Opendistrib/vendor/bower/chartjs/docs/01-Chart-Configuration.md

---

title: Chart Configuration

anchor: chart-configuration

Chart.js provides a number of options for changing the behaviour of created charts. These configuration options can be changed on a per chart basis by passing in an options object when creating the chart. Alternatively, the global configuration can be changed which will be used by all charts created after that point.

Creating a Chart with Options

To create a chart with configuration options, simply pass an object containing your configuration to the constructor. In the example below, a line chart is created and configured to not be responsive.

var chartInstance = new Chart(ctx, {
    type: 'line',
    data: data,
    options: {
        responsive: false
    }
});

Global Configuration

This concept was introduced in Chart.js 1.0 to keep configuration DRY, and allow for changing options globally across chart types, avoiding the need to specify options for each instance, or the default for a particular chart type.

Chart.js merges the options object passed to the chart with the global configuration using chart type defaults and scales defaults appropriately. This way you can be as specific as you would like in your individual chart configuration, while still changing the defaults for all chart types where applicable. The global general options are defined in Chart.defaults.global. The defaults for each chart type are discussed in the documentation for that chart type.

The following example would set the hover mode to ‘single’ for all charts where this was not overridden by the chart type defaults or the options passed to the constructor on creation.

Chart.defaults.global.hover.mode = 'single';

// Hover mode is set to single because it was not overridden here
var chartInstanceHoverModeSingle = new Chart(ctx, {
    type: 'line',
    data: data,
});

// This chart would have the hover mode that was passed in
var chartInstanceDifferentHoverMode = new Chart(ctx, {
    type: 'line',
    data: data,
    options: {
        hover: {
            // Overrides the global setting
            mode: 'label'
        }
    }
})

Global Font Settings

There are 4 special global settings that can change all of the fonts on the chart. These options are in Chart.defaults.global.

Name	Type	Default	Description
defaultFontColor	Color	’#666’	Default font color for all text
defaultFontFamily	String	”‘Helvetica Neue’, ‘Helvetica’, ‘Arial’, sans-serif”	Default font family for all text
defaultFontSize	Number	12	Default font size (in px) for text. Does not apply to radialLinear scale point labels
defaultFontStyle	String	‘normal’	Default font style. Does not apply to tooltip title or footer. Does not apply to chart title

Common Chart Configuration

The following options are applicable to all charts. The can be set on the global configuration, or they can be passed to the chart constructor.

Name	Type	Default	Description
responsive	Boolean	true	Resizes when the canvas container does.
responsiveAnimationDuration	Number	0	Duration in milliseconds it takes to animate to new size after a resize event.
maintainAspectRatio	Boolean	true	Maintain the original canvas aspect ratio (width / height) when resizing
events	Array[String]	["mousemove", "mouseout", "click", "touchstart", "touchmove", "touchend"]	Events that the chart should listen to for tooltips and hovering
onClick	Function	null	Called if the event is of type ‘mouseup’ or ‘click’. Called in the context of the chart and passed an array of active elements
legendCallback	Function	function (chart) { }	Function to generate a legend. Receives the chart object to generate a legend from. Default implementation returns an HTML string.
onResize	Function	null	Called when a resize occurs. Gets passed two arguemnts: the chart instance and the new size.

Title Configuration

The title configuration is passed into the options.title namespace. The global options for the chart title is defined in Chart.defaults.global.title.

Name	Type	Default	Description
display	Boolean	false	Display the title block
position	String	‘top’	Position of the title. Only ‘top’ or ‘bottom’ are currently allowed
fullWidth	Boolean	true	Marks that this box should take the full width of the canvas (pushing down other boxes)
fontSize	Number	12	Font size inherited from global configuration
fontFamily	String	”‘Helvetica Neue’, ‘Helvetica’, ‘Arial’, sans-serif”	Font family inherited from global configuration
fontColor	Color	”#666”	Font color inherited from global configuration
fontStyle	String	‘bold’	Font styling of the title.
padding	Number	10	Number of pixels to add above and below the title text
text	String	“	Title text

Example Usage

The example below would enable a title of ‘Custom Chart Title’ on the chart that is created.

var chartInstance = new Chart(ctx, {
    type: 'line',
    data: data,
    options: {
        title: {
            display: true,
            text: 'Custom Chart Title'
        }
    }
})

Legend Configuration

The legend configuration is passed into the options.legend namespace. The global options for the chart legend is defined in Chart.defaults.global.legend.

