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.

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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.

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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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Semi-circular Progress bar API reference

Example

An example of a Semi-circular Progress bar with tooltips, showing multiple values
<script>
    new RGraph.SemiCircularProgress({
        id: 'cvs',
        min: 0,
        max: 100,
        value: [48,32,12,8],
        options: {
            colors: ['#64E572','#FF81CE','#D5B5E7','#53F7FC'],
            centery: '+5',
            width: 50,
            radius: '-25',
            backgroundGrid: true,
            backgroundGridRadialsCount: 20,
            colorsStroke:        'transparent',
            labelsCenterIndex:   0,
            labelsCenterSize:    65,
            labelsCenterColor:   '#333',
            labelsCenterUnitsPost:   '%',
            scale: true,
            scaleMax: 100,
            scaleLabelsSize: 9,
            scaleUnitsPost: '%',
            scaleLabelsCount: 20,
            scaleLabelsOffsetr: 5,
            tooltips: '%{key}',
            tooltipsFormattedKeyLabels: ['Richard','John','Lucy','Pob'],
            tooltipsFormattedUnitsPost: '%'
        }
    }).draw();
</script>

Properties

You can use these properties to control how the chart appears. You can set them by including them in the options section of the configuration as shown above.

Chart configuration properties

Name: centerx
Description: 
You can use this to stipulate exactly the X coordinate where the chart should appear. It's normally a number, but it can also be a string like this: +20 or this: -20 If this is the case then the number is added to the calculated coordinate thus allowing you to adjust the X coordinate.
Default: null
Name: centery
Description: 
You can use this to stipulate exactly the Y coordinate where the chart should appear. It's normally a number, but it can also be a string like this: +20 or this: -20 If this is the case then the number is added to the calculated coordinate thus allowing you to adjust the Y coordinate.
Default: null
Name: radius
Description: 
You can use this to specify the radius of the chart. It's normally a number, but it can also be a string like this: +20 or this: -20 If this is the case then the number is added to the calculated number thus allowing you to adjust the radius.
Default: null
Name: anglesStart
Description: 
You can specify the angle that the progress should start at with this property. Keep in mind though - that by default the progress is positioned at the bottom of the canvas. Remember that there are three "constants" available for you to use: RGraph.HALFPI RGraph.PI RGraph.TWOPI
Default: Pi (3.14...)
Name: anglesEnd
Description: 
You can specify the angle that the progress should end at with this property. Keep in mind though - that by default the progress is positioned at the bottom of the canvas. Remember that there are three "constants" available for you to use: RGraph.HALFPI RGraph.PI RGraph.TWOPI
Default: 2 * Pi (6.28...)

Margin properties

Name: marginLeft
Description: 
The left margin of the chart, (the margin is where the labels and title are)).
Default: 35
Name: marginRight
Description: 
The right margin of the chart, (the margin is where the labels and title are).
Default: 35
Name: marginTop
Description: 
The top margin of the chart, (the margin is where the labels and title are).
Default: 35
Name: marginBottom
Description: 
The bottom margin of the chart, (the margin is where the labels and title are).
Default: 35

Color properties

Name: colors
Description: 
The color of the bar. In version 6.05, this was updated to accommodate multiple values on your chart. It now operates much like the colors property on a Vertical or Horizontal Progress bar.
Default: [#0c0, #f66, #66f, yellow, pink,#ccc,#cc0,#0cc,#c0c]
Name: colorsStroke
Description: 
This is the stroke color that's used for the inner part of the chart.
Default: #999

Background properties

Name: backgroundColor
Description: 
The background color (of the entire canvas).
Default: rgba(0,0,0,0)
Name: backgroundGrid
Description: 
Whether the background grid is drawn or not.
Default: true
Name: backgroundGridLinewidth
Description: 
The linewidth of the background grid.
Default: 1
Name: backgroundGridColor
Description: 
The color of the background grid.
Default: #ddd
Name: backgroundGridRadials
Description: 
Whether the radial lines (the lines that emanate from the center coordinates) are drawn or not.
Default: true
Name: backgroundGridRadialsCount
Description: 
The number of radial lines that are drawn.
Default: 10
Name: backgroundGridCircles
Description: 
Whether the semi-circular border lines are drawn on the background grid.
Default: true
Name: backgroundGridMargin
Description: 
This is the distance that the background grid extends to.
Default: 20
Name: backgroundFill
Description: 
By default a fill color is visible on the chart that is a faded version of the color that you give. You can disable this by setting this property to false.
Default: true
Name: backgroundFillColor
Description: 
This property allows you to set the specific color of the background fill. When setting this the automatic fading that's usually applied is not done - so you get exactly what you specify.
Default: null

