html时钟代码 博客

    var canvas = document.getElementById("clock");
    var ctx = canvas.getContext("2d");
    var radius = canvas.height / 2;

    ctx.translate(radius, radius);
    radius = radius * 0.9;

    setInterval(drawClock, 1000);

    function drawClock() {
        ctx.arc(0, 0, radius, 0, 2 * Math.PI);
        ctx.fillStyle = "white";
        ctx.fill();

        drawNumbers(ctx, radius);
        drawTime(ctx, radius);
    }

    function drawNumbers(ctx, radius) {
        var ang;
        var num;

        ctx.font = radius * 0.15 + "px Arial";
        ctx.textBaseline = "middle";
        ctx.textAlign = "center";

        for (num = 1; num <= 12; num++) {
            ang = num * Math.PI / 6;
            ctx.rotate(ang);
            ctx.translate(0, -radius * 0.85);
            ctx.rotate(-ang);
            ctx.fillText(num.toString(), 0, 0);
            ctx.rotate(ang);
            ctx.translate(0, radius * 0.85);
            ctx.rotate(-ang);
        }
    }

    function drawTime(ctx, radius) {
        var now = new Date();
        var hour = now.getHours();
        var minute = now.getMinutes();
        var second = now.getSeconds();

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

        minute = (minute * Math.PI / 30) + (second * Math.PI / (30 * 60));
        drawHand(ctx, minute, radius * 0.8, radius * 0.07);

        second = (second * Math.PI / 30);
        drawHand(ctx, second, radius * 0.9, radius * 0.02);
    }

    function drawHand(ctx, pos, length, width) {
        ctx.beginPath();
        ctx.lineWidth = width;
        ctx.lineCap = "round";
        ctx.moveTo(0, 0);
        ctx.rotate(pos);
        ctx.lineTo(0, -length);
        ctx.stroke();
        ctx.rotate(-pos);
    }