File: charts/js/CategoryImpl.js
/**
* Provides functionality for the handling of category axis data for a chart.
*
* @module charts
* @submodule axis-category-base
*/
var Y_Lang = Y.Lang;
/**
* CategoryImpl contains logic for managing category data. CategoryImpl is used by the following classes:
* <ul>
* <li>{{#crossLink "CategoryAxisBase"}}{{/crossLink}}</li>
* <li>{{#crossLink "CategoryAxis"}}{{/crossLink}}</li>
* </ul>
*
* @class CategoryImpl
* @constructor
* @submodule axis-category-base
*/
function CategoryImpl()
{
}
CategoryImpl.NAME = "categoryImpl";
CategoryImpl.ATTRS = {
/**
* Pattern used by the `labelFunction` to format a label. The default `labelFunction` values for
* `CategoryAxis` and `CategoryAxisBase` do not accept a format object. This value can be used by
* a custom method.
*
* @attribute labelFormat
* @type Object
*/
labelFormat: {
value: null
},
/**
* Determines whether and offset is automatically calculated for the edges of the axis.
*
* @attribute calculateEdgeOffset
* @type Boolean
*/
calculateEdgeOffset: {
value: true
}
/**
* Method used for formatting a label. This attribute allows for the default label formatting method to overridden.
* The method use would need to implement the arguments below and return a `String` or `HTMLElement`.
* <dl>
* <dt>val</dt><dd>Label to be formatted. (`String`)</dd>
* <dt>format</dt><dd>Template for formatting label. (optional)</dd>
* </dl>
*
* @attribute labelFunction
* @type Function
*/
};
CategoryImpl.prototype = {
/**
* Formats a label based on the axis type and optionally specified format.
*
* @method formatLabel
* @param {Object} value
* @return String
*/
formatLabel: function(val)
{
return val;
},
/**
* Object storing key data.
*
* @property _indices
* @private
*/
_indices: null,
/**
* Constant used to generate unique id.
*
* @property GUID
* @type String
* @private
*/
GUID: "yuicategoryaxis",
/**
* Type of data used in `Data`.
*
* @property _dataType
* @readOnly
* @private
*/
_type: "category",
/**
* Calculates the maximum and minimum values for the `Data`.
*
* @method _updateMinAndMax
* @private
*/
_updateMinAndMax: function()
{
this._dataMaximum = Math.max(this.get("data").length - 1, 0);
this._dataMinimum = 0;
},
/**
* Gets an array of values based on a key.
*
* @method _getKeyArray
* @param {String} key Value key associated with the data array.
* @param {Array} data Array in which the data resides.
* @return Array
* @private
*/
_getKeyArray: function(key, data)
{
var i = 0,
obj,
keyArr = [],
labels = [],
len = data.length;
if(!this._indices)
{
this._indices = {};
}
for(; i < len; ++i)
{
obj = data[i];
keyArr[i] = i;
labels[i] = obj[key];
}
this._indices[key] = keyArr;
return labels;
},
/**
* Returns an array of values based on an identifier key.
*
* @method getDataByKey
* @param {String} value value used to identify the array
* @return Array
*/
getDataByKey: function (value)
{
if(!this._indices)
{
this.get("keys");
}
var keys = this._indices;
if(keys && keys[value])
{
return keys[value];
}
return null;
},
/**
* Returns the total number of majorUnits that will appear on an axis.
*
* @method getTotalMajorUnits
* @param {Object} majorUnit Object containing properties related to the majorUnit.
* @param {Number} len Length of the axis.
* @return Number
*/
getTotalMajorUnits: function()
{
return this.get("data").length;
},
/**
* Returns a coordinate corresponding to a data values.
*
* @method _getCoordFromValue
* @param {Number} min The minimum for the axis.
* @param {Number} max The maximum for the axis.
* @param {Number} length The distance that the axis spans.
* @param {Number} dataValue A value used to ascertain the coordinate.
* @param {Number} offset Value in which to offset the coordinates.
* @param {Boolean} reverse Indicates whether the coordinates should start from
* the end of an axis. Only used in the numeric implementation.
* @return Number
* @private
*/
_getCoordFromValue: function(min, max, length, dataValue, offset)
{
var range,
multiplier,
valuecoord;
if(Y_Lang.isNumber(dataValue))
{
range = max - min;
multiplier = length/range;
valuecoord = (dataValue - min) * multiplier;
valuecoord = offset + valuecoord;
}
else
{
valuecoord = NaN;
}
return valuecoord;
},
/**
* Returns a value based of a key value and an index.
*
* @method getKeyValueAt
* @param {String} key value used to look up the correct array
* @param {Number} index within the array
* @return String
*/
getKeyValueAt: function(key, index)
{
var value = NaN,
keys = this.get("keys");
if(keys[key] && keys[key][index])
{
value = keys[key][index];
}
return value;
}
};
Y.CategoryImpl = CategoryImpl;