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RGraph: HTML5 canvas graph library - Documentation

The following documentation is available:

On this page:


Benefits of HTML5 canvas graphs

HTML5 introduces a new HTML element - the CANVAS tag. This tag allows for two dimensional drawing easily using Javascript. This makes it perfect for producing graphs. Because Javascript runs on your users computer, none of the stress on your server normally associated with producing graphs (as is currently the norm) is incurred. Not only that but because of the greater processing power that is typically available on users' computers, they will be much faster. And, because the code can be both compressed (for example if you're using Apache, mod_gzip will do this automatically for you) and cached, bandwidth usage can be massively reduced. This makes it economically attractive to employ, (ie it can save you money...).

Imagine, you are creating 100,000 graphs a day and the data is such that the resulting graphs cannot be cached. With the RGraph library you can reduce that figure to zero. All the processing and graph creation is done by each individual client, much like rendering the HTML you send to them. So you don't have to send any images, you simply send them the Javascript libraries once. So, much lower bandwidth bills and far less strain on your webserver.

And if that wasn't enough, because the graphs are created using Javascript, they will work offline if you view a .html page on your own PC. Download the archive and see! Useful if you need to do a presentation for example and want to use the same graph(s) as your website.


Browser support

Since the graphs are produced using HTML5 features (the new canvas tag), client support is currently:

The HTML5 canvas tag is part of the HTML5 specification, and all of the above browsers have some sort of support for it.

Canvas & Microsoft Internet Explorer (MSIE)
Microsoft Internet Explorer 8 doesn't natively support the HTML5 <canvas> tag. To support MSIE 8 you will need to use either Google Chrome Frame or ExCanvas from Google (which is included in the RGraph archive). Read more about Internet Explorer compatibility here.

Starting with preview 3 Microsoft Internet Explorer 9 has full support for <canvas>. You can view some screenshots here. MSIE 6 and 7 are not supported.

RGraph and older browsers
Older browsers (eg Chrome 1, Firefox 3, Safari 3, Opera 9.5) are supported, however if they don't support the canvas shadow or text APIs, these will naturally be unavailable. Earlier versions of these browsers may work, but are untested.


Improving the performance of your graphs

Although performance is excellent, (traditionally your webserver has been producing all of your graphs, and now the client produces them, and typically only one at a time), you may still want to tune RGraph further. The biggest thing you can do is use compression, which reduces the initial download time of the libraries, but there are a number of things you can do:

A reasonable performance strategy

Although there's a lot you can do in regards to performance, a few of the points here will suffice for most websites:

The number one thing you should do is compress your libraries. This has multiple benefits and provides by far the most gain, effectively for free. Secondly, use the minified libraries. Since you can download them here, you might as well use them. Then we have pre-emptive caching. Since most websites won't show graphs on the front page or will have a login page that is shown before any graphs, this effectively eliminates the graph library download. And lastly caching should be done as a matter of course. There's no reason to keep downloading the same library so even caching for only 30 minutes (or the duration of an average visit to your website) will produce results.


Implementing RGraph

Getting RGraph up and running is very easy and consists of three steps. If you're having trouble I suggest you get hold of a copy of Firefox along with Firebug - its Javascript error console will make debugging your issue much easier. Many problems are down to a library not having been included or not using the onload event when you need to. You might also benefit from using the Web Developer toolbar for Firefox. This allows you to easily disable caching, thus eliminating any problems that that causes. You could equally use the Chrome developer tools, which also provide a good quality Javascript console.

