RGraph is a JavaScript charts library based on HTML5 SVG and canvas. RGraph is mature (over 15 years old) and has a wealth of features making it an ideal choice to show charts on your website.

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Get the latest version of RGraph (version 6.17) from the download page. There's also older versions available, minified files and links to cdnjs.com hosted libraries.

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RGraph can be used for free under the GPL or if that doesn't suit your situation there's an inexpensive (£99) commercial license available.

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The rotate function

The rotate function rotates the canvas. There are a couple of things you need to keep in mind if you use this function:

Arguments to the function

An example

You can use the function like this:

    window.onload = function ()
        var canvas  = document.getElementById("cvs");
        var context = canvas.getContext('2d');

        // First translate the canvas so that the rotation point is at the bottom right of the canvas 
        context.translate(canvas.width, canvas.height)
        // Pi radians - which is 180 degrees
        context.moveTo(100, 100);
        context.lineTo(200, 200);