Bar chart API reference

Documentation about the Bar chart including information about all of the options that are available to you. The Bar chart is a very commonly used type of chart and is very versatile. As such there are lots of Bar chart demos available in the download that demonstrate what you can do with it.

Example

<script>
    // Some data that's to be shown on the bar chart. To show a stacked or grouped chart
    // each number should be an array of further numbers instead (as shown below).
    data = [280,45,133];
    
    // An example of the data used by stacked and grouped charts
    //data = [[1,5,6], [4,5,3], [7,8,9]]

    new RGraph.Bar({
        id: 'cvs',
        data: data,
        options: {
            xaxisLabels: ['Richard', 'Alex', 'Nick'],
            marginLeft: 45,
            backgroundGrid: true,
            colors: ['red']
        }
    }).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.

Background properties

PropertyDescriptionDefault
backgroundBarsCountThe number of background bars.5
backgroundBarsColor1The color of the background bars, (1 of 2). rgba(0,0,0,0)
backgroundBarsColor2The color of the background bars, (2 of 2). rgba(0,0,0,0)
backgroundGridWhether to show the background grid or not.true
backgroundGridColorThe color of the background grid.#ddd
backgroundGridHsizeThe horizontal background grid size.40
backgroundGridVsizeThe vertical background grid size.18
backgroundGridLinewidthThe width that the background grid lines are. Decimals (eg 0.5) are permitted.1
backgroundGridBorderDetermines whether a border line is drawn around the grid.true
backgroundGridHlinesDetermines whether to draw the horizontal grid lines.true
backgroundGridVlinesDetermines whether to draw the vertical grid lines.true
backgroundGridAutofitInstead of specifying a pixel width/height for the background grid, you can use autofit and specify how many horizontal and vertical lines you want.true
backgroundGridHlinesCountWhen using autofit this allows you to specify how many horizontal grid lines you want.5
backgroundGridVlinesCountWhen using autofit this allows you to specify how many vertical grid lines you want.20
backgroundGridAlignIf you want to have your grid lines line up with the labels (both X and Y axes), you can set this to true and RGraph will attempt to make the grid lines line up. If you have a hmargin set then the alignment will be thrown out.false
backgroundGridDottedIf you want to have your background grid dashed then set this to true.false
backgroundGridDashedIf you want to have your background grid dotted then set this to true. This takes precedence over dashed lines.false
backgroundHbarsAn array of information stipulating horizontal coloured bars. You can use these to indicate limits. Eg: myBar.set('hbars', [[75, 10, 'yellow'], [85, 15, 'red']]); This would give you two bars, one red and a lower yellow bar. The units correspond to your scale, and are the starting point and the height.null
backgroundImageIf you want to specify a background image to use on your chart, specify it with this property. If you use effects with a background image on your chart it may make the effect flicker. Using a background image with the ondraw event may mean that the event fires twice. There is a property that you can check though that is set when the image has loaded: obj.__rgraph_background_image_loaded__ Simply check this flag in your ondraw event. If it's true then the background image has loaded.null
backgroundImageStretchBy default your background image is stretched (if necessary) to cover the whole chart area (margins not included). If this is not what you want then set this property to false.true
backgroundImageXThe X position of the image. The coordinates are the top left corner of the image.null
backgroundImageYThe Y position of the image. The coordinates are the top left corner of the image.null
backgroundImageWThe width of the image. If you have a large canvas with many charts - you may need to specify this.null
backgroundImageHThe height of the image. If you have a large canvas with many charts - you may need to specify this.null
backgroundImageAlignInstead of specifying the coordinates of the image, you can instead simply align it top, bottom, left or right. Examples are:
  • top left
  • bottom right
  • bottom
  • right
null
backgroundImageAlphaThe alpha value (the opacity) of the image.1
backgroundColorIf you want to have a single background color for your chart you can use this. It doesn't cover the margins. If you want that then you can simply apply a CSS background color to the canvas tag.null

General axis properties

PropertyDescriptionDefault
axesTurns on/off the drawing of both of the axes.true
axesColorThe color of the axes.black
axesLinewidthThe linewidth of the axes.1