  1. Include the libraries (put this in your documents <HEAD>):
    <script src="RGraph.common.core.js"></script>
    <script src="RGraph.common.adjusting.js"></script> <!-- Just needed for adjusting -->
    <script src="RGraph.common.annotate.js"></script>  <!-- Just needed for annotating -->
    <script src="RGraph.common.context.js"></script>   <!-- Just needed for context menus -->
    <script src="RGraph.common.resizing.js"></script>  <!-- Just needed for resizing -->
    <script src="RGraph.common.tooltips.js"></script>  <!-- Just needed for tooltips -->
    <script src="RGraph.common.zoom.js"></script>      <!-- Just needed for zoom -->
    <script src=""></script>              <!-- Just needed for bar graphs -->
    <script src="RGraph.bipolar.js"></script>          <!-- Just needed for bi-polar graphs -->
    <script src="RGraph.funnel.js"></script>           <!-- Just needed for funnel charts -->
    <script src="RGraph.gantt.js"></script>            <!-- Just needed for gantt charts -->
    <script src="RGraph.hbar.js"></script>             <!-- Just needed for horizontal bar charts -->
    <script src="RGraph.hprogress.js"></script>        <!-- Just needed for horizontal progress bars -->
    <script src="RGraph.led.js"></script>              <!-- Just needed for LED charts -->
    <script src="RGraph.line.js"></script>             <!-- Just needed for line graphs -->
    <script src="RGraph.meter.js"></script>            <!-- Just needed for meter charts -->
    <script src="RGraph.odo.js"></script>              <!-- Just needed for odometers -->
    <script src="RGraph.pie.js"></script>              <!-- Just needed for pie charts -->
    <script src="RGraph.rose.js"></script>             <!-- Just needed for rose charts -->
    <script src="RGraph.rscatter.js"></script>         <!-- Just needed for rscatter charts -->
    <script src="RGraph.scatter.js"></script>          <!-- Just needed for scatter graphs -->
    <script src="RGraph.tradar.js"></script>           <!-- Just needed for traditional radar charts -->
    <script src="RGraph.vprogress.js"></script>        <!-- Just needed for vertical progress bars -->
  2. Add the canvas tag (put it where you want the graph to appear):
    <canvas id="myCanvas" width="600" height="250">[No canvas support]</canvas>
  3. Create the graph (since it is using the onload event, you can put this anywhere):
        window.onload = function ()
            var data = [280, 45, 133, 166, 84, 259, 266, 960, 219, 311, 67, 89];
            var bar = new RGraph.Bar('myCanvas', data);
            bar.Set('chart.labels', ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec']);
            bar.Set('chart.gutter', 35);

There's also a very basic example of using RGraph, that does very little. It can be helpful to illustrate how you can get RGraph up and running.

Common library split (17th April 2010)

The common library has now been split into separate files. This was because the single common library had become far too large. If you don't use any of the dynamic features, then you still need to change your code, as RGraph.common.js is now called RGraph.common.core.js.


Suggested structure for RGraph

Suggested structure for RGraph

The suggested layout structure for the RGraph libraries is shown on the right. The folder represents the root/top level of your website with the javascript directory beneath that. The css and images folders are shown for illustrative purposes only. If you follow this layout then your URLs to the RGraph libraries would be:


By using this structure you make RGraph easy to update should you need to, and also keep all the RGraph libraries in one, easy to find, place.


Integration with server side scripting

This is a very easy process, as easy as sending content to the browser. All you need to do is make the data variable contain the data you want to be displayed. Eg:

<script src="RGraph.common.core.js"></script>
<script src="RGraph.line.js"></script>

<canvas id="myCanvasTag" width="600" height="200">[No canvas support]</canvas>

    var data = [78,16,26,23,25,51,34,64,84,84];
    var line = new RGraph.Line("myCanvasTag", data);
    line.Set("chart.labels", ["Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov"]);

To get the above using PHP you could do this:

    // This simply makes a string out of the array of data
    $myData = join(',', array(78,16,26,23,25,51,34,64,84,84));

    // This prints out the required HTML markup
    print('<script src="RGraph.common.core.js"></script>' . "\n");
    print('<script src="RGraph.line.js"></script>' . "\n\n");
    print('<canvas id="myCanvasTag" width="600" height="200">[No canvas support]</canvas>' . "\n\n");
    print('<script>' . "\n");
    print('    var data = [' . $myData . '];' . "\n");
    print('    var line = new RGraph.Line("myCanvasTag", data);' . "\n");
    print('    line.Set("chart.labels", ["Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov"]);' . "\n");
    print('    line.Draw();' . "\n");

Strictly speaking the var isn't necessary, however if you put the code inside a function (like window.onload), it's probably best to do so as using var will make the variable local, and not global. So doing so will help prevent naming clashes.


