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.net Powerful JavaScript charts
About
RGraph is a JavaScript charts library based on HTML5 SVG and canvas. RGraph is mature (over 17 years old) and has a wealth of features making it an ideal choice to use for showing charts on your website.

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New datagrid in v6.21
In version 6.21 a new datagrid object has been added. This makes it easy to add static or dynamic data tables to your pages. It can be used whether you use the canvas or SVG libraries or entirely standalone.

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Download
Get the latest version of RGraph (version 6.21, 10th April 2025) from the download page. You can read the changelog here. There's also older versions available, minified files and links to cdnjs.com hosted libraries.

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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 (£129) commercial license available.

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The drawing API Circle object API reference

The circle object allows you to add a circle to your charts. You could use this as a "button" to provide extra information (with the circle tooltip) or simply to highlight a point. The circle object is very similar in function to the rect object.

Usage example

<script>
    line = new RGraph.Line({
        id: 'cvs',
        data: [4,9,1,3,2,6,5],
        options: {
            spline: true,
            backgroundGridVlines:false,
            backgroundGridBorder:false,
            xaxis: false,
            yaxis: false,
            xaxisLabels: ['Monday','Tuesday','Wednesday','Thursday','Friday','Saturday','Sunday'],
            marginInner: 5,
            tickmarksStyle: 'endcircle',
            tickmarksSize: 10,
            colors: ['black'],
            textSize: 16
        }
    }).draw();

    x      = line.coords[2][0];
    y      = line.coords[2][1];
    radius = 15;

    new RGraph.Drawing.Circle({
        id: 'cvs',
        x: x,
        y: y,
        radius: radius,
        options: {
            colorsStroke: 'black',
            colorsFill: 'rgba(255,0,0,0.7)',
            tooltips: ['<b>Example</b><br />This is an example tooltip'],
            shadow: true,
            shadowOffsetx: 0,
            shadowOffsety: 0,
            shadowBlur: 5,
            textSize: 14
        }
    }).draw();
</script>

Properties

Color properties

Name: colorsStroke
Description: 
The color used to stroke the circle.
Default: transparent
Name: colorsFill
Description: 
The color used to fill the circle.
Default: red

Shadow properties

Name: shadow
Description: 
This controls whether the shadow is enabled or not.
Default: false
Name: shadowColor
Description: 
The color of the shadow.
Default: gray
Name: shadowOffsetx
Description: 
The X offset that the shadow is drawn at.
Default: 3
Name: shadowOffsety
Description: 
The Y offset that the shadow is drawn at.
Default: 3
Name: shadowBlur
Description: 
The severity of the shadow blur.
Default: 3

Interactive features properties

Name: tooltips
Description: 
The tooltip for the circle. Even though you can only have one - this should still be an array: obj.set('tooltips', ['The tooltip']);
Default: null
Name: tooltipsEvent
Description: 
This can be click or mousemove and controls what event is used to trigger the tooltip.
Default: onclick
Name: tooltipsHighlight
Description: 
This stipulates whether the circle will be highlighted when the tooltip is shown.
Default: true
Name: tooltipsPersistent
Description: 
If you want the tooltips to persist after a click (ie they don't disappear) then you can set this property to true to get this behaviour. Keep in mind that if you have a lot of bars/segments/points/etc then it's possible for the chart to become quite crowded. If you need to subsequently clear all of the tooltips there's an api function available to do that for you and it's called: RGraph.tooltip.persistent.clear() If you want to access any (or all) of the tooltip div tags then you can do so using the RGraph.tooltip.persistent object. This option works when you have the tooltipsEvent property set to mousemove
Default: false
Name: tooltipsNohideonclear
Description: 
Not an option that you'll need particularly often if at all. Setting this to true means that when you call the RGraph.clear api function the tooltip DOES NOT get hidden.
Default: false
Name: tooltipsFormattedPoint
Description: 
When using formatted tooltip strings this is used as the point when using the %{value_formatted} option.
Default: .
Name: tooltipsFormattedThousand
Description: 
When using formatted tooltip strings this is used as the thousand separator when using the %{value_formatted} option.
Default: ,
Name: tooltipsFormattedDecimals
Description: 
When using formatted tooltip strings this specifies the number of decimals when using the %{value_formatted} option.
Default:  0
Name: tooltipsFormattedUnitsPre
Description: 
When using formatted tooltip strings these units are prepended to the number when using the %{value_formatted} option.
Default: (an empty string)
Name: tooltipsFormattedUnitsPost
Description: 
When using formatted tooltip strings these units are appended to the number when using the %{value_formatted} option.
Default: (an empty string)
Name: tooltipsFormattedListType
Description: 
With this property you can switch between an unordered list (the default) and an ordered list. Possible values are ul and ol.
Default: ul
Name: tooltipsFormattedListItems
Description: 
This should be a two-dimensional array of the list items that are to be shown for all of the tooltips. An example of this property is:
tooltipsFormattedListItems: [
    ['Bill','Jerry','Berty'], // First tooltip
    ['Gill','Carrie','Lucy'], // Second tooltip
    ['Pob','Nobby','Hilda']   // Third tooltip
]
You can use css to style this list - for example:
.RGraph_tooltip ul#rgraph_formatted_tooltips_list li {
    text-align: left;
    color: yellow;
}
Default: null
Name: tooltipsFormattedTableHeaders
Description: 
When showing a table in the tooltips this can be an array of headers for the table. These are added to the tooltip using th tags.
Default: null
Name: tooltipsFormattedTableData
Description: 
This is the data that is added to the table. This is a 3-dimensional array so it's easy to make a mistake. See the example, copy the code from it and then modify it suit. You'll create fewer bugs this way.
Default: null)
Name: tooltipsPointer
Description: 
By default the tooltips have a small triangular pointer that points to the shape that was clicked on. You can turn this off with this property.
Default: true
Name: tooltipsPointerCss
Description: 
If you want any css values applied to the tooltips pointer (a css border, for example) then specify an object containing those values to this property. For example: 
tooltips: {
    borderLeft: 'gray 2px solid',
    borderBottom: 'gray 2px solid'
}
Default: null
Name: tooltipsPointerOffsetx
Description: 
This allows you to adjust the vertical position of the tooltips pointer.
Default:  0
Name: tooltipsPointerOffsety
Description: 
This allows you to adjust the vertical position of the tooltips pointer (for example, if you add a border you may need to move it down slightly).
Default:  0
Name: tooltipsPositionStatic
Description: 
The new default (as of August 2020) is for tooltips to be positioned statically and not be dependent on the mouse position. If you don't want this for whatever reason, you can disable it with this setting. When you set it to false tooltips are positioned next to the mouse pointer.
Default: true
Name: tooltipsCss
Description: 
If you want to specify some css that gets applied to all of the tooltips, but don't want to use the RGraph.tooltips.style object (which gets applied to all of the tooltips on the page for every chart) you can use this property to give some per-object css for the tooltips. These are css styles that get applied to all of the tooltips for the specific object only. It should look like this:
tooltipsCss: {
    fontFamily: 'Verdana',
    fontSize: '20pt'
}
Default: null
Name: tooltipsOffsetx
Description: 
This property allows you to shift the tooltips left or right.
Default:  0
Name: tooltipsOffsety
Description: 
This property allows you to shift the tooltips up or down.
Default:  0

