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# RGraph: HTML5 canvas graph library - Bar chart documentation

The bar graph, along with the line chart, is probably the most configurable of all the charts available, simply because it's more common.

The example file is here.

- Properties
- Methods

    <script>
        window.onload = function ()
        {
            var data = [280,45,133,166,84,259,266,960,219,311];

            var bar = new RGraph.Bar('myCanvas', data);
            bar.Set('chart.labels', ['Richard', 'Alex', 'Nick', 'Scott', 'Kjnell', 'Doug', 'Charles', 'Michelle', 'Mark', 'Alison']);
            bar.Set('chart.gutter', 45);
            bar.Set('chart.background.barcolor1', 'rgba(255,255,255,1)');
            bar.Set('chart.background.barcolor2', 'rgba(255,255,255,1)');
            bar.Set('chart.background.grid', true);
            bar.Set('chart.colors', ['rgba(255,0,0,1)']);
            bar.Draw();
        }
    </script>

## Properties

You can use these properties to control how the bar graph apears. You can set them by using the Set() method. Eg:

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

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

### Background

chart.background.barcolor1
The color of the background bars, (1 of 2).
Default: white
chart.background.barcolor2
The color of the background bars, (2 of 2).
Default: white
chart.background.grid
Whether to show the background grid or not.
Default: true
chart.background.grid.color
The color of the background grid.
Default: #ddd
chart.background.grid.hsize
The horizontal background grid size.
Default: 40
chart.background.grid.vsize
The vertical background grid size.
Default: 18
chart.background.grid.width
The width that the background grid lines are. Decimals (eg 0.5) are permitted.
Default: 1
chart.background.grid.border
Determines whether a border line is drawn around the grid.
Default: true
chart.background.grid.hlines
Determines whether to draw the horizontal grid lines.
Default: true
chart.background.grid.vlines
Determines whether to draw the vertical grid lines.
Default: true
chart.background.grid.autofit
Instead of specifying a pixel width/height for the background grid, you can use autofit and specify how many horizontal and vertical lines you want.
Default: false
chart.background.grid.autofit.numhlines
When using autofit this allows you to specify how many horizontal grid lines you want.
Default: 7
chart.background.grid.autofit.numvlines
When using autofit this allows you to specify how many vertical grid lines you want.
Default: 20
chart.background.hbars
An 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.
Default: null

### Colors

chart.strokecolor
The color of the outline of the bars.
Default: #666
chart.colors
An array of the colors of the actual bars.
Default: An array - ['rgb(0,0,255)', '#0f0', '#00f', '#ff0', '#0ff', '#0f0']

### Margins

chart.hmargin
The horizontal margin (in pixels) of the graph.
Default: 5
chart.gutter
The gutter of the graph. This is the area outside of the X and Y axis - where the labels go. If you're short on space for your labels, try increasing this.
Default: 25

### Labels and text

chart.text.color
The color of the labels.
Default: black
chart.text.size
The size (in points) of the labels.
Default: 10
chart.text.angle
The angle of the horizontal text labels (at the bottom of the graph). This can be one of three values - 0, 45 or 90.
Default: 0 (Horizontal)
chart.text.font
The font used to render the text.
Default: Verdana
chart.labels
An array of the labels to be used on the graph.
Default: An empty array
chart.labels.above
If 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).
Default: false
chart.labels.above.decimals
This stipulates how many decimals are used in the above bar labels.
Default: 0
chart.labels.above.size
The font size of the above bar labels. Useful if you only have a few bars.
Default: false
chart.labels.ingraph
An array of labels for the graph which are drawn "inside" the graph. If you have 5 data points then this should have a corresponding number of elements, though there is a shorthand available.
Default: null
chart.ylabels
Can be true or false and determines whether the chart has Y axis labels.
Default: true
chart.ylabels.count
A value that controls how many Y labels there are. Previously (prior to 8th August 2010) this could be 1,3,5. Now it can be any number, but keep in mind that if you use this it may result in decimals.
Default: 5
chart.xlabels.offset
This allows you finer grained control over the X label positioning if you need it.
Default: 0
chart.numyticks
The number of Y tickmarks. If you have changed the number of Y labels, you may also want to change this to match.
Default: 10

### Titles

chart.title
The title of the graph, if any.
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
chart.title.xaxis
This allows to specify a title for the X axis.
Default: none
chart.title.yaxis
This allows to specify a title for the Y axis.
Default: none
chart.title.xaxis.pos
This is multiplied with the gutter to give the position of the X axis title.
Default: 0.25
chart.title.yaxis.pos
This is multiplied with the gutter to give the position of the Y axis title.
Default: 0.25

