mx.accessibility.SliderAccImpl

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

Review Needed

The SliderAccImpl class, also called the Slider Accessibility Implementation class, enables communication between an HSlider or VSlider component and a screen reader. Screen readers are used to translate screen content into synthesized speech or braille for visually impaired users.

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

An HSlider or VSlider reports the role ROLE_SLIDER (0x33) to a screen reader.

An HSlider or VSlider reports the following states to a screen reader:

STATE_SYSTEM_NORMAL (0x00000000)
STATE_SYSTEM_UNAVAILABLE (0x00000001)
STATE_SYSTEM_FOCUSED (0x00000004)
STATE_SYSTEM_FOCUSABLE (0x00100000)
STATE_SYSTEM_SELECTABLE (0x00200000)
STATE_SYSTEM_SELECTED (0x00000002)

An HSlider or VSlider dispatches the following events to a screen reader:

EVENT_OBJECT_FOCUS (0x8005)
EVENT_OBJECT_VALUECHANGE (0x800E)
EVENT_OBJECT_SELECTION (0x8006)

	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.	SliderAccImpl
		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

Public Methods

Hide Inherited Public Methods

Show Inherited Public Methods

	Method		Defined by
		SliderAccImpl(master:UIComponent) Creates a new SliderAccImpl instance for the specified Slider component.	SliderAccImpl
		accDoDefaultAction(childID:uint):void IAccessible method that performs the default action associated with the component that this AccessibilityImplementation represents or of one of its child elements.	AccessibilityImplementation
		accLocation(childID:uint):* IAccessible method for returning a `DisplayObject` or `Rectangle` specifying the bounding box of a child element in the AccessibilityImplementation.	AccessibilityImplementation
		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.	SliderAccImpl
		get_accDefaultAction(childID:uint):String IAccessible method for returning the default action of the component that this AccessibilityImplementation represents or of one of its child elements.	AccessibilityImplementation
		get_accFocus():uint IAccessible method for returning the unsigned integer ID of the child element, if any, that has child focus within the component.	AccessibilityImplementation
		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.	SliderAccImpl
		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 Slider.	SliderAccImpl
		get_accValue(childID:uint):String IAccessible method for returning the value of the Slider, which should be the value of the current Slider thumb as a percentage of the difference between the maximum and minimum values.	SliderAccImpl
		getChildIDArray():Array Method to return an array containing the unsigned integer IDs of all the thumbs in the Slider control.	SliderAccImpl

	Method	Defined by
		eventHandler(event:Event):void Override the generic event handler.	SliderAccImpl
		getName(childID:uint):String Method for returning the name of the Slider which is spoken out by the screen reader.	SliderAccImpl
		getState(childID:uint):uint Utility method determines state of the accessible component.	SliderAccImpl

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

SliderAccImpl

()

constructor

public function SliderAccImpl(master:UIComponent)

Creates a new SliderAccImpl instance for the specified Slider 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 SliderAccImpl instance is making accessible.

Method detail

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.Slider component.

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

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_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 Slider component, ( childID == 0 ), reports the role ROLE_SLIDER (0x33).

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 Slider. States are predefined for all the components in MSAA. Values are assigned to each state. Depending upon the Slider being Selectable, Selected and Focused, 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 Slider being Selectable, Selected and Focused

get_accValue

()

method

public override function get_accValue(childID:uint):String

IAccessible method for returning the value of the Slider, which should be the value of the current Slider thumb as a percentage of the difference between the maximum and minimum values.

Note that, at present, screen readers have difficulty interpreting sliders with multiple thumbs and tend to only speak the value of the first thumb. This is in part because the MSAA specification only provides an accessibility object model for a slider control with a single thumb. It is recommended that you avoid using sliders with multiple thumbs in applications where screen reader accessibility is a requirement.

Parameters

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

Returns

String — Value String

getChildIDArray

()

method

public override function getChildIDArray():Array

Method to return an array containing the unsigned integer IDs of all the thumbs in the Slider control.

Returns

Array — An array of unsigned integer IDs, one for each the Slider control's thumbs.

getName

()

method

protected override function getName(childID:uint):String

Method for returning the name of the Slider which is spoken out by the screen reader.

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 Slider control.

getState

()

method

protected override function getState(childID:uint):uint

Utility method determines state of the accessible component.

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 Slider or Slider thumb being enabled, Focusable, and Focused

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