A></TD>
        </TR>
        </TBODY>
    </TABLE>
    <UL id=idNum class=num></UL>
</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", 5, { 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" : ""; })
    }

  //   st.Run();
</SCRIPT>
</BODY></HTML>