### Shadow

chart.shadow
Whether a drop shadow is applied.
Default: false
chart.shadow.color
The color of the shadow.
Default: #666
chart.shadow.offsetx
The X offset of the shadow.
Default: 3
chart.shadow.offsety
The Y offset of the shadow.
Default: 3
chart.shadow.blur
The severity of the shadow blurring effect.
Default: 3

### Scale

chart.scale.decimals
The number of decimal places to display for the Y scale.
Default: 0
chart.scale.point
The character used as the decimal point.
Default: .
chart.scale.round
Whether to round the maximum scale value up or not. This will produce slightly better scales in some instances.
Default: null
chart.units.pre
The units that the Y axis is measured in. This string is displayed BEFORE the actual number, allowing you to specify values such as "$50".
Default: none
chart.units.post
The units that the Y axis is measured in. This string is displayed AFTER the actual number, allowing you to specify values such as "50ms".
Default: none
chart.ymax
The optional maximum Y scale value. If not specified then it will be calculated.
Default: null (It's calculated)

### Key

chart.key
An array of key information.
Default: [] (An empty array)
chart.key.background
The colour 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.position
Determines the position of the key.Either graph (default), or gutter.
Default: graph
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

### Interactive features

chart.contextmenu
An array of context menu items. More information on context menus is here.
Default: [] (An empty array)
chart.tooltips
A numerically indexed array of tooltips that are shown when a bar is clicked. These can contain HTML.
Default: null
chart.tooltips.effect
The animated effect used for showing tooltips. Can be either fade or expand.
Default: fade
chart.tooltips.event
This is the event that triggers the tooltips. It can be either onclick or onmousemove.
Default: onclick
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.tooltips.coords.adjust
When you translate (to make the best use of space for example) this allows you to adjust the tooltip coordinates accordingly.
Default: [0,0]
chart.crosshairs
If true, you will get a crosshair centering on the current mouse position.
Default: false
chart.crosshairs.linewidth
This controls the linewidth of the crosshairs.
Default: 1
chart.crosshairs.color
The color of the crosshairs.
Default: #333
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.adjustable
Defaulting to false, this determines whether your bar chart will be adjustable.
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

### Miscellaneous

chart.line
Formerly a boolean, this now stipulates a line graph object which is to be drawn on top of the bar chart. You can see an example here.
Default: null
chart.variant
This simply stipulates whether you want a regular bar chart, a dot chart, a pyramid chart a 3D chart, a sketch or a glassy chart. Possible values are:

- bar
- dot
- pyramid
- arrow
- 3d
- sketch
- glass

The pyramid, dot, arrow, sketch and glass variants are only effective for regular bar charts - not grouped or stacked charts.
Default: bar
chart.xaxispos
The position of the X axis. This can be bottom or center.
Default: bottom
chart.axis.color
The color of the axes.
Default: black
chart.grouping
How the bars are grouped, and it should be one of: grouped or stacked
Default: grouped

## Methods

obj.getBar()
This method makes it easier to get hold of which bar has been clicked on, or hovered over. It returns an array of:

- The graph object
- The X coordinate
- The Y coordinate
- The width of the bar
- The height of the bar
- The numerical index of the bar. This corresponds (for example) to the tooltips array, and the coordinates array

An 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>
        myGraph = new RGraph.Bar('myCanvas', [1.2, 1.3, 1.4, 1.5,6,1.9,2,2.1,2.5]);
        myGraph.Set('chart.labels', ['John', 'Barry', 'Rich', 'Craig', 'Tom', 'Frank', 'Helen', 'Joyce', 'Fred'])
        myGraph.Draw();

        RGraph.Register(myGraph);

        myGraph.canvas.onclick = function (e)
        {
            RGraph.Redraw();

            var canvas  = e.target;
            var context = canvas.getContext('2d');
            var obj     = canvas.__object__;
            var coords  = obj.getBar(e);

            if (coords) {
                var top    = coords[1];
                var left   = coords[2];
                var width  = coords[3];
                var height = coords[4];

                context.beginPath();
                    context.strokeStyle = 'black';
                    context.fillStyle = 'rgba(255,255,255,0.5)';
                    context.strokeRect(top, left, width, height);
                    context.fillRect(top, left, width, height);
                context.stroke();
                context.fill();
            }
        }
    </script>