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clock.js

// zmienne
var canvas, ctx;
var clockImage;
var startDate;

function clear() { 
    ctx.clearRect(0, 0, ctx.canvas.width, ctx.canvas.height);
}

function drawClock(date, x, y, width, height, city) {
    var size = Math.min(width, height);
    var maxSize = Math.min(ctx.canvas.width, ctx.canvas.height);
    var getRelativeSize = function(n) {
        return Math.ceil(n * size / maxSize);
    };

    // Dostosowanie rozmiarów
    var theta, hX, hY, weight;
    var clockRadius = size / 2;
    var fontSize = getRelativeSize(36);
    var offset = getRelativeSize(15);
    ctx.textAlign = 'center';
    ctx.textBaseline = 'middle';

    // Godzina
    var hours = date.getHours();
    var minutes = date.getMinutes();
    var seconds = date.getSeconds();
    hours = hours > 12 ? hours - 12 : hours;
    var hour = hours + minutes / 60;
    var minute = minutes + seconds / 60;

    // Zapisanie oryginalnego stanu
    ctx.save();

    // Tarcza zegara
    ctx.drawImage(clockImage, x, y, width, height);
    ctx.translate(x + width / 2, y + height / 2);

    // Miasto
    if (city !== undefined) {
        ctx.font = (fontSize + 4) + 'px Arial';
        ctx.fillStyle = '#000';
        ctx.fillText(city, 0, height / 2 + 8);
    }

    // Godziny na tarczy
    ctx.font = fontSize + 'px Arial';
    ctx.fillStyle = '#000';
    for (var n = 1; n <= 12; n++) {
        theta = (n - 3) * (Math.PI * 2) / 12;
        hX = clockRadius * 0.7 * Math.cos(theta);
        hY = clockRadius * 0.7 * Math.sin(theta);
        ctx.fillText(n, hX, hY);
    }

    // Wskazówka godzinowa
    ctx.save();
    weight = getRelativeSize(5);
    theta = (hour - 3) * 2 * Math.PI / 12;
    ctx.rotate(theta);
    ctx.beginPath();
    ctx.moveTo(-offset, -weight);
    ctx.lineTo(-offset, weight);
    ctx.lineTo(clockRadius * 0.5, 1);
    ctx.lineTo(clockRadius * 0.5, -1);
    ctx.fill();
    ctx.restore();

    // Wskazówka minutowa
    ctx.save();
    weight = getRelativeSize(4);
    theta = (minute - 15) * 2 * Math.PI / 60;
    ctx.rotate(theta);
    ctx.beginPath();
    ctx.moveTo(-offset, -weight);
    ctx.lineTo(-offset, weight);
    ctx.lineTo(clockRadius * 0.8, 1);
    ctx.lineTo(clockRadius * 0.8, -1);
    ctx.fillStyle = '#040';
    ctx.fill();
    ctx.restore();

    // Wskazówka sekundowa
    ctx.save();
    weight = getRelativeSize(5);
    theta = (seconds - 15) * 2 * Math.PI / 60;
    ctx.rotate(theta);
    ctx.beginPath();
    ctx.moveTo(-offset, -weight);
    ctx.lineTo(-offset, weight);
    ctx.lineTo(clockRadius * 0.9, 1);
    ctx.lineTo(clockRadius * 0.9, -1);
    ctx.fillStyle = '#0f0';
    ctx.fill();
    ctx.restore();

    // Przywrócenie oryginalnego stanu
    ctx.restore();
}

function pad(n) {
    return n < 10 ? '0'+n : n;
}

function drawStopwatch(x, y, width, height) {
    ctx.font = '52px Arial';
    ctx.fillStyle = '#000';
    ctx.textAlign = 'center';
    ctx.textBaseline = 'middle';

    var dateNow = new Date();
    var time = dateNow.getTime() - startDate.getTime();

    var h = Math.floor( time / (60 * 60 * 1000) );
    time = time % (60 * 60 * 1000);
    var m = Math.floor( time / (60 * 1000) );
    time = time % (60 * 1000);
    var s = Math.floor( time / 1000 );

    var formatedTime = pad(h) + ':' + pad(m) + ':' + pad(s);

    ctx.save();
    ctx.fillText(formatedTime, x + width / 2, y + height / 2);
    ctx.restore();
}

function getUtcDate(offset) {
    var date = new Date();
    var utcMs = date.getTime() + (date.getTimezoneOffset() * 60000);
    return new Date(utcMs + (3600000 * offset));
}

function drawScene() { 
    clear(); 
    
    var dateLocal = new Date();
    var dateNewYork = getUtcDate(-4);
    var dateLondon = getUtcDate(1);
    var dateTokyo = getUtcDate(9);

    // Lewy mały zegar - New York
    drawClock(dateNewYork, 100, 250, 100, 100, 'New York -4');

    // Środkowy mały zegar - Londyn
    drawClock(dateLondon, 200, 290, 100, 100, 'London +1');

    // Prawy mały zegar - Tokyo
    drawClock(dateTokyo, 300, 250, 100, 100, 'Tokyo +9');

    // Zegar czasu lokalnego (główny)
    drawClock(dateLocal, 0, 0, 500, 500);

    // Stoper
    drawStopwatch(0, 500, 500, 100);
}

$(function(){
    startDate = new Date();
    canvas = document.getElementById('canvas');
    ctx = canvas.getContext('2d');

    clockImage = new Image();
    clockImage.src = 'images/cface.png';

    setInterval(drawScene, 1000); 
});

index.html

<!DOCTYPE html>
<html lang="en" >
    <head>
        <meta charset="utf-8" />
        <title>Zegar</title>
        <link href="style.css" rel="stylesheet" type="text/css" />
        <script src="http://code.jquery.com/jquery-latest.min.js"></script>
        <script src="clock.js"></script>
    </head>
    <body>
        <header>
            <h2>Zegar HTML 5</h2>          
        </header>
        <div class="clocks">
            <canvas id="canvas" width="500" height="600"></canvas>
        </div>
    </body>
</html>

style.css

*{
    margin:0;
    padding:0;
}
body {
    background-color:#eee;
    color:#fff;
    font:14px/1.3 Arial,sans-serif;
}
header {
    background-color:#212121;
    box-shadow: 0 -1px 2px #111111;
    display:block;
    height:70px;
    position:relative;
    width:100%;
    z-index:100;
}
header h2 {
    font-size:22px;
    font-weight:normal;
    left:50%;
    margin-left:-400px;
    padding:22px 0;
    position:absolute;
    width:540px;
}
header a.stuts,a.stuts:visited {
    border:none;
    text-decoration:none;
    color:#fcfcfc;
    font-size:14px;
    left:50%;
    line-height:31px;
    margin:23px 0 0 110px;
    position:absolute;
    top:0;
}
header .stuts span {
    font-size:22px;
    font-weight:bold;
    margin-left:5px;
}
.clocks {
    height: 500px;
    margin: 25px auto;
    position: relative;
    width: 500px;
}