66.环形加载动画（canvas/svg）

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        body {
            margin: 0;
            padding: 0;
            text-align: center;
        }
    </style>
</head>

<body>
    <canvas id="canvas"></canvas>
    <script>
        let canvasWidth = 200;
        let canvasHeight = 200;
        let centerX = canvasWidth / 2;
        let centerY = canvasHeight / 2;
        let r = canvasWidth / 2 - 10;
        let canvas = document.getElementById('canvas');
        canvas.width = canvasWidth;
        canvas.height = canvasHeight;
        let ctx = canvas.getContext('2d');
        let sRad = Math.PI * 2;
        let step = 0;


        function loading() {
            ctx.beginPath();
            ctx.clearRect(0, 0, canvasWidth, canvasHeight);
            ctx.strokeStyle = "orange";
            ctx.font = "26px Arial";
            ctx.textAlign = "center";
            ctx.fillStyle = "orange";
            ctx.lineWidth = 10;
            let text = parseInt(parseFloat(step) * 100) + '%'
            ctx.fillText(text, centerX, centerY);
            ctx.arc(centerX, centerY, r, 0, sRad * step, false);
            ctx.stroke();
        }

        function render() {

            if (step > 1) {
                cancelAnimationFrame(render)
                return
            }
            requestAnimationFrame(render);
            step += 0.01;
            loading()

        }
        render()
    </script>
</body>

</html>

　//svg

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>SVG</title>
    <style>
        body {
            background: #1a1a1a;

        }

        body>div {
            text-align: center;
        }

        .ring_circle {
            stroke-dasharray: 10 20;
            transition: stroke-dasharray 0.35s;
        }
    </style>
</head>

<body>
    <div>
        <svg class="progress-ring" width="120px" height="120px">
            <circle class="ring_circle" stroke="white" stroke-width="4" fill="transparent" r="52" cx="60" cy="60" />
        </svg>

    </div>
    <script>
        let circle = document.querySelector('.ring_circle');
        let radius = circle.r.baseVal.value;
        var circrumference = radius * Math.PI * 2;
        circle.style.strokeDasharray = circrumference + " " + circrumference;
        circle.style.strokeDashoffset = circrumference;
        var i = 1;
        var ite = null;
        function setProgress(percent) {
            const offset = circrumference - percent / 100 * circrumference;
            circle.style.strokeDashoffset = offset;
        }
        if (ite) clearInterval(ite);
        ite = setInterval(() => {
            i += 2;
            if (i > 100){
                i = 100;
                clearInterval(ite)
            }
            setProgress(i)
        }, 16)
    </script>
</body>

</html>

来源：https://www.cnblogs.com/famLiu/p/10878093.html

标签

canvas