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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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Get the latest version of RGraph (version 6.19, 28th September 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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Thermometer chart API reference

Example

A thermometer chart with tooltips
<script>
    new RGraph.Thermometer({
        id: 'cvs',
        min: 0,
        max: 100,
        value: 52,
        options: {
            colors: ['Gradient(red:#f33:red)'],
            marginLeft: 35,
            marginRight: 35,
            tooltips: 'Todays temperature
%{key}', tooltipsFormattedKeyLabels: ['London'], tooltipsFormattedUnitsPost: 'c', tooltipsCss: { fontSize: '18pt', textAlign: 'left' } } }).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.

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

Background properties

Name: backgroundColor
Description: 
The default background color.
Default: white

Color properties

Name: colors
Description: 
An array of the colors of the bars.
Default: ['Gradient(#c00:red:#f66:#fcc)']
Name: colorsStroke
Description: 
The color of the border around the Thermometer.
Default: black

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
Name: titleSide
Description: 
This is the text that is used as the title on the left-hand-side of the Thermometer.
Default: An empty string
Name: titleSideFont
Description: 
The font that the title is rendered in.
Default: null
Name: titleSideSize
Description: 
The size of the title.
Default: null
Name: titleSideColor
Description: 
The color of the title.
Default: null
Name: titleSideBold
Description: 
Whether the title is bold or not.
Default: null
Name: titleSideItalic
Description: 
Whether the title is italic or not.
Default: null
Name: titleSideOffsetx
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: titleSideOffsety
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

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: 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: true
Name: textBold
Description: 
Whether text on the Thermometer chart is bold or not.
Default: false
Name: textItalic
Description: 
Whether text on the Thermometer chart is italic or not.
Default: false
Name: textFont
Description: 
The font used to render text on the Thermometer chart.
Default: Arial, Verdana, sans-serif
Name: textSize
Description: 
The size of text on the Thermometer chart.
Default: 12
Name: textColor
Description: 
The color of text on the Thermometer chart.
Default: black
Name: labelsValue
Description: 
This controls whether the Thermometer charts value is shown as a label.
Default: true
Name: labelsValueDecimals
Description: 
This controls how many decimals are shown if the value is being shown. It falls back to use scaleDecimals if this is not specified.
Default:  0
Name: labelsValuePoint
Description: 
The decimal point character. It falls back to use scalePoint if this is not specified.
Default: null
Name: labelsValueThousand
Description: 
The character that's used as the thousand separator. It falls back to use scaleThousand if this is not specified.
Default: null
Name: labelsValueUnitsPre
Description: 
Units that are prepended to the value. It falls back to use scaleUnitsPre if this is not specified.
Default: null
Name: labelsValueUnitsPost
Description: 
Units that are appended to the value. It falls back to use scaleUnitsPost if this is not specified.
Default: null
Name: labelsValueFont
Description: 
The font used to render the label. This defaults to the textFont setting.
Default: null
Name: labelsValueSize
Description: 
The size of the value label. This defaults to the textSize setting.
Default: null
Name: labelsValueColor
Description: 
The color of the value label. This defaults to the textColor setting.
Default: null
Name: labelsValueBold
Description: 
Whether the labelsValue label is bold or not. This falls back to the textBold setting.
Default: null
Name: labelsValueItalic
Description: 
Whether the labelsValue label is italic or not. This falls back to the textItalic setting.
Default: null
Name: labelsValueOffsetx
Description: 
This allows you finer-grained control in the horizontal direction over the text positioning if you need it.
Default:  0
Name: labelsValueOffsety
Description: 
This allows you finer-grained control in the vertical direction over the text positioning if you need it.
Default:  0
Name: labelsCount
Description: 
A value that controls how many scale labels there are. Keep in mind that if you use this it may result in decimals, and to see the full number you may need to use the scaleDecimals property.
Default: 5
Name: labelsFont
Description: 
The font used by the vertical labels.
Default: null
Name: labelsSize
Description: 
The size of the vertical labels.
Default: null
Name: labelsColor
Description: 
The color of the vertical labels.
Default: null
Name: labelsBold
Description: 
Whether the vertical labels are bold or not.
Default: null
Name: labelsItalic
Description: 
Whether the vertical labels are italic or not.
Default: null
Name: labelsDecimals
Description: 
How many decimals are displayed.
Default: null
Name: labelsUnitsPre
Description: 
Units that are prepended to the label.
Default: null
Name: labelsUnitsPost
Description: 
Units that are appended to the label.
Default: null
Name: labelsPoint
Description: 
The point character used by the labels.
Default: null
Name: labelsThousand
Description: 
The thousand character used by the labels.
Default: null
Name: labelsOffsetx
Description: 
This allows you finer-grained control in the horizontal direction over the text positioning if you need it.
Default:  0
Name: labelsOffsety
Description: 
This allows you finer-grained control in the vertical direction over the text positioning if you need it.
Default:  0
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

