The CategoryAxis class lets charts represent data
grouped by a set of discrete values along an axis.
You typically use the CategoryAxis class to define
a set of labels that appear along an axis of a chart.
For example, charts that render data according to City,
Year, Business unit, and so on.
You are not required to explicitly set the dataProvider property
on a CategoryAxis. A CategoryAxis used in a chart inherits its
dataProvider property from the containing chart.
While you can use the same data provider to provide data
to the chart and categories to the CategoryAxis, a CategoryAxis
can optimize rendering if its data provider is relatively static.
If possible, ensure that the categories are relatively static
and that changing data is stored in separate data providers.
The dataProvider property can accept
either an array of strings or an array of records (Objects)
with a property that specifies the category name.
If you specify a categoryField property,
the CategoryAxis assumes that the data provider is an array of Objects.
If the value of the categoryField property is null,
the CategoryAxis assumes that the data provider is an array of Strings.
Specifies a method that returns the value that should be used as
categoryValue for current item.If this property is set, the return
value of the custom data function takes precedence over
categoryField
The custom dataFunction has the following signature:
function_name (axis:CategoryAxis, item:Object):Object { ...
The baseline position for the axis.
Some series, such as ColumnSeries or AreaSeries, use this value to
define the base of a filled region when no minimum value is specified.
Implementation public function get baseline():Number
categoryField
property
categoryField:String
Language Version :
ActionScript 3.0
Product Version :
Flex 3
Runtime Versions :
Flash Player 9, AIR 1.1
Specifies the field of the data provider
containing the text for the labels.
If this property is null, CategoryAxis assumes
that the dataProvider contains an array of Strings.
The default value is null.
Implementation public function get categoryField():String public function set categoryField(value:String):void
dataFunction
property
dataFunction:Function
Language Version :
ActionScript 3.0
Product Version :
Flex 3
Runtime Versions :
Flash Player 9, AIR 1.1
Specifies a method that returns the value that should be used as
categoryValue for current item.If this property is set, the return
value of the custom data function takes precedence over
categoryField
The custom dataFunction has the following signature:
axis is the current axis that uses this dataFunctionitem is the item in the dataProvider that is considered.
This function returns an object.
An example usage of a customized dataFunction is to return a value
from a dataProvider that has items with nested fields
Implementation public function get dataFunction():Function public function set dataFunction(value:Function):void
Example
public function myFunction(axis:CategoryAxis,item:Object):Object {
return(item.Country.State);
}
dataProvider
property
dataProvider:Object
Language Version :
ActionScript 3.0
Product Version :
Flex 3
Runtime Versions :
Flash Player 9, AIR 1.1
Specifies the data source containing the label names.
The dataProvider can be an Array of Strings, an Array of Objects,
or any object that implements the IList or ICollectionView interface.
If the dataProvider is an Array of Strings,
ensure that the categoryField property
is set to null.
If the dataProvider is an Array of Objects,
set the categoryField property
to the name of the field that contains the label text.
Implementation public function get dataProvider():Object public function set dataProvider(value:Object):void
labelFunction
property
labelFunction:Function
Language Version :
ActionScript 3.0
Product Version :
Flex 3
Runtime Versions :
Flash Player 9, AIR 1.1
Specifies a function that defines the labels that are generated
for each item in the CategoryAxis's dataProvider.
If no labelFunction is provided,
the axis labels default to the value of the category itself.
The labelFunction method for a CategoryAxis
has the following signature:
function function_name(categoryValue:Object, previousCategoryValue:Object, axis:CategoryAxis, categoryItem:Object):String { ... }
Where:
categoryValue is the value of the category to be represented.
previousCategoryValue is the value of the previous category on the axis.
axis is the CategoryAxis being rendered.
categoryItem is the item from the dataProvider
that is being represented.
Flex displays the returned String as the axis label.
If the categoryField property is not set, the value
will be the same as the categoryValue property.
Implementation public function get labelFunction():Function public function set labelFunction(value:Function):void
padding
property
padding:Number
Language Version :
ActionScript 3.0
Product Version :
Flex 3
Runtime Versions :
Flash Player 9, AIR 1.1
Specifies the padding added to either side of the axis
when rendering data on the screen.