X axis properties

PropertyDescriptionDefault
xaxisWhether the X axis is drawn.true
xaxisPositionThe position of the X axis. This can be bottom, center or top.bottom
xaxisTickmarksLastWhen you're combining the Bar and Line charts, you may want to use this property to stop the end X tick from being drawn.false (the end tick IS drawn)
xaxisTickmarksCountThis controls the number of X tick marks on the X axis.null
xaxisLabelsAngleThe angle of the horizontal text labels (at the bottom of the chart). This can be from 90 to -90 degrees.0 (Horizontal)
xaxisLabelsAn array of the labels to be used on the chart.An empty array
xaxisLabelsSizeThe size of the text.null
xaxisLabelsFontWhich font is used to render the text.null
xaxisLabelsItalicWhether the labels are italic or not.null
xaxisLabelsBoldWhether the labels are bold or not.null
xaxisLabelsColorThe color of the labels.null
xaxisLabelsOffsetxThis allows you finer grained control in the horizontal direction over the X label positioning if you need it.0
xaxisLabelsOffsetyThis allows you finer grained control in the vertical direction over the X label positioning if you need it.0
xaxisTitleThis allows you to specify a title for the X axis.none
xaxisTitleSizeThis allows you to specify a size for the X axis title.null
xaxisTitleFontThis allows you to specify a font for the X axis title.null
xaxisTitleBoldThis controls whether the X axis title is bold or not.null
xaxisTitleItalicThis controls whether the X axis title is italic or not.null
xaxisTitleColorThis controls the color of the X axis title.null
xaxisTitleXBy giving this you can specifically set the X position of the X axis title.null
xaxisTitleYBy giving this you can specifically set the Y position of the X axis title.null
xaxisTitlePosThis is multiplied with the margin to give the position of the X axis title.0.25

Y axis properties

PropertyDescriptionDefault
yaxisWhether the Y axis is drawn.true
yaxisPositionSpecifies the Y axis position. Can be left or right.left
yaxisTickmarksCountThe number of Y tick marks.10
yaxisLabelsCan be true or false and determines whether the chart has Y axis labels.true
yaxisLabelsCountA value that controls how many Y labels there are. This value could formerly be either 1/3/5/10 however now it can be any number.5
yaxisLabelsSpecificYou can use this option to give your own Y labels (eg ['Low', 'Medium', 'High']. Note: Since March 2013 you may now need to add an extra (optionally) empty element to the array of labels to achieve your desired result.null
yaxisLabelsOffsetxThis allows you finer grained control in the horizontal direction over the Y label positioning if you need it.0
yaxisLabelsOffsetyThis allows you finer grained control in the vertical direction over the Y label positioning if you need it.0
yaxisLabelsFontThe font that's used by the Y axis labels.null
yaxisLabelsSizeThe size of the Y axis labels.null
yaxisLabelsColorThe color of the Y axis labels.null
yaxisLabelsBoldWhether the Y axis labels are bold or not.null
yaxisLabelsItalicWhether the Y axis labels are italic or not.null
yaxisTitleThis allows you to specify a title for the Y axis.none
yaxisTitleSizeThis allows you to specify a size for the Y axis title.null
yaxisTitleFontThis allows you to specify a font for the Y axis title.null
yaxisTitleBoldThis controls whether the Y axis title is bold or not.null
yaxisTitleColorThis controls what color the Y axis is.null
yaxisTitleItalicThis controls whether the Y axis is italic or not.null
yaxisTitlePosThis is multiplied with the margin to give the position of the Y axis title.0.25
yaxisTitleXBy giving this you can specifically set the X position of the Y axis title.null
yaxisTitleYBy giving this you can specifically set the Y position of the Y axis title.null
yaxisScaleUnitsPreThe units that the Y axis is measured in. This string is displayed BEFORE the actual number, allowing you to specify values such as "$50".none
yaxisScaleUnitsPostThe units that the Y axis is measured in. This string is displayed AFTER the actual number, allowing you to specify values such as "50ms".none
yaxisScaleMaxThe optional maximum Y scale value. If not specified then it will be calculated.null (It's calculated)
yaxisScaleMinThe optional minimum Y scale value. If not specified then it will be 0.0
yaxisScaleFormatterTo allow thoroughly custom formats of numbers in the scale, you can use this option to specify a function that is used by RGraph to format numbers. This function should handle ALL of the formatting. Eg:

function myFormatter(obj, num)
{
    return num + 'F'; // An example of formatting
}
myGraph.set('scale.formatter', myFormatter);
null
yaxisScaleRoundWhether to round the scale up. eg A maximum value of 59 results in scale to 100.false
yaxisScaleDecimalsThe number of decimal places to display for the Y scale.0
yaxisScalePointThe character used as the decimal point..
yaxisScaleThousandThe character used as the thousand separator.,
yaxisScaleZerostartWhether the scale starts at zero or not.true