Shadow properties

Name: shadow
Description: 
Whether a drop shadow is applied.
Default: false
Name: shadowColor
Description: 
The color of the shadow.
Default: rgba(220,220,220,1)
Name: shadowOffsetx
Description: 
The horizontal offset of the shadow.
Default: 2
Name: shadowOffsety
Description: 
The vertical offset of the shadow.
Default: 2
Name: shadowBlur
Description: 
The severity of the shadow blurring effect.
Default: 2

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 a 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: textAccessibleOverflow
Description: 
This can be visible or hidden and it controls whether the text is clipped to the edges of the canvas. It defaults to be visible and means you can set small margins if you wish.
Default: visible
Name: textAccessiblePointerevents
Description: 
This controls whether the dom text responds to mouse-based events or not (it sets the pointer-events css property to none).
Default: false
Name: textFont
Description: 
The font used to render the text.
Default: Arial, Verdana, sans-serif
Name: textColor
Description: 
The color of the labels.
Default: black
Name: textSize
Description: 
The size of the text (in points).
Default: 12
Name: textBold
Description: 
Whether the text is bold or not.
Default: false
Name: textItalic
Description: 
Whether the text is italic or not.
Default: false
Name: labelsMin
Description: 
Whether the minimum label is shown or not.
Default: true
Name: labelsMinColor
Description: 
The color of the minimum label.
Default: null
Name: labelsMinFont
Description: 
The font of the minimum label.
Default: null
Name: labelsMinBold
Description: 
Whether the minimum label is bold or not.
Default: null
Name: labelsMinSize
Description: 
The size of the minimum label.
Default: null
Name: labelsMinItalic
Description: 
Whether the minimum label is italic or not.
Default: null
Name: labelsMinOffsetAngle
Description: 
Any offset to add to the angle that the minimum label uses (measured in radians).
Default:  0
Name: labelsMinOffsetx
Description: 
Any horizontal offset to add to the X coordinate that the minimum label uses.
Default:  0
Name: labelsMinOffsety
Description: 
Any vertical offset to add to the Y coordinate that the minimum label uses.
Default: 5
Name: labelsMinUnitsPre
Description: 
Units that are prepended to the number.
Default: null
Name: labelsMinUnitsPost
Description: 
Units that are appended to the number.
Default: null
Name: labelsMinPoint
Description: 
The decimal point separator for the minimum label.
Default: null
Name: labelsMinThousand
Description: 
The thousand separator for the minimum label.
Default: null
Name: labelsMinDecimals
Description: 
The number of decimals that are displayed.
Default: null
Name: labelsMinSpecific
Description: 
You can use this property to set the minimum label to exactly what you want.
Default: null
Name: labelsMax
Description: 
Whether the maximum label is shown or not.
Default: true
Name: labelsMaxColor
Description: 
The color of the maximum label.
Default: null
Name: labelsMaxFont
Description: 
The font of the maximum label.
Default: null
Name: labelsMaxBold
Description: 
Whether the maximum label is bold or not.
Default: null
Name: labelsMaxSize
Description: 
The size of the maximum label.
Default: null
Name: labelsMaxItalic
Description: 
Whether the maximum label is italic or not.
Default: null
Name: labelsMaxOffsetAngle
Description: 
Any offset to add to the angle that the maximum label uses (measured in radians).
Default:  0
Name: labelsMaxOffsetx
Description: 
Any horizontal offset to add to the X coordinate that the maximum label uses.
Default:  0
Name: labelsMaxOffsety
Description: 
Any vertical offset to add to the Y coordinate that the maximum label uses.
Default: 5
Name: labelsMaxUnitsPre
Description: 
Units that are prepended to the number.
Default: null
Name: labelsMaxUnitsPost
Description: 
Units that are appended to the number.
Default: null
Name: labelsMaxPoint
Description: 
The decimal point separator for the maximum label.
Default: null
Name: labelsMaxThousand
Description: 
The thousand separator for the maximum label.
Default: null
Name: labelsMaxDecimals
Description: 
The number of decimals that are displayed.
Default: null
Name: labelsMaxSpecific
Description: 
You can use this property to set the maximum label to exactly what you want.
Default: null
Name: labelsCenter
Description: 
Whether the center label is displayed or not.
Default: true
Name: labelsCenterFont
Description: 
The font used to draw the center label.
Default: null
Name: labelsCenterBold
Description: 
Whether the center label is bold or not.
Default: null
Name: labelsCenterItalic
Description: 
Whether the center label is italic or not.
Default: null
Name: labelsCenterSize
Description: 
The size of the center label.
Default: 40
Name: labelsCenterColor
Description: 
The color of the center label.
Default: null
Name: labelsCenterFade
Description: 
If true, and you're using the grow effect, this will cause the center label to fade in after the grow effect has run (but only the first time).
Default: false
Name: labelsCenterUnitsPre
Description: 
Units that are prepended to the number.
Default: null
Name: labelsCenterUnitsPost
Description: 
Units that are appended to the number.
Default: null
Name: labelsCenterPoint
Description: 
The decimal point separator for the center label.
Default: null
Name: labelsCenterThousand
Description: 
The thousand separator for the center label.
Default: null
Name: labelsCenterDecimals
Description: 
The number of decimals that are displayed.
Default: null
Name: labelsCenterOffsetx
Description: 
This allows you finer-grained control in the horizontal direction over the text positioning if you need it.
Default:  0
Name: labelsCenterOffsety
Description: 
This allows you finer-grained control in the vertical direction over the text positioning if you need it.
Default:  0
Name: labelsCenterIndex
Description: 
If you have multiple values shown on your chart (ie you have an array of numbers instead of a single number) this is the array index of the value that you wish to show.
Default:  0
Name: labelsCenterSpecific
Description: 
You can use this property to set the center label to exactly what you want.
Default: null
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