Shadow properties

Name: shadow
Description: 
Whether a drop shadow is applied.
Default: true
Name: shadowColor
Description: 
The color of the shadow.
Default: gray
Name: shadowOffsetx
Description: 
The horizontal offset of the shadow.
Default:  0
Name: shadowOffsety
Description: 
The vertical offset of the shadow.
Default:  0
Name: shadowBlur
Description: 
The severity of the shadow blurring effect.
Default: 15

Scale properties

Name: scaleVisible
Description: 
Defaulting to false, this controls whether the scale is visible.
Default: false
Name: scaleDecimals
Description: 
This allows you to control the number of decimals that the labels have.
Default:  0
Name: scalePoint
Description: 
The character that's used as the decimal point.
Default: .
Name: scaleThousand
Description: 
The character that's used as the thousand separator.
Default: ,
Name: scaleUnitsPre
Description: 
The units that the y-axis is measured in. This string is displayed before the number, allowing you to specify values such as $50.
Default: none
Name: scaleUnitsPost
Description: 
The units that the y-axis is measured in. This string is displayed after the number, allowing you to specify values such as 50ms.
Default: none

Interactive features properties

Name: adjustable
Description: 
Defaulting to false, this determines whether your bar chart will be adjustable.
Default: false
Name: tooltips
Description: 
A numerically indexed array of tooltips that are shown when a bar is clicked. These can contain html.
Default: null
Name: tooltipsHighlight
Description: 
Set this to false if you don't want your charts to be highlighted.
Default: true
Name: tooltipsEffect
Description: 
The effect used for showing tooltips. Possible values are slide fade or none.
Default: slide
Name: tooltipsEvent
Description: 
This is the event that triggers the tooltips. It can be either click or mousemove.
Default: onclick
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: tooltipsCssClass
Description: 
This is the name of the css class the chart uses.
Default: RGraph_tooltip
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
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 about 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

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: clearto
Description: 
This is used in animations and effects as the default color to use when clearing the canvas.
Default: null
Name: bulbBottomRadiusAdjust
Description: 
If you want to add or remove a little (or a lot) from the bottom bulb radius you use this (use negative numbers to subtract).
Default:  0
Name: bulbBottomRadius
Description: 
Use this property to set the bottom bulb radius.
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 X coordinate of the main body of the Thermometer.
y The Y coordinate of the main body of the Thermometer.
width The width of the main body of the Thermometer.
height The height of the main body of the Thermometer.
dataset As there's only ever one element on the Thermometer chart this is always zero.
index As there's only ever one element on the Thermometer chart this is always zero.
sequentialIndex As there's only ever one element on the Thermometer chart this is always zero.
tooltip If a tooltip is associated with the chart this will be it.id: strings are expanded for you (where the tooltip text is retrieved from the CHTML tag with the matching ID).
<script>
    thermometer.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 Thermometer chart. If you need to
            // highlight the whole of the Thermometer chart you can use the highlight
            // function: obj.highlight(shape)
            obj.path(
                'lw 10 b r % % % % s black f red',
                shape.x, shape.y, shape.width, shape.height
            );
        }
    }
</script>

obj.getValue(mixed)

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. Not simply the coordinates of the mouse. The argument can either be an event object (for use in event listener functions) OR a two-element array consisting of the X and Y coordinates (ie when you're not necessarily in an event listener). It returns null if the mouse or coordinates are in the margin areas. An example:

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

obj.getYCoord(value)

This method can be used to get an appropriate Y coordinate for a value when you're doing custom drawing on the chart. It returns null if the value is out of range.


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.Thermometer({
    id: 'cvs',
    min: 0,
    max: 100,
    value: 56,
    options: {
    }
}).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.

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

There's only one coordinates property with the Thermometer chart because there's only one selectable area - the vertical indicator bar. This doesn't include the round bell of the Thermometer 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.Thermometer({
    id: 'cvs',
    min: 0,
    max: 100,
    value: 56,
    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 that are 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.Thermometer({
        id: 'cvs',
        min: 0,
        max: 100,
        value: 56,
        options: {
            marginLeft: 35
        }
    }).grow({frames: 60}, myCallback)
</script>