Color properties

PropertyDescriptionDefault
colorsAn array of the colors of the bars.An array - ['rgb(0,0,255)', '#0f0', '#00f', '#ff0', '#0ff', '#0f0']
colorsStrokeThe color of the outline of the bars.rgba(0,0,0,0)
colorsSequentialIf true, for regular bar charts, (not stacked or grouped), the colors that you specify will be used in a sequential fashion.false

Margin properties

PropertyDescriptionDefault
hmarginThe horizontal margin (in pixels) of the chart. The horizontal margin is on the inside of the axes.5
hmarginGroupedIn a grouped bar chart this is the margin between bars that are on the same group. You can see examples of the hmargins in the examples folder of the download archive (eg the demos/bar-grouped2.html file).1
marginLeftThe left margin of the chart, (the margin is where the labels and title are)).25
marginRightThe right margin of the chart, (the margin is where the labels and title are).25
marginTopThe top margin of the chart, (the margin is where the labels and title are).25
marginBottomThe bottom margin of the chart, (the margin is where the labels and title are).25

Other label properties

PropertyDescriptionDefault
textAccessibleA 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>
true
textAccessibleOverflowThis 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.visible
textAccessiblePointereventsThis controls whether the DOM text responds to mouse based events or not (it sets the pointer-events CSS property to none).true
textFontThe font used to render the text.Arial, Verdana, sans-serif
textSizeThe size (in points) of the labels.12
textColorThe color of the labels.black
textBoldWhether the font used to render the text is bold or not.false
textItalicWhether the font used to render the text is italic or not.false
labelsAboveIf true, values will be shown above the bars. For regular and stacked bar charts units are included, whereas for grouped bar charts they're not (usually there isn't enough space for them).false
labelsAboveDecimalsThis stipulates how many decimals are used in the above bar labels.0
labelsAboveUnitsPreThe units to put on the above labels. These are positioned BEFORE the number.none
labelsAboveUnitsPostThe units to put on the above labels. These are positioned AFTER the number.none
labelsAbovePointThe character used as the labelsAbove decimal separator..
labelsAboveThousandThe character used as the labelsAbove thousand separator.,
labelsAboveBackgroundThe background-color of the labels above the bars.rgba(0,0,0,0)
labelsAboveSizeThe font size of the above bar labels. Useful if you only have a few bars.null
labelsAboveColorThe color of the labels above the bars.null
labelsAboveBoldWhether the labelsAbove labels are bold or not.null
labelsAboveItalicWhether the labelsAbove labels are italic or not.null
labelsAboveFontThe font face that is used to render the text.null
labelsAboveOffsetThe distance of the labels above the bars (in pixels).4
labelsAboveAngleYou can use this to angle the text shown above the bars. It can be anything from -90 to 90 (degrees).null
labelsAboveSpecificIf instead of the values you want to show arbitrary text - you can with this. It should be an arry of the labels to be shown.null
labelsIngraphAn array of labels for the chart which are drawn "inside" the chart. If you have 5 data points then this should have a corresponding number of elements, though there is a shorthand style available.null
labelsIngraphFontThe font that the ingraph labels are rendered in.null
labelsIngraphSizeThe size of the ingraph labels.null
labelsIngraphColorThe color of the ingraph labels.null
labelsIngraphBoldWhether the ingraph labels are bold or not.null
labelsIngraphItalicWhether the ingraph labels are italic or not.null

Title properties

PropertyDescriptionDefault
titleThe title of the chart, if any.null
titleFontThe font that the title is rendered in. If not specified the textFont setting is used (usually Arial).null
titleSizeThe size of the title. If not specified the size is usually 2pt bigger than the textSize setting.null
titleBoldWhether the title is bold or not.mull
titleItalicWhether the title is italic or not.null
titleColorThe color of the title.null
titleBackgroundThe background color (if any) for the title.null
titleXTo 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.null
titleYTo 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.null

Shadow properties

PropertyDescriptionDefault
shadowWhether a drop shadow is applied.false
shadowColorThe color of the shadow.#aaa
shadowOffsetxThe X offset of the shadow.0
shadowOffsetyThe Y offset of the shadow.0
shadowBlurThe severity of the shadow blurring effect.15

Key properties

The key properties are documented on the key documentation page.

