HTML5 Canvas实战

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function clockTest() {
    var canvas = document.getElementById('canvas');
    if (!(canvas && canvas.getContext)) {
        return;
    }
    var ct = canvas.getContext('2d');
    var w = canvas.width = 500;
    var h = canvas.height = 300;
    var r1 = 95;
    var c3 = ct.createLinearGradient(0, 0, 0, h);

    c3.addColorStop(0, '#FFF');
    c3.addColorStop(0.2, '#dad9e0');
    c3.addColorStop(0.4, '#adb0b6');
    c3.addColorStop(0.6, '#8f8f99');
    c3.addColorStop(0.8, '#86878b');
    c3.addColorStop(1, '#88898e');

    var c4 = ct.createRadialGradient(w / 2, h / 2, w, w, w, w);
    c4.addColorStop(0, 'rgba(0,0,0,1)');
    c4.addColorStop(0.2, 'rgba(0,0,0,0.8)');
    c4.addColorStop(0.3, 'rgba(0,0,0,0)');
    c4.addColorStop(0, 'rgba(0,0,0,0)');

    function clock() {
        var d = new Date();
        var dH = d.getHours();
        var dM = d.getMinutes();
        var dS = d.getSeconds();
        //return;
        ct.clearRect(0, 0, w, h);
        ct.save();
        ct.beginPath();
        ct.strokeStyle = 'rgba(0,0,0,0.1)';
        ct.fillStyle = c3;
        ct.arc(w / 2, h / 2, 135, 0, Math.PI * 2, true);
        ct.closePath();
        ct.fill();
        ct.stroke();
        ct.restore();

        ct.save();
        ct.beginPath();
        ct.strokeStyle = 'rgba(0,0,0,0.1)';
        ct.fillStyle = '#E2E9F1';
        ct.arc(w / 2, h / 2, 120, 0, Math.PI * 2, true);
        ct.closePath();
        ct.fill();
        ct.stroke();
        ct.restore();

        for (var i = 0; i < 60; i++) {
            ct.save();
            ct.lineCap = 'square';
            ct.beginPath();
            if (i % 5 === 0) {
                ct.lineWidth = 5;
                ct.strokeStyle = '#333';
            } else {
                ct.lineWidth = 2;
                ct.strokeStyle = '#333';
            }
            ct.translate(w / 2, h / 2);
            ct.rotate(i * 6 * Math.PI / 180);
            ct.moveTo(0, -120);
            if (i % 5 === 0) {
                ct.lineTo(0, -105);
            } else {
                ct.lineTo(0, -110);
            }
            ct.closePath();
            ct.stroke();
            ct.restore();
        }

        ct.save();
        ct.translate(w / 2, h / 2);
        ct.fillColor = '#369';
        ct.textAlign = 'center';
        ct.textBaseline = 'middle';
        ct.font = '25px times new roman';
        ct.fillText(12, 0, -r1);
        ct.fillText(3, r1, -0);
        ct.fillText(6, 0, r1);
        ct.fillText(9, -r1, -0);
        ct.fillStyle = '#333';
        ct.font = '16px verdara';
        ct.fillText('KINGWELL', 0, 50);
        ct.restore();

        ct.save();
        ct.beginPath();
        ct.translate(w / 2, h / 2);
        ct.rotate((dH + dM / 60) * 30 * Math.PI / 180);
        ct.lineWidth = 10;
        ct.strokeStyle = '#222';
        ct.moveTo(0, 15);
        ct.lineTo(0, -70);
        ct.closePath();
        ct.stroke();
        ct.restore();

        ct.save();
        ct.beginPath();
        ct.translate(w / 2, h / 2);
        ct.rotate((dM + dS / 60) * 6 * Math.PI / 180);
        ct.lineWidth = 6;
        ct.strokeStyle = '#333';
        ct.moveTo(0, 20);
        ct.lineTo(0, -90);
        ct.closePath();
        ct.stroke();
        ct.restore();

        ct.save();
        ct.beginPath();
        ct.translate(w / 2, h / 2);
        ct.rotate(dS * 6 * Math.PI / 180);
        ct.lineWidth = 2;
        ct.strokeStyle = '#C00';
        ct.moveTo(0, 25);
        ct.lineTo(0, -100);
        ct.closePath();
        ct.stroke();
        ct.restore();

        ct.save();
        ct.beginPath();
        ct.translate(w / 2, h / 2);
        ct.arc(0, 0, 6, 0, Math.PI * 2, true);
        ct.fillStyle = '#C00';
        ct.closePath();
        ct.fill();
        ct.restore();
        setTimeout(clock, 1000);
    }