mx.accessibility.TabBarAccImpl

Package	mx.accessibility
Class	public class TabBarAccImpl
Inheritance	TabBarAccImpl AccImpl AccessibilityImplementation

Review Needed

The TabBarAccImpl class, also called the TabBar or TabNavigatior Accessibility Implementation class, enables communication between a TabBar/TabNavigatior component and a screen reader. Screen readers are used to translate screen content into synthesized speech or braille for visually impaired users.

The TabBarAccImpl class supports system roles, object-based events, and states.

A TabBar or TabNavigatior reports the role ROLE_SYSTEM_PAGETABLIST (0x3C) to a screen reader. Each of the Tab items returns the role ROLE_SYSTEM_PAGETAB (0x25).

A TabBar reports the following states to a screen reader:

STATE_SYSTEM_NORMAL (0x00000000)
STATE_SYSTEM_UNAVAILABLE (0x00000001)
STATE_SYSTEM_FOCUSED (0x00000004)
STATE_SYSTEM_FOCUSABLE (0x00100000)

Additionally, Tab items report the following states:

STATE_SYSTEM_SELECTED (0x00000002)
STATE_SYSTEM_SELECTABLE (0x00200000)
STATE_SYSTEM_FOCUSABLE (0x00100000)
STATE_SYSTEM_FOCUSED (0x00000004)

A TabBar dispatches the following events to a screen reader:

EVENT_OBJECT_FOCUS (0x8005)
EVENT_OBJECT_SELECTION (0x8006)

See also

mx.containers.TabNavigator;
mx.controls.TabBar
mx.controls.tabBarClasses.Tab
mx.accessibility.AccImpl
Microsoft Accessibility Developer Center Object Roles

	Property	Defined by
		errno : uint Errors are indicated out-of-band, rather than in return values.	AccessibilityImplementation
		stub : Boolean If a component is released without an ActionScript accessibility implementation, it is strongly suggested that a component accessibility stub be included.	AccessibilityImplementation

	Property	Defined by
		eventsToHandle : Array [read-only] All AccImpl subclasses must override this function by returning an array of strings of the events for which the class should listen from its master component.	TabBarAccImpl
		master : UIComponent A reference to the UIComponent instance that this AccImpl instance is making accessible.	AccImpl
		role : uint Accessibility Role of the component being made accessible.	AccImpl

	Method	Defined by
		TabBarAccImpl(master:UIComponent) Creates a new TabBarAccImpl instance for the specified TabBar component.	TabBarAccImpl
		accDoDefaultAction(childID:uint):void IAccessible method for performing the default action associated with a Tab, which is to select the Tab.	TabBarAccImpl
		accLocation(childID:uint):* IAccessible method for returning the bounding box of a Tab.	TabBarAccImpl
		accSelect(selFlag:uint, childID:uint):void IAccessible method for altering the selection in the component that this AccessibilityImplementation represents.	AccessibilityImplementation
		enableAccessibility():void [static] Method call for enabling accessibility for a component.	TabBarAccImpl
		get_accDefaultAction(childID:uint):String IAccessible method for returning the default action of a Tab, which is "Switch".	TabBarAccImpl
		get_accFocus():uint IAccessible method for returning the child focus of the TabBar.	TabBarAccImpl
		get_accName(childID:uint):String IAccessible method for returning the name for the component that this AccessibilityImplementation represents or for one of its child elements.	AccImpl
		get_accRole(childID:uint):uint IAccessible method for returning system role for the component.	TabBarAccImpl
		get_accSelection():Array IAccessible method for returning an array containing the IDs of all child elements that are selected.	AccessibilityImplementation
		get_accState(childID:uint):uint IAccessible method for returning the state of the Tabs.	TabBarAccImpl
		get_accValue(childID:uint):String IAccessible method for returning the runtime value of the component that this AccessibilityImplementation represents or of one of its child elements.	AccessibilityImplementation
		getChildIDArray():Array Method to return an array containing the unsigned integer IDs of all Tabs in the TabBarAccImpl.	TabBarAccImpl

	Method	Defined by
		eventHandler(event:Event):void Override the generic event handler.	TabBarAccImpl
		getName(childID:uint):String Method for returning the name of a TabBar's child Tab which is spoken out by the screen reader.	TabBarAccImpl
		getState(childID:uint):uint Returns the state of the accessible component.	AccImpl

Property detail

eventsToHandle

property

eventsToHandle:Array [read-only]

All AccImpl subclasses must override this function by returning an array of strings of the events for which the class should listen from its master component.

