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 use for showing charts on your website.

More »

 

Download
Get the latest version of RGraph (version 6.18, 1st June 2024) 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.

More »

 

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.

More »

The drawing API Image object API reference

The image object allows you to add images to your charts. The image can, for example, be used as a way to provide an extra tooltip to your users or it can be used as a background image instead of using the built-in backgroundImage option.

The advantage, in this case, is that by using the image drawing object as the background image instead of specifying a background image for the Line chart (which you can do with the backgroundImage option) is that you can click the background and have the click event triggered or show a tooltip.


Usage example

<script>
    new RGraph.Line({
        id: 'cvs',
        data: [4,9,1,3,2,6,5],
        options: {
            xaxisLabels: ['Mon','Tue','Wed','Thu','Fri','Sat','Sun'],
            marginInner: 5,
            tickmarksStyle: 'endcircle',
            colors: ['black'],
            tooltips: ['A','B','C','D','E','F','G'],
            marginBottom: 35,
            textSize: 10
        }
    }).draw();

    image = new RGraph.Drawing.Image({
        id: 'cvs',
        x: 40,
        y: 40,
        src: '/images/logo.png', // CHANGE THIS TO AN IMAGE ON YOUR WEBSITE
        options: {
            width: 32,
            height: 32,
            tooltips: ['Your logo!'],
            textSize: 10
        }
    }).draw();
</script>

Properties

Configuration properties

Name: width
Description: 
If you want to stretch or shrink your image - use this to set the width.
Default: null
Name: height
Description: 
If you want to stretch or shrink your image - use this to set the height.
Default: null
Name: halign
Description: 
This determines the horizontal alignment of the image (left/center/right).
Default: left
Name: valign
Description: 
This determines the vertical alignment of the image (bottom/center/top).
Default: top

Background properties

Name: backgroundColor
Description: 
The background color for the image. This is effective if your image uses transparency.
Default: rgba(0,0,0,0)

Color properties

Name: colorsAlpha
Description: 
Use this to set the alpha value (the transparency) of the image.
Default: 1

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: 5

Interactive features properties

Name: tooltips
Description: 
The tooltip for the background image. 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: 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

Border properties

Name: border
Description: 
This controls whether a border is drawn around the image.
Default: false
Name: borderLinewidth
Description: 
This is the linewidth of the image.
Default: 1
Name: borderColor
Description: 
This is the color of the border.
Default: black
Name: borderRadius
Description: 
This is the severity of the curve used for the corners.
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 chart 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)

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 image 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 X coordinate of the image.
y The Y coordinate of the image.
width The width of the image.
height The height of the image.
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>
    image.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 Image object.
            obj.path(
                'lw 10 b r % % % % s black f rgba(255,0,0,0.25)',
                shape.x, shape.y, shape.width, shape.height
            );
        }
    }
</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.Image({
    id: 'cvs',
    x: 64,
    y: 64,
    src: '/images/logo.png',
}).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.