Integration with PHP & MySQL

This is a simple matter of formatting what you get back from MySQL into a string, as the MySQL dump and PHP code below shows (it's based on a database called RGraph_example):

# Table structure for table `daily_statistics`

CREATE TABLE `daily_statistics` (
  `st_day` char(9) NOT NULL,
  `st_statistics` tinyint(4) NOT NULL,
  UNIQUE KEY `st_day` (`st_day`)

# Dumping data for table `daily_statistics`

INSERT INTO `daily_statistics` VALUES ('Mon', 124);
INSERT INTO `daily_statistics` VALUES ('Tue', 95);
INSERT INTO `daily_statistics` VALUES ('Wed', 64);
INSERT INTO `daily_statistics` VALUES ('Thu', 94);
INSERT INTO `daily_statistics` VALUES ('Fri', 75);
INSERT INTO `daily_statistics` VALUES ('Sat', 98);
INSERT INTO `daily_statistics` VALUES ('Sun', 84);
    * Change these to your own credentials
    $hostname = "localhost";
    $username = "root";
    $password = "PASSWORD";
    $database = "RGraph_example";
    $connection = mysql_connect($hostname, $username, $password) OR die('Could not connect to MySQL: ' . mysql_error());
    $result = mysql_query("SELECT st_day, st_statistics FROM daily_statistics");
    if ($result) {
        $labels = array();
        $data   = array();
        while ($row = mysql_fetch_assoc($result)) {
            $labels[] = $row["st_day"];
            $data[]   = $row["st_statistics"];

        // Now you can aggregate all the data into one string
        $data_string = "[" . implode(", ", $data) . "]";
        $labels_string = "['" . implode("', '", $labels) . "']";
    } else {
        print('MySQL query failed with error: ' . mysql_error());

    <!-- Don't forget to update these paths -->

    <script src="libraries/RGraph.common.core.js" ></script>
    <script src="libraries/RGraph.line.js" ></script>

    <canvas id="cvs" width="600" height="250">[No canvas support]</canvas>
        graph = new RGraph.Line('cvs', <?php print($data_string) ?>);
        graph.Set('chart.background.grid.autofit', true);
        graph.Set('chart.gutter', 17);
        graph.Set('chart.hmargin', 10);
        graph.Set('chart.tickmarks', 'endcircle');
        graph.Set('chart.labels', <?php print($labels_string) ?>);
        graph.context.translate(12, 0);


This PHP code provides the data in two strings - $labels_string and $data_string.. These variables are then used in the RGraph code to provide the data and the labels.



Making AJAX requests

If you want to get data from your server using AJAX, here is a simple function that you could use to get the data:

    * Makes an AJAX call. It calls the given callback (a function) when ready
    * @param string   url      The URL to retrieve
    * @param function callback A function object that is called when the response is ready, there's an example below
    *                          called "myCallback".
    function AjaxCall (url, callback)
        // Mozilla, Safari, ...
        if (window.XMLHttpRequest) {
            var httpRequest = new XMLHttpRequest();
        // MSIE
        } else if (window.ActiveXObject) {
            var httpRequest = new ActiveXObject("Microsoft.XMLHTTP");
        httpRequest.onreadystatechange = callback;
       'GET', url, true);

    * This sample callback function is called when the data is ready (readyState=4)
    function myCallback ()
        if (this.readyState == 4 && this.status == 200) {
            // Everything is good, the response is received

And you would use it like this:

    AjaxCall('', myCallback);


Support forum

Google Groups
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Support is available via a Google Groups forum. If you think that the issue you have is common, try the issues page first, and then try searching the forum in case your question has been answered previously. If that all yields nothing, post a question to the forum.

If you want to keep up-to-date on RGraph, then subscribe to the group, as I post update notifications here. You can also follow me on Twitter. I post update notifications here along with HTML5 related news.