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利用原生js加透明度做的淡入淡出效果轮播图练习

利用原生js加透明度做的淡入淡出效果轮播图练习

作者: 深漂浪子 | 来源:发表于2019-06-03 15:52 被阅读0次
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
    <style>
        *{margin: 0;padding: 0;}
        a{text-decoration:none;}
         #box{
            width: 800px;
            height: 400px;
            margin: 40px auto;
            position: relative;
            overflow:hidden;
        }
        ul,li{
            list-style:none;
        }
        #box ul li{
            width: 800px;
            height: 800px;
            position: absolute;
            opacity: 0;
            filter:alpha(opacity(0));
        }
        #box ul li:first-child{
            opacity: 1;
            filter:alpha(opacity(100));
        }
        #box ul li img{
            width: 800px;
            height: 400px;
        } 
        #direction{
            position:relative;
        }
        #direction>a{
            width: 50px;
            height: 60px;
            background: rgba(0,0,0,0.5);
            color:#fff;
            position:absolute;
            top:170px;
            font-size:30px;
            text-align:center;
            line-height:60px;
        }
        #direction>a:nth-child(2){
            right:0;
        }
        #btn{
            position:absolute;
            left:42%;
            bottom:0;
        }
        #btn>a{
            float:left;
            width: 20px;
            height:20px;
            border-radius:50%;
            background:#f40;
            margin-right:10px;
        }
        #btn .active{
            background:#fff;
        }
    </style>
</head>
<body>
    <div id="box">
        <ul>
            <li><img src="https://pic.kuaizhan.com/g3/22/0b/4bea-7962-4826-9500-206a3854fc4133/imageView/v1/thumbnail/640x0" alt=""></li>
            <li><img src="https://pic.kuaizhan.com/g3/7a/14/c501-c458-4f9d-84d9-69c6e4f294d204/imageView/v1/thumbnail/640x0" alt=""></li>
            <li><img src="https://pic.kuaizhan.com/g3/c7/06/7422-de98-43dd-b4fc-4dac60c6adb403/imageView/v1/thumbnail/640x0" alt=""></li>
            <li><img src="https://pic.kuaizhan.com/g3/04/cd/743b-e472-4451-a787-261861174a5634/imageView/v1/thumbnail/640x0" alt=""></li>
        </ul>
        <div id="direction">
            <a href="##">&lt;</a>
            <a href="##">&gt;</a>
        </div>
        <div id="btn">
            <a href="##" class="active"></a>
            <a href="##"></a>
            <a href="##"></a>
            <a href="##"></a>
        </div>
    </div>

    <script>
        //获取非行间样式
        function getStyle(obj,attr){
            if(obj.currentStyle){
                return obj.currentStyle[attr];
            }else{
                return getComputedStyle(obj,false)[attr];
            }
        }

        //完美运动框架
        function move(obj,json,fn){
            clearInterval(obj.timer);
            obj.timer = setInterval(function(){
                var bStop = true;
                for(var attr in json){
                    //先判断是否是透明度
                    var iCur;
                    if(attr == "opacity"){
                        iCur = parseInt(parseFloat(getStyle(obj,attr))*100);
                    }else{
                        iCur = parseInt(getStyle(obj,attr));
                    }

                    //算速度

                    var speed = (json[attr] - iCur)/8;
                    speed = speed>0?Math.ceil(speed):Math.floor(speed);

                    if(json[attr] != iCur){
                        bStop = false;
                    }

                    if(attr == "opacity"){
                        obj.style.opacity = (iCur+speed)/100;
                        obj.style.filter = "alpha(opacity:"+(iCur+speed)+")"
                    }else{
                        obj.style[attr] = iCur+speed+'px';
                    }
                }

                if(bStop){
                    clearInterval(obj.timer);
                    fn&&fn();
                }
            },30)
    }
    </script>
    <script>
        var box=document.getElementById("box");
        var aLi = document.querySelectorAll("#box>ul>li");
        var aDir = document.querySelectorAll("#direction>a");
        var aBtn = document.querySelectorAll("#btn>a");
        var iHiddle = 0,iShow = 0;//iHiddle表示隐藏的下标,iShow表示显示的下标
        var timer;

        //动画的原理
        function toImg(){
            move(aLi[iHiddle],{opacity:0});//隐藏
            move(aLi[iShow],{opacity:100});//显示
            iHiddle=iShow;
            //使进度条自动跟随图片运动
            for(var i=0;i<aBtn.length;i++){
                aBtn[i].className="";
            }
            aBtn[iShow].className="active";   
        }

        //让图自动播放
        function autoPlay(){
            timer=setInterval(function(){
                if(iShow==aLi.length-1){
                    iShow=0;    
                }else{
                    iShow++;
                }
                toImg();
            },2000)         
        }
        autoPlay();
        //当鼠标移入时停止自动播放
        box.onmouseover=function(){
            clearInterval(timer);
        }
        //当鼠标移出时继续自动播放
        box.onmouseout=function(){
            autoPlay();
        }

        //点击左按钮向左播放
        aDir[0].onclick=function(){
            if(iShow==0){
                iShow=aLi.length-1;
            }else{
                iShow--;
            }
            toImg();
        }
        //点击有按钮向右播放
        aDir[1].onclick=function(){
            if(iShow==aLi.length-1){
                iShow=0;    
            }else{
                iShow++;
            }
            toImg();
        }

        //让鼠标移入时进度条自动回到那个点上
        for(var j=0;j<aBtn.length;j++){
            aBtn[j].index=j;//先存入一下标
            aBtn[j].onmouseenter=function(){
                //让其他元素隐藏
                for(var k=0;k<aBtn.length;k++){
                    aBtn[k].className="";
                    move(aLi[k],{opacity:0});
                }
                //让你移入的那个元素显示
                this.className="active";
                move(aLi[this.index],{opacity:100});
                iShow=this.index;//使移入的那个元素下标跟播放时的下标统一一下
                iHiddle=iShow;
            }
        }
    </script>
</body>
</html>

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      本文标题:利用原生js加透明度做的淡入淡出效果轮播图练习

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