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

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Linear gradients

Linear gradients can be used in place of regular color definitions to add gradients to your canvas. They are specified using the gradient api and can consist of multiple colors. The createLinearGradient function is used to create the gradient and then the addColorStop function is used to add color stops along the gradient from left to right.

Arguments to the function

An example

<script>
    window.onload = function ()
    {
        var canvas  = document.getElementById("cvs");
        var context = canvas.getContext('2d');
    
        // This creates the gradient from black to red to white
        var gradient = context.createLinearGradient(0,0,600,0);
        gradient.addColorStop(0, 'black');
        gradient.addColorStop(0.5, 'red');
        gradient.addColorStop(1, 'white');
        
        context.fillStyle = gradient
        context.strokeStyle = 'black';
        context.strokeRect(10,10,580,230);
        context.fillRect(10,10,580,230);
    }
</script>

See also