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RGraph: HTML5 canvas graph library - Pie chart documentation

The pie chart can be used, for example, to represent something that is akin to percentages. ie A set of data that should be taken as part of a whole.

The example file is here. 

<script>
    window.onload = function ()
    {
        var data = [564,155,499,611,322];
    
        var pie = new RGraph.Pie('myPie', data);
        pie.Set('chart.labels', ['Abc', 'Def', 'Ghi', 'Jkl', 'Mno']);
        pie.Set('chart.linewidth', 5);
        pie.Set('chart.stroke', '#fff');
        pie.Draw();
    }
</script>

Properties

You can use these properties to control how the pie chart looks. You can set them by using the Set() method. Eg:

myPie.Set('name', 'value');

Chart configuration

chart.width
This controls the width of the graph. You can set this to (for example) 600 and have your canvas 650px wide giving an extra 50px for labels.
Default: null (By default the canvas width is used)

chart.height
This controls the height of the graph. You can set this to (for example) 250 and have your canvas 300px heigh giving an extra 50px for labels.
Default: null (By default the canvas height is used)

Margins

chart.gutter
The gutter of the graph (for text labels).
Default: 25

Colors

chart.colors
Colors to be used for the pie segments.
Default: ['rgb(255,0,0)', '#ddd', 'rgb(0,255,0)', 'rgb(0,0,255)', 'rgb(255,255,0)', 'rgb(0,255,255)', 'red', 'pink', 'black', 'white']

chart.strokestyle
The color of the seperating lines. By setting this to your background color, and setting the linewidth to approx. 5, it will make the pie chart look "exploded".
Default: #999

Labels and text

chart.text.size
The size of the text (in points).
Default: 10

chart.text.font
The font used to render the text.
Default: Verdana

chart.text.color
The color of the labels.
Default: black

chart.labels
An array of labels to be used for the chart.
Default: [] (an empty array)

chart.labels.sticks
Stipulates that small sticks for the labels are shown. The example page has an example of this.
Default: false

chart.labels.sticks.color
Sets the color of the label sticks.
Default: #aaa

Titles

chart.title
The title of the pie chart.
Default: none

chart.title.background
The background color (if any) for the title.
Default: null

chart.title.color
The color of the title.
Default: black

chart.title.hpos
This allows you to completely override the horizontal positioning of the title. It should be a number between 0 and 1, and is multiplied with the whole width of the canvas and then used as the horizontal position.
Default: null

chart.title.vpos
This allows you to completely override the vertical positioning of the title. It should be a number between 0 and 1, and is multiplied with the gutter and then used as the vertical position. It can be useful if you need to have a large gutter.
Default: null

Shadows

chart.shadow
Whether a simple shadow effect is applied.
Default: false

chart.shadow.color
The color of the shadow.
Default: rgba(0,0,0,0.5)

chart.shadow.blur
The severity of the shadow blurring effect.
Default: 3

chart.shadow.offsetx
The X offset of the shadow.
Default: 3

chart.shadow.offsety
The Y offset of the shadow.
Default: 3

Interactive features

chart.tooltips
An array of tooltips, starting from the middle right (ie east) axis, and going clockwise sequentially.
Default: [] (An empty array)

chart.tooltips.event
This can be onclick or onmousemove and determines which event is used for tooltips.
Default: onclick

chart.tooltips.effect
The animated effect used for showing tooltips. Can be either fade or expand.
Default: fade

chart.tooltips.css.class
This is the name of the CSS class the graph uses.
Default: RGraph_tooltip

chart.tooltips.override
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

chart.contextmenu
An array of context menu items. More information on context menus is here.
Default: [] (An empty array)

chart.annotatable
Whether annotations are enabled for the chart (ie you can draw on the chart interactively.
Default: false

chart.annotate.color
If you do not allow the use of the palette, then this will be the only colour allowed for annotations.
Default: black

chart.resizable
Defaulting to false, this determines whether your graph 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).
Default: false

chart.resize.handle.adjust
If you're right aligning your chart then you may need this to adjust the position of the resize handle.
Default: [0,0]

chart.resize.handle.background
With 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.
Default: null

