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HTML5 Canvas Clock (Keeps Accurate Time)

· Web Dev Zone

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For our new lesson I have prepared a nice pure HTML5 clock. This is a pretty easy script, but it is very easy and impressive (as usual). Of course – anything necessary will be in the canvas object.

Here are our demo and downloadable packages:

Live Demo

download in package


Ok, download the source files and let's start coding!


Step 1. HTML

This is the markup for our clocks

index.html

<!DOCTYPE html>
<html lang="en" >
    <head>
        <meta charset="utf-8" />
        <title>HTML5 Clocks | Script Tutorials</title>
        <link href="css/main.css" rel="stylesheet" type="text/css" />
        <script src="http://code.jquery.com/jquery-latest.min.js"></script>
        <script src="js/script.js"></script>
    </head>
    <body>
        <header>
            <h2>HTML5 Clocks</h2>
            <a href="http://www.script-tutorials.com/html5-clocks/" class="stuts">Back to original tutorial on <span>Script Tutorials</span></a>
        </header>
        <div class="clocks">
            <canvas id="canvas" width="500" height="500"></canvas>
        </div>
    </body>
</html>

Step 2. CSS

Here are all required stylesheets.

css/main.css

.clocks {
    height: 500px;
    margin: 25px auto;
    position: relative;
    width: 500px;
}

Step 3. JS

js/script.js

// inner variables
var canvas, ctx;
var clockRadius = 250;
var clockImage;

// draw functions :
function clear() { // clear canvas function
    ctx.clearRect(0, 0, ctx.canvas.width, ctx.canvas.height);
}

function drawScene() { // main drawScene function
    clear(); // clear canvas

    // get current time
    var date = new Date();
    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;

    // save current context
    ctx.save();

    // draw clock image (as background)
    ctx.drawImage(clockImage, 0, 0, 500, 500);

    ctx.translate(canvas.width / 2, canvas.height / 2);
    ctx.beginPath();

    // draw numbers
    ctx.font = '36px Arial';
    ctx.fillStyle = '#000';
    ctx.textAlign = 'center';
    ctx.textBaseline = 'middle';
    for (var n = 1; n <= 12; n++) {
        var theta = (n - 3) * (Math.PI * 2) / 12;
        var x = clockRadius * 0.7 * Math.cos(theta);
        var y = clockRadius * 0.7 * Math.sin(theta);
        ctx.fillText(n, x, y);
    }

    // draw hour
    ctx.save();
    var theta = (hour - 3) * 2 * Math.PI / 12;
    ctx.rotate(theta);
    ctx.beginPath();
    ctx.moveTo(-15, -5);
    ctx.lineTo(-15, 5);
    ctx.lineTo(clockRadius * 0.5, 1);
    ctx.lineTo(clockRadius * 0.5, -1);
    ctx.fill();
    ctx.restore();

    // draw minute
    ctx.save();
    var theta = (minute - 15) * 2 * Math.PI / 60;
    ctx.rotate(theta);
    ctx.beginPath();
    ctx.moveTo(-15, -4);
    ctx.lineTo(-15, 4);
    ctx.lineTo(clockRadius * 0.8, 1);
    ctx.lineTo(clockRadius * 0.8, -1);
    ctx.fill();
    ctx.restore();

    // draw second
    ctx.save();
    var theta = (seconds - 15) * 2 * Math.PI / 60;
    ctx.rotate(theta);
    ctx.beginPath();
    ctx.moveTo(-15, -3);
    ctx.lineTo(-15, 3);
    ctx.lineTo(clockRadius * 0.9, 1);
    ctx.lineTo(clockRadius * 0.9, -1);
    ctx.fillStyle = '#0f0';
    ctx.fill();
    ctx.restore();

    ctx.restore();
}

// initialization
$(function(){
    canvas = document.getElementById('canvas');
    ctx = canvas.getContext('2d');

    // var width = canvas.width;
    // var height = canvas.height;

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

    setInterval(drawScene, 1000); // loop drawScene
});

I have defined the main timer to redraw the scene. Each step (tick) script defines the current time, and draws clock-hand arrows (hour arrow, minute arrow and second arrow).


Live Demo

download in package


Conclusion

Hope that today’s html5 clocks was impressive for you as always. We have made another nice html5 tutorial. I will be glad to see your thanks and comments. Good luck!

 

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Published at DZone with permission of Andrey Prikaznov, DZone MVB. See the original article here.

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