About
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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License
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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Download
Get the latest version of RGraph (version 6.16) from the download page. There's also older versions available, minified files and links to cdnjs.com hosted libraries.

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Radial gradients

Radial gradients can be used in place of regular color definitions to add gradients to your canvas. They're different to linear gradients because they're circular in nature, as the name suggests. They're specified using the gradient api and can consist of multiple colors. The createRadialGradient function is used to create the gradient and then the addColorStop function is used to add points along the gradient - similar to linear gradients.

Arguments to the function

An example

<script>
    window.onload = function ()
    {
        var canvas  = document.getElementById('cvs');
        var context = canvas.getContext('2d');
        
        // Create the gradient
        var gradient = context.createRadialGradient(175,75,0,175,75,100);
        gradient.addColorStop(0, 'white');
        gradient.addColorStop(1, 'rgb(255,125,125)');
        
        context.beginPath();
        context.fillStyle = gradient
        context.arc(125,125,100,0,Math.PI * 2, false);
        context.fill();
    }
</script>

See also