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DropDownListBaseAccImpl

Package | spark.accessibility
Class | public class DropDownListBaseAccImpl
Inheritance | DropDownListBaseAccImpl ListBaseAccImpl AccImpl flash.accessibility.AccessibilityImplementation
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.

Protected Properties
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| Property | Defined By
--- | --- | ---
|  | eventsToHandle : Array [read-only] All subclasses must override this function by returning an array of strings of the events to listen for. | AccImpl
|  | 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
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| Method | Defined By
--- | --- | ---
|  | DropDownListBaseAccImpl(master:UIComponent) Constructor. | DropDownListBaseAccImpl
|  | enableAccessibility():void [static] Enables accessibility in the DropDownListBase class. | DropDownListBaseAccImpl
|  | getFormName(component:UIComponent):String [static] Method for supporting Form Accessibility. | AccImpl
|  | isAncestorDisabled(component:UIComponent):Boolean [static] Returns true if an ancestor of the component has enabled set to false. | AccImpl

Protected Methods
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| Method | Defined By
--- | --- | ---
|  | eventHandler(event:Event):void Generic event handler. | AccImpl
|  | getName(childID:uint):String Returns the name of the accessible component. | AccImpl
|  | 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.

Wed Nov 15 2017, 09:50 AM +01:00