canvas 

<!DOCTYPE html>
<html>

<head>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <title></title>
    <style type="text/css">
        canvas {
            border: 1px solid #333;
        }
    </style>
</head>


<body>
    <!-- canvas画布的大小，不能用css来调整，用属性来调整 -->


    <canvas id="canvas" width="600" height="400"></canvas>


</body>
<script type="text/javascript">
    //获取画布
    let canvas = document.getElementById("canvas");


    //获取上下文
    let ctx = canvas.getContext("2d");


    ctx.translate(300,200)


    //绘制大圆
    ctx.arc(0,0,200,0,Math.PI*2,false)
    ctx.stroke()
    
    //绘制上面的线
    ctx.beginPath()
    ctx.moveTo(0,-200)
    ctx.lineTo(0,0)
    ctx.stroke()
    
    //绘制右边的线
    ctx.beginPath()
    ctx.moveTo(0,0)
    let x=200*Math.cos(30*(Math.PI/180))
    let y=200*Math.sin(30*(Math.PI/180))
    ctx.lineTo(x,y)
    ctx.stroke()


    //绘制左边的线
    ctx.beginPath()
    ctx.moveTo(0,0)
    let x2=200*Math.cos(150*(Math.PI/180))
    let y2=200*Math.sin(150*(Math.PI/180))
    ctx.lineTo(x2,y2)
    ctx.stroke()





</script>


</html>

 

 

posted @ 2022-01-12 02:20  coffeemil  阅读(69)  评论(0)    收藏  举报