Scale properties

Name: scale
Description: 
Whether a scale is shown on the chart. If true the minimum and maximum value that you give to the constructor will be used by default.
Default: false
Name: scaleMin
Description: 
This is the minimum value for the scale. This just affects the scale on the chart - not the bar itself.
Default:  0
Name: scaleMax
Description: 
This is the maximum value for the scale. You don't have to give it and if you don't it will be the same as the max value that you give when you create the chart. This just affects the scale on the chart - not the bar that represents the value.
Default: null
Name: scaleLabelsCount
Description: 
This property allows you to stipulate how many labels there are on the scale.
Default: 10
Name: scaleLabelsColor
Description: 
The color of the labels (defaults to the textColor property).
Default: null
Name: scaleLabelsFont
Description: 
The font of the labels (defaults to the textFont property)
Default: null
Name: scaleLabelsSize
Description: 
The size of the labels (defaults to the textSize property)
Default: null
Name: scaleLabelsBold
Description: 
Whether the scale labels are bold or not (defaults to the textBold property)
Default: null
Name: scaleLabelsItalic
Description: 
Whether the scale labels are italic or not (defaults to the textItalic property)
Default: null
Name: scaleLabelsOffsetr
Description: 
If you want to offset the scale labels (radially) you can do that with this property.
Default:  0
Name: scaleLabelsOffsetx
Description: 
If you want to offset the scale labels (in the X-direction) you can do that with this property.
Default:  0
Name: scaleLabelsOffsety
Description: 
If you want to offset the scale labels (in the Y-direction) you can do that with this property.
Default:  0
Name: scaleUnitsPre
Description: 
These units are prepended to the scale numbers on the chart.
Default: none
Name: scaleUnitsPost
Description: 
These units are appended to the scale numbers on the chart.
Default: none
Name: scaleDecimals
Description: 
This stipulates how many decimal places are shown on the scale numbers on the chart.
Default:  0
Name: scalePoint
Description: 
The character that's used as the decimal point for the scale.
Default: .
Name: scaleThousand
Description: 
The character that's used as the thousand separator for the scale.
Default: ,
Name: scaleFormatter
Description: 
If you want to handle the formatting of the scale yourself you can do so with this property. It should be a function that returns the formatted number.
Default: null