Interactive features properties

PropertyDescriptionDefault
contextmenuAn array of context menu items. More information about context menus is here.[] (An empty array)
tooltipsA numerically indexed array of tooltips that are shown when a bar is clicked. These can contain HTML.null
tooltipsEffectThe effect used for showing tooltips. Can be either fade or none.fade
tooltipsEventThis is the event that triggers the tooltips. It can be either onclick or onmousemove.onclick
tooltipsCssClassThis is the name of the CSS class the chart uses.RGraph_tooltip
tooltipsOverrideIf you wish to handle showing tooltips yourself, this should be a function which does just that. There's more information on the tooltips documentation page.null
tooltipsHighlightSet this to false if you don't want your charts to be highlighted.true
tooltipsNohideonclearNot 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.false
tooltipsHotspotXonlyIf set to true the hotspot for the tooltips will ignore the height of the bar and extend from top margin down to the bottom margin. This can be useful when you have zero value bars but still want to see the tooltips.false
crosshairsIf true, you will get a crosshair centering on the current mouse position.false
crosshairsLinewidthThis controls the linewidth of the crosshairs.1
crosshairsColorThe color of the crosshairs.#333
crosshairsHlineThis determines whether the horizontal crosshair is shown.true
crosshairsVlineThis determines whether the vertical crosshair is shown.true
annotatableWhether annotations are enabled for the chart (ie you can draw on the chart interactively.false
annotatableColorIf you do not allow the use of the palette, then this will be the only colour allowed for annotations.black
annotatableLinewidthThis is the line width of the annotations.1
resizableDefaulting to false, this determines whether your chart will be resizable. Because of the numerous event handlers this has to install code on, This feature is unlikely to work with other dynamic features (the context menu is fine however).false
resizableHandleBackgroundWith this you can specify the background color for the resize handle. If you're adjusting the position of the handle then you may need this to make the handle stand out more.null
resizableMinwidthThis allows you to set a minimum width that the chart can be resized to.null
resizableMinheightThis allows you to set a minimum height that the chart can be resized to.null
resizableMaxwidthThis allows you to set a maximum width that the chart can be resized to.null
resizableMaxheightThis allows you to set a maximum height that the chart can be resized to.null
adjustableDefaulting to false, this determines whether your bar chart will be adjustable.false
adjustableOnlyThis should be an array of values that determine whether a Bar is adjustable or not. A truthy value for when it is, a falsey value for when it's not.null

Event properties

PropertyDescriptionDefault
eventsClickIf you want to add your own onclick function you can do so by assigning it to this property. See here for details.null
eventsMousemoveIf you want to add your own onmousemove function you can do so by assigning it to this property. See here for details.null
eventsMouseoverIf you want to add your own onmouseover function you can do so by assigning it to this property. See here for details.null
eventsMouseoutIf you want to add your own onmouseout function you can do so by assigning it to this property. See here for details.null