Key

chart.key
An array of key information.
Default: [] (An empty array)

chart.key.background
The color of the key background. Typically white, you could set this to something like rgba(255,255,255,0.7) to allow people to see things behind it.
Default: white

chart.key.halign
Instead of specifying the exact x/y coordinates, you can use this property to simply specify whether the key hould be aligned left or right.
Default: right

chart.key.position
Determines the position of the key.Either graph (default), or gutter.
Default: graph

chart.key.position.x
This allows you to specify a specific X coordinate for the key.
Default: null

chart.key.position.y
This allows you to specify a specific Y coordinate for the key.
Default: null

chart.key.position.gutter.boxed
If you have the key in gutter mode (ie horizontal), this allows you to give a background color.
Default: true

chart.key.shadow
Whether a small drop shadow is applied to the key.
Default: false

chart.key.shadow.color
The color of the shadow.
Default: #666

chart.key.shadow.blur
The extent of the blurring effect used on the shadow.
Default: 3

chart.key.shadow.offsetx
The X offset of the shadow.
Default: 2

chart.key.shadow.offsety
The Y offset of the shadow.
Default: 2

chart.key.rounded
This controls whether the corners of the key (in graph mode) are curved. If the key is gutter mode, this has no effect.
Default: false

chart.key.color.shape
This can be square, circle or line and controls how the color indicators in the key appear.
Default: square

chart.key.linewidth
The line width of the surrounding border on the key.
Default: 1

Zoom

chart.zoom.mode
Can be used to control whether the zoom is in thumbnail or canvas mode. Possible values are: thumbnail and canvas.
Default: canvas

chart.zoom.factor
This is the factor that the graph will be zoomed by (bigger values means more zoom)
Default: 1.5

chart.zoom.fade.in
Whether the zoomed canvas fades in or not. This also can be used to control the fade in for the zoom in thumbnail mode.
Default: true

chart.zoom.fade.out
Whether the zoomed canvas fades out or not. This also can be used to control the fade in for the zoom in thumbnail mode.
Default: true

chart.zoom.hdir
The horizontal direction of the zoom. Possible values are: left, center, right
Default: right

chart.zoom.vdir
The vertical direction of the zoom. Possible values are: up, center, down
Default: down

chart.zoom.delay
The delay (in milliseconds) between frames.
Default: 50

chart.zoom.frames
The number of frames in the zoom animation.
Default: 10

chart.zoom.shadow
Whether or not the zoomed canvas has a shadow or not.
Default: true

chart.zoom.thumbnail.width
When the zoom is in thumbnail mode, this is the width (in pixels) of the thumbnail.
Default: 75

chart.zoom.thumbnail.height
When the zoom is in thumbnail mode, this is the height (in pixels) of the thumbnail.
Default: 75

chart.zoom.background
Defaulting to true, this determines whether the zoom has a dark, semi-opaque background that covers the entire web page.
Default: true

Scale

chart.units.pre
The units that the value is measured in. This string is displayed BEFORE the actual number, allowing you to specify values such as "$50" and is only used if chart.value.text is true.
Default: none

chart.units.post
The units that the value is measured in. This string is displayed AFTER the actual number, allowing you to specify values such as "50ms" and is only used if chart.value.text is true.
Default: none

Miscellaneous

chart.align
Whether to left, center or right align the pie chart.
Default: center

chart.linewidth
By setting this to roughly 5, and setting the strokestyle to the same colour as your background colour,you will get a segment separation effect.
Default: 1

chart.variant
This can be either pie (the default) or donut. Setting this to donut is how you get a donut chart.
Default: pie

chart.value.text
Set this to true if you want the value displayed in text beow the center of the pointer.
Default: false

chart.highlight.style
Can be either 2d or 3d and determines which style of segment highlighting is used in conjunction with tooltips.
Default: 2d

chart.highlight.style.2d.fill
When 2D highlighting for tooltips is used, this controls the color of the highlighting. The former name for this property was chart.highlight.style.2d.color.
Default: rgba(255,255,255,0.5)

chart.highlight.style.2d.stroke
When 2D highlighting for tooltips is used, this controls the stroke color of the highlighting.
Default: rgba(255,255,255,0)


 

Methods

obj.getSegment()

obj.getSegment() makes it easy to determine which segment of the Pie chart was clicked on. It provides: 
<script>
    RGraph.Register(myGraph);
    
    myGraph.canvas.onclick = function (e)
    {
        RGraph.FixEventObject(e);
        RGraph.Redraw();

        var canvas  = e.target;
        var context = canvas.getContext('2d');
        var obj     = canvas.__object__;
        var segment = obj.getSegment(e);
        
        if (segment) {
            context.fillStyle = 'rgba(255,255,255,0.5)';
            context.beginPath();
                
                // Angles are provided in degrees, so convert them to radians
                segment[3] /= 57.29;
                segment[4] /= 57.29;
            
                context.moveTo(segment[0], segment[1]);
                context.arc(segment[0], segment[1], segment[2], segment[3], segment[4], 0);
            context.stroke();
            context.fill();
            
            e.stopPropagation();
        }
    }
    
    window.onclick = function (e)
    {
        RGraph.Redraw();
    }
</script>
Important Note

This method was formerly a common object method, called RGraph.getSegment(e), but has now (6th March 2011) been moved to be part of the Pie chart object.