Name	Type	Default	Description
display	Boolean	true	Is the legend displayed
position	String	‘top’	Position of the legend. Options are ‘top’ or ‘bottom’
fullWidth	Boolean	true	Marks that this box should take the full width of the canvas (pushing down other boxes)
onClick	Function	function(event, legendItem) {}	A callback that is called when a click is registered on top of a label item
labels	Object	-	See the Legend Label Configuration section below.

Legend Label Configuration

The legend label configuration is nested below the legend configuration using the labels key.

Name	Type	Default	Description
boxWidth	Number	40	Width of coloured box
fontSize	Number	12	Font size inherited from global configuration
fontStyle	String	“normal”	Font style inherited from global configuration
fontColor	Color	”#666”	Font color inherited from global configuration
fontFamily	String	”‘Helvetica Neue’, ‘Helvetica’, ‘Arial’, sans-serif”	Font family inherited from global configuration
padding	Number	10	Padding between rows of colored boxes
generateLabels:	Function	function(chart) { }	Generates legend items for each thing in the legend. Default implementation returns the text + styling for the color box. See Legend Item for details.

Legend Item Interface

Items passed to the legend onClick function are the ones returned from labels.generateLabels. These items must implement the following interface.

{
    // Label that will be displayed
    text: String,

    // Fill style of the legend box
    fillStyle: Color,

    // If true, this item represents a hidden dataset. Label will be rendered with a strike-through effect
    hidden: Boolean,

    // For box border. See https://developer.mozilla.org/en/docs/Web/API/CanvasRenderingContext2D/lineCap
    lineCap: String,

    // For box border. See https://developer.mozilla.org/en-US/docs/Web/API/CanvasRenderingContext2D/setLineDash
    lineDash: Array[Number],

    // For box border. See https://developer.mozilla.org/en-US/docs/Web/API/CanvasRenderingContext2D/lineDashOffset
    lineDashOffset: Number,

    // For box border. See https://developer.mozilla.org/en-US/docs/Web/API/CanvasRenderingContext2D/lineJoin
    lineJoin: String,

    // Width of box border 
    lineWidth: Number,

    // Stroke style of the legend box
    strokeStyle: Color
}

Example

The following example will create a chart with the legend enabled and turn all of the text red in color.

var chartInstance = new Chart(ctx, {
    type: 'bar',
    data: data,
    options: {
        legend: {
            display: true,
            labels: {
                fontColor: 'rgb(255, 99, 132)'
            }
        }
    }
});

Tooltip Configuration

The title configuration is passed into the options.tooltips namespace. The global options for the chart tooltips is defined in Chart.defaults.global.tooltips.