Miscellaneous properties

PropertyDescriptionDefault
highlightStyleBy 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.null
highlightStrokeIf you use tooltips, this controls the colour of the highlight stroke.black
highlightFillIf you use tooltips, this controls the colour of the highlight fill.rgba(255,255,255,0.5)
variantThis stipulates whether you want a regular bar chart or a 3D chart. In August 2015 the 3D variant has much improved perspective. Possible values are:
  • bar
  • 3d
bar
variantThreedOffsetxThis determines the size of the offset in the X direction.10
variantThreedOffsetyThis determines the size of the offset in the Y direction.5
variantThreedXaxisThis allows you to turn on/off the 3D X axis.true
variantThreedYaxisThis allows you to turn on/off the 3D Y axis.true
groupingHow the bars are grouped, and it should be one of: grouped or stacked.grouped
bevelledIf true the bars will be given a 3D bevelled appearance.false
cleartoThis is used in animations and effects as the default color to use when clearing the canvas.null
errorbarsThis should be an array of errorbar information or it can simply be a number instead (see below).false
errorbarsLinewidthThis is the linewidth of the errorbars.1
errorbarsColorThis is the color of the errorbars. You can also override the color in the errorbar array.black
errorbarsCappedThis dictates whether the errorbars have caps on their ends or not.true
errorbarsCappedWidthThis is the width of the caps (in total) on the end of the errorbar.14
combinedEffectSet this to the name of an effect (eg grow ) and the CombinedChart object will use that effect to draw the chart instead of the regular draw() function.null
combinedEffectOptionsThis should be a STRING that contains a JavaScript object of options for the effect function like this:
combinedchartEffectOptions: '{frames: 300}'
It has to be a string because of a quirk of the option parsing system.
null
combinedEffectCallbackA function that runs when this objects effect has completed.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 easier to get hold of which bar has been clicked on, or hovered over. It returns an array of:

The shape also includes textual indexes like this: shape['object'] And they are:

Example usage is:
<canvas id="cvs" width="600" height="250">[No canvas support]</canvas>

<script src="RGraph.common.core.js"></script>
<script src="RGraph.bar.js"></script>

<script>
    bar = new RGraph.Bar({
        id: 'cvs',
        data: [1.2, 1.3, 1.4, 1.5,6,1.9,2,2.1,2.5],
        options: {
            xaxisLabels: ['John', 'Barry', 'Rich', 'Craig', 'Tom', 'Frank', 'Helen', 'Joyce', 'Fred']
        }
    }).draw();
    
    bar.canvas.onclick = function (e)
    {
        RGraph.Redraw();
    
        var ca  = e.target;
        var co  = ca.getContext('2d');
        var obj = ca.__object__;
        var coords  = obj.getShape(e);
        
        if (coords) {
            var top    = coords[1];
            var left   = coords[2];
            var width  = coords[3];
            var height = coords[4];
            
            co.strokeStyle = 'black';
            co.fillStyle = 'rgba(255,255,255,0.5)';
            co.strokeRect(top, left, width, height);
            co.fillRect(top, left, width, height);
        }
    }
</script>
obj.getShapeByX(event)

This method is similar to the above, but only uses the X coordinate to determine the relevant bar.

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 in an event listener function). It returns null if the mouse or coordinates are in the margin areas. An example:

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

This method can be used to get a 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 in a similar way 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 exec option and method

The exec function is documented here.

Errorbars

Errorbars can allow you to show an upper and lower range for a particular bar like the examples/bar-errorbars.html example page in the download archive shows. You can specify errorbars like this:

var bar = new RGraph.Bar({
    id: 'cvs',
    data: [12,18,10,9,6,20,18],
    options: {
        xaxisLabels: ['Monday','Tuesday','Wednesday','Thursday','Friday','Saturday','Sunday'],
        shadow: false,
        colors: ['red'],
        colorsStroke: 'rgba(0,0,0,0)',
        errorbars: [ [5,3], [2,6], [5,15,'blue',5,45] ],
        errorbarsLinewidth: 2,   // The default linewidth
        errorbarsColor: 'gray',  // The default color
        errorbarsCapped: true,   // Whether the ends of the errorbar have terminating lines
        errorbarsCappedWidth: 14 // The default width of the caps
    }                
}).draw();

This would give you three errorbars and the elements of each errorbar array are (each one is optional):

Note about the data_arr array

Sometimes you may wish to view your data as one big array, instead of one array per dataset. In this case the obj.data_arr is available. This is one long array containing all of the individual data points.

Animation 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>
    /**
    * The optional callback function that's called when the effect is complete
    */
    function myCallback (obj)
    {
        // ...
    }

    var obj = new RGraph.Bar({
        id: 'cvs',
        data: [3,4,7,5,6,9,8],
        options: {
            marginLeft: 35,
            hmargin: 60
        }
    }).wave({frames: 60}, myCallback);
    // .grow({frames: 60}, myCallback);
</script>