Implementation
protected function get eventsToHandle():Array

Constructor detail

TabBarAccImpl

()

constructor

public function TabBarAccImpl(master:UIComponent)

Creates a new TabBarAccImpl instance for the specified TabBar component.

Direct calls to the AccImpl subclass constructors are unneccessary. When a Flex project is compiled with Generate accessible SWF file set to true, the compiler instantiates the accessibility implementations for the components used in the project that have them by calling the the static enableAccessibility() method.

Parameters

master:UIComponent — The UIComponent instance that this TabBarAccImpl instance is making accessible.

Method detail

accDoDefaultAction

()

method

public override function accDoDefaultAction(childID:uint):void

IAccessible method for performing the default action associated with a Tab, which is to select the Tab.

Parameters

childID:uint — An unsigned integer corresponding to one of the component's child elements as defined by getChildIDArray().

accLocation

()

method

public override function accLocation(childID:uint):*

IAccessible method for returning the bounding box of a Tab.

Parameters

childID:uint — An unsigned integer corresponding to one of the component's child elements as defined by getChildIDArray().

Returns

* — A child Tab.

enableAccessibility

()

method

public static function enableAccessibility():void

Method call for enabling accessibility for a component. This method is required for the compiler to activate the accessibility classes for a component.

When a Flex project is compiled with the Generate accessible SWF file set to true, the Flex compiler automatically enables accessibility implementations for the components used in the project that have them.

Accessible component classes should include the [AccessibilityClass] meta tag to specify the appropriate AccImpl subclass or accessibility implementation and let the compiler know to call enableAccessibility().

Example
Following is an example showing how the [AccessibilityClass] meta tag specifies the appropriate AccImpl subclass or accessibility implementation for the mx.controls.TabBar component.

[AccessibilityClass(implementation="mx.accessibility.TabBarAccImpl")]

eventHandler

()

method

protected override function eventHandler(event:Event):void

Override the generic event handler. Each AccImpl subclass must implement this method to listen for events from its master component.

Parameters

event:Event — The event object.

get_accDefaultAction

()

method

public override function get_accDefaultAction(childID:uint):String

IAccessible method for returning the default action of a Tab, which is "Switch".

Parameters

childID:uint — An unsigned integer corresponding to one of the component's child elements as defined by getChildIDArray().

Returns

String — DefaultAction String

get_accFocus

()

method

public override function get_accFocus():uint

IAccessible method for returning the child focus of the TabBar.

Returns

uint — A child id corresponding to the focusedIndex of the TabBar component instance.

get_accRole

()

method

public override function get_accRole(childID:uint):uint

IAccessible method for returning system role for the component. System roles are predefined for all the components in MSAA.

A TabBar component, ( childID == 0 ), reports the role ROLE_SYSTEM_PAGETABLIST (0x3c). Items of a ListBase component ( childID >= 1 ) report the role ROLE_SYSTEM_PAGETAB (0x25).

Parameters

childID:uint — An unsigned integer corresponding to one of the component's child elements as defined by getChildIDArray().

Returns

uint — Role associated with the component.

get_accState

()

method

public override function get_accState(childID:uint):uint

IAccessible method for returning the state of the Tabs. States are predefined for all the components in MSAA. Values are assigned to each state. Depending upon the Tab being Selectable, Focusable, Focused, or Selected, a value is returned.

Parameters

childID:uint — An unsigned integer corresponding to one of the component's child elements as defined by getChildIDArray().

Returns

uint — State depending upon the Tab being Selectable, Focusable, Focused, or Selected

getChildIDArray

()

method

public override function getChildIDArray():Array

Method to return an array containing the unsigned integer IDs of all Tabs in the TabBarAccImpl.

Returns

Array — An array of unsigned integer IDs, one for each the TabBar's child Tabs.

getName

()

method

protected override function getName(childID:uint):String

Method for returning the name of a TabBar's child Tab which is spoken out by the screen reader.

This method should return the label of the child Tab corresponding to the childID parameter. The string "Active" is appended for the active Tab.

Parameters

childID:uint — An unsigned integer corresponding to one of the component's child elements as defined by getChildIDArray().

Returns

String — Name string corresponding to the child Tab.

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