Name	Type	Default	Description
enabled	Boolean	true	Are tooltips
custom	Function	null	See section below
mode	String	‘single’	Sets which elements appear in the tooltip. Acceptable options are 'single' or 'label'. single highlights the closest element. label highlights elements in all datasets at the same X value.
itemSort	Function	undefined	Allows sorting of tooltip items. Must implement a function that can be passed to Array.prototype.sort
backgroundColor	Color	‘rgba(0,0,0,0.8)’	Background color of the tooltip
titleFontFamily	String	”‘Helvetica Neue’, ‘Helvetica’, ‘Arial’, sans-serif”	Font family for tooltip title inherited from global font family
titleFontSize	Number	12	Font size for tooltip title inherited from global font size
titleFontStyle	String	“bold”
titleFontColor	Color	”#fff”	Font color for tooltip title
titleSpacing	Number	2	Spacing to add to top and bottom of each title line.
titleMarginBottom	Number	6	Margin to add on bottom of title section
bodyFontFamily	String	”‘Helvetica Neue’, ‘Helvetica’, ‘Arial’, sans-serif”	Font family for tooltip items inherited from global font family
bodyFontSize	Number	12	Font size for tooltip items inherited from global font size
bodyFontStyle	String	“normal”
bodyFontColor	Color	”#fff”	Font color for tooltip items.
bodySpacing	Number	2	Spacing to add to top and bottom of each tooltip item
footerFontFamily	String	”‘Helvetica Neue’, ‘Helvetica’, ‘Arial’, sans-serif”	Font family for tooltip footer inherited from global font family.
footerFontSize	Number	12	Font size for tooltip footer inherited from global font size.
footerFontStyle	String	“bold”	Font style for tooltip footer.
footerFontColor	Color	”#fff”	Font color for tooltip footer.
footerSpacing	Number	2	Spacing to add to top and bottom of each footer line.
footerMarginTop	Number	6	Margin to add before drawing the footer
xPadding	Number	6	Padding to add on left and right of tooltip
yPadding	Number	6	Padding to add on top and bottom of tooltip
caretSize	Number	5	Size, in px, of the tooltip arrow
cornerRadius	Number	6	Radius of tooltip corner curves
multiKeyBackground	Color	”#fff”	Color to draw behind the colored boxes when multiple items are in the tooltip
callbacks	Object		See the callbacks section below

Tooltip Callbacks

The tooltip label configuration is nested below the tooltip configuration using the callbacks key. The tooltip has the following callbacks for providing text. For all functions, ‘this’ will be the tooltip object created from the Chart.Tooltip constructor.

All functions are called with the same arguments: a tooltip item and the data object passed to the chart. All functions must return either a string or an array of strings. Arrays of strings are treated as multiple lines of text.

Callback	Arguments	Description
beforeTitle	Array[tooltipItem], data	Text to render before the title
title	Array[tooltipItem], data	Text to render as the title
afterTitle	Array[tooltipItem], data	Text to render after the title
beforeBody	Array[tooltipItem], data	Text to render before the body section
beforeLabel	tooltipItem, data	Text to render before an individual label
label	tooltipItem, data	Text to render for an individual item in the tooltip
labelColor	tooltipItem, chartInstace	Returns the colors to render for the tooltip item. Return as an object containing two parameters: borderColor and backgroundColor.
afterLabel	tooltipItem, data	Text to render after an individual label
afterBody	Array[tooltipItem], data	Text to render after the body section
beforeFooter	Array[tooltipItem], data	Text to render before the footer section
footer	Array[tooltipItem], data	Text to render as the footer
afterFooter	Array[tooltipItem], data	Text to render after the footer section

Tooltip Item Interface

The tooltip items passed to the tooltip callbacks implement the following interface.

{
    // X Value of the tooltip as a string
    xLabel: String,

    // Y value of the tooltip as a string
    yLabel: String,

    // Index of the dataset the item comes from
    datasetIndex: Number,

    // Index of this data item in the dataset
    index: Number
}

Hover Configuration

The hover configuration is passed into the options.hover namespace. The global hover configuration is at Chart.defaults.global.hover.

Name	Type	Default	Description
mode	String	‘single’	Sets which elements hover. Acceptable options are 'single', 'label', or 'dataset'. single highlights the closest element. label highlights elements in all datasets at the same X value. dataset highlights the closest dataset.
animationDuration	Number	400	Duration in milliseconds it takes to animate hover style changes
onHover	Function	null	Called when any of the events fire. Called in the context of the chart and passed an array of active elements (bars, points, etc)

Animation Configuration

The following animation options are available. The global options for are defined in Chart.defaults.global.animation.

Name	Type	Default	Description
duration	Number	1000	The number of milliseconds an animation takes.
easing	String	“easeOutQuart”	Easing function to use.
onProgress	Function	none	Callback called on each step of an animation. Passed a single argument, an object, containing the chart instance and an object with details of the animation.
onComplete	Function	none	Callback called at the end of an animation. Passed the same arguments as onProgress

Animation Callbacks

The onProgress and onComplete callbacks are useful for synchronizing an external draw to the chart animation. The callback is passed an object that implements the following interface. An example usage of these callbacks can be found on Github. This sample displays a progress bar showing how far along the animation is.

