Using HTML5 to Create Charts and Graphs

Andrey Prikaznov

Feb. 20, 12 · Interview

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Today I found an interesting library – flotr2: an opensource library for drawing HTML5 charts and graphs. It allows you to draw charts in different formats such as:

lines
bars
candles
pies
bubbles

Also, it doesn’t require any additional libraries such as jQuery or Prototype. And finally – it has good compatibility with different browsers.

Here is our demo and a downloadable package:

Live Demo

Downloadable Package

Ok, download the source files and lets start coding!

Step 1. HTML

Here is the markup of our final page:

index.html

<!DOCTYPE html>
<html lang="en" >
    <head>
        <meta charset="utf-8" />
        <title>HTML5 charts and graphs - using Flotr2 | Script Tutorials</title>
        <link href="css/main.css" rel="stylesheet" type="text/css" />
        <script src="js/flotr2.min.js"></script>
        <!--[if lt IE 9]>
        <script type="text/javascript" src="js/flashcanvas.js"></script>
        <![endif]-->
    </head>
    <body>
        <header>
            <h2>HTML5 charts and graphs - using Flotr2</h2>
            <a href="http://www.script-tutorials.com/html5-charts-and-graphs/" class="stuts">Back to original tutorial on <span>Script Tutorials</span></a>
        </header>
        <div id="container" class="container"></div>
        <div class="controls">
            <h3>Function:</h3>
            <p>
                <input type="radio" name="func" value="1" onclick="toggleFunc(1)" checked> sin
                <input type="radio" name="func" value="2" onclick="toggleFunc(2)"> sin(1/x)
            </p>
            <h3>Visual mode:</h3>
            <p>
                <input type="radio" name="mode" value="1" onclick="toggleMode(1)" checked> #1
                <input type="radio" name="mode" value="2" onclick="toggleMode(2)"> #2
                <input type="radio" name="mode" value="3" onclick="toggleMode(3)"> #3
            </p>
        </div>
        <script src="js/script.js"></script>
    </body>
</html>

Step 2. CSS

Here are all the stylesheets:

css/main.css

/* page layout styles */
*{
    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;
}
.container {
    color: #000;
    margin: 20px auto;
    overflow: hidden;
    position: relative;
    width: 600px;
    height: 400px;
}
.controls {
    border: 1px dashed gray;
    color: #000;
    margin: 20px auto;
    padding: 25px;
    position: relative;
    width: 550px;
}
.controls p {
    margin-bottom: 10px;
}
.controls input {
    margin-left: 10px;
}

Step 3. JS

js/flotr2.min.js and js/flashcanvas.js

Both libraries are required and available in our package.

Next – our custom file where I have implemented two different functions and three visual modes for charts.

js/script.js

var container = document.getElementById('container');
var start = (new Date).getTime();
var data, graph, offset, i;

var mode = 1;
var fmode = 1; // 1- basic sin, 2 - sin(1/x)

// toggle mode
function toggleMode(i) {
    mode = i;
}
// toggle func
function toggleFunc(i) {
    fmode = i;
}

// Draw a sine curve at time t
function animateSine (t) {
    data = [];
    data2 = [];

    // little offset between steps
    offset = 2 * Math.PI * (t - start) / 10000;

    if (fmode == 2 && offset > 15) {
        start = t;
    }

    for (i = 0; i < 4 * Math.PI; i += 0.2) {
        if (fmode == 1) {
            data.push([i, Math.sin(i - offset)]);
            data2.push([i, Math.sin(i*2 - offset)]);
        } else if (fmode == 2) {
            data.push([i, Math.sin(1/(i-offset))]);
            // data2.push([i, Math.sin(1/(i*2-offset))]);
        }
    }

    // prepare properties
    var properties;
    switch (mode) {
        case 1:
            properties = {
                yaxis : {
                    max : 2,
                    min : -2
                }
            };
            break;
        case 2:
            properties = {
                yaxis : {
                    max : 2,
                    min : -2
                },
                bars: {
                    show: true,
                    horizontal: false,
                    shadowSize: 0,
                    barWidth: 0.5
                }
            };
            break;
        case 3:
            properties = {
                yaxis : {
                    max : 2,
                    min : -2
                },
                radar: {
                    show: true
                },
                grid: {
                    circular: true,
                    minorHorizontalLines: true
                }
            };
            break;
        case 4:
            properties = {
                yaxis : {
                    max : 2,
                    min : -2
                },
                bubbles: {
                    show: true,
                    baseRadius: 5
                },
            };
            break;
    }

    // draw graph
    if (fmode == 1) {
        graph = Flotr.draw(container, [ data, data2 ], properties);
    } else if (fmode == 2) {
        graph = Flotr.draw(container, [ data ], properties);
    }

    // main loop
    setTimeout(function () {
        animateSine((new Date).getTime());
    }, 50);
}

animateSine(start);

Full documentation for the flotr2 library is available here.

Conclusion

As usual, I hope that today’s lesson was interesting for everyone. I welcome any questions or comments and Good Luck!

Source: http://www.script-tutorials.com/html5-charts-and-graphs/

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