Title properties

Name: title
Description: 
The title of the chart, if any.
Default: null
Name: titleFont
Description: 
The font that the title is rendered in. If not specified the textFont setting is used (usually Arial).
Default: null
Name: titleSize
Description: 
The size of the title. If not specified the size is usually 4pt bigger than the textSize setting.
Default: null
Name: titleBold
Description: 
Whether the title is bold or not.
Default: null
Name: titleItalic
Description: 
Whether the title is italic or not.
Default: null
Name: titleColor
Description: 
The color of the title.
Default: null
Name: titleX
Description: 
To give the exact X coordinate for the title - use this. This can also be a string like this: "-5" - in which case it's converted to a number and added to the calculated coordinate - allowing you to adjust the calculated coordinate.
Default: null
Name: titleY
Description: 
To give the exact Y coordinate for the title - use this. This can also be a string like this: "-5" - in which case it's converted to a number and added to the calculated coordinate - allowing you to adjust the calculated coordinate.
Default: null
Name: titleHalign
Description: 
The horizontal alignment of the title.
Default: center (can change depending on other options)
Name: titleValign
Description: 
The vertical alignment of the title.
Default: center (can change depending on other options)
Name: titleOffsetx
Description: 
You can use this property to adjust the positioning of the title in the horizontal direction (positive values adjust the title to the right and negative values adjust it to the left).
Default:  0
Name: titleOffsety
Description: 
You can use this property to adjust the positioning of the title in the vertical direction (positive values adjust the title downwards and negative values adjust it upwards).
Default:  0
Name: titleSubtitle
Description: 
The subtitle of the chart. If a subtitle is specified the title is moved up to accommodate it. As such you might need to give a larger marginTop value.
Default: null
Name: titleSubtitleSize
Description: 
The size of the font used to render the subtitle.
Default: null
Name: titleSubtitleColor
Description: 
The color of the subtitle.
Default: #aaa
Name: titleSubtitleFont
Description: 
The font used to render the subtitle.
Default: null
Name: titleSubtitleBold
Description: 
Whether the subtitle is bold or not.
Default: null
Name: titleSubtitleItalic
Description: 
Whether the subtitle is italic or not.
Default: null
Name: titleSubtitleOffsetx
Description: 
Use this property to adjust the horizontal position of the subtitle.
Default:  0
Name: titleSubtitleOffsety
Description: 
Use this property to adjust the vertical position of the subtitle.
Default:  0

Interactive features properties

Name: tooltips
Description: 
An array of tooltips. These are shown when the progress bar is clicked on. Tooltips can contain html.
Default: An empty array
Name: tooltipsEffect
Description: 
The effect used for showing tooltips. Possible values are slide fade or none.
Default: slide
Name: tooltipsOverride
Description: 
If you wish to handle showing tooltips yourself, this should be a function object which does just that. There's more information on the tooltips documentation page.
Default: null
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: tooltipsFormattedKeyColors
Description: 
When using formatted tooltip strings you can give specific colors for the %{key} option to use.
Default: null
Name: tooltipsFormattedKeyColorsShape
Description: 
This is the shape that's used in the tooltip key. It can be square or circle
Default: square
Name: tooltipsFormattedKeyColorsCss
Description: 
By using this property you can add css values to the key color shape that appears in the tooltip key. Note the property name is "color" and not "colors" like previous properties. It should be an object of css properties like this:
tooltipsFormattedKeyColorsCss : {
    border: "1px solid #ddd";
}
Default: null
Name: tooltipsFormattedKeyLabels
Description: 
When using formatted tooltip strings these are the labels that are displayed.
Default: [] (an empty array)
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-dimension 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:
tooltipsPointerCss: {
    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: tooltipsCssClass
Description: 
This is the name of the css class the chart uses.
Default: RGraph_tooltip
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
Name: tooltipsHotspotIgnore
Description: 
This can be a number of things and can be used to ignore certain tooltip hotspots - which can allow charts to the rear to be clickable. There's an example of this in the download archive called pie-tooltipshotspotignore.html. You can use the transparent color to allow the rear chart to be seen in such a case. It can be:
  • A single boolean value (ie true or false) to enable or disable all of the hotspots - true means the hotspot will be ignored
  • A single number (the zero-indexed number corresponding to the hotspot to ignore)
  • An array of numbers (the numbers are the indexes of hotspots to ignore)
  • An array of boolean true or false values - the position of these values correspond to the index(es) of the segments to ignore (for example [false, false, true, false, false] - true means the corresponding hotspot will be ignored)
Default: null
Name: contextmenu
Description: 
An array of context menu items. More information on context menus is here.
Default: [] (An empty array)
Name: annotatable
Description: 
Whether annotations are enabled for the chart (ie you can draw on the chart interactively.
Default: false
Name: annotatableColor
Description: 
If you do not allow the use of the palette, then this will be the only color allowed for annotations.
Default: black
Name: annotatableLinewidth
Description: 
This is the linewidth of the annotations.
Default: 1
Name: adjustable
Description: 
Defaulting to false, this determines whether your chart will be adjustable.
Default: false

Key properties

The key properties are documented on the key documentation page.

