html5 canvas时钟-优快云博客

本文链接：https://blog.youkuaiyun.com/luoruowen/article/details/143831479
<!DOCTYPE html>
<html lang="zh">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Canvas 时钟</title>
    <style>
        canvas {
            display: block;
            margin: 50px auto;
            background-color: #f0f0f0;
            border: 2px solid #333;
            border-radius: 50%;
        }
    </style>
</head>
<body>
<canvas id="clockCanvas" width="400" height="400"></canvas>
<script >
    const canvas = document.getElementById("clockCanvas");
    const ctx = canvas.getContext("2d");
    const radius = canvas.width / 2;

    // 将绘图原点移至中心
    ctx.translate(radius, radius);

    // 时钟半径
    const clockRadius = radius * 0.9;

    function drawClock() {
        drawFace(ctx, clockRadius);
        drawNumbers(ctx, clockRadius);
        drawTime(ctx, clockRadius);
    }

    // 绘制钟表表盘
    function drawFace(ctx, radius) {
        ctx.beginPath();
        ctx.arc(0, 0, radius, 0, 2 * Math.PI);
        ctx.fillStyle = "white";
        ctx.fill();

        ctx.strokeStyle = "#333";
        ctx.lineWidth = radius * 0.05;
        ctx.stroke();

        ctx.beginPath();
        ctx.arc(0, 0, radius * 0.1, 0, 2 * Math.PI);
        ctx.fillStyle = "#333";
        ctx.fill();
    }

    // 绘制数字
    function drawNumbers(ctx, radius) {
        ctx.font = `${radius * 0.15}px Arial`;
        ctx.textBaseline = "middle";
        ctx.textAlign = "center";
        for (let num = 1; num <= 12; num++) {
            const angle = (num * Math.PI) / 6;
            const x = radius * 0.85 * Math.cos(angle);
            const y = radius * 0.85 * Math.sin(angle);
            ctx.fillText(num.toString(), x, y);
        }
    }

    // 绘制时针、分针和秒针
    function drawTime(ctx, radius) {
        const now = new Date();
        const hour = now.getHours();
        const minute = now.getMinutes();
        const second = now.getSeconds();

        // 时针
        const hourAngle =
            ((hour % 12) * Math.PI) / 6 +
            (minute * Math.PI) / (6 * 60) +
            (second * Math.PI) / (360 * 60);
        drawHand(ctx, hourAngle, radius * 0.5, radius * 0.07);

        // 分针
        const minuteAngle = (minute * Math.PI) / 30 + (second * Math.PI) / (30 * 60);
        drawHand(ctx, minuteAngle, radius * 0.8, radius * 0.05);

        // 秒针
        const secondAngle = (second * Math.PI) / 30;
        drawHand(ctx, secondAngle, radius * 0.9, radius * 0.02, "red");
    }

    // 绘制指针
    function drawHand(ctx, angle, length, width, color = "#333") {
        ctx.beginPath();
        ctx.lineWidth = width;
        ctx.lineCap = "round";
        ctx.strokeStyle = color;
        ctx.moveTo(0, 0);
        ctx.rotate(angle);
        ctx.lineTo(0, -length);
        ctx.stroke();
        ctx.rotate(-angle);
    }

    // 每秒更新时钟
    setInterval(drawClock, 1000);

    // 初始化时钟
    drawClock();

</script>
</body>
</html>