Set to 0 to map the first category to the
very beginning of the axis and the last category to the end.
Set to 0.5 to leave padding of half the width
of a category on the axis between the beginning of the axis
and the first category and between the last category
and the end of the axis.
This is useful for chart types that render beyond the bounds
of the category, such as columns and bars.
However, when used as the horizontalAxis in a LineChart or AreaChart,
it is reset to 0.
The default value is 0.5.
Implementation public function get padding():Number public function set padding(value:Number):void
ticksBetweenLabels
property
ticksBetweenLabels:Boolean
Language Version :
ActionScript 3.0
Product Version :
Flex 3
Runtime Versions :
Flash Player 9, AIR 1.1
Specifies the location of major tick marks on the axis,
relative to the category labels.
If true, tick marks (and any associated grid lines)
appear between the categories.
If false, tick marks appear in the middle of the category,
aligned with the label.
Implementation public function get ticksBetweenLabels():Boolean public function set ticksBetweenLabels(value:Boolean):void
Constructor Detail
CategoryAxis
()
Constructor
public function CategoryAxis()
Language Version :
ActionScript 3.0
Product Version :
Flex 3
Runtime Versions :
Flash Player 9, AIR 1.1
Constructor.
Method Detail
filterCache
()
method
public function filterCache(cache:Array, field:String, filteredField:String):void
Language Version :
ActionScript 3.0
Product Version :
Flex 3
Runtime Versions :
Flash Player 9, AIR 1.1
Filters a set of values of arbitrary type
to a set of numbers that can be mapped.
Parameters
cache:Array — An Array of objects where converted values
are read from and stored.
field:String — The field of the objects in the cache Array
containing the pre-filtered values.
filteredField:String — The field of the objects in the cache Array
where filtered values should be stored.
formatForScreen
()
method
public function formatForScreen(value:Object):String
Language Version :
ActionScript 3.0
Product Version :
Flex 3
Runtime Versions :
Flash Player 9, AIR 1.1
Formats values for display in DataTips.
Returns a user-readable string.
Determines the range to estimate what the axis labels should be.
The axis almost immediately calls the getLabels() method
to get the real values.
The axis uses the estimated values to adjust chart margins,
so any difference between the estimated labels and actual labels
(returned from the getLabels() method) results in scaling
the labels to fit.
An axis need only return the minimum and maximum labels
when returning an estimate.
If the label set is fairly static, without depending on the size
of the axis being rendered on screen, an axis can return the entire
label set from this function, and mark the estimate as accurate.
public function invertTransform(value:Number):Object
Language Version :
ActionScript 3.0
Product Version :
Flex 3
Runtime Versions :
Flash Player 9, AIR 1.1
Maps a position along the axis back to a numeric data value.
Parameters
value:Number — The bound of the axis.
This parameter should be between 0 and 1,
with 0 representing the minimum bound of the axis, and 1 the maximum.
Returns
Object — An object containing the transformed value.
mapCache
()
method
public function mapCache(cache:Array, field:String, convertedField:String, indexValues:Boolean = false):void
Language Version :
ActionScript 3.0
Product Version :
Flex 3
Runtime Versions :
Flash Player 9, AIR 1.1
Converts a set of values of arbitrary type
to a set of numbers that can be transformed into screen coordinates.
Parameters
cache:Array — An Array of objects where converted values
are read from and stored.
field:String — The field of the objects in the cache Array
containing the pre-converted values.
convertedField:String — The field of the objects in the cache Array
where converted values should be stored.
indexValues:Boolean (default = false) — This parameter is true if the values being mapped
are index values, and false if they are natural data values.
preferDropLabels
()
method
public function preferDropLabels():Boolean
Language Version :
ActionScript 3.0
Product Version :
Flex 3
Runtime Versions :
Flash Player 9, AIR 1.1
Determines how the axis handles overlapping labels.
Typically, numeric ranges return true,
while discrete value-based ranges do not.
You can can override this property by setting it directly on the axis.
Returns
Boolean — true if labels can be dropped without loss of data;
otherwise, false.
Invoked when an AxisRenderer is unable to cleanly render
the labels without overlap, and would like the Axis object
to reduce the set of labels.