Miscellaneous properties

Name: variant
Description: 
By setting this to rounded you can get the ends of the bar and the background rounded instead of square. If you do this you'll probably also want to set labelsMin and labelsMax to false. There's an example of this style in the download archive called semicircularprogress-rounded.html
Default: default
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: 
If you use tooltips, this controls the color of the highlight stroke.
Default: black
Name: highlightFill
Description: 
If you use tooltips, this controls the color of the highlight fill.
Default: rgba(255,255,255,0.5)
Name: clearto
Description: 
This is used in animations and effects as the default color to use when clearing the canvas.
Default: null
Name: responsive
Description: 
This option is new to the July 2023 release (v6.13) and allows you to inline the responsive configuration instead of appending it on to the end of the object it as a function. The documentation and demo pages have been updated to use this new option. You can read more about the responsive feature by reading the responsive configuration page.
Default: null

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 bar when it's 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 progress bar.
y The center Y coordinate of the progress bar.
angleStart The start angle of the indicator bar (it's measured in radians).
angleEnd The end angle of the indicator bar (it's measured in radians).
radiusInner The radius of the inside of the indicator bar.
radiusOuter The radius of the outside of the indicator bar.
dataset As there's only ever one bar on the progress bar this is always zero.
index As there's only ever one bar on the progress bar this is always zero.
sequentialIndex As there's only ever one bar on the progress bar this is always zero.
tooltip If a tooltip is associated with the bar 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>
    semicircularprogress.canvas.onclick = function (e)
    {
        RGraph.redraw();
    
        var canvas = e.target,
            obj    = canvas.__object__,
            shape  = obj.getShape(e);

        if (shape) {            
            // Draw the outside of the semi-circular progress
            obj.path(
                'lw 10 b a % % % % % false',
                shape.x, shape.y, shape.radiusOuter, shape.angleStart, shape.angleEnd
            );

            // Draw the inside of the semi-circular progress
            obj.path(
                'a % % % % % true c s black f red',
                shape.x, shape.y, shape.radiusInner, shape.angleEnd, shape.angleStart
            );
        }
    }
</script>

obj.getValue(event)

This method can be used to get the value at a particular point or at the mouse coordinates, based on the scale that is in use. You pass it an event object.

myChart.canvas.onclick = function (e)
{
    var obj   = e.target.__object__;
    var value = obj.getValue(e);
    
    // ...
}

obj.getAngle(value)

This method can be used to retrieve the correct angle (in radians) for the given value.

<script>
    angle = obj.getAngle(7);
</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:

.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.SemiCircularProgress({
    id: 'cvs',
    min: 0,
    max: 100,
    value: 56,
    options: {
    }
}).on('draw', function (obj)
{
    // Put your draw event code here

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

obj.exec(function)

The exec function is documented here.


obj.responsive(configuration)

The responsive function helps your charts respond to different browser window sizes and screen resolutions. For example, for smaller screens, you might want to have angled labels or show shorter versions of them completely.

Update: There is now the responsive configuration option available to you and this is now the preferred method of configuration.

The responsive function and configuration option are documented on their own page here.

The coordinates properties

The obj.coords array holds all of the necessary information to redraw the segments that are drawn on the chart

Events

RGraph supports custom events that allow you to easily add interactivity to your charts if required. The following events are available:

For example:
new RGraph.SemiCircularProgress({
    id: 'cvs',
    min: 0,
    max: 100,
    value: 44,
    options: {
    }
}).on('draw', function (obj)
{
    console.log('The draw event has fired');
    
}).draw();

Effects

These effects are available and can be used instead of the draw function. There are also generic effects available which you can see here: Generic effects and transitions
<script>
    //
    // Optional callback function that's called when the effect is complete.
    //
    function myCallback (obj)
    {
        // ...
    }

    new RGraph.SemiCircularProgress({
        id: 'cvs',
        min: 0,
        max: 100,
        value: 56,
        options: {
            marginLeft: 35
        }
    }).grow({frames: 60}, myCallback);
</script>