Adobe® Flex® 4 Language Reference
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spark.accessibility 
DropDownListBaseAccImpl 
Packagespark.accessibility
Classpublic class DropDownListBaseAccImpl
InheritanceDropDownListBaseAccImpl Inheritance ListBaseAccImpl Inheritance AccImpl Inheritance AccessibilityImplementation Inheritance Object
Subclasses ComboBoxAccImpl

Language Version: ActionScript 3.0
Product Version: Flex 4
Runtime Versions: Flash Player 10, AIR 1.5

DropDownListAccImpl is the accessibility implementation class for spark.components.supportClasses.DropDownListBase.

Although ComboBox has its own accessibility implementation subclass, DropDownList simply uses the one for DropDownListBase. Therefore, the rest of this description refers to the commonly-used DropDownList component rather than the DropDownListBase base class.

When a Spark DropDownList is created, its accessibilityImplementation property is set to an instance of this class. The Flash Player then uses this class to allow MSAA clients such as screen readers to see and manipulate the DropDownList. See the mx.accessibility.AccImpl and flash.accessibility.AccessibilityImplementation classes for background information about accessibility implementation classes and MSAA.

Children

The MSAA children of a DropDownList are its list items. The number of children is the number of items in the dataProvider not just the number of visible renderers.

As described below, the accessibility of the list items is managed by the DropDownList; the accessibilityImplementation and accessibilityProperties of the item renderers are ignored by the Flash Player.

Role

The MSAA Role of a DropDownList is ROLE_SYSTEM_COMBOBOX.

The Role of each list item is ROLE_SYSTEM_LISTITEM.

Name

The MSAA Name of a DropDownList is, by default, an empty string. When wrapped in a FormItem element, the Name is the FormItem's label. To override this behavior, set the DropDownList's accessibilityName property.

The Name of each list item is determined by the DropDownList's itemToLabel() method.

When the Name of the DropDownList or one of its items changes, a DropDownList dispatches the MSAA event EVENT_OBJECT_NAMECHANGE with the proper childID for a list item or 0 for itself.

Description

The MSAA Description of a DropDownList is, by default, an empty string, but you can set the DropDownList's accessibilityDescription property.

The Description of each list item is the empty string.

State

The MSAA State of a DropDownList is a combination of:

  • STATE_SYSTEM_UNAVAILABLE (when enabled is false)
  • STATE_SYSTEM_FOCUSABLE (when enabled is true)
  • STATE_SYSTEM_FOCUSED (when enabled is true and the DropDownList has focus)
  • STATE_SYSTEM_EXPANDED (when it is open)
  • STATE_SYSTEM_COLLAPSED (when it is closed)

The State of a list item is a combination of:

  • STATE_SYSTEM_FOCUSABLE
  • STATE_SYSTEM_FOCUSED (when it has focus)
  • STATE_SYSTEM_SELECTABLE
  • STATE_SYSTEM_SELECTED (when it is selected)

When the State of the DropDownList or one of its list items changes, a DropDownList dispatches the MSAA event EVENT_OBJECT_STATECHANGE with the proper childID for the list item or 0 for itself.

Value

The MSAA Value of a DropDownList is the MSAA Name of the currently selected list item.

The Value of each list item is the empty string.

When the Value of the DropDownList changes, it dispatches the MSAA event EVENT_OBJECT_VALUECHANGE.

Location

The MSAA Location of a DropDownList or a list item is its bounding rectangle.

Default Action

A DropDownList does not have an MSAA DefaultAction

The DefaultAction of a list item is "Double click".

Focus

The DropDownList itself can receive focus, as well as its list items (either while the DropDownList is collapsed or expanded). The EVENT_OBJECT_FOCUS is fired when this happens.

Selection

The DropDownList allows a single item to be selected, in which case an EVENT_OBJECT_SELECTION event is fired.