The method is passed the two labels that are overlapping.
Parameters
intervalStart:AxisLabel — The start of the interval where labels overlap.
intervalEnd:AxisLabel — The end of the interval where labels overlap.
Returns
AxisLabelSet — A new label set that resolves the overlap by reducing
the number of labels.
transformCache
()
method
public function transformCache(cache:Array, field:String, convertedField:String):void
Language Version :
ActionScript 3.0
Product Version :
Flex 3
Runtime Versions :
Flash Player 9, AIR 1.1
Maps a set of values from data space to screen space.
Parameters
cache:Array — An Array of objects where mapped values
are read from and stored.
field:String — The field of the objects in the cache Array
containing the pre-mapped values.
convertedField:String — The field of the objects in the cache Array
where mapped values should be stored.
update
()
method
public function update():void
Language Version :
ActionScript 3.0
Product Version :
Flex 3
Runtime Versions :
Flash Player 9, AIR 1.1
Updates the chart.
This can be called multiple times per frame.
Examples
HLOCChartExample.mxml
<?xml version="1.0"?>
<!--
Licensed to the Apache Software Foundation (ASF) under one or more
contributor license agreements. See the NOTICE file distributed with
this work for additional information regarding copyright ownership.
The ASF licenses this file to You under the Apache License, Version 2.0
(the "License"); you may not use this file except in compliance with
the License. You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
-->
<!-- Simple example to demonstrate the HLOCChart control. -->
<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009"
xmlns:s="library://ns.adobe.com/flex/spark"
xmlns:mx="library://ns.adobe.com/flex/mx">
<fx:Script>
<![CDATA[
import mx.collections.ArrayCollection;
[Bindable]
private var stockDataAC:ArrayCollection = new ArrayCollection( [
{ Date: "25-Jul", Open: 40.55, High: 40.75, Low: 40.24, Close:40.31},
{ Date: "26-Jul", Open: 40.15, High: 40.78, Low: 39.97, Close:40.34},
{ Date: "27-Jul", Open: 40.38, High: 40.66, Low: 40, Close:40.63},
{ Date: "28-Jul", Open: 40.49, High: 40.99, Low: 40.3, Close:40.98},
{ Date: "29-Jul", Open: 40.13, High: 40.4, Low: 39.65, Close:39.95},
{ Date: "1-Aug", Open: 39.00, High: 39.50, Low: 38.7, Close:38.6},
{ Date: "2-Aug", Open: 38.68, High: 39.34, Low: 37.75, Close:38.84},
{ Date: "3-Aug", Open: 38.76, High: 38.76, Low: 38.03, Close:38.12},
{ Date: "4-Aug", Open: 37.98, High: 37.98, Low: 36.56, Close:36.69},
{ Date: "5-Aug", Open: 36.61, High: 37, Low: 36.48, Close:36.86} ]);
]]>
</fx:Script>
<fx:Declarations>
<!-- Define custom Stroke for the wick and ticks. -->
<mx:SolidColorStroke id="s1" color="0x000000" weight="5" joints="bevel" caps="square"/>
</fx:Declarations>
<mx:Panel title="HLOCChart Control Example" height="100%" width="100%">
<mx:HLOCChart id="hlocchart" height="100%" width="100%"
paddingRight="5" paddingLeft="5"
showDataTips="true" dataProvider="{stockDataAC}">
<mx:verticalAxis>
<mx:LinearAxis id="vaxis" baseAtZero="false" title="Price"/>
</mx:verticalAxis>
<mx:horizontalAxis>
<mx:CategoryAxis id="haxis" categoryField="Date" title="Date"/>
</mx:horizontalAxis>
<mx:horizontalAxisRenderers>
<mx:AxisRenderer axis="{haxis}" canDropLabels="true"/>
</mx:horizontalAxisRenderers>
<mx:series>
<mx:HLOCSeries
openField="Open"
highField="High"
lowField="Low"
closeField="Close"
stroke="{s1}"
openTickStroke="{s1}"
closeTickStroke="{s1}"
openTickLength="7"
closeTickLength="7"
/>
</mx:series>
</mx:HLOCChart>
</mx:Panel>
</s:Application>
AxisBase 
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