{
    // Chart object
    chartInstance,

    // Contains details of the on-going animation
    animationObject,
}

Animation Object

The animation object passed to the callbacks is of type Chart.Animation. The object has the following parameters.

{
    // Current Animation frame number
    currentStep: Number,

    // Number of animation frames
    numSteps: Number,

    // Animation easing to use
    easing: String,

    // Function that renders the chart
    render: Function,

    // User callback
    onAnimationProgress: Function,

    // User callback
    onAnimationComplete: Function
}

Element Configuration

The global options for elements are defined in Chart.defaults.global.elements.

Options can be configured for four different types of elements; arc, lines, points, and rectangles. When set, these options apply to all objects of that type unless specifically overridden by the configuration attached to a dataset.

Arc Configuration

Arcs are used in the polar area, doughnut and pie charts. They can be configured with the following options. The global arc options are stored in Chart.defaults.global.elements.arc.

Name	Type	Default	Description
backgroundColor	Color	‘rgba(0,0,0,0.1)’	Default fill color for arcs. Inherited from the global default
borderColor	Color	’#fff’	Default stroke color for arcs
borderWidth	Number	2	Default stroke width for arcs

Line Configuration

Line elements are used to represent the line in a line chart. The global line options are stored in Chart.defaults.global.elements.line.

Name	Type	Default	Description
tension	Number	0.4	Default bezier curve tension. Set to 0 for no bezier curves.
backgroundColor	Color	‘rgba(0,0,0,0.1)’	Default line fill color
borderWidth	Number	3	Default line stroke width
borderColor	Color	‘rgba(0,0,0,0.1)’	Default line stroke color
borderCapStyle	String	‘butt’	Default line cap style. See MDN
borderDash	Array	[]	Default line dash. See MDN
borderDashOffset	Number	0.0	Default line dash offset. See MDN
borderJoinStyle	String	‘miter’	Default line join style. See MDN
fill	Boolean	true	If true, the line is filled.

Point Configuration

Point elements are used to represent the points in a line chart or a bubble chart. The global point options are stored in Chart.defaults.global.elements.point.

Name	Type	Default	Description
radius	Number	3	Default point radius
pointStyle	String	‘circle’	Default point style
backgroundColor	Color	‘rgba(0,0,0,0.1)’	Default point fill color
borderWidth	Number	1	Default point stroke width
borderColor	Color	‘rgba(0,0,0,0.1)’	Default point stroke color
hitRadius	Number	1	Extra radius added to point radius for hit detection
hoverRadius	Number	4	Default point radius when hovered
hoverBorderWidth	Number	1	Default stroke width when hovered

Rectangle Configuration

Rectangle elements are used to represent the bars in a bar chart. The global rectangle options are stored in Chart.defaults.global.elements.rectange.

Name	Type	Default	Description
backgroundColor	Color	‘rgba(0,0,0,0.1)’	Default bar fill color
borderWidth	Number	0	Default bar stroke width
borderColor	Color	‘rgba(0,0,0,0.1)’	Default bar stroke color
borderSkipped	String	‘bottom’	Default skipped (excluded) border for rectangle. Can be one of bottom, left, top, right

Colors

When supplying colors to Chart options, you can use a number of formats. You can specify the color as a string in hexadecimal, RGB, or HSL notations. If a color is needed, but not specified, Chart.js will use the global default color. This color is stored at Chart.defaults.global.defaultColor. It is initially set to ‘rgb(0, 0, 0, 0.1)’;

You can also pass a CanvasGradient object. You will need to create this before passing to the chart, but using it you can achieve some interesting effects.

The final option is to pass a CanvasPattern object. For example, if you wanted to fill a dataset with a pattern from an image you could do the following.

var img = new Image();
img.src = 'https://example.com/my_image.png';
img.onload = function() {
    var ctx = document.getElementById('canvas').getContext('2d');
    var fillPattern = ctx.createPattern(img, 'repeat');

    var chart = new Chart(ctx, {
        data: {
            labels: ['Item 1', 'Item 2', 'Item 3'],
            datasets: [{
                data: [10, 20, 30],
                backgroundColor: fillPattern
            }]
        }
    })
}