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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
- Methods

## 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');

- Margins
- Colors
- Labels and text
- Titles
- Shadows
- Interactive features
- Key
- Zoom
- Scale
- Miscellaneous

### 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.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.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

### Key

chart.key
An array of strings used as the key for the chart. This can be used in place of labels if you prefer.
Default: null (ie no key is drawn)
chart.key.background
The background color of the key.
Default: white
chart.key.shadow
Whether the key casts a drop shadow.
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

### 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

## Methods

RGraph.getSegment()
RGraph.getSegment() makes it easy to determine which segment of the Pie chart was clicked on. It provides:

- Originating X coordinate
- Originating Y coordinate
- The radius of the segment
- The starting angle (in degrees)
- The ending angle (in degrees)

    <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 = RGraph.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>