Labels and text properties

Name: textAccessible
Description: 
A new feature in 2016 that allows you to use dom text in place of canvas text. It makes for much higher quality text that you can also select if desired (for copy/paste operations). It won't fit all situations and you can read more about the DOM text feature here. A good way to control borders/margins/padding etc is not to set them on the canvas but to wrap the canvas in a div and set them on that like this: 
<div style="margin-left: 50px; display: inline-block">
    <canvas id="cvs" width="650" height="250"></canvas>
</div>
Default: false
Name: text
Description: 
This allows you to add custom text to your chart if you want to. There's a dedicated page that describes this option here.
Default: null

Miscellaneous properties

Name: highlightStyle
Description: 
By default this is null but you can set it to a function if you wish so that function is called to do the highlighting. It's passed the shape object as an argument.
Default: null
Name: highlightStroke
Description: 
This is the color that the circle is highlighted (the stroke) in when the tooltip is shown.
Default: black
Name: highlightFill
Description: 
This is the color that the circle is highlighted in (the fill) when the tooltip is shown.
Default: rgba(255,255,255,0.7)
Name: linewidth
Description: 
This is the linewidth that is used when stroking the circle.
Default: 2

Methods

obj.get(name)
An accessor that you can use to retrieve the values of properties.

obj.set(name, value)
An accessor that you can use to set the values of properties.

obj.getShape(event)
This method makes it easy to get hold of the background when it has been clicked on or hovered over. It returns an object which has the following indexes available:
object The chart object.
x The center X coordinate of the circle.
y The center Y coordinate of the circle.
radius The radius of the circle.
dataset As there's only ever one element this is always zero.
index As there's only ever one element this is always zero.
sequentialIndex As there's only ever one element this is always zero.
tooltip If a tooltip is associated with the Background object this will be it.id: strings are expanded for you (where the tooltip text is retrieved from the html tag with the matching ID). 
<script>
    circle.canvas.onclick = function (e)
    {
        RGraph.redraw();
    
        var canvas = e.target,
            obj    = canvas.__object__,
            shape  = obj.getShape(e);

        if (shape) {            
            // Highlight the main body of the Background object.
            obj.path(
                'lw 10 b a % % % 0 6.29 false s black f red',
                shape.x, shape.y, shape.radius
            );
        }
    }
</script>

obj.on(event, function)

This method can be used to set an event listener on an object. It operates similarly to the jquery on function. The first argument is the event that you wish to attach to and the second is the handler function. For example: 

obj.on('draw', function (obj)
{
    // Put your event code here
});

The function is useful if you use method chaining when creating your charts: 

var obj = new RGraph.Drawing.Circle({
    id: 'cvs',
}).on('draw', function (obj)
{
    // Put your draw event code here

}).on('click', function (e, shape)
{
    // Handle the click event

}).draw();
obj.exec(function)

The exec function is documented here.