Public Properties
 PropertyDefined By
 Inheritedconstructor : Object
A reference to the class object or constructor function for a given object instance.
Object
 Inheritederrno : uint
Indicates an error code.
AccessibilityImplementation
 Inheritedprototype : Object
[static] A reference to the prototype object of a class or function object.
Object
 Inheritedstub : Boolean
Used to create a component accessibility stub.
AccessibilityImplementation
Protected Properties
 PropertyDefined By
 InheritedeventsToHandle : Array
[read-only] All subclasses must override this function by returning an array of strings of the events to listen for.
AccImpl
 Inheritedmaster : UIComponent
A reference to the UIComponent instance that this AccImpl instance is making accessible.
AccImpl
 Inheritedrole : uint
Accessibility role of the component being made accessible.
AccImpl
Public Methods
 MethodDefined By
  
Constructor.
DropDownListBaseAccImpl
 Inherited
An IAccessible method that performs the default action associated with the component that this AccessibilityImplementation represents or of one of its child elements.
AccessibilityImplementation
 Inherited
accLocation(childID:uint):*
MSAA method for returning a DisplayObject or Rectangle specifying the bounding box of a child element in the AccessibilityImplementation.
AccessibilityImplementation
 Inherited
accSelect(operation:uint, childID:uint):void
IAccessible method for altering the selection in the component that this AccessibilityImplementation represents.
AccessibilityImplementation
  
[static] Enables accessibility in the DropDownListBase class.
DropDownListBaseAccImpl
 Inherited
MSAA method for returning the default action of the component that this AccessibilityImplementation represents or of one of its child elements.
AccessibilityImplementation
 Inherited
MSAA method for returning the unsigned integer ID of the child element, if any, that has child focus within the component.
AccessibilityImplementation
 Inherited
MSAA method for returning the name for the component that this AccessibilityImplementation represents or for one of its child elements.
AccessibilityImplementation
 Inherited
MSAA method for returning the system role for the component that this AccessibilityImplementation represents or for one of its child elements.
AccessibilityImplementation
 Inherited
MSAA method for returning an array containing the IDs of all child elements that are selected.
AccessibilityImplementation
 Inherited
IAccessible method for returning the current runtime state of the component that this AccessibilityImplementation represents or of one of its child elements.
AccessibilityImplementation
 Inherited
MSAA method for returning the runtime value of the component that this AccessibilityImplementation represents or of one of its child elements.
AccessibilityImplementation
 Inherited
Returns an array containing the unsigned integer IDs of all child elements in the AccessibilityImplementation.
AccessibilityImplementation
 Inherited
[static] Method for supporting Form Accessibility.
AccImpl
 Inherited
Indicates whether an object has a specified property defined.
Object
 Inherited
[static] Method for supporting state Accessibility.
AccImpl
 Inherited
Returns true or false to indicate whether a text object having a bounding box specified by a x, y, width, and height should be considered a label for the component that this AccessibilityImplementation represents.
AccessibilityImplementation
 Inherited
Indicates whether an instance of the Object class is in the prototype chain of the object specified as the parameter.
Object
 Inherited
Indicates whether the specified property exists and is enumerable.
Object
 Inherited
Sets the availability of a dynamic property for loop operations.
Object
 Inherited
Returns the string representation of this object, formatted according to locale-specific conventions.
Object
 Inherited
Returns the string representation of the specified object.
Object
 Inherited
Returns the primitive value of the specified object.
Object
Protected Methods
 MethodDefined By
 Inherited
Generic event handler.
AccImpl
 Inherited
Returns the name of the accessible component.
AccImpl
 Inherited
getState(childID:uint):uint
Utility method to determine state of the accessible component.
AccImpl
Constructor Detail

DropDownListBaseAccImpl

()Constructor
public function DropDownListBaseAccImpl(master:UIComponent)

Language Version: ActionScript 3.0
Product Version: Flex 4
Runtime Versions: Flash Player 10, AIR 1.5

Constructor.

Parameters
master:UIComponent — The UIComponent instance that this AccImpl instance is making accessible.
Method Detail

enableAccessibility

()method
public static function enableAccessibility():void

Language Version: ActionScript 3.0
Product Version: Flex 4
Runtime Versions: Flash Player 10, AIR 1.5

Enables accessibility in the DropDownListBase class.

This method is called by application startup code that is autogenerated by the MXML compiler. Afterwards, when instances of DropDownListBase are initialized, their accessibilityImplementation property will be set to an instance of this class.