可拖拽进度条

能够实进度条的拖拽功能，数字也随之变化
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
    <style type="text/css">
        .watermarkOpacity_div {
            width:300px;
            height:300px;
        }
        .proNum {
            padding-left:16px;
        }
        .proNum input {
            width:70px;
            height: 32px;
            font-size: 14px;
            color: #82899b;
            margin: 7px 10px 0 0;
            text-align: center;
            border: 1px solid #d6dae3;
            border-radius: 3px;
        }
        .proNum label {
            color:#6c748a;
            font-size:16px;
        }
        .watermarkOpacity_progress {
            background: #eaebeb none repeat scroll 0 0;
            border-radius: 100px;
            height: 6px;
            margin: 26px 0 0 16px;
            width: 245px;
        }
        .watermarkOpacity_progress p {
            background: #1589f4 none repeat scroll 0 0;
            border-radius: 100px;
            width:0;
            height: 100%;
            max-width: 100%;
            min-width: 0;
            position: relative;
        }
        .watermarkOpacity_progress p i {
            background: #fff none repeat scroll 0 0;
            border-radius: 50%;
            box-shadow: 0 0 3px 1px rgba(0, 0, 0, 0.3);
            cursor: pointer;
            height: 13px;
            position: absolute;
            right: -6px;
            top: -4px;
            width: 13px;
            z-index: 2;
        }
        .applicationScope_main label {
            color: #6c748a;
            cursor: pointer;
            font-size: 16px;
            height: 46px;
            line-height: 46px;
            margin-right: 60px;
        }
        .applicationScope_main label input {
            cursor: pointer;
            margin-right: 12px;
        }
    </style>
</head>
<body>
    <div class="watermarkOpacity_div">
        <div class="proNum">
            <input class="col-sm-8 form-control" id="opacity" value="0" type="text"><label class="perCent">%</label>
        </div>
        <div class="watermarkOpacity_progress">
            <p><i></i></p>
        </div>
    </div>

    <script type="text/javascript" src="http://code.jquery.com/jquery-latest.js"></script>
    <script type="text/javascript">
        progress();

        //进度条拖拽
        function progress(){
            var pro_w=$(".watermarkOpacity_progress").width();
            //初始化
            var per_num=$(".proNum input").val();
            var new_pro=pro_w*per_num/100;
            $(".watermarkOpacity_progress p").css({"width":new_pro});

            //改变百分比
            $(".proNum input").keyup(function(){
                var keyNum=$(this).val();
                var key_pro=keyNum*pro_w/100;
                $(".watermarkOpacity_progress p").css({"width":key_pro});
            })


            var dragging = false;
            var iX,oX;
            $(".watermarkOpacity_progress i").mousedown(function(e){
                dragging = true; 
                iX = e.clientX - this.offsetLeft - 6;
                return false;
            })
            $(".watermarkOpacity_div").mousemove(function(e){
                if (dragging) {
                    var e = e || window.event;
                    oX = e.clientX - iX;
                    $(".watermarkOpacity_progress p").css({"width":oX + "px"});
                    var per=oX/pro_w*100;
                    if(oX<=0){
                        $(".proNum input").val("0");
                    }else if(oX>=pro_w){
                        $(".proNum input").val("100");
                    }else{
                        per=Math.round(per);
                        $(".proNum input").val(per);
                    }
                    return false;
                } 
            })
            $("body").mouseup(function(e) {
                dragging = false;
            })
        }
    </script>
</body>
</html>