js css3实现钟表效果

原理：

利用transform-origin改变旋转的圆心，实现秒数和分钟数的刻度线，利用transfrom translate实现钟表小时刻度的显示

html:

<div class="time">
            <div class="line"></div>
            <div class="hour-line"></div>
            <div class="second-line"></div>
            <div class="minute-line"></div>
        </div>

1 绘制圆盘

.time{
width: 300px;
height: 300px;
border-radius: 50%;
margin: 100px auto;
background-color: #000;
color: #fff;
position: relative;
padding: 5px;
}

2 绘制秒数

css

.second,.minute,.hour{
                position: absolute;
                left: 0;
                right: 0;
                top: 0;
                bottom: 0;
            }
            .second div,.minute div{
                background-color: #fff;
                position:absolute;
                width: 2px;
                left: 50%;
                top: 50%;
                transform: translate(50%,145px);
            }
            .second div{
                height: 5px;
                
            }

js：

function draw(num,r,className,flag){
            for(var i=0; i<num; i++){
                var x=Math.cos(2*Math.PI/360*(360/num*i-60))*r;//如果是小时绘制出来从是0度1刻度开始，与始终的角度偏差60度，所以要减60
                var y=Math.sin(2*Math.PI/360*(360/num*i-60))*r;
                if(flag){
                    var second=$('<div class="hour"><div style="transform:translate('+x+'px,'+y+'px)">'+(i+1)+'</div></div><div class="'+className+'"  style="transform:rotate('+360/num*i+'deg) "><div></div></div>');
                }else{
                    var second=$('<div class="'+className+'"  style="transform:rotate('+360/num*i+'deg) "><div></div></div>');
                }
                
                $(".time").append(second);
            }
        }


draw(60,145,'second');

绘制的是60个刻度，每个刻度的角度是360/60*i

4 绘制分钟刻度，12个刻度线，原理同上

css

.minute div{
                height: 10px;
                transrform: translate(50%,135px);
            }

draw(12,120,'minute',true)

没有减60 是这样的

5 绘制钟表中心点以及秒针分针时针

css:

.time .line,.time .hour-line,.time .minute-line,.time .second-line{
                position:absolute;
                top: 50%;
                left: 50%;
                background-color: #fff;
                transform-origin: left top;
                /*transform: rotate(-90deg);*/
                
            }
            .time .line{
                width: 14px;
                height: 14px;
                border-radius: 50%;
                margin-left: -7px;
                margin-top: -7px;
            }
            .time .hour-line{
                width: 70px;
                height: 4px;
                margin-top: -2px;
            }
                .time .minute-line{
                width: 90px;
                height: 2px;
                margin-top: -2px;
            }
                .time .second-line{
                width: 120px;
                height: 2px;
                margin-top: -1px;
            }

获取当前时间，获取时分秒，获取时针分针秒针旋转的角度，算出的角度是从0开始旋转的，需要减去90度

    function drawLine(hour,minute,second){
            var secondAngle=360/60*second-90;//秒
            var minuteAngle=360/60*minute-90;//秒
            var hourAngle=360/12*(hour+minute/60)-90;//秒 
            $(".hour-line").css({
                'transform':"rotate("+hourAngle+"deg)"
            });
            $(".minute-line").css({
                'transform':"rotate("+minuteAngle+"deg)"
            });
            $(".second-line").css({
                'transform':"rotate("+secondAngle+"deg)"
            });
        }





setInterval(function(){
            var time=new Date();
            var hour=time.getHours();
            if(hour>12){
                hour=hour-12;
            }
            var minute=time.getMinutes();
            var second=time.getSeconds();
            drawLine(hour,minute,second);
        },1000);

最终效果

整体代码：

<!DOCTYPE  >
<html>
    <head>
        <title>
        </title>
        <style type="text/css">
            body,html{
                margin: 0;
                padding: 0;
            }
            .time{
                 300px;
                height: 300px;
                border-radius: 50%;
                margin: 100px auto;
                background-color: #000;
                color: #fff;
                position: relative;
                padding: 5px;
            }
            .second,.minute,.hour{
                position: absolute;
                left: 0;
                right: 0;
                top: 0;
                bottom: 0;
            }
            .second div,.minute div{
                background-color: #fff;
                position:absolute;
                 2px;
                left: 50%;
                top: 50%;
                transform: translate(50%,145px);
            }
            .second div{
                height: 5px;
                
            }
            .minute div{
                height: 10px;
                transrform: translate(50%,135px);
            }
            .hour div{
                position:absolute;
                left: 50%;
                top: 50%;
                margin-top: -10px;
                margin-left: -9px;
            }
            .time .line,.time .hour-line,.time .minute-line,.time .second-line{
                position:absolute;
                top: 50%;
                left: 50%;
                background-color: #fff;
                transform-origin: left top;
                /*transform: rotate(-90deg);*/
                
            }
            .time .line{
                 14px;
                height: 14px;
                border-radius: 50%;
                margin-left: -7px;
                margin-top: -7px;
            }
            .time .hour-line{
                 70px;
                height: 4px;
                margin-top: -2px;
            }
                .time .minute-line{
                 90px;
                height: 2px;
                margin-top: -2px;
            }
                .time .second-line{
                 120px;
                height: 2px;
                margin-top: -1px;
            }
        </style>
    </head>
    <body>
        <div class="time">
            <div class="line"></div>
            <div class="hour-line"></div>
            <div class="second-line"></div>
            <div class="minute-line"></div>
        </div>
    </body>
    <script src="http://www.jq22.com/jquery/jquery-1.10.2.js">
    </script>
    <script type="text/javascript">
        window.onload=function(){
         draw(60,145,'second');
         draw(12,120,'minute',true);
        setInterval(function(){
            var time=new Date();
            var hour=time.getHours();
            if(hour>12){
                hour=hour-12;
            }
            var minute=time.getMinutes();
            var second=time.getSeconds();
            drawLine(hour,minute,second);
        },1000);

        }
        
        
        function drawLine(hour,minute,second){
            var secondAngle=360/60*second-90;//秒
            var minuteAngle=360/60*minute-90;//秒
            var hourAngle=360/12*(hour+minute/60)-90;//秒 
            $(".hour-line").css({
                'transform':"rotate("+hourAngle+"deg)"
            });
            $(".minute-line").css({
                'transform':"rotate("+minuteAngle+"deg)"
            });
            $(".second-line").css({
                'transform':"rotate("+secondAngle+"deg)"
            });
        }
        function draw(num,r,className,flag){
            for(var i=0; i<num; i++){
                var x=Math.cos(2*Math.PI/360*(360/num*i-60))*r;
                var y=Math.sin(2*Math.PI/360*(360/num*i-60))*r;
                if(flag){
                    var second=$('<div class="hour"><div style="transform:translate('+x+'px,'+y+'px)">'+(i+1)+'</div></div><div class="'+className+'"  style="transform:rotate('+360/num*i+'deg) "><div></div></div>');
                }else{
                    var second=$('<div class="'+className+'"  style="transform:rotate('+360/num*i+'deg) "><div></div></div>');
                }
                
                $(".time").append(second);
            }
        }
    </script>
</html>

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原文地址：https://www.cnblogs.com/xiaofenguo/p/10622391.html